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1/*
2 * linux/kernel/seccomp.c
3 *
4 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
5 *
6 * Copyright (C) 2012 Google, Inc.
7 * Will Drewry <wad@chromium.org>
8 *
9 * This defines a simple but solid secure-computing facility.
10 *
11 * Mode 1 uses a fixed list of allowed system calls.
12 * Mode 2 allows user-defined system call filters in the form
13 * of Berkeley Packet Filters/Linux Socket Filters.
14 */
15
16#include <linux/atomic.h>
17#include <linux/audit.h>
18#include <linux/compat.h>
19#include <linux/sched.h>
20#include <linux/seccomp.h>
21
22/* #define SECCOMP_DEBUG 1 */
23
24#ifdef CONFIG_SECCOMP_FILTER
25#include <asm/syscall.h>
26#include <linux/filter.h>
27#include <linux/ptrace.h>
28#include <linux/security.h>
29#include <linux/slab.h>
30#include <linux/tracehook.h>
31#include <linux/uaccess.h>
32
33/**
34 * struct seccomp_filter - container for seccomp BPF programs
35 *
36 * @usage: reference count to manage the object lifetime.
37 * get/put helpers should be used when accessing an instance
38 * outside of a lifetime-guarded section. In general, this
39 * is only needed for handling filters shared across tasks.
40 * @prev: points to a previously installed, or inherited, filter
41 * @len: the number of instructions in the program
42 * @insns: the BPF program instructions to evaluate
43 *
44 * seccomp_filter objects are organized in a tree linked via the @prev
45 * pointer. For any task, it appears to be a singly-linked list starting
46 * with current->seccomp.filter, the most recently attached or inherited filter.
47 * However, multiple filters may share a @prev node, by way of fork(), which
48 * results in a unidirectional tree existing in memory. This is similar to
49 * how namespaces work.
50 *
51 * seccomp_filter objects should never be modified after being attached
52 * to a task_struct (other than @usage).
53 */
54struct seccomp_filter {
55 atomic_t usage;
56 struct seccomp_filter *prev;
57 unsigned short len; /* Instruction count */
58 struct sock_filter_int insnsi[];
59};
60
61/* Limit any path through the tree to 256KB worth of instructions. */
62#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
63
64/*
65 * Endianness is explicitly ignored and left for BPF program authors to manage
66 * as per the specific architecture.
67 */
68static void populate_seccomp_data(struct seccomp_data *sd)
69{
70 struct task_struct *task = current;
71 struct pt_regs *regs = task_pt_regs(task);
72 unsigned long args[6];
73
74 sd->nr = syscall_get_nr(task, regs);
75 sd->arch = syscall_get_arch();
76 syscall_get_arguments(task, regs, 0, 6, args);
77 sd->args[0] = args[0];
78 sd->args[1] = args[1];
79 sd->args[2] = args[2];
80 sd->args[3] = args[3];
81 sd->args[4] = args[4];
82 sd->args[5] = args[5];
83 sd->instruction_pointer = KSTK_EIP(task);
84}
85
86/**
87 * seccomp_check_filter - verify seccomp filter code
88 * @filter: filter to verify
89 * @flen: length of filter
90 *
91 * Takes a previously checked filter (by sk_chk_filter) and
92 * redirects all filter code that loads struct sk_buff data
93 * and related data through seccomp_bpf_load. It also
94 * enforces length and alignment checking of those loads.
95 *
96 * Returns 0 if the rule set is legal or -EINVAL if not.
97 */
98static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
99{
100 int pc;
101 for (pc = 0; pc < flen; pc++) {
102 struct sock_filter *ftest = &filter[pc];
103 u16 code = ftest->code;
104 u32 k = ftest->k;
105
106 switch (code) {
107 case BPF_S_LD_W_ABS:
108 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
109 /* 32-bit aligned and not out of bounds. */
110 if (k >= sizeof(struct seccomp_data) || k & 3)
111 return -EINVAL;
112 continue;
113 case BPF_S_LD_W_LEN:
114 ftest->code = BPF_LD | BPF_IMM;
115 ftest->k = sizeof(struct seccomp_data);
116 continue;
117 case BPF_S_LDX_W_LEN:
118 ftest->code = BPF_LDX | BPF_IMM;
119 ftest->k = sizeof(struct seccomp_data);
120 continue;
121 /* Explicitly include allowed calls. */
122 case BPF_S_RET_K:
123 case BPF_S_RET_A:
124 case BPF_S_ALU_ADD_K:
125 case BPF_S_ALU_ADD_X:
126 case BPF_S_ALU_SUB_K:
127 case BPF_S_ALU_SUB_X:
128 case BPF_S_ALU_MUL_K:
129 case BPF_S_ALU_MUL_X:
130 case BPF_S_ALU_DIV_X:
131 case BPF_S_ALU_AND_K:
132 case BPF_S_ALU_AND_X:
133 case BPF_S_ALU_OR_K:
134 case BPF_S_ALU_OR_X:
135 case BPF_S_ALU_XOR_K:
136 case BPF_S_ALU_XOR_X:
137 case BPF_S_ALU_LSH_K:
138 case BPF_S_ALU_LSH_X:
139 case BPF_S_ALU_RSH_K:
140 case BPF_S_ALU_RSH_X:
141 case BPF_S_ALU_NEG:
142 case BPF_S_LD_IMM:
143 case BPF_S_LDX_IMM:
144 case BPF_S_MISC_TAX:
145 case BPF_S_MISC_TXA:
146 case BPF_S_ALU_DIV_K:
147 case BPF_S_LD_MEM:
148 case BPF_S_LDX_MEM:
149 case BPF_S_ST:
150 case BPF_S_STX:
151 case BPF_S_JMP_JA:
152 case BPF_S_JMP_JEQ_K:
153 case BPF_S_JMP_JEQ_X:
154 case BPF_S_JMP_JGE_K:
155 case BPF_S_JMP_JGE_X:
156 case BPF_S_JMP_JGT_K:
157 case BPF_S_JMP_JGT_X:
158 case BPF_S_JMP_JSET_K:
159 case BPF_S_JMP_JSET_X:
160 sk_decode_filter(ftest, ftest);
161 continue;
162 default:
163 return -EINVAL;
164 }
165 }
166 return 0;
167}
168
169/**
170 * seccomp_run_filters - evaluates all seccomp filters against @syscall
171 * @syscall: number of the current system call
172 *
173 * Returns valid seccomp BPF response codes.
174 */
175static u32 seccomp_run_filters(int syscall)
176{
177 struct seccomp_filter *f;
178 struct seccomp_data sd;
179 u32 ret = SECCOMP_RET_ALLOW;
180
181 /* Ensure unexpected behavior doesn't result in failing open. */
182 if (WARN_ON(current->seccomp.filter == NULL))
183 return SECCOMP_RET_KILL;
184
185 populate_seccomp_data(&sd);
186
187 /*
188 * All filters in the list are evaluated and the lowest BPF return
189 * value always takes priority (ignoring the DATA).
190 */
191 for (f = current->seccomp.filter; f; f = f->prev) {
192 u32 cur_ret = sk_run_filter_int_seccomp(&sd, f->insnsi);
193 if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
194 ret = cur_ret;
195 }
196 return ret;
197}
198
199/**
200 * seccomp_attach_filter: Attaches a seccomp filter to current.
201 * @fprog: BPF program to install
202 *
203 * Returns 0 on success or an errno on failure.
204 */
205static long seccomp_attach_filter(struct sock_fprog *fprog)
206{
207 struct seccomp_filter *filter;
208 unsigned long fp_size = fprog->len * sizeof(struct sock_filter);
209 unsigned long total_insns = fprog->len;
210 struct sock_filter *fp;
211 int new_len;
212 long ret;
213
214 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
215 return -EINVAL;
216
217 for (filter = current->seccomp.filter; filter; filter = filter->prev)
218 total_insns += filter->len + 4; /* include a 4 instr penalty */
219 if (total_insns > MAX_INSNS_PER_PATH)
220 return -ENOMEM;
221
222 /*
223 * Installing a seccomp filter requires that the task have
224 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
225 * This avoids scenarios where unprivileged tasks can affect the
226 * behavior of privileged children.
227 */
228 if (!current->no_new_privs &&
229 security_capable_noaudit(current_cred(), current_user_ns(),
230 CAP_SYS_ADMIN) != 0)
231 return -EACCES;
232
233 fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN);
234 if (!fp)
235 return -ENOMEM;
236
237 /* Copy the instructions from fprog. */
238 ret = -EFAULT;
239 if (copy_from_user(fp, fprog->filter, fp_size))
240 goto free_prog;
241
242 /* Check and rewrite the fprog via the skb checker */
243 ret = sk_chk_filter(fp, fprog->len);
244 if (ret)
245 goto free_prog;
246
247 /* Check and rewrite the fprog for seccomp use */
248 ret = seccomp_check_filter(fp, fprog->len);
249 if (ret)
250 goto free_prog;
251
252 /* Convert 'sock_filter' insns to 'sock_filter_int' insns */
253 ret = sk_convert_filter(fp, fprog->len, NULL, &new_len);
254 if (ret)
255 goto free_prog;
256
257 /* Allocate a new seccomp_filter */
258 ret = -ENOMEM;
259 filter = kzalloc(sizeof(struct seccomp_filter) +
260 sizeof(struct sock_filter_int) * new_len,
261 GFP_KERNEL|__GFP_NOWARN);
262 if (!filter)
263 goto free_prog;
264
265 ret = sk_convert_filter(fp, fprog->len, filter->insnsi, &new_len);
266 if (ret)
267 goto free_filter;
268 kfree(fp);
269
270 atomic_set(&filter->usage, 1);
271 filter->len = new_len;
272
273 /*
274 * If there is an existing filter, make it the prev and don't drop its
275 * task reference.
276 */
277 filter->prev = current->seccomp.filter;
278 current->seccomp.filter = filter;
279 return 0;
280
281free_filter:
282 kfree(filter);
283free_prog:
284 kfree(fp);
285 return ret;
286}
287
288/**
289 * seccomp_attach_user_filter - attaches a user-supplied sock_fprog
290 * @user_filter: pointer to the user data containing a sock_fprog.
291 *
292 * Returns 0 on success and non-zero otherwise.
293 */
294static long seccomp_attach_user_filter(char __user *user_filter)
295{
296 struct sock_fprog fprog;
297 long ret = -EFAULT;
298
299#ifdef CONFIG_COMPAT
300 if (is_compat_task()) {
301 struct compat_sock_fprog fprog32;
302 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
303 goto out;
304 fprog.len = fprog32.len;
305 fprog.filter = compat_ptr(fprog32.filter);
306 } else /* falls through to the if below. */
307#endif
308 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
309 goto out;
310 ret = seccomp_attach_filter(&fprog);
311out:
312 return ret;
313}
314
315/* get_seccomp_filter - increments the reference count of the filter on @tsk */
316void get_seccomp_filter(struct task_struct *tsk)
317{
318 struct seccomp_filter *orig = tsk->seccomp.filter;
319 if (!orig)
320 return;
321 /* Reference count is bounded by the number of total processes. */
322 atomic_inc(&orig->usage);
323}
324
325/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
326void put_seccomp_filter(struct task_struct *tsk)
327{
328 struct seccomp_filter *orig = tsk->seccomp.filter;
329 /* Clean up single-reference branches iteratively. */
330 while (orig && atomic_dec_and_test(&orig->usage)) {
331 struct seccomp_filter *freeme = orig;
332 orig = orig->prev;
333 kfree(freeme);
334 }
335}
336
337/**
338 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
339 * @syscall: syscall number to send to userland
340 * @reason: filter-supplied reason code to send to userland (via si_errno)
341 *
342 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
343 */
344static void seccomp_send_sigsys(int syscall, int reason)
345{
346 struct siginfo info;
347 memset(&info, 0, sizeof(info));
348 info.si_signo = SIGSYS;
349 info.si_code = SYS_SECCOMP;
350 info.si_call_addr = (void __user *)KSTK_EIP(current);
351 info.si_errno = reason;
352 info.si_arch = syscall_get_arch();
353 info.si_syscall = syscall;
354 force_sig_info(SIGSYS, &info, current);
355}
356#endif /* CONFIG_SECCOMP_FILTER */
357
358/*
359 * Secure computing mode 1 allows only read/write/exit/sigreturn.
