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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 insns[];
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 * get_u32 - returns a u32 offset into data
66 * @data: a unsigned 64 bit value
67 * @index: 0 or 1 to return the first or second 32-bits
68 *
69 * This inline exists to hide the length of unsigned long. If a 32-bit
70 * unsigned long is passed in, it will be extended and the top 32-bits will be
71 * 0. If it is a 64-bit unsigned long, then whatever data is resident will be
72 * properly returned.
73 *
74 * Endianness is explicitly ignored and left for BPF program authors to manage
75 * as per the specific architecture.
76 */
77static inline u32 get_u32(u64 data, int index)
78{
79 return ((u32 *)&data)[index];
80}
81
82/* Helper for bpf_load below. */
83#define BPF_DATA(_name) offsetof(struct seccomp_data, _name)
84/**
85 * bpf_load: checks and returns a pointer to the requested offset
86 * @off: offset into struct seccomp_data to load from
87 *
88 * Returns the requested 32-bits of data.
89 * seccomp_check_filter() should assure that @off is 32-bit aligned
90 * and not out of bounds. Failure to do so is a BUG.
91 */
92u32 seccomp_bpf_load(int off)
93{
94 struct pt_regs *regs = task_pt_regs(current);
95 if (off == BPF_DATA(nr))
96 return syscall_get_nr(current, regs);
97 if (off == BPF_DATA(arch))
98 return syscall_get_arch(current, regs);
99 if (off >= BPF_DATA(args[0]) && off < BPF_DATA(args[6])) {
100 unsigned long value;
101 int arg = (off - BPF_DATA(args[0])) / sizeof(u64);
102 int index = !!(off % sizeof(u64));
103 syscall_get_arguments(current, regs, arg, 1, &value);
104 return get_u32(value, index);
105 }
106 if (off == BPF_DATA(instruction_pointer))
107 return get_u32(KSTK_EIP(current), 0);
108 if (off == BPF_DATA(instruction_pointer) + sizeof(u32))
109 return get_u32(KSTK_EIP(current), 1);
110 /* seccomp_check_filter should make this impossible. */
111 BUG();
112}
113
114/**
115 * seccomp_check_filter - verify seccomp filter code
116 * @filter: filter to verify
117 * @flen: length of filter
118 *
119 * Takes a previously checked filter (by sk_chk_filter) and
120 * redirects all filter code that loads struct sk_buff data
121 * and related data through seccomp_bpf_load. It also
122 * enforces length and alignment checking of those loads.
123 *
124 * Returns 0 if the rule set is legal or -EINVAL if not.
125 */
126static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
127{
128 int pc;
129 for (pc = 0; pc < flen; pc++) {
130 struct sock_filter *ftest = &filter[pc];
131 u16 code = ftest->code;
132 u32 k = ftest->k;
133
134 switch (code) {
135 case BPF_S_LD_W_ABS:
136 ftest->code = BPF_S_ANC_SECCOMP_LD_W;
137 /* 32-bit aligned and not out of bounds. */
138 if (k >= sizeof(struct seccomp_data) || k & 3)
139 return -EINVAL;
140 continue;
141 case BPF_S_LD_W_LEN:
142 ftest->code = BPF_S_LD_IMM;
143 ftest->k = sizeof(struct seccomp_data);
144 continue;
145 case BPF_S_LDX_W_LEN:
146 ftest->code = BPF_S_LDX_IMM;
147 ftest->k = sizeof(struct seccomp_data);
148 continue;
149 /* Explicitly include allowed calls. */
150 case BPF_S_RET_K:
151 case BPF_S_RET_A:
152 case BPF_S_ALU_ADD_K:
153 case BPF_S_ALU_ADD_X:
154 case BPF_S_ALU_SUB_K:
155 case BPF_S_ALU_SUB_X:
156 case BPF_S_ALU_MUL_K:
157 case BPF_S_ALU_MUL_X:
158 case BPF_S_ALU_DIV_X:
159 case BPF_S_ALU_AND_K:
160 case BPF_S_ALU_AND_X:
161 case BPF_S_ALU_OR_K:
162 case BPF_S_ALU_OR_X:
163 case BPF_S_ALU_LSH_K:
164 case BPF_S_ALU_LSH_X:
165 case BPF_S_ALU_RSH_K:
166 case BPF_S_ALU_RSH_X:
167 case BPF_S_ALU_NEG:
168 case BPF_S_LD_IMM:
169 case BPF_S_LDX_IMM:
170 case BPF_S_MISC_TAX:
171 case BPF_S_MISC_TXA:
172 case BPF_S_ALU_DIV_K:
173 case BPF_S_LD_MEM:
174 case BPF_S_LDX_MEM:
175 case BPF_S_ST:
176 case BPF_S_STX:
177 case BPF_S_JMP_JA:
178 case BPF_S_JMP_JEQ_K:
179 case BPF_S_JMP_JEQ_X:
180 case BPF_S_JMP_JGE_K:
181 case BPF_S_JMP_JGE_X:
182 case BPF_S_JMP_JGT_K:
183 case BPF_S_JMP_JGT_X:
184 case BPF_S_JMP_JSET_K:
185 case BPF_S_JMP_JSET_X:
186 continue;
187 default:
188 return -EINVAL;
189 }
190 }
191 return 0;
192}
193
194/**
195 * seccomp_run_filters - evaluates all seccomp filters against @syscall
196 * @syscall: number of the current system call
197 *
198 * Returns valid seccomp BPF response codes.
199 */
200static u32 seccomp_run_filters(int syscall)
201{
202 struct seccomp_filter *f;
203 u32 ret = SECCOMP_RET_ALLOW;
204
205 /* Ensure unexpected behavior doesn't result in failing open. */
206 if (WARN_ON(current->seccomp.filter == NULL))
207 return SECCOMP_RET_KILL;
208
209 /*
210 * All filters in the list are evaluated and the lowest BPF return
211 * value always takes priority (ignoring the DATA).
212 */
213 for (f = current->seccomp.filter; f; f = f->prev) {
214 u32 cur_ret = sk_run_filter(NULL, f->insns);
215 if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
216 ret = cur_ret;
217 }
218 return ret;
219}
220
221/**
222 * seccomp_attach_filter: Attaches a seccomp filter to current.
223 * @fprog: BPF program to install
224 *
225 * Returns 0 on success or an errno on failure.
226 */
227static long seccomp_attach_filter(struct sock_fprog *fprog)
228{
229 struct seccomp_filter *filter;
230 unsigned long fp_size = fprog->len * sizeof(struct sock_filter);
231 unsigned long total_insns = fprog->len;
232 long ret;
233
234 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
235 return -EINVAL;
236
237 for (filter = current->seccomp.filter; filter; filter = filter->prev)
238 total_insns += filter->len + 4; /* include a 4 instr penalty */
239 if (total_insns > MAX_INSNS_PER_PATH)
240 return -ENOMEM;
241
242 /*
243 * Installing a seccomp filter requires that the task have
244 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
245 * This avoids scenarios where unprivileged tasks can affect the
246 * behavior of privileged children.