360 * To be fully secure this must be combined with rlimit
361 * to limit the stack allocations too.
362 */
363static int mode1_syscalls[] = {
364 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
365 0, /* null terminated */
366};
367
368#ifdef CONFIG_COMPAT
369static int mode1_syscalls_32[] = {
370 __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
371 0, /* null terminated */
372};
373#endif
374
375int __secure_computing(int this_syscall)
376{
377 int mode = current->seccomp.mode;
378 int exit_sig = 0;
379 int *syscall;
380 u32 ret;
381
382 switch (mode) {
383 case SECCOMP_MODE_STRICT:
384 syscall = mode1_syscalls;
385#ifdef CONFIG_COMPAT
386 if (is_compat_task())
387 syscall = mode1_syscalls_32;
388#endif
389 do {
390 if (*syscall == this_syscall)
391 return 0;
392 } while (*++syscall);
393 exit_sig = SIGKILL;
394 ret = SECCOMP_RET_KILL;
395 break;
396#ifdef CONFIG_SECCOMP_FILTER
397 case SECCOMP_MODE_FILTER: {
398 int data;
399 struct pt_regs *regs = task_pt_regs(current);
400 ret = seccomp_run_filters(this_syscall);
401 data = ret & SECCOMP_RET_DATA;
402 ret &= SECCOMP_RET_ACTION;
403 switch (ret) {
404 case SECCOMP_RET_ERRNO:
405 /* Set the low-order 16-bits as a errno. */
406 syscall_set_return_value(current, regs,
407 -data, 0);
408 goto skip;
409 case SECCOMP_RET_TRAP:
410 /* Show the handler the original registers. */
411 syscall_rollback(current, regs);
412 /* Let the filter pass back 16 bits of data. */
413 seccomp_send_sigsys(this_syscall, data);
414 goto skip;
415 case SECCOMP_RET_TRACE:
416 /* Skip these calls if there is no tracer. */
417 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
418 syscall_set_return_value(current, regs,
419 -ENOSYS, 0);
420 goto skip;
421 }
422 /* Allow the BPF to provide the event message */
423 ptrace_event(PTRACE_EVENT_SECCOMP, data);
424 /*
425 * The delivery of a fatal signal during event
426 * notification may silently skip tracer notification.
427 * Terminating the task now avoids executing a system
428 * call that may not be intended.
429 */
430 if (fatal_signal_pending(current))
431 break;
432 if (syscall_get_nr(current, regs) < 0)
433 goto skip; /* Explicit request to skip. */
434
435 return 0;
436 case SECCOMP_RET_ALLOW:
437 return 0;
438 case SECCOMP_RET_KILL:
439 default:
440 break;
441 }
442 exit_sig = SIGSYS;
443 break;
444 }
445#endif
446 default:
447 BUG();
448 }
449
450#ifdef SECCOMP_DEBUG
451 dump_stack();
452#endif
453 audit_seccomp(this_syscall, exit_sig, ret);
454 do_exit(exit_sig);
455#ifdef CONFIG_SECCOMP_FILTER
456skip:
457 audit_seccomp(this_syscall, exit_sig, ret);
458#endif
459 return -1;
460}
461
462long prctl_get_seccomp(void)
463{
464 return current->seccomp.mode;
465}
466
467/**
468 * prctl_set_seccomp: configures current->seccomp.mode
469 * @seccomp_mode: requested mode to use
470 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
471 *
472 * This function may be called repeatedly with a @seccomp_mode of
473 * SECCOMP_MODE_FILTER to install additional filters. Every filter
474 * successfully installed will be evaluated (in reverse order) for each system
475 * call the task makes.
476 *
477 * Once current->seccomp.mode is non-zero, it may not be changed.
478 *
479 * Returns 0 on success or -EINVAL on failure.
480 */
481long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
482{
483 long ret = -EINVAL;
484
485 if (current->seccomp.mode &&
486 current->seccomp.mode != seccomp_mode)
487 goto out;
488
489 switch (seccomp_mode) {
490 case SECCOMP_MODE_STRICT:
491 ret = 0;
492#ifdef TIF_NOTSC
493 disable_TSC();
494#endif
495 break;
496#ifdef CONFIG_SECCOMP_FILTER
497 case SECCOMP_MODE_FILTER:
498 ret = seccomp_attach_user_filter(filter);
499 if (ret)
500 goto out;
501 break;
502#endif
503 default:
504 goto out;
505 }
506
507 current->seccomp.mode = seccomp_mode;
508 set_thread_flag(TIF_SECCOMP);
509out:
510 return ret;
511}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/kernel/seccomp.c
4 *
5 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 *
7 * Copyright (C) 2012 Google, Inc.
8 * Will Drewry <wad@chromium.org>
9 *
10 * This defines a simple but solid secure-computing facility.
11 *
12 * Mode 1 uses a fixed list of allowed system calls.
13 * Mode 2 allows user-defined system call filters in the form
14 * of Berkeley Packet Filters/Linux Socket Filters.
15 */
16#define pr_fmt(fmt) "seccomp: " fmt
17
18#include <linux/refcount.h>
19#include <linux/audit.h>
20#include <linux/compat.h>
21#include <linux/coredump.h>
22#include <linux/kmemleak.h>
23#include <linux/nospec.h>
24#include <linux/prctl.h>
25#include <linux/sched.h>
26#include <linux/sched/task_stack.h>
27#include <linux/seccomp.h>
28#include <linux/slab.h>
29#include <linux/syscalls.h>
30#include <linux/sysctl.h>
31
32/* Not exposed in headers: strictly internal use only. */
33#define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1)
34
35#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
36#include <asm/syscall.h>
37#endif
38
39#ifdef CONFIG_SECCOMP_FILTER
40#include <linux/file.h>
41#include <linux/filter.h>
42#include <linux/pid.h>
43#include <linux/ptrace.h>
44#include <linux/capability.h>
45#include <linux/uaccess.h>
46#include <linux/anon_inodes.h>
47#include <linux/lockdep.h>
48
49/*
50 * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
51 * wrong direction flag in the ioctl number. This is the broken one,
52 * which the kernel needs to keep supporting until all userspaces stop
53 * using the wrong command number.
54 */
55#define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
56
57enum notify_state {
58 SECCOMP_NOTIFY_INIT,
59 SECCOMP_NOTIFY_SENT,
60 SECCOMP_NOTIFY_REPLIED,
61};
62
63struct seccomp_knotif {
64 /* The struct pid of the task whose filter triggered the notification */
65 struct task_struct *task;
66
67 /* The "cookie" for this request; this is unique for this filter. */
68 u64 id;
69
70 /*
71 * The seccomp data. This pointer is valid the entire time this
72 * notification is active, since it comes from __seccomp_filter which
73 * eclipses the entire lifecycle here.
74 */
75 const struct seccomp_data *data;
76
77 /*
78 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
79 * struct seccomp_knotif is created and starts out in INIT. Once the
80 * handler reads the notification off of an FD, it transitions to SENT.
81 * If a signal is received the state transitions back to INIT and
82 * another message is sent. When the userspace handler replies, state
83 * transitions to REPLIED.
84 */
85 enum notify_state state;
86
87 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
88 int error;
89 long val;
90 u32 flags;
91
92 /*
93 * Signals when this has changed states, such as the listener
94 * dying, a new seccomp addfd message, or changing to REPLIED
95 */
96 struct completion ready;
97
98 struct list_head list;
99
100 /* outstanding addfd requests */
101 struct list_head addfd;
102};
103
104/**
105 * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
106 *
107 * @file: A reference to the file to install in the other task
108 * @fd: The fd number to install it at. If the fd number is -1, it means the
109 * installing process should allocate the fd as normal.
110 * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
111 * is allowed.
112 * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
113 * @setfd: whether or not SECCOMP_ADDFD_FLAG_SETFD was set during notify_addfd
114 * @ret: The return value of the installing process. It is set to the fd num
115 * upon success (>= 0).
116 * @completion: Indicates that the installing process has completed fd
117 * installation, or gone away (either due to successful
118 * reply, or signal)
119 * @list: list_head for chaining seccomp_kaddfd together.
120 *
121 */
122struct seccomp_kaddfd {
123 struct file *file;
124 int fd;
125 unsigned int flags;
126 __u32 ioctl_flags;
127
128 union {
129 bool setfd;
130 /* To only be set on reply */
131 int ret;
132 };
133 struct completion completion;
134 struct list_head list;
135};
136
137/**
138 * struct notification - container for seccomp userspace notifications. Since
139 * most seccomp filters will not have notification listeners attached and this
140 * structure is fairly large, we store the notification-specific stuff in a
141 * separate structure.
142 *
143 * @requests: A semaphore that users of this notification can wait on for
144 * changes. Actual reads and writes are still controlled with
145 * filter->notify_lock.
146 * @flags: A set of SECCOMP_USER_NOTIF_FD_* flags.
147 * @next_id: The id of the next request.
148 * @notifications: A list of struct seccomp_knotif elements.
149 */
150
151struct notification {
152 atomic_t requests;
153 u32 flags;
154 u64 next_id;
155 struct list_head notifications;
156};
157
158#ifdef SECCOMP_ARCH_NATIVE
159/**
160 * struct action_cache - per-filter cache of seccomp actions per
161 * arch/syscall pair
162 *
163 * @allow_native: A bitmap where each bit represents whether the
164 * filter will always allow the syscall, for the
165 * native architecture.
166 * @allow_compat: A bitmap where each bit represents whether the
167 * filter will always allow the syscall, for the
168 * compat architecture.
169 */
170struct action_cache {
171 DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
172#ifdef SECCOMP_ARCH_COMPAT
173 DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
174#endif
175};
176#else
177struct action_cache { };
178
179static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
180 const struct seccomp_data *sd)
181{
182 return false;
183}
184
185static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
186{
187}
188#endif /* SECCOMP_ARCH_NATIVE */
189
190/**
191 * struct seccomp_filter - container for seccomp BPF programs
192 *
193 * @refs: Reference count to manage the object lifetime.
194 * A filter's reference count is incremented for each directly
195 * attached task, once for the dependent filter, and if
196 * requested for the user notifier. When @refs reaches zero,
197 * the filter can be freed.
198 * @users: A filter's @users count is incremented for each directly
199 * attached task (filter installation, fork(), thread_sync),
200 * and once for the dependent filter (tracked in filter->prev).
201 * When it reaches zero it indicates that no direct or indirect
202 * users of that filter exist. No new tasks can get associated with
203 * this filter after reaching 0. The @users count is always smaller
204 * or equal to @refs. Hence, reaching 0 for @users does not mean
205 * the filter can be freed.
206 * @cache: cache of arch/syscall mappings to actions
207 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
208 * @wait_killable_recv: Put notifying process in killable state once the
209 * notification is received by the userspace listener.
210 * @prev: points to a previously installed, or inherited, filter
211 * @prog: the BPF program to evaluate
212 * @notif: the struct that holds all notification related information
213 * @notify_lock: A lock for all notification-related accesses.
214 * @wqh: A wait queue for poll if a notifier is in use.
215 *
216 * seccomp_filter objects are organized in a tree linked via the @prev
217 * pointer. For any task, it appears to be a singly-linked list starting
218 * with current->seccomp.filter, the most recently attached or inherited filter.
219 * However, multiple filters may share a @prev node, by way of fork(), which
220 * results in a unidirectional tree existing in memory. This is similar to
221 * how namespaces work.
222 *
223 * seccomp_filter objects should never be modified after being attached
224 * to a task_struct (other than @refs).
225 */
226struct seccomp_filter {
227 refcount_t refs;
228 refcount_t users;
229 bool log;
230 bool wait_killable_recv;
231 struct action_cache cache;
232 struct seccomp_filter *prev;
233 struct bpf_prog *prog;
234 struct notification *notif;
235 struct mutex notify_lock;
236 wait_queue_head_t wqh;
237};
238
239/* Limit any path through the tree to 256KB worth of instructions. */
240#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
241
242/*
243 * Endianness is explicitly ignored and left for BPF program authors to manage
244 * as per the specific architecture.
245 */
246static void populate_seccomp_data(struct seccomp_data *sd)
247{
248 /*
249 * Instead of using current_pt_reg(), we're already doing the work
250 * to safely fetch "current", so just use "task" everywhere below.
251 */
252 struct task_struct *task = current;
253 struct pt_regs *regs = task_pt_regs(task);
254 unsigned long args[6];
255
256 sd->nr = syscall_get_nr(task, regs);
257 sd->arch = syscall_get_arch(task);
258 syscall_get_arguments(task, regs, args);
259 sd->args[0] = args[0];
260 sd->args[1] = args[1];
261 sd->args[2] = args[2];
262 sd->args[3] = args[3];
263 sd->args[4] = args[4];
264 sd->args[5] = args[5];
265 sd->instruction_pointer = KSTK_EIP(task);
266}
267
268/**
269 * seccomp_check_filter - verify seccomp filter code
270 * @filter: filter to verify
271 * @flen: length of filter
272 *
273 * Takes a previously checked filter (by bpf_check_classic) and
274 * redirects all filter code that loads struct sk_buff data
275 * and related data through seccomp_bpf_load. It also
276 * enforces length and alignment checking of those loads.
277 *
278 * Returns 0 if the rule set is legal or -EINVAL if not.
279 */
280static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
281{
282 int pc;
283 for (pc = 0; pc < flen; pc++) {
284 struct sock_filter *ftest = &filter[pc];
285 u16 code = ftest->code;
286 u32 k = ftest->k;
287
288 switch (code) {
289 case BPF_LD | BPF_W | BPF_ABS:
290 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
291 /* 32-bit aligned and not out of bounds. */
292 if (k >= sizeof(struct seccomp_data) || k & 3)
293 return -EINVAL;
294 continue;
295 case BPF_LD | BPF_W | BPF_LEN:
296 ftest->code = BPF_LD | BPF_IMM;
297 ftest->k = sizeof(struct seccomp_data);
298 continue;
299 case BPF_LDX | BPF_W | BPF_LEN:
300 ftest->code = BPF_LDX | BPF_IMM;
301 ftest->k = sizeof(struct seccomp_data);
302 continue;
303 /* Explicitly include allowed calls. */
304 case BPF_RET | BPF_K:
305 case BPF_RET | BPF_A:
306 case BPF_ALU | BPF_ADD | BPF_K:
307 case BPF_ALU | BPF_ADD | BPF_X:
308 case BPF_ALU | BPF_SUB | BPF_K:
309 case BPF_ALU | BPF_SUB | BPF_X:
310 case BPF_ALU | BPF_MUL | BPF_K:
311 case BPF_ALU | BPF_MUL | BPF_X:
312 case BPF_ALU | BPF_DIV | BPF_K:
313 case BPF_ALU | BPF_DIV | BPF_X:
314 case BPF_ALU | BPF_AND | BPF_K:
315 case BPF_ALU | BPF_AND | BPF_X:
316 case BPF_ALU | BPF_OR | BPF_K:
317 case BPF_ALU | BPF_OR | BPF_X:
318 case BPF_ALU | BPF_XOR | BPF_K:
319 case BPF_ALU | BPF_XOR | BPF_X:
320 case BPF_ALU | BPF_LSH | BPF_K:
321 case BPF_ALU | BPF_LSH | BPF_X:
322 case BPF_ALU | BPF_RSH | BPF_K:
323 case BPF_ALU | BPF_RSH | BPF_X:
324 case BPF_ALU | BPF_NEG:
325 case BPF_LD | BPF_IMM:
326 case BPF_LDX | BPF_IMM:
327 case BPF_MISC | BPF_TAX:
328 case BPF_MISC | BPF_TXA:
329 case BPF_LD | BPF_MEM:
330 case BPF_LDX | BPF_MEM:
331 case BPF_ST:
332 case BPF_STX:
333 case BPF_JMP | BPF_JA:
334 case BPF_JMP | BPF_JEQ | BPF_K:
335 case BPF_JMP | BPF_JEQ | BPF_X:
336 case BPF_JMP | BPF_JGE | BPF_K:
337 case BPF_JMP | BPF_JGE | BPF_X:
338 case BPF_JMP | BPF_JGT | BPF_K:
339 case BPF_JMP | BPF_JGT | BPF_X:
340 case BPF_JMP | BPF_JSET | BPF_K:
341 case BPF_JMP | BPF_JSET | BPF_X:
342 continue;
343 default:
344 return -EINVAL;
345 }
346 }
347 return 0;
348}
349
350#ifdef SECCOMP_ARCH_NATIVE
351static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
352 size_t bitmap_size,
353 int syscall_nr)
354{
355 if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
356 return false;
357 syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
358
359 return test_bit(syscall_nr, bitmap);
360}
361
362/**
363 * seccomp_cache_check_allow - lookup seccomp cache
364 * @sfilter: The seccomp filter
365 * @sd: The seccomp data to lookup the cache with
366 *
367 * Returns true if the seccomp_data is cached and allowed.
368 */
369static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
370 const struct seccomp_data *sd)
371{
372 int syscall_nr = sd->nr;
373 const struct action_cache *cache = &sfilter->cache;
374
375#ifndef SECCOMP_ARCH_COMPAT
376 /* A native-only architecture doesn't need to check sd->arch. */
377 return seccomp_cache_check_allow_bitmap(cache->allow_native,
378 SECCOMP_ARCH_NATIVE_NR,
379 syscall_nr);
380#else
381 if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
382 return seccomp_cache_check_allow_bitmap(cache->allow_native,
383 SECCOMP_ARCH_NATIVE_NR,
384 syscall_nr);
385 if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
386 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
387 SECCOMP_ARCH_COMPAT_NR,
388 syscall_nr);
389#endif /* SECCOMP_ARCH_COMPAT */
390
391 WARN_ON_ONCE(true);
392 return false;
393}
394#endif /* SECCOMP_ARCH_NATIVE */
395
396#define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
397/**
398 * seccomp_run_filters - evaluates all seccomp filters against @sd
399 * @sd: optional seccomp data to be passed to filters
400 * @match: stores struct seccomp_filter that resulted in the return value,
401 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
402 * be unchanged.
403 *
404 * Returns valid seccomp BPF response codes.
405 */
406static u32 seccomp_run_filters(const struct seccomp_data *sd,
407 struct seccomp_filter **match)
408{
409 u32 ret = SECCOMP_RET_ALLOW;
410 /* Make sure cross-thread synced filter points somewhere sane. */
411 struct seccomp_filter *f =
412 READ_ONCE(current->seccomp.filter);
413
414 /* Ensure unexpected behavior doesn't result in failing open. */
415 if (WARN_ON(f == NULL))
416 return SECCOMP_RET_KILL_PROCESS;
417
418 if (seccomp_cache_check_allow(f, sd))
419 return SECCOMP_RET_ALLOW;
420
421 /*
422 * All filters in the list are evaluated and the lowest BPF return
423 * value always takes priority (ignoring the DATA).
424 */
425 for (; f; f = f->prev) {
426 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
427
428 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
429 ret = cur_ret;
430 *match = f;
431 }
432 }
433 return ret;
434}
435#endif /* CONFIG_SECCOMP_FILTER */
436
437static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
438{
439 assert_spin_locked(¤t->sighand->siglock);
440
441 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
442 return false;
443
444 return true;
445}
446
447void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
448
449static inline void seccomp_assign_mode(struct task_struct *task,
450 unsigned long seccomp_mode,
451 unsigned long flags)
452{
453 assert_spin_locked(&task->sighand->siglock);
454
455 task->seccomp.mode = seccomp_mode;
456 /*
457 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
458 * filter) is set.
459 */
460 smp_mb__before_atomic();
461 /* Assume default seccomp processes want spec flaw mitigation. */
462 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
463 arch_seccomp_spec_mitigate(task);
464 set_task_syscall_work(task, SECCOMP);
465}
466
467#ifdef CONFIG_SECCOMP_FILTER
468/* Returns 1 if the parent is an ancestor of the child. */
469static int is_ancestor(struct seccomp_filter *parent,
470 struct seccomp_filter *child)
471{
472 /* NULL is the root ancestor. */
473 if (parent == NULL)
474 return 1;
475 for (; child; child = child->prev)
476 if (child == parent)
477 return 1;
478 return 0;
479}
480
481/**
482 * seccomp_can_sync_threads: checks if all threads can be synchronized
483 *
484 * Expects sighand and cred_guard_mutex locks to be held.
485 *
486 * Returns 0 on success, -ve on error, or the pid of a thread which was
487 * either not in the correct seccomp mode or did not have an ancestral
488 * seccomp filter.
489 */
490static inline pid_t seccomp_can_sync_threads(void)
491{
492 struct task_struct *thread, *caller;
493
494 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
495 assert_spin_locked(¤t->sighand->siglock);
496
497 /* Validate all threads being eligible for synchronization. */
498 caller = current;
499 for_each_thread(caller, thread) {
500 pid_t failed;
501
502 /* Skip current, since it is initiating the sync. */
503 if (thread == caller)
504 continue;
505 /* Skip exited threads. */
506 if (thread->flags & PF_EXITING)
507 continue;
508
509 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
510 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
511 is_ancestor(thread->seccomp.filter,
512 caller->seccomp.filter)))
513 continue;
514
515 /* Return the first thread that cannot be synchronized. */
516 failed = task_pid_vnr(thread);
517 /* If the pid cannot be resolved, then return -ESRCH */
518 if (WARN_ON(failed == 0))
519 failed = -ESRCH;
520 return failed;
521 }
522
523 return 0;
524}
525
526static inline void seccomp_filter_free(struct seccomp_filter *filter)
527{
528 if (filter) {
529 bpf_prog_destroy(filter->prog);
530 kfree(filter);
531 }
532}
533
534static void __seccomp_filter_orphan(struct seccomp_filter *orig)
535{
536 while (orig && refcount_dec_and_test(&orig->users)) {
537 if (waitqueue_active(&orig->wqh))
538 wake_up_poll(&orig->wqh, EPOLLHUP);
539 orig = orig->prev;
540 }
541}
542
543static void __put_seccomp_filter(struct seccomp_filter *orig)
544{
545 /* Clean up single-reference branches iteratively. */
546 while (orig && refcount_dec_and_test(&orig->refs)) {
547 struct seccomp_filter *freeme = orig;
548 orig = orig->prev;
549 seccomp_filter_free(freeme);
550 }
551}
552
553static void __seccomp_filter_release(struct seccomp_filter *orig)
554{
555 /* Notify about any unused filters in the task's former filter tree. */
556 __seccomp_filter_orphan(orig);
557 /* Finally drop all references to the task's former tree. */
558 __put_seccomp_filter(orig);
559}
560
561/**
562 * seccomp_filter_release - Detach the task from its filter tree,
563 * drop its reference count, and notify
564 * about unused filters
565 *
566 * @tsk: task the filter should be released from.