247 */
248 if (!current->no_new_privs &&
249 security_capable_noaudit(current_cred(), current_user_ns(),
250 CAP_SYS_ADMIN) != 0)
251 return -EACCES;
252
253 /* Allocate a new seccomp_filter */
254 filter = kzalloc(sizeof(struct seccomp_filter) + fp_size,
255 GFP_KERNEL|__GFP_NOWARN);
256 if (!filter)
257 return -ENOMEM;
258 atomic_set(&filter->usage, 1);
259 filter->len = fprog->len;
260
261 /* Copy the instructions from fprog. */
262 ret = -EFAULT;
263 if (copy_from_user(filter->insns, fprog->filter, fp_size))
264 goto fail;
265
266 /* Check and rewrite the fprog via the skb checker */
267 ret = sk_chk_filter(filter->insns, filter->len);
268 if (ret)
269 goto fail;
270
271 /* Check and rewrite the fprog for seccomp use */
272 ret = seccomp_check_filter(filter->insns, filter->len);
273 if (ret)
274 goto fail;
275
276 /*
277 * If there is an existing filter, make it the prev and don't drop its
278 * task reference.
279 */
280 filter->prev = current->seccomp.filter;
281 current->seccomp.filter = filter;
282 return 0;
283fail:
284 kfree(filter);
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 */
294long 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(current, task_pt_regs(current));
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 ret = seccomp_run_filters(this_syscall);
400 data = ret & SECCOMP_RET_DATA;
401 ret &= SECCOMP_RET_ACTION;
402 switch (ret) {
403 case SECCOMP_RET_ERRNO:
404 /* Set the low-order 16-bits as a errno. */
405 syscall_set_return_value(current, task_pt_regs(current),
406 -data, 0);
407 goto skip;
408 case SECCOMP_RET_TRAP:
409 /* Show the handler the original registers. */
410 syscall_rollback(current, task_pt_regs(current));
411 /* Let the filter pass back 16 bits of data. */
412 seccomp_send_sigsys(this_syscall, data);
413 goto skip;
414 case SECCOMP_RET_TRACE:
415 /* Skip these calls if there is no tracer. */
416 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP))
417 goto skip;
418 /* Allow the BPF to provide the event message */
419 ptrace_event(PTRACE_EVENT_SECCOMP, data);
420 /*
421 * The delivery of a fatal signal during event
422 * notification may silently skip tracer notification.
423 * Terminating the task now avoids executing a system
424 * call that may not be intended.
425 */
426 if (fatal_signal_pending(current))
427 break;
428 return 0;
429 case SECCOMP_RET_ALLOW:
430 return 0;
431 case SECCOMP_RET_KILL:
432 default:
433 break;
434 }
435 exit_sig = SIGSYS;
436 break;
437 }
438#endif
439 default:
440 BUG();
441 }
442
443#ifdef SECCOMP_DEBUG
444 dump_stack();
445#endif
446 audit_seccomp(this_syscall, exit_sig, ret);
447 do_exit(exit_sig);
448#ifdef CONFIG_SECCOMP_FILTER
449skip:
450 audit_seccomp(this_syscall, exit_sig, ret);
451#endif
452 return -1;
453}
454
455long prctl_get_seccomp(void)
456{
457 return current->seccomp.mode;
458}
459
460/**
461 * prctl_set_seccomp: configures current->seccomp.mode
462 * @seccomp_mode: requested mode to use
463 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
464 *
465 * This function may be called repeatedly with a @seccomp_mode of
466 * SECCOMP_MODE_FILTER to install additional filters. Every filter
467 * successfully installed will be evaluated (in reverse order) for each system
468 * call the task makes.
469 *
470 * Once current->seccomp.mode is non-zero, it may not be changed.
471 *
472 * Returns 0 on success or -EINVAL on failure.
473 */
474long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
475{
476 long ret = -EINVAL;
477
478 if (current->seccomp.mode &&
479 current->seccomp.mode != seccomp_mode)
480 goto out;
481
482 switch (seccomp_mode) {
483 case SECCOMP_MODE_STRICT:
484 ret = 0;
485#ifdef TIF_NOTSC
486 disable_TSC();
487#endif
488 break;
489#ifdef CONFIG_SECCOMP_FILTER
490 case SECCOMP_MODE_FILTER:
491 ret = seccomp_attach_user_filter(filter);
492 if (ret)
493 goto out;
494 break;
495#endif
496 default:
497 goto out;
498 }
499
500 current->seccomp.mode = seccomp_mode;
501 set_thread_flag(TIF_SECCOMP);
502out:
503 return ret;
504}
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#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
33#include <asm/syscall.h>
34#endif
35
36#ifdef CONFIG_SECCOMP_FILTER
37#include <linux/file.h>
38#include <linux/filter.h>
39#include <linux/pid.h>
40#include <linux/ptrace.h>
41#include <linux/capability.h>
42#include <linux/tracehook.h>
43#include <linux/uaccess.h>
44#include <linux/anon_inodes.h>
45#include <linux/lockdep.h>
46
47/*
48 * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
49 * wrong direction flag in the ioctl number. This is the broken one,
50 * which the kernel needs to keep supporting until all userspaces stop
51 * using the wrong command number.
52 */
53#define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
54
55enum notify_state {
56 SECCOMP_NOTIFY_INIT,
57 SECCOMP_NOTIFY_SENT,
58 SECCOMP_NOTIFY_REPLIED,
59};
60
61struct seccomp_knotif {
62 /* The struct pid of the task whose filter triggered the notification */
63 struct task_struct *task;
64
65 /* The "cookie" for this request; this is unique for this filter. */
66 u64 id;
67
68 /*
69 * The seccomp data. This pointer is valid the entire time this
70 * notification is active, since it comes from __seccomp_filter which
71 * eclipses the entire lifecycle here.
72 */
73 const struct seccomp_data *data;
74
75 /*
76 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
77 * struct seccomp_knotif is created and starts out in INIT. Once the
78 * handler reads the notification off of an FD, it transitions to SENT.
79 * If a signal is received the state transitions back to INIT and
80 * another message is sent. When the userspace handler replies, state
81 * transitions to REPLIED.
82 */
83 enum notify_state state;
84
85 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
86 int error;
87 long val;
88 u32 flags;
89
90 /*
91 * Signals when this has changed states, such as the listener
92 * dying, a new seccomp addfd message, or changing to REPLIED
93 */
94 struct completion ready;
95
96 struct list_head list;
97
98 /* outstanding addfd requests */
99 struct list_head addfd;
100};
101
102/**
103 * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
104 *
105 * @file: A reference to the file to install in the other task
106 * @fd: The fd number to install it at. If the fd number is -1, it means the
107 * installing process should allocate the fd as normal.