567 *
568 * This function should only be called when the task is exiting as
569 * it detaches it from its filter tree. PF_EXITING has to be set
570 * for the task.
571 */
572void seccomp_filter_release(struct task_struct *tsk)
573{
574 struct seccomp_filter *orig;
575
576 if (WARN_ON((tsk->flags & PF_EXITING) == 0))
577 return;
578
579 spin_lock_irq(&tsk->sighand->siglock);
580 orig = tsk->seccomp.filter;
581 /* Detach task from its filter tree. */
582 tsk->seccomp.filter = NULL;
583 spin_unlock_irq(&tsk->sighand->siglock);
584 __seccomp_filter_release(orig);
585}
586
587/**
588 * seccomp_sync_threads: sets all threads to use current's filter
589 *
590 * @flags: SECCOMP_FILTER_FLAG_* flags to set during sync.
591 *
592 * Expects sighand and cred_guard_mutex locks to be held, and for
593 * seccomp_can_sync_threads() to have returned success already
594 * without dropping the locks.
595 *
596 */
597static inline void seccomp_sync_threads(unsigned long flags)
598{
599 struct task_struct *thread, *caller;
600
601 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
602 assert_spin_locked(¤t->sighand->siglock);
603
604 /* Synchronize all threads. */
605 caller = current;
606 for_each_thread(caller, thread) {
607 /* Skip current, since it needs no changes. */
608 if (thread == caller)
609 continue;
610
611 /*
612 * Skip exited threads. seccomp_filter_release could have
613 * been already called for this task.
614 */
615 if (thread->flags & PF_EXITING)
616 continue;
617
618 /* Get a task reference for the new leaf node. */
619 get_seccomp_filter(caller);
620
621 /*
622 * Drop the task reference to the shared ancestor since
623 * current's path will hold a reference. (This also
624 * allows a put before the assignment.)
625 */
626 __seccomp_filter_release(thread->seccomp.filter);
627
628 /* Make our new filter tree visible. */
629 smp_store_release(&thread->seccomp.filter,
630 caller->seccomp.filter);
631 atomic_set(&thread->seccomp.filter_count,
632 atomic_read(&caller->seccomp.filter_count));
633
634 /*
635 * Don't let an unprivileged task work around
636 * the no_new_privs restriction by creating
637 * a thread that sets it up, enters seccomp,
638 * then dies.
639 */
640 if (task_no_new_privs(caller))
641 task_set_no_new_privs(thread);
642
643 /*
644 * Opt the other thread into seccomp if needed.
645 * As threads are considered to be trust-realm
646 * equivalent (see ptrace_may_access), it is safe to
647 * allow one thread to transition the other.
648 */
649 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
650 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
651 flags);
652 }
653}
654
655/**
656 * seccomp_prepare_filter: Prepares a seccomp filter for use.
657 * @fprog: BPF program to install
658 *
659 * Returns filter on success or an ERR_PTR on failure.
660 */
661static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
662{
663 struct seccomp_filter *sfilter;
664 int ret;
665 const bool save_orig =
666#if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
667 true;
668#else
669 false;
670#endif
671
672 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
673 return ERR_PTR(-EINVAL);
674
675 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
676
677 /*
678 * Installing a seccomp filter requires that the task has
679 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
680 * This avoids scenarios where unprivileged tasks can affect the
681 * behavior of privileged children.
682 */
683 if (!task_no_new_privs(current) &&
684 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
685 return ERR_PTR(-EACCES);
686
687 /* Allocate a new seccomp_filter */
688 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
689 if (!sfilter)
690 return ERR_PTR(-ENOMEM);
691
692 mutex_init(&sfilter->notify_lock);
693 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
694 seccomp_check_filter, save_orig);
695 if (ret < 0) {
696 kfree(sfilter);
697 return ERR_PTR(ret);
698 }
699
700 refcount_set(&sfilter->refs, 1);
701 refcount_set(&sfilter->users, 1);
702 init_waitqueue_head(&sfilter->wqh);
703
704 return sfilter;
705}
706
707/**
708 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
709 * @user_filter: pointer to the user data containing a sock_fprog.
710 *
711 * Returns 0 on success and non-zero otherwise.
712 */
713static struct seccomp_filter *
714seccomp_prepare_user_filter(const char __user *user_filter)
715{
716 struct sock_fprog fprog;
717 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
718
719#ifdef CONFIG_COMPAT
720 if (in_compat_syscall()) {
721 struct compat_sock_fprog fprog32;
722 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
723 goto out;
724 fprog.len = fprog32.len;
725 fprog.filter = compat_ptr(fprog32.filter);
726 } else /* falls through to the if below. */
727#endif
728 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
729 goto out;
730 filter = seccomp_prepare_filter(&fprog);
731out:
732 return filter;
733}
734
735#ifdef SECCOMP_ARCH_NATIVE
736/**
737 * seccomp_is_const_allow - check if filter is constant allow with given data
738 * @fprog: The BPF programs
739 * @sd: The seccomp data to check against, only syscall number and arch
740 * number are considered constant.
741 */
742static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
743 struct seccomp_data *sd)
744{
745 unsigned int reg_value = 0;
746 unsigned int pc;
747 bool op_res;
748
749 if (WARN_ON_ONCE(!fprog))
750 return false;
751
752 /* Our single exception to filtering. */
753#ifdef __NR_uretprobe
754#ifdef SECCOMP_ARCH_COMPAT
755 if (sd->arch == SECCOMP_ARCH_NATIVE)
756#endif
757 if (sd->nr == __NR_uretprobe)
758 return true;
759#endif
760
761 for (pc = 0; pc < fprog->len; pc++) {
762 struct sock_filter *insn = &fprog->filter[pc];
763 u16 code = insn->code;
764 u32 k = insn->k;
765
766 switch (code) {
767 case BPF_LD | BPF_W | BPF_ABS:
768 switch (k) {
769 case offsetof(struct seccomp_data, nr):
770 reg_value = sd->nr;
771 break;
772 case offsetof(struct seccomp_data, arch):
773 reg_value = sd->arch;
774 break;
775 default:
776 /* can't optimize (non-constant value load) */
777 return false;
778 }
779 break;
780 case BPF_RET | BPF_K:
781 /* reached return with constant values only, check allow */
782 return k == SECCOMP_RET_ALLOW;
783 case BPF_JMP | BPF_JA:
784 pc += insn->k;
785 break;
786 case BPF_JMP | BPF_JEQ | BPF_K:
787 case BPF_JMP | BPF_JGE | BPF_K:
788 case BPF_JMP | BPF_JGT | BPF_K:
789 case BPF_JMP | BPF_JSET | BPF_K:
790 switch (BPF_OP(code)) {
791 case BPF_JEQ:
792 op_res = reg_value == k;
793 break;
794 case BPF_JGE:
795 op_res = reg_value >= k;
796 break;
797 case BPF_JGT:
798 op_res = reg_value > k;
799 break;
800 case BPF_JSET:
801 op_res = !!(reg_value & k);
802 break;
803 default:
804 /* can't optimize (unknown jump) */
805 return false;
806 }
807
808 pc += op_res ? insn->jt : insn->jf;
809 break;
810 case BPF_ALU | BPF_AND | BPF_K:
811 reg_value &= k;
812 break;
813 default:
814 /* can't optimize (unknown insn) */
815 return false;
816 }
817 }
818
819 /* ran off the end of the filter?! */
820 WARN_ON(1);
821 return false;
822}
823
824static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
825 void *bitmap, const void *bitmap_prev,
826 size_t bitmap_size, int arch)
827{
828 struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
829 struct seccomp_data sd;
830 int nr;
831
832 if (bitmap_prev) {
833 /* The new filter must be as restrictive as the last. */
834 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
835 } else {
836 /* Before any filters, all syscalls are always allowed. */
837 bitmap_fill(bitmap, bitmap_size);
838 }
839
840 for (nr = 0; nr < bitmap_size; nr++) {
841 /* No bitmap change: not a cacheable action. */
842 if (!test_bit(nr, bitmap))
843 continue;
844
845 sd.nr = nr;
846 sd.arch = arch;
847
848 /* No bitmap change: continue to always allow. */
849 if (seccomp_is_const_allow(fprog, &sd))
850 continue;
851
852 /*
853 * Not a cacheable action: always run filters.
854 * atomic clear_bit() not needed, filter not visible yet.
855 */
856 __clear_bit(nr, bitmap);
857 }
858}
859
860/**
861 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
862 * @sfilter: The seccomp filter
863 *
864 * Returns 0 if successful or -errno if error occurred.
865 */
866static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
867{
868 struct action_cache *cache = &sfilter->cache;
869 const struct action_cache *cache_prev =
870 sfilter->prev ? &sfilter->prev->cache : NULL;
871
872 seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
873 cache_prev ? cache_prev->allow_native : NULL,
874 SECCOMP_ARCH_NATIVE_NR,
875 SECCOMP_ARCH_NATIVE);
876
877#ifdef SECCOMP_ARCH_COMPAT
878 seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
879 cache_prev ? cache_prev->allow_compat : NULL,
880 SECCOMP_ARCH_COMPAT_NR,
881 SECCOMP_ARCH_COMPAT);
882#endif /* SECCOMP_ARCH_COMPAT */
883}
884#endif /* SECCOMP_ARCH_NATIVE */
885
886/**
887 * seccomp_attach_filter: validate and attach filter
888 * @flags: flags to change filter behavior
889 * @filter: seccomp filter to add to the current process
890 *
891 * Caller must be holding current->sighand->siglock lock.
892 *
893 * Returns 0 on success, -ve on error, or
894 * - in TSYNC mode: the pid of a thread which was either not in the correct
895 * seccomp mode or did not have an ancestral seccomp filter
896 * - in NEW_LISTENER mode: the fd of the new listener
897 */
898static long seccomp_attach_filter(unsigned int flags,
899 struct seccomp_filter *filter)
900{
901 unsigned long total_insns;
902 struct seccomp_filter *walker;
903
904 assert_spin_locked(¤t->sighand->siglock);
905
906 /* Validate resulting filter length. */
907 total_insns = filter->prog->len;
908 for (walker = current->seccomp.filter; walker; walker = walker->prev)
909 total_insns += walker->prog->len + 4; /* 4 instr penalty */
910 if (total_insns > MAX_INSNS_PER_PATH)
911 return -ENOMEM;
912
913 /* If thread sync has been requested, check that it is possible. */
914 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
915 int ret;
916
917 ret = seccomp_can_sync_threads();
918 if (ret) {
919 if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
920 return -ESRCH;
921 else
922 return ret;
923 }
924 }
925
926 /* Set log flag, if present. */
927 if (flags & SECCOMP_FILTER_FLAG_LOG)
928 filter->log = true;
929
930 /* Set wait killable flag, if present. */
931 if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
932 filter->wait_killable_recv = true;
933
934 /*
935 * If there is an existing filter, make it the prev and don't drop its
936 * task reference.
937 */
938 filter->prev = current->seccomp.filter;
939 seccomp_cache_prepare(filter);
940 current->seccomp.filter = filter;
941 atomic_inc(¤t->seccomp.filter_count);
942
943 /* Now that the new filter is in place, synchronize to all threads. */
944 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
945 seccomp_sync_threads(flags);
946
947 return 0;
948}
949
950static void __get_seccomp_filter(struct seccomp_filter *filter)
951{
952 refcount_inc(&filter->refs);
953}
954
955/* get_seccomp_filter - increments the reference count of the filter on @tsk */
956void get_seccomp_filter(struct task_struct *tsk)
957{
958 struct seccomp_filter *orig = tsk->seccomp.filter;
959 if (!orig)
960 return;
961 __get_seccomp_filter(orig);
962 refcount_inc(&orig->users);
963}
964
965#endif /* CONFIG_SECCOMP_FILTER */
966
967/* For use with seccomp_actions_logged */
968#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
969#define SECCOMP_LOG_KILL_THREAD (1 << 1)
970#define SECCOMP_LOG_TRAP (1 << 2)
971#define SECCOMP_LOG_ERRNO (1 << 3)
972#define SECCOMP_LOG_TRACE (1 << 4)
973#define SECCOMP_LOG_LOG (1 << 5)
974#define SECCOMP_LOG_ALLOW (1 << 6)
975#define SECCOMP_LOG_USER_NOTIF (1 << 7)
976
977static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
978 SECCOMP_LOG_KILL_THREAD |
979 SECCOMP_LOG_TRAP |
980 SECCOMP_LOG_ERRNO |
981 SECCOMP_LOG_USER_NOTIF |
982 SECCOMP_LOG_TRACE |
983 SECCOMP_LOG_LOG;
984
985static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
986 bool requested)
987{
988 bool log = false;
989
990 switch (action) {
991 case SECCOMP_RET_ALLOW:
992 break;
993 case SECCOMP_RET_TRAP:
994 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
995 break;
996 case SECCOMP_RET_ERRNO:
997 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
998 break;
999 case SECCOMP_RET_TRACE:
1000 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
1001 break;
1002 case SECCOMP_RET_USER_NOTIF:
1003 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
1004 break;
1005 case SECCOMP_RET_LOG:
1006 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
1007 break;
1008 case SECCOMP_RET_KILL_THREAD:
1009 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
1010 break;
1011 case SECCOMP_RET_KILL_PROCESS:
1012 default:
1013 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
1014 }
1015
1016 /*
1017 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1018 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1019 * any action from being logged by removing the action name from the
1020 * seccomp_actions_logged sysctl.
1021 */
1022 if (!log)
1023 return;
1024
1025 audit_seccomp(syscall, signr, action);
1026}
1027
1028/*
1029 * Secure computing mode 1 allows only read/write/exit/sigreturn.
1030 * To be fully secure this must be combined with rlimit
1031 * to limit the stack allocations too.
1032 */
1033static const int mode1_syscalls[] = {
1034 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1035#ifdef __NR_uretprobe
1036 __NR_uretprobe,
1037#endif
1038 -1, /* negative terminated */
1039};
1040
1041static void __secure_computing_strict(int this_syscall)
1042{
1043 const int *allowed_syscalls = mode1_syscalls;
1044#ifdef CONFIG_COMPAT
1045 if (in_compat_syscall())
1046 allowed_syscalls = get_compat_mode1_syscalls();
1047#endif
1048 do {
1049 if (*allowed_syscalls == this_syscall)
1050 return;
1051 } while (*++allowed_syscalls != -1);
1052
1053#ifdef SECCOMP_DEBUG
1054 dump_stack();
1055#endif
1056 current->seccomp.mode = SECCOMP_MODE_DEAD;
1057 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1058 do_exit(SIGKILL);
1059}
1060
1061#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1062void secure_computing_strict(int this_syscall)
1063{
1064 int mode = current->seccomp.mode;
1065
1066 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1067 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1068 return;
1069
1070 if (mode == SECCOMP_MODE_DISABLED)
1071 return;
1072 else if (mode == SECCOMP_MODE_STRICT)
1073 __secure_computing_strict(this_syscall);
1074 else
1075 BUG();
1076}
1077#else
1078
1079#ifdef CONFIG_SECCOMP_FILTER
1080static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1081{
1082 /*
1083 * Note: overflow is ok here, the id just needs to be unique per
1084 * filter.
1085 */
1086 lockdep_assert_held(&filter->notify_lock);
1087 return filter->notif->next_id++;
1088}
1089
1090static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
1091{
1092 int fd;
1093
1094 /*
1095 * Remove the notification, and reset the list pointers, indicating
1096 * that it has been handled.
1097 */
1098 list_del_init(&addfd->list);
1099 if (!addfd->setfd)
1100 fd = receive_fd(addfd->file, NULL, addfd->flags);
1101 else
1102 fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1103 addfd->ret = fd;
1104
1105 if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1106 /* If we fail reset and return an error to the notifier */
1107 if (fd < 0) {
1108 n->state = SECCOMP_NOTIFY_SENT;
1109 } else {
1110 /* Return the FD we just added */
1111 n->flags = 0;
1112 n->error = 0;
1113 n->val = fd;
1114 }
1115 }
1116
1117 /*
1118 * Mark the notification as completed. From this point, addfd mem
1119 * might be invalidated and we can't safely read it anymore.
1120 */
1121 complete(&addfd->completion);
1122}
1123
1124static bool should_sleep_killable(struct seccomp_filter *match,
1125 struct seccomp_knotif *n)
1126{
1127 return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
1128}
1129
1130static int seccomp_do_user_notification(int this_syscall,
1131 struct seccomp_filter *match,
1132 const struct seccomp_data *sd)
1133{
1134 int err;
1135 u32 flags = 0;
1136 long ret = 0;
1137 struct seccomp_knotif n = {};
1138 struct seccomp_kaddfd *addfd, *tmp;
1139
1140 mutex_lock(&match->notify_lock);
1141 err = -ENOSYS;
1142 if (!match->notif)
1143 goto out;
1144
1145 n.task = current;
1146 n.state = SECCOMP_NOTIFY_INIT;
1147 n.data = sd;
1148 n.id = seccomp_next_notify_id(match);
1149 init_completion(&n.ready);
1150 list_add_tail(&n.list, &match->notif->notifications);
1151 INIT_LIST_HEAD(&n.addfd);
1152
1153 atomic_inc(&match->notif->requests);
1154 if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1155 wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM);
1156 else
1157 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1158
1159 /*
1160 * This is where we wait for a reply from userspace.
1161 */
1162 do {
1163 bool wait_killable = should_sleep_killable(match, &n);
1164
1165 mutex_unlock(&match->notify_lock);
1166 if (wait_killable)
1167 err = wait_for_completion_killable(&n.ready);
1168 else
1169 err = wait_for_completion_interruptible(&n.ready);
1170 mutex_lock(&match->notify_lock);
1171
1172 if (err != 0) {
1173 /*
1174 * Check to see if the notifcation got picked up and
1175 * whether we should switch to wait killable.
1176 */
1177 if (!wait_killable && should_sleep_killable(match, &n))
1178 continue;
1179
1180 goto interrupted;
1181 }
1182
1183 addfd = list_first_entry_or_null(&n.addfd,
1184 struct seccomp_kaddfd, list);
1185 /* Check if we were woken up by a addfd message */
1186 if (addfd)
1187 seccomp_handle_addfd(addfd, &n);
1188
1189 } while (n.state != SECCOMP_NOTIFY_REPLIED);
1190
1191 ret = n.val;
1192 err = n.error;
1193 flags = n.flags;
1194
1195interrupted:
1196 /* If there were any pending addfd calls, clear them out */
1197 list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1198 /* The process went away before we got a chance to handle it */
1199 addfd->ret = -ESRCH;
1200 list_del_init(&addfd->list);
1201 complete(&addfd->completion);
1202 }
1203
1204 /*
1205 * Note that it's possible the listener died in between the time when
1206 * we were notified of a response (or a signal) and when we were able to
1207 * re-acquire the lock, so only delete from the list if the
1208 * notification actually exists.
1209 *
1210 * Also note that this test is only valid because there's no way to
1211 * *reattach* to a notifier right now. If one is added, we'll need to
1212 * keep track of the notif itself and make sure they match here.
1213 */
1214 if (match->notif)
1215 list_del(&n.list);
1216out:
1217 mutex_unlock(&match->notify_lock);
1218
1219 /* Userspace requests to continue the syscall. */
1220 if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1221 return 0;
1222
1223 syscall_set_return_value(current, current_pt_regs(),
1224 err, ret);
1225 return -1;
1226}
1227
1228static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1229 const bool recheck_after_trace)
1230{
1231 u32 filter_ret, action;
1232 struct seccomp_filter *match = NULL;
1233 int data;
1234 struct seccomp_data sd_local;
1235
1236 /*
1237 * Make sure that any changes to mode from another thread have
1238 * been seen after SYSCALL_WORK_SECCOMP was seen.
1239 */
1240 smp_rmb();
1241
1242 if (!sd) {
1243 populate_seccomp_data(&sd_local);
1244 sd = &sd_local;
1245 }
1246
1247 filter_ret = seccomp_run_filters(sd, &match);
1248 data = filter_ret & SECCOMP_RET_DATA;
1249 action = filter_ret & SECCOMP_RET_ACTION_FULL;
1250
1251 switch (action) {
1252 case SECCOMP_RET_ERRNO:
1253 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1254 if (data > MAX_ERRNO)
1255 data = MAX_ERRNO;
1256 syscall_set_return_value(current, current_pt_regs(),
1257 -data, 0);
1258 goto skip;
1259
1260 case SECCOMP_RET_TRAP:
1261 /* Show the handler the original registers. */
1262 syscall_rollback(current, current_pt_regs());
1263 /* Let the filter pass back 16 bits of data. */
1264 force_sig_seccomp(this_syscall, data, false);
1265 goto skip;
1266
1267 case SECCOMP_RET_TRACE:
1268 /* We've been put in this state by the ptracer already. */
1269 if (recheck_after_trace)
1270 return 0;
1271
1272 /* ENOSYS these calls if there is no tracer attached. */
1273 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1274 syscall_set_return_value(current,
1275 current_pt_regs(),
1276 -ENOSYS, 0);
1277 goto skip;
1278 }
1279
1280 /* Allow the BPF to provide the event message */
1281 ptrace_event(PTRACE_EVENT_SECCOMP, data);
1282 /*
1283 * The delivery of a fatal signal during event
1284 * notification may silently skip tracer notification,
1285 * which could leave us with a potentially unmodified
1286 * syscall that the tracer would have liked to have
1287 * changed. Since the process is about to die, we just
1288 * force the syscall to be skipped and let the signal
1289 * kill the process and correctly handle any tracer exit
1290 * notifications.
1291 */
1292 if (fatal_signal_pending(current))
1293 goto skip;
1294 /* Check if the tracer forced the syscall to be skipped. */
1295 this_syscall = syscall_get_nr(current, current_pt_regs());
1296 if (this_syscall < 0)
1297 goto skip;
1298
1299 /*
1300 * Recheck the syscall, since it may have changed. This
1301 * intentionally uses a NULL struct seccomp_data to force
1302 * a reload of all registers. This does not goto skip since
1303 * a skip would have already been reported.
1304 */
1305 if (__seccomp_filter(this_syscall, NULL, true))
1306 return -1;
1307
1308 return 0;
1309
1310 case SECCOMP_RET_USER_NOTIF:
1311 if (seccomp_do_user_notification(this_syscall, match, sd))
1312 goto skip;
1313
1314 return 0;
1315
1316 case SECCOMP_RET_LOG:
1317 seccomp_log(this_syscall, 0, action, true);
1318 return 0;
1319
1320 case SECCOMP_RET_ALLOW:
1321 /*
1322 * Note that the "match" filter will always be NULL for
1323 * this action since SECCOMP_RET_ALLOW is the starting
1324 * state in seccomp_run_filters().