108 * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
109 * is allowed.
110 * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
111 * @ret: The return value of the installing process. It is set to the fd num
112 * upon success (>= 0).
113 * @completion: Indicates that the installing process has completed fd
114 * installation, or gone away (either due to successful
115 * reply, or signal)
116 *
117 */
118struct seccomp_kaddfd {
119 struct file *file;
120 int fd;
121 unsigned int flags;
122 __u32 ioctl_flags;
123
124 union {
125 bool setfd;
126 /* To only be set on reply */
127 int ret;
128 };
129 struct completion completion;
130 struct list_head list;
131};
132
133/**
134 * struct notification - container for seccomp userspace notifications. Since
135 * most seccomp filters will not have notification listeners attached and this
136 * structure is fairly large, we store the notification-specific stuff in a
137 * separate structure.
138 *
139 * @request: A semaphore that users of this notification can wait on for
140 * changes. Actual reads and writes are still controlled with
141 * filter->notify_lock.
142 * @next_id: The id of the next request.
143 * @notifications: A list of struct seccomp_knotif elements.
144 */
145struct notification {
146 struct semaphore request;
147 u64 next_id;
148 struct list_head notifications;
149};
150
151#ifdef SECCOMP_ARCH_NATIVE
152/**
153 * struct action_cache - per-filter cache of seccomp actions per
154 * arch/syscall pair
155 *
156 * @allow_native: A bitmap where each bit represents whether the
157 * filter will always allow the syscall, for the
158 * native architecture.
159 * @allow_compat: A bitmap where each bit represents whether the
160 * filter will always allow the syscall, for the
161 * compat architecture.
162 */
163struct action_cache {
164 DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
165#ifdef SECCOMP_ARCH_COMPAT
166 DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
167#endif
168};
169#else
170struct action_cache { };
171
172static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
173 const struct seccomp_data *sd)
174{
175 return false;
176}
177
178static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
179{
180}
181#endif /* SECCOMP_ARCH_NATIVE */
182
183/**
184 * struct seccomp_filter - container for seccomp BPF programs
185 *
186 * @refs: Reference count to manage the object lifetime.
187 * A filter's reference count is incremented for each directly
188 * attached task, once for the dependent filter, and if
189 * requested for the user notifier. When @refs reaches zero,
190 * the filter can be freed.
191 * @users: A filter's @users count is incremented for each directly
192 * attached task (filter installation, fork(), thread_sync),
193 * and once for the dependent filter (tracked in filter->prev).
194 * When it reaches zero it indicates that no direct or indirect
195 * users of that filter exist. No new tasks can get associated with
196 * this filter after reaching 0. The @users count is always smaller
197 * or equal to @refs. Hence, reaching 0 for @users does not mean
198 * the filter can be freed.
199 * @cache: cache of arch/syscall mappings to actions
200 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
201 * @prev: points to a previously installed, or inherited, filter
202 * @prog: the BPF program to evaluate
203 * @notif: the struct that holds all notification related information
204 * @notify_lock: A lock for all notification-related accesses.
205 * @wqh: A wait queue for poll if a notifier is in use.
206 *
207 * seccomp_filter objects are organized in a tree linked via the @prev
208 * pointer. For any task, it appears to be a singly-linked list starting
209 * with current->seccomp.filter, the most recently attached or inherited filter.
210 * However, multiple filters may share a @prev node, by way of fork(), which
211 * results in a unidirectional tree existing in memory. This is similar to
212 * how namespaces work.
213 *
214 * seccomp_filter objects should never be modified after being attached
215 * to a task_struct (other than @refs).
216 */
217struct seccomp_filter {
218 refcount_t refs;
219 refcount_t users;
220 bool log;
221 struct action_cache cache;
222 struct seccomp_filter *prev;
223 struct bpf_prog *prog;
224 struct notification *notif;
225 struct mutex notify_lock;
226 wait_queue_head_t wqh;
227};
228
229/* Limit any path through the tree to 256KB worth of instructions. */
230#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
231
232/*
233 * Endianness is explicitly ignored and left for BPF program authors to manage
234 * as per the specific architecture.
235 */
236static void populate_seccomp_data(struct seccomp_data *sd)
237{
238 /*
239 * Instead of using current_pt_reg(), we're already doing the work
240 * to safely fetch "current", so just use "task" everywhere below.
241 */
242 struct task_struct *task = current;
243 struct pt_regs *regs = task_pt_regs(task);
244 unsigned long args[6];
245
246 sd->nr = syscall_get_nr(task, regs);
247 sd->arch = syscall_get_arch(task);
248 syscall_get_arguments(task, regs, args);
249 sd->args[0] = args[0];
250 sd->args[1] = args[1];
251 sd->args[2] = args[2];
252 sd->args[3] = args[3];
253 sd->args[4] = args[4];
254 sd->args[5] = args[5];
255 sd->instruction_pointer = KSTK_EIP(task);
256}
257
258/**
259 * seccomp_check_filter - verify seccomp filter code
260 * @filter: filter to verify
261 * @flen: length of filter
262 *
263 * Takes a previously checked filter (by bpf_check_classic) and
264 * redirects all filter code that loads struct sk_buff data
265 * and related data through seccomp_bpf_load. It also
266 * enforces length and alignment checking of those loads.
267 *
268 * Returns 0 if the rule set is legal or -EINVAL if not.