1325 */
1326 return 0;
1327
1328 case SECCOMP_RET_KILL_THREAD:
1329 case SECCOMP_RET_KILL_PROCESS:
1330 default:
1331 current->seccomp.mode = SECCOMP_MODE_DEAD;
1332 seccomp_log(this_syscall, SIGSYS, action, true);
1333 /* Dump core only if this is the last remaining thread. */
1334 if (action != SECCOMP_RET_KILL_THREAD ||
1335 (atomic_read(¤t->signal->live) == 1)) {
1336 /* Show the original registers in the dump. */
1337 syscall_rollback(current, current_pt_regs());
1338 /* Trigger a coredump with SIGSYS */
1339 force_sig_seccomp(this_syscall, data, true);
1340 } else {
1341 do_exit(SIGSYS);
1342 }
1343 return -1; /* skip the syscall go directly to signal handling */
1344 }
1345
1346 unreachable();
1347
1348skip:
1349 seccomp_log(this_syscall, 0, action, match ? match->log : false);
1350 return -1;
1351}
1352#else
1353static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1354 const bool recheck_after_trace)
1355{
1356 BUG();
1357
1358 return -1;
1359}
1360#endif
1361
1362int __secure_computing(const struct seccomp_data *sd)
1363{
1364 int mode = current->seccomp.mode;
1365 int this_syscall;
1366
1367 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1368 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1369 return 0;
1370
1371 this_syscall = sd ? sd->nr :
1372 syscall_get_nr(current, current_pt_regs());
1373
1374 switch (mode) {
1375 case SECCOMP_MODE_STRICT:
1376 __secure_computing_strict(this_syscall); /* may call do_exit */
1377 return 0;
1378 case SECCOMP_MODE_FILTER:
1379 return __seccomp_filter(this_syscall, sd, false);
1380 /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
1381 case SECCOMP_MODE_DEAD:
1382 WARN_ON_ONCE(1);
1383 do_exit(SIGKILL);
1384 return -1;
1385 default:
1386 BUG();
1387 }
1388}
1389#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1390
1391long prctl_get_seccomp(void)
1392{
1393 return current->seccomp.mode;
1394}
1395
1396/**
1397 * seccomp_set_mode_strict: internal function for setting strict seccomp
1398 *
1399 * Once current->seccomp.mode is non-zero, it may not be changed.
1400 *
1401 * Returns 0 on success or -EINVAL on failure.
1402 */
1403static long seccomp_set_mode_strict(void)
1404{
1405 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1406 long ret = -EINVAL;
1407
1408 spin_lock_irq(¤t->sighand->siglock);
1409
1410 if (!seccomp_may_assign_mode(seccomp_mode))
1411 goto out;
1412
1413#ifdef TIF_NOTSC
1414 disable_TSC();
1415#endif
1416 seccomp_assign_mode(current, seccomp_mode, 0);
1417 ret = 0;
1418
1419out:
1420 spin_unlock_irq(¤t->sighand->siglock);
1421
1422 return ret;
1423}
1424
1425#ifdef CONFIG_SECCOMP_FILTER
1426static void seccomp_notify_free(struct seccomp_filter *filter)
1427{
1428 kfree(filter->notif);
1429 filter->notif = NULL;
1430}
1431
1432static void seccomp_notify_detach(struct seccomp_filter *filter)
1433{
1434 struct seccomp_knotif *knotif;
1435
1436 if (!filter)
1437 return;
1438
1439 mutex_lock(&filter->notify_lock);
1440
1441 /*
1442 * If this file is being closed because e.g. the task who owned it
1443 * died, let's wake everyone up who was waiting on us.
1444 */
1445 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1446 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1447 continue;
1448
1449 knotif->state = SECCOMP_NOTIFY_REPLIED;
1450 knotif->error = -ENOSYS;
1451 knotif->val = 0;
1452
1453 /*
1454 * We do not need to wake up any pending addfd messages, as
1455 * the notifier will do that for us, as this just looks
1456 * like a standard reply.
1457 */
1458 complete(&knotif->ready);
1459 }
1460
1461 seccomp_notify_free(filter);
1462 mutex_unlock(&filter->notify_lock);
1463}
1464
1465static int seccomp_notify_release(struct inode *inode, struct file *file)
1466{
1467 struct seccomp_filter *filter = file->private_data;
1468
1469 seccomp_notify_detach(filter);
1470 __put_seccomp_filter(filter);
1471 return 0;
1472}
1473
1474/* must be called with notif_lock held */
1475static inline struct seccomp_knotif *
1476find_notification(struct seccomp_filter *filter, u64 id)
1477{
1478 struct seccomp_knotif *cur;
1479
1480 lockdep_assert_held(&filter->notify_lock);
1481
1482 list_for_each_entry(cur, &filter->notif->notifications, list) {
1483 if (cur->id == id)
1484 return cur;
1485 }
1486
1487 return NULL;
1488}
1489
1490static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
1491 void *key)
1492{
1493 /* Avoid a wakeup if event not interesting for us. */
1494 if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1495 return 0;
1496 return autoremove_wake_function(wait, mode, sync, key);
1497}
1498
1499static int recv_wait_event(struct seccomp_filter *filter)
1500{
1501 DEFINE_WAIT_FUNC(wait, recv_wake_function);
1502 int ret;
1503
1504 if (refcount_read(&filter->users) == 0)
1505 return 0;
1506
1507 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1508 return 0;
1509
1510 for (;;) {
1511 ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);
1512
1513 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1514 break;
1515 if (refcount_read(&filter->users) == 0)
1516 break;
1517
1518 if (ret)
1519 return ret;
1520
1521 schedule();
1522 }
1523 finish_wait(&filter->wqh, &wait);
1524 return 0;
1525}
1526
1527static long seccomp_notify_recv(struct seccomp_filter *filter,
1528 void __user *buf)
1529{
1530 struct seccomp_knotif *knotif = NULL, *cur;
1531 struct seccomp_notif unotif;
1532 ssize_t ret;
1533
1534 /* Verify that we're not given garbage to keep struct extensible. */
1535 ret = check_zeroed_user(buf, sizeof(unotif));
1536 if (ret < 0)
1537 return ret;
1538 if (!ret)
1539 return -EINVAL;
1540
1541 memset(&unotif, 0, sizeof(unotif));
1542
1543 ret = recv_wait_event(filter);
1544 if (ret < 0)
1545 return ret;
1546
1547 mutex_lock(&filter->notify_lock);
1548 list_for_each_entry(cur, &filter->notif->notifications, list) {
1549 if (cur->state == SECCOMP_NOTIFY_INIT) {
1550 knotif = cur;
1551 break;
1552 }
1553 }
1554
1555 /*
1556 * If we didn't find a notification, it could be that the task was
1557 * interrupted by a fatal signal between the time we were woken and
1558 * when we were able to acquire the rw lock.
1559 */
1560 if (!knotif) {
1561 ret = -ENOENT;
1562 goto out;
1563 }
1564
1565 unotif.id = knotif->id;
1566 unotif.pid = task_pid_vnr(knotif->task);
1567 unotif.data = *(knotif->data);
1568
1569 knotif->state = SECCOMP_NOTIFY_SENT;
1570 wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1571 ret = 0;
1572out:
1573 mutex_unlock(&filter->notify_lock);
1574
1575 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1576 ret = -EFAULT;
1577
1578 /*
1579 * Userspace screwed up. To make sure that we keep this
1580 * notification alive, let's reset it back to INIT. It
1581 * may have died when we released the lock, so we need to make
1582 * sure it's still around.
1583 */
1584 mutex_lock(&filter->notify_lock);
1585 knotif = find_notification(filter, unotif.id);
1586 if (knotif) {
1587 /* Reset the process to make sure it's not stuck */
1588 if (should_sleep_killable(filter, knotif))
1589 complete(&knotif->ready);
1590 knotif->state = SECCOMP_NOTIFY_INIT;
1591 atomic_inc(&filter->notif->requests);
1592 wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);
1593 }
1594 mutex_unlock(&filter->notify_lock);
1595 }
1596
1597 return ret;
1598}
1599
1600static long seccomp_notify_send(struct seccomp_filter *filter,
1601 void __user *buf)
1602{
1603 struct seccomp_notif_resp resp = {};
1604 struct seccomp_knotif *knotif;
1605 long ret;
1606
1607 if (copy_from_user(&resp, buf, sizeof(resp)))
1608 return -EFAULT;
1609
1610 if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1611 return -EINVAL;
1612
1613 if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1614 (resp.error || resp.val))
1615 return -EINVAL;
1616
1617 ret = mutex_lock_interruptible(&filter->notify_lock);
1618 if (ret < 0)
1619 return ret;
1620
1621 knotif = find_notification(filter, resp.id);
1622 if (!knotif) {
1623 ret = -ENOENT;
1624 goto out;
1625 }
1626
1627 /* Allow exactly one reply. */
1628 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1629 ret = -EINPROGRESS;
1630 goto out;
1631 }
1632
1633 ret = 0;
1634 knotif->state = SECCOMP_NOTIFY_REPLIED;
1635 knotif->error = resp.error;
1636 knotif->val = resp.val;
1637 knotif->flags = resp.flags;
1638 if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1639 complete_on_current_cpu(&knotif->ready);
1640 else
1641 complete(&knotif->ready);
1642out:
1643 mutex_unlock(&filter->notify_lock);
1644 return ret;
1645}
1646
1647static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1648 void __user *buf)
1649{
1650 struct seccomp_knotif *knotif;
1651 u64 id;
1652 long ret;
1653
1654 if (copy_from_user(&id, buf, sizeof(id)))
1655 return -EFAULT;
1656
1657 ret = mutex_lock_interruptible(&filter->notify_lock);
1658 if (ret < 0)
1659 return ret;
1660
1661 knotif = find_notification(filter, id);
1662 if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1663 ret = 0;
1664 else
1665 ret = -ENOENT;
1666
1667 mutex_unlock(&filter->notify_lock);
1668 return ret;
1669}
1670
1671static long seccomp_notify_set_flags(struct seccomp_filter *filter,
1672 unsigned long flags)
1673{
1674 long ret;
1675
1676 if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1677 return -EINVAL;
1678
1679 ret = mutex_lock_interruptible(&filter->notify_lock);
1680 if (ret < 0)
1681 return ret;
1682 filter->notif->flags = flags;
1683 mutex_unlock(&filter->notify_lock);
1684 return 0;
1685}
1686
1687static long seccomp_notify_addfd(struct seccomp_filter *filter,
1688 struct seccomp_notif_addfd __user *uaddfd,
1689 unsigned int size)
1690{
1691 struct seccomp_notif_addfd addfd;
1692 struct seccomp_knotif *knotif;
1693 struct seccomp_kaddfd kaddfd;
1694 int ret;
1695
1696 BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1697 BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1698
1699 if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1700 return -EINVAL;
1701
1702 ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1703 if (ret)
1704 return ret;
1705
1706 if (addfd.newfd_flags & ~O_CLOEXEC)
1707 return -EINVAL;
1708
1709 if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
1710 return -EINVAL;
1711
1712 if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1713 return -EINVAL;
1714
1715 kaddfd.file = fget(addfd.srcfd);
1716 if (!kaddfd.file)
1717 return -EBADF;
1718
1719 kaddfd.ioctl_flags = addfd.flags;
1720 kaddfd.flags = addfd.newfd_flags;
1721 kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1722 kaddfd.fd = addfd.newfd;
1723 init_completion(&kaddfd.completion);
1724
1725 ret = mutex_lock_interruptible(&filter->notify_lock);
1726 if (ret < 0)
1727 goto out;
1728
1729 knotif = find_notification(filter, addfd.id);
1730 if (!knotif) {
1731 ret = -ENOENT;
1732 goto out_unlock;
1733 }
1734
1735 /*
1736 * We do not want to allow for FD injection to occur before the
1737 * notification has been picked up by a userspace handler, or after
1738 * the notification has been replied to.
1739 */
1740 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1741 ret = -EINPROGRESS;
1742 goto out_unlock;
1743 }
1744
1745 if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1746 /*
1747 * Disallow queuing an atomic addfd + send reply while there are
1748 * some addfd requests still to process.
1749 *
1750 * There is no clear reason to support it and allows us to keep
1751 * the loop on the other side straight-forward.
1752 */
1753 if (!list_empty(&knotif->addfd)) {
1754 ret = -EBUSY;
1755 goto out_unlock;
1756 }
1757
1758 /* Allow exactly only one reply */
1759 knotif->state = SECCOMP_NOTIFY_REPLIED;
1760 }
1761
1762 list_add(&kaddfd.list, &knotif->addfd);
1763 complete(&knotif->ready);
1764 mutex_unlock(&filter->notify_lock);
1765
1766 /* Now we wait for it to be processed or be interrupted */
1767 ret = wait_for_completion_interruptible(&kaddfd.completion);
1768 if (ret == 0) {
1769 /*
1770 * We had a successful completion. The other side has already
1771 * removed us from the addfd queue, and
1772 * wait_for_completion_interruptible has a memory barrier upon
1773 * success that lets us read this value directly without
1774 * locking.
1775 */
1776 ret = kaddfd.ret;
1777 goto out;
1778 }
1779
1780 mutex_lock(&filter->notify_lock);
1781 /*
1782 * Even though we were woken up by a signal and not a successful
1783 * completion, a completion may have happened in the mean time.
1784 *
1785 * We need to check again if the addfd request has been handled,
1786 * and if not, we will remove it from the queue.
1787 */
1788 if (list_empty(&kaddfd.list))
1789 ret = kaddfd.ret;
1790 else
1791 list_del(&kaddfd.list);
1792
1793out_unlock:
1794 mutex_unlock(&filter->notify_lock);
1795out:
1796 fput(kaddfd.file);
1797
1798 return ret;
1799}
1800
1801static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1802 unsigned long arg)
1803{
1804 struct seccomp_filter *filter = file->private_data;
1805 void __user *buf = (void __user *)arg;
1806
1807 /* Fixed-size ioctls */
1808 switch (cmd) {
1809 case SECCOMP_IOCTL_NOTIF_RECV:
1810 return seccomp_notify_recv(filter, buf);
1811 case SECCOMP_IOCTL_NOTIF_SEND:
1812 return seccomp_notify_send(filter, buf);
1813 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1814 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1815 return seccomp_notify_id_valid(filter, buf);
1816 case SECCOMP_IOCTL_NOTIF_SET_FLAGS:
1817 return seccomp_notify_set_flags(filter, arg);
1818 }
1819
1820 /* Extensible Argument ioctls */
1821#define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1822 switch (EA_IOCTL(cmd)) {
1823 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1824 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1825 default:
1826 return -EINVAL;
1827 }
1828}
1829
1830static __poll_t seccomp_notify_poll(struct file *file,
1831 struct poll_table_struct *poll_tab)
1832{
1833 struct seccomp_filter *filter = file->private_data;
1834 __poll_t ret = 0;
1835 struct seccomp_knotif *cur;
1836
1837 poll_wait(file, &filter->wqh, poll_tab);
1838
1839 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1840 return EPOLLERR;
1841
1842 list_for_each_entry(cur, &filter->notif->notifications, list) {
1843 if (cur->state == SECCOMP_NOTIFY_INIT)
1844 ret |= EPOLLIN | EPOLLRDNORM;
1845 if (cur->state == SECCOMP_NOTIFY_SENT)
1846 ret |= EPOLLOUT | EPOLLWRNORM;
1847 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1848 break;
1849 }
1850
1851 mutex_unlock(&filter->notify_lock);
1852
1853 if (refcount_read(&filter->users) == 0)
1854 ret |= EPOLLHUP;
1855
1856 return ret;
1857}
1858
1859static const struct file_operations seccomp_notify_ops = {
1860 .poll = seccomp_notify_poll,
1861 .release = seccomp_notify_release,
1862 .unlocked_ioctl = seccomp_notify_ioctl,
1863 .compat_ioctl = seccomp_notify_ioctl,
1864};
1865
1866static struct file *init_listener(struct seccomp_filter *filter)
1867{
1868 struct file *ret;
1869
1870 ret = ERR_PTR(-ENOMEM);
1871 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1872 if (!filter->notif)
1873 goto out;
1874
1875 filter->notif->next_id = get_random_u64();
1876 INIT_LIST_HEAD(&filter->notif->notifications);
1877
1878 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1879 filter, O_RDWR);
1880 if (IS_ERR(ret))
1881 goto out_notif;
1882
1883 /* The file has a reference to it now */
1884 __get_seccomp_filter(filter);
1885
1886out_notif:
1887 if (IS_ERR(ret))
1888 seccomp_notify_free(filter);
1889out:
1890 return ret;
1891}
1892
1893/*
1894 * Does @new_child have a listener while an ancestor also has a listener?
1895 * If so, we'll want to reject this filter.
1896 * This only has to be tested for the current process, even in the TSYNC case,
1897 * because TSYNC installs @child with the same parent on all threads.
1898 * Note that @new_child is not hooked up to its parent at this point yet, so
1899 * we use current->seccomp.filter.
1900 */
1901static bool has_duplicate_listener(struct seccomp_filter *new_child)
1902{
1903 struct seccomp_filter *cur;
1904
1905 /* must be protected against concurrent TSYNC */
1906 lockdep_assert_held(¤t->sighand->siglock);
1907
1908 if (!new_child->notif)
1909 return false;
1910 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1911 if (cur->notif)
1912 return true;
1913 }
1914
1915 return false;
1916}
1917
1918/**
1919 * seccomp_set_mode_filter: internal function for setting seccomp filter
1920 * @flags: flags to change filter behavior
1921 * @filter: struct sock_fprog containing filter
1922 *
1923 * This function may be called repeatedly to install additional filters.
1924 * Every filter successfully installed will be evaluated (in reverse order)
1925 * for each system call the task makes.
1926 *
1927 * Once current->seccomp.mode is non-zero, it may not be changed.
1928 *
1929 * Returns 0 on success or -EINVAL on failure.
1930 */
1931static long seccomp_set_mode_filter(unsigned int flags,
1932 const char __user *filter)
1933{
1934 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1935 struct seccomp_filter *prepared = NULL;
1936 long ret = -EINVAL;
1937 int listener = -1;
1938 struct file *listener_f = NULL;
1939
1940 /* Validate flags. */
1941 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1942 return -EINVAL;
1943
1944 /*
1945 * In the successful case, NEW_LISTENER returns the new listener fd.
1946 * But in the failure case, TSYNC returns the thread that died. If you
1947 * combine these two flags, there's no way to tell whether something
1948 * succeeded or failed. So, let's disallow this combination if the user
1949 * has not explicitly requested no errors from TSYNC.
1950 */
1951 if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1952 (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1953 ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1954 return -EINVAL;
1955
1956 /*
1957 * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
1958 * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
1959 */
1960 if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
1961 ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
1962 return -EINVAL;
1963
1964 /* Prepare the new filter before holding any locks. */
1965 prepared = seccomp_prepare_user_filter(filter);
1966 if (IS_ERR(prepared))
1967 return PTR_ERR(prepared);
1968
1969 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1970 listener = get_unused_fd_flags(O_CLOEXEC);
1971 if (listener < 0) {
1972 ret = listener;
1973 goto out_free;
1974 }
1975
1976 listener_f = init_listener(prepared);
1977 if (IS_ERR(listener_f)) {
1978 put_unused_fd(listener);
1979 ret = PTR_ERR(listener_f);
1980 goto out_free;
1981 }
1982 }
1983
1984 /*
1985 * Make sure we cannot change seccomp or nnp state via TSYNC
1986 * while another thread is in the middle of calling exec.
1987 */
1988 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1989 mutex_lock_killable(¤t->signal->cred_guard_mutex))
1990 goto out_put_fd;
1991
1992 spin_lock_irq(¤t->sighand->siglock);
1993
1994 if (!seccomp_may_assign_mode(seccomp_mode))
1995 goto out;
1996
1997 if (has_duplicate_listener(prepared)) {
1998 ret = -EBUSY;
1999 goto out;
2000 }
2001
2002 ret = seccomp_attach_filter(flags, prepared);
2003 if (ret)
2004 goto out;
2005 /* Do not free the successfully attached filter. */
2006 prepared = NULL;
2007
2008 seccomp_assign_mode(current, seccomp_mode, flags);
2009out:
2010 spin_unlock_irq(¤t->sighand->siglock);
2011 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
2012 mutex_unlock(¤t->signal->cred_guard_mutex);
2013out_put_fd:
2014 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
2015 if (ret) {
2016 listener_f->private_data = NULL;
2017 fput(listener_f);
2018 put_unused_fd(listener);
2019 seccomp_notify_detach(prepared);
2020 } else {
2021 fd_install(listener, listener_f);
2022 ret = listener;
2023 }
2024 }
2025out_free:
2026 seccomp_filter_free(prepared);
2027 return ret;
2028}
2029#else
2030static inline long seccomp_set_mode_filter(unsigned int flags,
2031 const char __user *filter)
2032{
2033 return -EINVAL;
2034}
2035#endif
2036
2037static long seccomp_get_action_avail(const char __user *uaction)
2038{
2039 u32 action;
2040
2041 if (copy_from_user(&action, uaction, sizeof(action)))
2042 return -EFAULT;
2043
2044 switch (action) {
2045 case SECCOMP_RET_KILL_PROCESS:
2046 case SECCOMP_RET_KILL_THREAD:
2047 case SECCOMP_RET_TRAP:
2048 case SECCOMP_RET_ERRNO:
2049 case SECCOMP_RET_USER_NOTIF:
2050 case SECCOMP_RET_TRACE:
2051 case SECCOMP_RET_LOG:
2052 case SECCOMP_RET_ALLOW:
2053 break;
2054 default:
2055 return -EOPNOTSUPP;
2056 }
2057
2058 return 0;
2059}
2060
2061static long seccomp_get_notif_sizes(void __user *usizes)
2062{
2063 struct seccomp_notif_sizes sizes = {
2064 .seccomp_notif = sizeof(struct seccomp_notif),
2065 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
2066 .seccomp_data = sizeof(struct seccomp_data),
2067 };
2068
2069 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
2070 return -EFAULT;
2071
2072 return 0;
2073}
2074
2075/* Common entry point for both prctl and syscall. */
2076static long do_seccomp(unsigned int op, unsigned int flags,
2077 void __user *uargs)
2078{
2079 switch (op) {
2080 case SECCOMP_SET_MODE_STRICT:
2081 if (flags != 0 || uargs != NULL)
2082 return -EINVAL;
2083 return seccomp_set_mode_strict();
2084 case SECCOMP_SET_MODE_FILTER:
2085 return seccomp_set_mode_filter(flags, uargs);
2086 case SECCOMP_GET_ACTION_AVAIL:
2087 if (flags != 0)
2088 return -EINVAL;
2089
2090 return seccomp_get_action_avail(uargs);
2091 case SECCOMP_GET_NOTIF_SIZES:
2092 if (flags != 0)
2093 return -EINVAL;
2094
2095 return seccomp_get_notif_sizes(uargs);
2096 default:
2097 return -EINVAL;
2098 }
2099}
2100
2101SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
2102 void __user *, uargs)
2103{
2104 return do_seccomp(op, flags, uargs);
2105}
2106
2107/**
2108 * prctl_set_seccomp: configures current->seccomp.mode
2109 * @seccomp_mode: requested mode to use
2110 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2111 *
2112 * Returns 0 on success or -EINVAL on failure.
2113 */
2114long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
2115{
2116 unsigned int op;
2117 void __user *uargs;
2118
2119 switch (seccomp_mode) {
2120 case SECCOMP_MODE_STRICT:
2121 op = SECCOMP_SET_MODE_STRICT;
2122 /*
2123 * Setting strict mode through prctl always ignored filter,
2124 * so make sure it is always NULL here to pass the internal
2125 * check in do_seccomp().