269 */
270static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
271{
272 int pc;
273 for (pc = 0; pc < flen; pc++) {
274 struct sock_filter *ftest = &filter[pc];
275 u16 code = ftest->code;
276 u32 k = ftest->k;
277
278 switch (code) {
279 case BPF_LD | BPF_W | BPF_ABS:
280 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
281 /* 32-bit aligned and not out of bounds. */
282 if (k >= sizeof(struct seccomp_data) || k & 3)
283 return -EINVAL;
284 continue;
285 case BPF_LD | BPF_W | BPF_LEN:
286 ftest->code = BPF_LD | BPF_IMM;
287 ftest->k = sizeof(struct seccomp_data);
288 continue;
289 case BPF_LDX | BPF_W | BPF_LEN:
290 ftest->code = BPF_LDX | BPF_IMM;
291 ftest->k = sizeof(struct seccomp_data);
292 continue;
293 /* Explicitly include allowed calls. */
294 case BPF_RET | BPF_K:
295 case BPF_RET | BPF_A:
296 case BPF_ALU | BPF_ADD | BPF_K:
297 case BPF_ALU | BPF_ADD | BPF_X:
298 case BPF_ALU | BPF_SUB | BPF_K:
299 case BPF_ALU | BPF_SUB | BPF_X:
300 case BPF_ALU | BPF_MUL | BPF_K:
301 case BPF_ALU | BPF_MUL | BPF_X:
302 case BPF_ALU | BPF_DIV | BPF_K:
303 case BPF_ALU | BPF_DIV | BPF_X:
304 case BPF_ALU | BPF_AND | BPF_K:
305 case BPF_ALU | BPF_AND | BPF_X:
306 case BPF_ALU | BPF_OR | BPF_K:
307 case BPF_ALU | BPF_OR | BPF_X:
308 case BPF_ALU | BPF_XOR | BPF_K:
309 case BPF_ALU | BPF_XOR | BPF_X:
310 case BPF_ALU | BPF_LSH | BPF_K:
311 case BPF_ALU | BPF_LSH | BPF_X:
312 case BPF_ALU | BPF_RSH | BPF_K:
313 case BPF_ALU | BPF_RSH | BPF_X:
314 case BPF_ALU | BPF_NEG:
315 case BPF_LD | BPF_IMM:
316 case BPF_LDX | BPF_IMM:
317 case BPF_MISC | BPF_TAX:
318 case BPF_MISC | BPF_TXA:
319 case BPF_LD | BPF_MEM:
320 case BPF_LDX | BPF_MEM:
321 case BPF_ST:
322 case BPF_STX:
323 case BPF_JMP | BPF_JA:
324 case BPF_JMP | BPF_JEQ | BPF_K:
325 case BPF_JMP | BPF_JEQ | BPF_X:
326 case BPF_JMP | BPF_JGE | BPF_K:
327 case BPF_JMP | BPF_JGE | BPF_X:
328 case BPF_JMP | BPF_JGT | BPF_K:
329 case BPF_JMP | BPF_JGT | BPF_X:
330 case BPF_JMP | BPF_JSET | BPF_K:
331 case BPF_JMP | BPF_JSET | BPF_X:
332 continue;
333 default:
334 return -EINVAL;
335 }
336 }
337 return 0;
338}
339
340#ifdef SECCOMP_ARCH_NATIVE
341static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
342 size_t bitmap_size,
343 int syscall_nr)
344{
345 if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
346 return false;
347 syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
348
349 return test_bit(syscall_nr, bitmap);
350}
351
352/**
353 * seccomp_cache_check_allow - lookup seccomp cache
354 * @sfilter: The seccomp filter
355 * @sd: The seccomp data to lookup the cache with
356 *
357 * Returns true if the seccomp_data is cached and allowed.
358 */
359static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
360 const struct seccomp_data *sd)
361{
362 int syscall_nr = sd->nr;
363 const struct action_cache *cache = &sfilter->cache;
364
365#ifndef SECCOMP_ARCH_COMPAT
366 /* A native-only architecture doesn't need to check sd->arch. */
367 return seccomp_cache_check_allow_bitmap(cache->allow_native,
368 SECCOMP_ARCH_NATIVE_NR,
369 syscall_nr);
370#else
371 if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
372 return seccomp_cache_check_allow_bitmap(cache->allow_native,
373 SECCOMP_ARCH_NATIVE_NR,
374 syscall_nr);
375 if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
376 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
377 SECCOMP_ARCH_COMPAT_NR,
378 syscall_nr);
379#endif /* SECCOMP_ARCH_COMPAT */
380
381 WARN_ON_ONCE(true);
382 return false;
383}
384#endif /* SECCOMP_ARCH_NATIVE */
385
386/**
387 * seccomp_run_filters - evaluates all seccomp filters against @sd
388 * @sd: optional seccomp data to be passed to filters
389 * @match: stores struct seccomp_filter that resulted in the return value,
390 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
391 * be unchanged.
392 *
393 * Returns valid seccomp BPF response codes.
394 */
395#define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
396static u32 seccomp_run_filters(const struct seccomp_data *sd,
397 struct seccomp_filter **match)
398{
399 u32 ret = SECCOMP_RET_ALLOW;
400 /* Make sure cross-thread synced filter points somewhere sane. */
401 struct seccomp_filter *f =
402 READ_ONCE(current->seccomp.filter);
403
404 /* Ensure unexpected behavior doesn't result in failing open. */
405 if (WARN_ON(f == NULL))
406 return SECCOMP_RET_KILL_PROCESS;
407
408 if (seccomp_cache_check_allow(f, sd))
409 return SECCOMP_RET_ALLOW;
410
411 /*
412 * All filters in the list are evaluated and the lowest BPF return
413 * value always takes priority (ignoring the DATA).
414 */
415 for (; f; f = f->prev) {
416 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
417
418 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
419 ret = cur_ret;
420 *match = f;
421 }
422 }
423 return ret;
424}
425#endif /* CONFIG_SECCOMP_FILTER */
426
427static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
428{
429 assert_spin_locked(¤t->sighand->siglock);
430
431 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
432 return false;
433
434 return true;
435}
436
437void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
438
439static inline void seccomp_assign_mode(struct task_struct *task,
440 unsigned long seccomp_mode,
441 unsigned long flags)
442{
443 assert_spin_locked(&task->sighand->siglock);
444
445 task->seccomp.mode = seccomp_mode;
446 /*
447 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
448 * filter) is set.
449 */
450 smp_mb__before_atomic();
451 /* Assume default seccomp processes want spec flaw mitigation. */
452 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
453 arch_seccomp_spec_mitigate(task);
454 set_task_syscall_work(task, SECCOMP);
455}
456
457#ifdef CONFIG_SECCOMP_FILTER
458/* Returns 1 if the parent is an ancestor of the child. */
459static int is_ancestor(struct seccomp_filter *parent,
460 struct seccomp_filter *child)
461{
462 /* NULL is the root ancestor. */
463 if (parent == NULL)
464 return 1;
465 for (; child; child = child->prev)
466 if (child == parent)
467 return 1;
468 return 0;
469}
470
471/**
472 * seccomp_can_sync_threads: checks if all threads can be synchronized
473 *
474 * Expects sighand and cred_guard_mutex locks to be held.
475 *
476 * Returns 0 on success, -ve on error, or the pid of a thread which was
477 * either not in the correct seccomp mode or did not have an ancestral
478 * seccomp filter.
479 */
480static inline pid_t seccomp_can_sync_threads(void)
481{
482 struct task_struct *thread, *caller;
483
484 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
485 assert_spin_locked(¤t->sighand->siglock);
486
487 /* Validate all threads being eligible for synchronization. */
488 caller = current;
489 for_each_thread(caller, thread) {
490 pid_t failed;
491
492 /* Skip current, since it is initiating the sync. */
493 if (thread == caller)
494 continue;
495
496 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
497 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
498 is_ancestor(thread->seccomp.filter,
499 caller->seccomp.filter)))
500 continue;
501
502 /* Return the first thread that cannot be synchronized. */
503 failed = task_pid_vnr(thread);
504 /* If the pid cannot be resolved, then return -ESRCH */
505 if (WARN_ON(failed == 0))
506 failed = -ESRCH;
507 return failed;
508 }
509
510 return 0;
511}
512
513static inline void seccomp_filter_free(struct seccomp_filter *filter)
514{
515 if (filter) {
516 bpf_prog_destroy(filter->prog);
517 kfree(filter);
518 }
519}
520
521static void __seccomp_filter_orphan(struct seccomp_filter *orig)
522{
523 while (orig && refcount_dec_and_test(&orig->users)) {
524 if (waitqueue_active(&orig->wqh))
525 wake_up_poll(&orig->wqh, EPOLLHUP);
526 orig = orig->prev;
527 }
528}
529
530static void __put_seccomp_filter(struct seccomp_filter *orig)
531{
532 /* Clean up single-reference branches iteratively. */
533 while (orig && refcount_dec_and_test(&orig->refs)) {
534 struct seccomp_filter *freeme = orig;
535 orig = orig->prev;
536 seccomp_filter_free(freeme);
537 }
538}
539
540static void __seccomp_filter_release(struct seccomp_filter *orig)
541{
542 /* Notify about any unused filters in the task's former filter tree. */
543 __seccomp_filter_orphan(orig);
544 /* Finally drop all references to the task's former tree. */
545 __put_seccomp_filter(orig);
546}
547
548/**
549 * seccomp_filter_release - Detach the task from its filter tree,
550 * drop its reference count, and notify
551 * about unused filters
552 *
553 * This function should only be called when the task is exiting as
554 * it detaches it from its filter tree. As such, READ_ONCE() and
555 * barriers are not needed here, as would normally be needed.
556 */
557void seccomp_filter_release(struct task_struct *tsk)
558{
559 struct seccomp_filter *orig = tsk->seccomp.filter;
560
561 /* We are effectively holding the siglock by not having any sighand. */
562 WARN_ON(tsk->sighand != NULL);
563
564 /* Detach task from its filter tree. */
565 tsk->seccomp.filter = NULL;
566 __seccomp_filter_release(orig);
567}
568
569/**
570 * seccomp_sync_threads: sets all threads to use current's filter
571 *
572 * Expects sighand and cred_guard_mutex locks to be held, and for
573 * seccomp_can_sync_threads() to have returned success already
574 * without dropping the locks.
575 *
576 */
577static inline void seccomp_sync_threads(unsigned long flags)
578{
579 struct task_struct *thread, *caller;
580
581 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
582 assert_spin_locked(¤t->sighand->siglock);
583
584 /* Synchronize all threads. */
585 caller = current;
586 for_each_thread(caller, thread) {
587 /* Skip current, since it needs no changes. */
588 if (thread == caller)
589 continue;
590
591 /* Get a task reference for the new leaf node. */
592 get_seccomp_filter(caller);
593
594 /*
595 * Drop the task reference to the shared ancestor since
596 * current's path will hold a reference. (This also
597 * allows a put before the assignment.)
598 */
599 __seccomp_filter_release(thread->seccomp.filter);
600
601 /* Make our new filter tree visible. */
602 smp_store_release(&thread->seccomp.filter,
603 caller->seccomp.filter);
604 atomic_set(&thread->seccomp.filter_count,
605 atomic_read(&caller->seccomp.filter_count));
606
607 /*
608 * Don't let an unprivileged task work around
609 * the no_new_privs restriction by creating
610 * a thread that sets it up, enters seccomp,
611 * then dies.
612 */
613 if (task_no_new_privs(caller))
614 task_set_no_new_privs(thread);
615
616 /*
617 * Opt the other thread into seccomp if needed.
618 * As threads are considered to be trust-realm
619 * equivalent (see ptrace_may_access), it is safe to
620 * allow one thread to transition the other.
621 */
622 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
623 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
624 flags);
625 }
626}
627
628/**
629 * seccomp_prepare_filter: Prepares a seccomp filter for use.
630 * @fprog: BPF program to install
631 *
632 * Returns filter on success or an ERR_PTR on failure.
633 */
634static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
635{
636 struct seccomp_filter *sfilter;
637 int ret;
638 const bool save_orig =
639#if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
640 true;
641#else
642 false;
643#endif
644
645 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
646 return ERR_PTR(-EINVAL);
647
648 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
649
650 /*
651 * Installing a seccomp filter requires that the task has
652 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
653 * This avoids scenarios where unprivileged tasks can affect the
654 * behavior of privileged children.
655 */
656 if (!task_no_new_privs(current) &&
657 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
658 return ERR_PTR(-EACCES);
659
660 /* Allocate a new seccomp_filter */
661 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
662 if (!sfilter)
663 return ERR_PTR(-ENOMEM);
664
665 mutex_init(&sfilter->notify_lock);
666 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
667 seccomp_check_filter, save_orig);
668 if (ret < 0) {
669 kfree(sfilter);
670 return ERR_PTR(ret);
671 }
672
673 refcount_set(&sfilter->refs, 1);
674 refcount_set(&sfilter->users, 1);
675 init_waitqueue_head(&sfilter->wqh);
676
677 return sfilter;
678}
679
680/**
681 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
682 * @user_filter: pointer to the user data containing a sock_fprog.
683 *
684 * Returns 0 on success and non-zero otherwise.
685 */
686static struct seccomp_filter *
687seccomp_prepare_user_filter(const char __user *user_filter)
688{
689 struct sock_fprog fprog;
690 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
691
692#ifdef CONFIG_COMPAT
693 if (in_compat_syscall()) {
694 struct compat_sock_fprog fprog32;
695 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
696 goto out;
697 fprog.len = fprog32.len;
698 fprog.filter = compat_ptr(fprog32.filter);
699 } else /* falls through to the if below. */
700#endif
701 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
702 goto out;
703 filter = seccomp_prepare_filter(&fprog);
704out:
705 return filter;
706}
707
708#ifdef SECCOMP_ARCH_NATIVE
709/**
710 * seccomp_is_const_allow - check if filter is constant allow with given data
711 * @fprog: The BPF programs
712 * @sd: The seccomp data to check against, only syscall number and arch
713 * number are considered constant.