2126 */
2127 uargs = NULL;
2128 break;
2129 case SECCOMP_MODE_FILTER:
2130 op = SECCOMP_SET_MODE_FILTER;
2131 uargs = filter;
2132 break;
2133 default:
2134 return -EINVAL;
2135 }
2136
2137 /* prctl interface doesn't have flags, so they are always zero. */
2138 return do_seccomp(op, 0, uargs);
2139}
2140
2141#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2142static struct seccomp_filter *get_nth_filter(struct task_struct *task,
2143 unsigned long filter_off)
2144{
2145 struct seccomp_filter *orig, *filter;
2146 unsigned long count;
2147
2148 /*
2149 * Note: this is only correct because the caller should be the (ptrace)
2150 * tracer of the task, otherwise lock_task_sighand is needed.
2151 */
2152 spin_lock_irq(&task->sighand->siglock);
2153
2154 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2155 spin_unlock_irq(&task->sighand->siglock);
2156 return ERR_PTR(-EINVAL);
2157 }
2158
2159 orig = task->seccomp.filter;
2160 __get_seccomp_filter(orig);
2161 spin_unlock_irq(&task->sighand->siglock);
2162
2163 count = 0;
2164 for (filter = orig; filter; filter = filter->prev)
2165 count++;
2166
2167 if (filter_off >= count) {
2168 filter = ERR_PTR(-ENOENT);
2169 goto out;
2170 }
2171
2172 count -= filter_off;
2173 for (filter = orig; filter && count > 1; filter = filter->prev)
2174 count--;
2175
2176 if (WARN_ON(count != 1 || !filter)) {
2177 filter = ERR_PTR(-ENOENT);
2178 goto out;
2179 }
2180
2181 __get_seccomp_filter(filter);
2182
2183out:
2184 __put_seccomp_filter(orig);
2185 return filter;
2186}
2187
2188long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2189 void __user *data)
2190{
2191 struct seccomp_filter *filter;
2192 struct sock_fprog_kern *fprog;
2193 long ret;
2194
2195 if (!capable(CAP_SYS_ADMIN) ||
2196 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2197 return -EACCES;
2198 }
2199
2200 filter = get_nth_filter(task, filter_off);
2201 if (IS_ERR(filter))
2202 return PTR_ERR(filter);
2203
2204 fprog = filter->prog->orig_prog;
2205 if (!fprog) {
2206 /* This must be a new non-cBPF filter, since we save
2207 * every cBPF filter's orig_prog above when
2208 * CONFIG_CHECKPOINT_RESTORE is enabled.
2209 */
2210 ret = -EMEDIUMTYPE;
2211 goto out;
2212 }
2213
2214 ret = fprog->len;
2215 if (!data)
2216 goto out;
2217
2218 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2219 ret = -EFAULT;
2220
2221out:
2222 __put_seccomp_filter(filter);
2223 return ret;
2224}
2225
2226long seccomp_get_metadata(struct task_struct *task,
2227 unsigned long size, void __user *data)
2228{
2229 long ret;
2230 struct seccomp_filter *filter;
2231 struct seccomp_metadata kmd = {};
2232
2233 if (!capable(CAP_SYS_ADMIN) ||
2234 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2235 return -EACCES;
2236 }
2237
2238 size = min_t(unsigned long, size, sizeof(kmd));
2239
2240 if (size < sizeof(kmd.filter_off))
2241 return -EINVAL;
2242
2243 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2244 return -EFAULT;
2245
2246 filter = get_nth_filter(task, kmd.filter_off);
2247 if (IS_ERR(filter))
2248 return PTR_ERR(filter);
2249
2250 if (filter->log)
2251 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2252
2253 ret = size;
2254 if (copy_to_user(data, &kmd, size))
2255 ret = -EFAULT;
2256
2257 __put_seccomp_filter(filter);
2258 return ret;
2259}
2260#endif
2261
2262#ifdef CONFIG_SYSCTL
2263
2264/* Human readable action names for friendly sysctl interaction */
2265#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2266#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2267#define SECCOMP_RET_TRAP_NAME "trap"
2268#define SECCOMP_RET_ERRNO_NAME "errno"
2269#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2270#define SECCOMP_RET_TRACE_NAME "trace"
2271#define SECCOMP_RET_LOG_NAME "log"
2272#define SECCOMP_RET_ALLOW_NAME "allow"
2273
2274static const char seccomp_actions_avail[] =
2275 SECCOMP_RET_KILL_PROCESS_NAME " "
2276 SECCOMP_RET_KILL_THREAD_NAME " "
2277 SECCOMP_RET_TRAP_NAME " "
2278 SECCOMP_RET_ERRNO_NAME " "
2279 SECCOMP_RET_USER_NOTIF_NAME " "
2280 SECCOMP_RET_TRACE_NAME " "
2281 SECCOMP_RET_LOG_NAME " "
2282 SECCOMP_RET_ALLOW_NAME;
2283
2284struct seccomp_log_name {
2285 u32 log;
2286 const char *name;
2287};
2288
2289static const struct seccomp_log_name seccomp_log_names[] = {
2290 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2291 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2292 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2293 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2294 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2295 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2296 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2297 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2298 { }
2299};
2300
2301static bool seccomp_names_from_actions_logged(char *names, size_t size,
2302 u32 actions_logged,
2303 const char *sep)
2304{
2305 const struct seccomp_log_name *cur;
2306 bool append_sep = false;
2307
2308 for (cur = seccomp_log_names; cur->name && size; cur++) {
2309 ssize_t ret;
2310
2311 if (!(actions_logged & cur->log))
2312 continue;
2313
2314 if (append_sep) {
2315 ret = strscpy(names, sep, size);
2316 if (ret < 0)
2317 return false;
2318
2319 names += ret;
2320 size -= ret;
2321 } else
2322 append_sep = true;
2323
2324 ret = strscpy(names, cur->name, size);
2325 if (ret < 0)
2326 return false;
2327
2328 names += ret;
2329 size -= ret;
2330 }
2331
2332 return true;
2333}
2334
2335static bool seccomp_action_logged_from_name(u32 *action_logged,
2336 const char *name)
2337{
2338 const struct seccomp_log_name *cur;
2339
2340 for (cur = seccomp_log_names; cur->name; cur++) {
2341 if (!strcmp(cur->name, name)) {
2342 *action_logged = cur->log;
2343 return true;
2344 }
2345 }
2346
2347 return false;
2348}
2349
2350static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2351{
2352 char *name;
2353
2354 *actions_logged = 0;
2355 while ((name = strsep(&names, " ")) && *name) {
2356 u32 action_logged = 0;
2357
2358 if (!seccomp_action_logged_from_name(&action_logged, name))
2359 return false;
2360
2361 *actions_logged |= action_logged;
2362 }
2363
2364 return true;
2365}
2366
2367static int read_actions_logged(const struct ctl_table *ro_table, void *buffer,
2368 size_t *lenp, loff_t *ppos)
2369{
2370 char names[sizeof(seccomp_actions_avail)];
2371 struct ctl_table table;
2372
2373 memset(names, 0, sizeof(names));
2374
2375 if (!seccomp_names_from_actions_logged(names, sizeof(names),
2376 seccomp_actions_logged, " "))
2377 return -EINVAL;
2378
2379 table = *ro_table;
2380 table.data = names;
2381 table.maxlen = sizeof(names);
2382 return proc_dostring(&table, 0, buffer, lenp, ppos);
2383}
2384
2385static int write_actions_logged(const struct ctl_table *ro_table, void *buffer,
2386 size_t *lenp, loff_t *ppos, u32 *actions_logged)
2387{
2388 char names[sizeof(seccomp_actions_avail)];
2389 struct ctl_table table;
2390 int ret;
2391
2392 if (!capable(CAP_SYS_ADMIN))
2393 return -EPERM;
2394
2395 memset(names, 0, sizeof(names));
2396
2397 table = *ro_table;
2398 table.data = names;
2399 table.maxlen = sizeof(names);
2400 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2401 if (ret)
2402 return ret;
2403
2404 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2405 return -EINVAL;
2406
2407 if (*actions_logged & SECCOMP_LOG_ALLOW)
2408 return -EINVAL;
2409
2410 seccomp_actions_logged = *actions_logged;
2411 return 0;
2412}
2413
2414static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2415 int ret)
2416{
2417 char names[sizeof(seccomp_actions_avail)];
2418 char old_names[sizeof(seccomp_actions_avail)];
2419 const char *new = names;
2420 const char *old = old_names;
2421
2422 if (!audit_enabled)
2423 return;
2424
2425 memset(names, 0, sizeof(names));
2426 memset(old_names, 0, sizeof(old_names));
2427
2428 if (ret)
2429 new = "?";
2430 else if (!actions_logged)
2431 new = "(none)";
2432 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2433 actions_logged, ","))
2434 new = "?";
2435
2436 if (!old_actions_logged)
2437 old = "(none)";
2438 else if (!seccomp_names_from_actions_logged(old_names,
2439 sizeof(old_names),
2440 old_actions_logged, ","))
2441 old = "?";
2442
2443 return audit_seccomp_actions_logged(new, old, !ret);
2444}
2445
2446static int seccomp_actions_logged_handler(const struct ctl_table *ro_table, int write,
2447 void *buffer, size_t *lenp,
2448 loff_t *ppos)
2449{
2450 int ret;
2451
2452 if (write) {
2453 u32 actions_logged = 0;
2454 u32 old_actions_logged = seccomp_actions_logged;
2455
2456 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2457 &actions_logged);
2458 audit_actions_logged(actions_logged, old_actions_logged, ret);
2459 } else
2460 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2461
2462 return ret;
2463}
2464
2465static struct ctl_table seccomp_sysctl_table[] = {
2466 {
2467 .procname = "actions_avail",
2468 .data = (void *) &seccomp_actions_avail,
2469 .maxlen = sizeof(seccomp_actions_avail),
2470 .mode = 0444,
2471 .proc_handler = proc_dostring,
2472 },
2473 {
2474 .procname = "actions_logged",
2475 .mode = 0644,
2476 .proc_handler = seccomp_actions_logged_handler,
2477 },
2478};
2479
2480static int __init seccomp_sysctl_init(void)
2481{
2482 register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
2483 return 0;
2484}
2485
2486device_initcall(seccomp_sysctl_init)
2487
2488#endif /* CONFIG_SYSCTL */
2489
2490#ifdef CONFIG_SECCOMP_CACHE_DEBUG
2491/* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2492static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2493 const void *bitmap, size_t bitmap_size)
2494{
2495 int nr;
2496
2497 for (nr = 0; nr < bitmap_size; nr++) {
2498 bool cached = test_bit(nr, bitmap);
2499 char *status = cached ? "ALLOW" : "FILTER";
2500
2501 seq_printf(m, "%s %d %s\n", name, nr, status);
2502 }
2503}
2504
2505int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2506 struct pid *pid, struct task_struct *task)
2507{
2508 struct seccomp_filter *f;
2509 unsigned long flags;
2510
2511 /*
2512 * We don't want some sandboxed process to know what their seccomp
2513 * filters consist of.
2514 */
2515 if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2516 return -EACCES;
2517
2518 if (!lock_task_sighand(task, &flags))
2519 return -ESRCH;
2520
2521 f = READ_ONCE(task->seccomp.filter);
2522 if (!f) {
2523 unlock_task_sighand(task, &flags);
2524 return 0;
2525 }
2526
2527 /* prevent filter from being freed while we are printing it */
2528 __get_seccomp_filter(f);
2529 unlock_task_sighand(task, &flags);
2530
2531 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2532 f->cache.allow_native,
2533 SECCOMP_ARCH_NATIVE_NR);
2534
2535#ifdef SECCOMP_ARCH_COMPAT
2536 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2537 f->cache.allow_compat,
2538 SECCOMP_ARCH_COMPAT_NR);
2539#endif /* SECCOMP_ARCH_COMPAT */
2540
2541 __put_seccomp_filter(f);
2542 return 0;
2543}
2544#endif /* CONFIG_SECCOMP_CACHE_DEBUG */