714 */
715static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
716 struct seccomp_data *sd)
717{
718 unsigned int reg_value = 0;
719 unsigned int pc;
720 bool op_res;
721
722 if (WARN_ON_ONCE(!fprog))
723 return false;
724
725 for (pc = 0; pc < fprog->len; pc++) {
726 struct sock_filter *insn = &fprog->filter[pc];
727 u16 code = insn->code;
728 u32 k = insn->k;
729
730 switch (code) {
731 case BPF_LD | BPF_W | BPF_ABS:
732 switch (k) {
733 case offsetof(struct seccomp_data, nr):
734 reg_value = sd->nr;
735 break;
736 case offsetof(struct seccomp_data, arch):
737 reg_value = sd->arch;
738 break;
739 default:
740 /* can't optimize (non-constant value load) */
741 return false;
742 }
743 break;
744 case BPF_RET | BPF_K:
745 /* reached return with constant values only, check allow */
746 return k == SECCOMP_RET_ALLOW;
747 case BPF_JMP | BPF_JA:
748 pc += insn->k;
749 break;
750 case BPF_JMP | BPF_JEQ | BPF_K:
751 case BPF_JMP | BPF_JGE | BPF_K:
752 case BPF_JMP | BPF_JGT | BPF_K:
753 case BPF_JMP | BPF_JSET | BPF_K:
754 switch (BPF_OP(code)) {
755 case BPF_JEQ:
756 op_res = reg_value == k;
757 break;
758 case BPF_JGE:
759 op_res = reg_value >= k;
760 break;
761 case BPF_JGT:
762 op_res = reg_value > k;
763 break;
764 case BPF_JSET:
765 op_res = !!(reg_value & k);
766 break;
767 default:
768 /* can't optimize (unknown jump) */
769 return false;
770 }
771
772 pc += op_res ? insn->jt : insn->jf;
773 break;
774 case BPF_ALU | BPF_AND | BPF_K:
775 reg_value &= k;
776 break;
777 default:
778 /* can't optimize (unknown insn) */
779 return false;
780 }
781 }
782
783 /* ran off the end of the filter?! */
784 WARN_ON(1);
785 return false;
786}
787
788static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
789 void *bitmap, const void *bitmap_prev,
790 size_t bitmap_size, int arch)
791{
792 struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
793 struct seccomp_data sd;
794 int nr;
795
796 if (bitmap_prev) {
797 /* The new filter must be as restrictive as the last. */
798 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
799 } else {
800 /* Before any filters, all syscalls are always allowed. */
801 bitmap_fill(bitmap, bitmap_size);
802 }
803
804 for (nr = 0; nr < bitmap_size; nr++) {
805 /* No bitmap change: not a cacheable action. */
806 if (!test_bit(nr, bitmap))
807 continue;
808
809 sd.nr = nr;
810 sd.arch = arch;
811
812 /* No bitmap change: continue to always allow. */
813 if (seccomp_is_const_allow(fprog, &sd))
814 continue;
815
816 /*
817 * Not a cacheable action: always run filters.
818 * atomic clear_bit() not needed, filter not visible yet.
819 */
820 __clear_bit(nr, bitmap);
821 }
822}
823
824/**
825 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
826 * @sfilter: The seccomp filter
827 *
828 * Returns 0 if successful or -errno if error occurred.
829 */
830static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
831{
832 struct action_cache *cache = &sfilter->cache;
833 const struct action_cache *cache_prev =
834 sfilter->prev ? &sfilter->prev->cache : NULL;
835
836 seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
837 cache_prev ? cache_prev->allow_native : NULL,
838 SECCOMP_ARCH_NATIVE_NR,
839 SECCOMP_ARCH_NATIVE);
840
841#ifdef SECCOMP_ARCH_COMPAT
842 seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
843 cache_prev ? cache_prev->allow_compat : NULL,
844 SECCOMP_ARCH_COMPAT_NR,
845 SECCOMP_ARCH_COMPAT);
846#endif /* SECCOMP_ARCH_COMPAT */
847}
848#endif /* SECCOMP_ARCH_NATIVE */
849
850/**
851 * seccomp_attach_filter: validate and attach filter
852 * @flags: flags to change filter behavior
853 * @filter: seccomp filter to add to the current process
854 *
855 * Caller must be holding current->sighand->siglock lock.
856 *
857 * Returns 0 on success, -ve on error, or
858 * - in TSYNC mode: the pid of a thread which was either not in the correct
859 * seccomp mode or did not have an ancestral seccomp filter
860 * - in NEW_LISTENER mode: the fd of the new listener
861 */
862static long seccomp_attach_filter(unsigned int flags,
863 struct seccomp_filter *filter)
864{
865 unsigned long total_insns;
866 struct seccomp_filter *walker;
867
868 assert_spin_locked(¤t->sighand->siglock);
869
870 /* Validate resulting filter length. */
871 total_insns = filter->prog->len;
872 for (walker = current->seccomp.filter; walker; walker = walker->prev)
873 total_insns += walker->prog->len + 4; /* 4 instr penalty */
874 if (total_insns > MAX_INSNS_PER_PATH)
875 return -ENOMEM;
876
877 /* If thread sync has been requested, check that it is possible. */
878 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
879 int ret;
880
881 ret = seccomp_can_sync_threads();
882 if (ret) {
883 if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
884 return -ESRCH;
885 else
886 return ret;
887 }
888 }
889
890 /* Set log flag, if present. */
891 if (flags & SECCOMP_FILTER_FLAG_LOG)
892 filter->log = true;
893
894 /*
895 * If there is an existing filter, make it the prev and don't drop its
896 * task reference.
897 */
898 filter->prev = current->seccomp.filter;
899 seccomp_cache_prepare(filter);
900 current->seccomp.filter = filter;
901 atomic_inc(¤t->seccomp.filter_count);
902
903 /* Now that the new filter is in place, synchronize to all threads. */
904 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
905 seccomp_sync_threads(flags);
906
907 return 0;
908}
909
910static void __get_seccomp_filter(struct seccomp_filter *filter)
911{
912 refcount_inc(&filter->refs);
913}
914
915/* get_seccomp_filter - increments the reference count of the filter on @tsk */
916void get_seccomp_filter(struct task_struct *tsk)
917{
918 struct seccomp_filter *orig = tsk->seccomp.filter;
919 if (!orig)
920 return;
921 __get_seccomp_filter(orig);
922 refcount_inc(&orig->users);
923}
924
925static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
926{
927 clear_siginfo(info);
928 info->si_signo = SIGSYS;
929 info->si_code = SYS_SECCOMP;
930 info->si_call_addr = (void __user *)KSTK_EIP(current);
931 info->si_errno = reason;
932 info->si_arch = syscall_get_arch(current);
933 info->si_syscall = syscall;
934}
935
936/**
937 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
938 * @syscall: syscall number to send to userland
939 * @reason: filter-supplied reason code to send to userland (via si_errno)
940 *
941 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
942 */
943static void seccomp_send_sigsys(int syscall, int reason)
944{
945 struct kernel_siginfo info;
946 seccomp_init_siginfo(&info, syscall, reason);
947 force_sig_info(&info);
948}
949#endif /* CONFIG_SECCOMP_FILTER */
950
951/* For use with seccomp_actions_logged */
952#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
953#define SECCOMP_LOG_KILL_THREAD (1 << 1)
954#define SECCOMP_LOG_TRAP (1 << 2)
955#define SECCOMP_LOG_ERRNO (1 << 3)
956#define SECCOMP_LOG_TRACE (1 << 4)
957#define SECCOMP_LOG_LOG (1 << 5)
958#define SECCOMP_LOG_ALLOW (1 << 6)
959#define SECCOMP_LOG_USER_NOTIF (1 << 7)
960
961static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
962 SECCOMP_LOG_KILL_THREAD |
963 SECCOMP_LOG_TRAP |
964 SECCOMP_LOG_ERRNO |
965 SECCOMP_LOG_USER_NOTIF |
966 SECCOMP_LOG_TRACE |
967 SECCOMP_LOG_LOG;
968
969static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
970 bool requested)
971{
972 bool log = false;
973
974 switch (action) {
975 case SECCOMP_RET_ALLOW:
976 break;
977 case SECCOMP_RET_TRAP:
978 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
979 break;
980 case SECCOMP_RET_ERRNO:
981 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
982 break;
983 case SECCOMP_RET_TRACE:
984 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
985 break;
986 case SECCOMP_RET_USER_NOTIF:
987 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
988 break;
989 case SECCOMP_RET_LOG:
990 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
991 break;
992 case SECCOMP_RET_KILL_THREAD:
993 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
994 break;
995 case SECCOMP_RET_KILL_PROCESS:
996 default:
997 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
998 }
999
1000 /*
1001 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1002 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1003 * any action from being logged by removing the action name from the
1004 * seccomp_actions_logged sysctl.
1005 */
1006 if (!log)
1007 return;
1008
1009 audit_seccomp(syscall, signr, action);
1010}
1011
1012/*
1013 * Secure computing mode 1 allows only read/write/exit/sigreturn.
1014 * To be fully secure this must be combined with rlimit
1015 * to limit the stack allocations too.
1016 */
1017static const int mode1_syscalls[] = {
1018 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1019 -1, /* negative terminated */
1020};
1021
1022static void __secure_computing_strict(int this_syscall)
1023{
1024 const int *allowed_syscalls = mode1_syscalls;
1025#ifdef CONFIG_COMPAT
1026 if (in_compat_syscall())
1027 allowed_syscalls = get_compat_mode1_syscalls();
1028#endif
1029 do {
1030 if (*allowed_syscalls == this_syscall)
1031 return;
1032 } while (*++allowed_syscalls != -1);
1033
1034#ifdef SECCOMP_DEBUG
1035 dump_stack();
1036#endif
1037 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1038 do_exit(SIGKILL);
1039}
1040
1041#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1042void secure_computing_strict(int this_syscall)
1043{
1044 int mode = current->seccomp.mode;
1045
1046 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1047 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1048 return;
1049
1050 if (mode == SECCOMP_MODE_DISABLED)
1051 return;
1052 else if (mode == SECCOMP_MODE_STRICT)
1053 __secure_computing_strict(this_syscall);
1054 else
1055 BUG();
1056}
1057#else
1058
1059#ifdef CONFIG_SECCOMP_FILTER
1060static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1061{
1062 /*
1063 * Note: overflow is ok here, the id just needs to be unique per
1064 * filter.
1065 */
1066 lockdep_assert_held(&filter->notify_lock);
1067 return filter->notif->next_id++;
1068}
1069
1070static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
1071{
1072 int fd;
1073
1074 /*
1075 * Remove the notification, and reset the list pointers, indicating
1076 * that it has been handled.
1077 */
1078 list_del_init(&addfd->list);
1079 if (!addfd->setfd)
1080 fd = receive_fd(addfd->file, addfd->flags);
1081 else
1082 fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1083 addfd->ret = fd;
1084
1085 if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1086 /* If we fail reset and return an error to the notifier */
1087 if (fd < 0) {
1088 n->state = SECCOMP_NOTIFY_SENT;
1089 } else {
1090 /* Return the FD we just added */
1091 n->flags = 0;
1092 n->error = 0;
1093 n->val = fd;
1094 }
1095 }
1096
1097 /*
1098 * Mark the notification as completed. From this point, addfd mem
1099 * might be invalidated and we can't safely read it anymore.
1100 */
1101 complete(&addfd->completion);
1102}
1103
1104static int seccomp_do_user_notification(int this_syscall,
1105 struct seccomp_filter *match,
1106 const struct seccomp_data *sd)
1107{
1108 int err;
1109 u32 flags = 0;
1110 long ret = 0;
1111 struct seccomp_knotif n = {};
1112 struct seccomp_kaddfd *addfd, *tmp;
1113
1114 mutex_lock(&match->notify_lock);
1115 err = -ENOSYS;
1116 if (!match->notif)
1117 goto out;
1118
1119 n.task = current;
1120 n.state = SECCOMP_NOTIFY_INIT;
1121 n.data = sd;
1122 n.id = seccomp_next_notify_id(match);
1123 init_completion(&n.ready);
1124 list_add(&n.list, &match->notif->notifications);
1125 INIT_LIST_HEAD(&n.addfd);
1126
1127 up(&match->notif->request);
1128 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1129
1130 /*
1131 * This is where we wait for a reply from userspace.
1132 */
1133 do {
1134 mutex_unlock(&match->notify_lock);
1135 err = wait_for_completion_interruptible(&n.ready);
1136 mutex_lock(&match->notify_lock);
1137 if (err != 0)
1138 goto interrupted;
1139
1140 addfd = list_first_entry_or_null(&n.addfd,
1141 struct seccomp_kaddfd, list);
1142 /* Check if we were woken up by a addfd message */
1143 if (addfd)
1144 seccomp_handle_addfd(addfd, &n);
1145
1146 } while (n.state != SECCOMP_NOTIFY_REPLIED);
1147
1148 ret = n.val;
1149 err = n.error;
1150 flags = n.flags;
1151
1152interrupted:
1153 /* If there were any pending addfd calls, clear them out */
1154 list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1155 /* The process went away before we got a chance to handle it */
1156 addfd->ret = -ESRCH;
1157 list_del_init(&addfd->list);
1158 complete(&addfd->completion);
1159 }
1160
1161 /*
1162 * Note that it's possible the listener died in between the time when
1163 * we were notified of a response (or a signal) and when we were able to
1164 * re-acquire the lock, so only delete from the list if the
1165 * notification actually exists.
1166 *
1167 * Also note that this test is only valid because there's no way to
1168 * *reattach* to a notifier right now. If one is added, we'll need to
1169 * keep track of the notif itself and make sure they match here.
1170 */
1171 if (match->notif)
1172 list_del(&n.list);
1173out:
1174 mutex_unlock(&match->notify_lock);
1175
1176 /* Userspace requests to continue the syscall. */
1177 if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1178 return 0;
1179
1180 syscall_set_return_value(current, current_pt_regs(),
1181 err, ret);
1182 return -1;
1183}
1184
1185static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1186 const bool recheck_after_trace)
1187{
1188 u32 filter_ret, action;
1189 struct seccomp_filter *match = NULL;
1190 int data;
1191 struct seccomp_data sd_local;
1192
1193 /*
1194 * Make sure that any changes to mode from another thread have
1195 * been seen after SYSCALL_WORK_SECCOMP was seen.
1196 */
1197 smp_rmb();
1198
1199 if (!sd) {
1200 populate_seccomp_data(&sd_local);
1201 sd = &sd_local;
1202 }
1203
1204 filter_ret = seccomp_run_filters(sd, &match);
1205 data = filter_ret & SECCOMP_RET_DATA;
1206 action = filter_ret & SECCOMP_RET_ACTION_FULL;
1207
1208 switch (action) {
1209 case SECCOMP_RET_ERRNO:
1210 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1211 if (data > MAX_ERRNO)
1212 data = MAX_ERRNO;
1213 syscall_set_return_value(current, current_pt_regs(),
1214 -data, 0);
1215 goto skip;
1216
1217 case SECCOMP_RET_TRAP:
1218 /* Show the handler the original registers. */
1219 syscall_rollback(current, current_pt_regs());
1220 /* Let the filter pass back 16 bits of data. */
1221 seccomp_send_sigsys(this_syscall, data);
1222 goto skip;
1223
1224 case SECCOMP_RET_TRACE:
1225 /* We've been put in this state by the ptracer already. */
1226 if (recheck_after_trace)
1227 return 0;
1228
1229 /* ENOSYS these calls if there is no tracer attached. */
1230 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1231 syscall_set_return_value(current,
1232 current_pt_regs(),
1233 -ENOSYS, 0);
1234 goto skip;
1235 }
1236
1237 /* Allow the BPF to provide the event message */
1238 ptrace_event(PTRACE_EVENT_SECCOMP, data);
1239 /*
1240 * The delivery of a fatal signal during event
1241 * notification may silently skip tracer notification,
1242 * which could leave us with a potentially unmodified
1243 * syscall that the tracer would have liked to have
1244 * changed. Since the process is about to die, we just
1245 * force the syscall to be skipped and let the signal
1246 * kill the process and correctly handle any tracer exit
1247 * notifications.
1248 */
1249 if (fatal_signal_pending(current))
1250 goto skip;
1251 /* Check if the tracer forced the syscall to be skipped. */
1252 this_syscall = syscall_get_nr(current, current_pt_regs());
1253 if (this_syscall < 0)
1254 goto skip;
1255
1256 /*
1257 * Recheck the syscall, since it may have changed. This
1258 * intentionally uses a NULL struct seccomp_data to force
1259 * a reload of all registers. This does not goto skip since
1260 * a skip would have already been reported.
1261 */
1262 if (__seccomp_filter(this_syscall, NULL, true))
1263 return -1;
1264
1265 return 0;
1266
1267 case SECCOMP_RET_USER_NOTIF:
1268 if (seccomp_do_user_notification(this_syscall, match, sd))
1269 goto skip;
1270
1271 return 0;
1272
1273 case SECCOMP_RET_LOG:
1274 seccomp_log(this_syscall, 0, action, true);
1275 return 0;
1276
1277 case SECCOMP_RET_ALLOW:
1278 /*
1279 * Note that the "match" filter will always be NULL for
1280 * this action since SECCOMP_RET_ALLOW is the starting
1281 * state in seccomp_run_filters().
1282 */
1283 return 0;
1284
1285 case SECCOMP_RET_KILL_THREAD:
1286 case SECCOMP_RET_KILL_PROCESS:
1287 default:
1288 seccomp_log(this_syscall, SIGSYS, action, true);
1289 /* Dump core only if this is the last remaining thread. */
1290 if (action != SECCOMP_RET_KILL_THREAD ||
1291 get_nr_threads(current) == 1) {
1292 kernel_siginfo_t info;
1293
1294 /* Show the original registers in the dump. */
1295 syscall_rollback(current, current_pt_regs());
1296 /* Trigger a manual coredump since do_exit skips it. */
1297 seccomp_init_siginfo(&info, this_syscall, data);
1298 do_coredump(&info);
1299 }
1300 if (action == SECCOMP_RET_KILL_THREAD)
1301 do_exit(SIGSYS);
1302 else
1303 do_group_exit(SIGSYS);
1304 }
1305
1306 unreachable();
1307
1308skip:
1309 seccomp_log(this_syscall, 0, action, match ? match->log : false);
1310 return -1;
1311}
1312#else
1313static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1314 const bool recheck_after_trace)
1315{
1316 BUG();
1317
1318 return -1;
1319}
1320#endif
1321
1322int __secure_computing(const struct seccomp_data *sd)
1323{
1324 int mode = current->seccomp.mode;
1325 int this_syscall;
1326
1327 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1328 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1329 return 0;
1330
1331 this_syscall = sd ? sd->nr :
1332 syscall_get_nr(current, current_pt_regs());
1333
1334 switch (mode) {
1335 case SECCOMP_MODE_STRICT:
1336 __secure_computing_strict(this_syscall); /* may call do_exit */
1337 return 0;
1338 case SECCOMP_MODE_FILTER:
1339 return __seccomp_filter(this_syscall, sd, false);
1340 default:
1341 BUG();
1342 }
1343}
1344#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1345
1346long prctl_get_seccomp(void)
1347{
1348 return current->seccomp.mode;
1349}
1350
1351/**
1352 * seccomp_set_mode_strict: internal function for setting strict seccomp
1353 *
1354 * Once current->seccomp.mode is non-zero, it may not be changed.
1355 *
1356 * Returns 0 on success or -EINVAL on failure.
1357 */
1358static long seccomp_set_mode_strict(void)
1359{
1360 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1361 long ret = -EINVAL;
1362
1363 spin_lock_irq(¤t->sighand->siglock);
1364
1365 if (!seccomp_may_assign_mode(seccomp_mode))
1366 goto out;
1367
1368#ifdef TIF_NOTSC
1369 disable_TSC();
1370#endif
1371 seccomp_assign_mode(current, seccomp_mode, 0);
1372 ret = 0;
1373
1374out:
1375 spin_unlock_irq(¤t->sighand->siglock);
1376
1377 return ret;
1378}
1379
1380#ifdef CONFIG_SECCOMP_FILTER
1381static void seccomp_notify_free(struct seccomp_filter *filter)
1382{
1383 kfree(filter->notif);
1384 filter->notif = NULL;
1385}
1386
1387static void seccomp_notify_detach(struct seccomp_filter *filter)
1388{
1389 struct seccomp_knotif *knotif;
1390
1391 if (!filter)
1392 return;
1393
1394 mutex_lock(&filter->notify_lock);
1395
1396 /*
1397 * If this file is being closed because e.g. the task who owned it
1398 * died, let's wake everyone up who was waiting on us.
1399 */
1400 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1401 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1402 continue;
1403
1404 knotif->state = SECCOMP_NOTIFY_REPLIED;
1405 knotif->error = -ENOSYS;
1406 knotif->val = 0;
1407
1408 /*
1409 * We do not need to wake up any pending addfd messages, as
1410 * the notifier will do that for us, as this just looks
1411 * like a standard reply.
1412 */
1413 complete(&knotif->ready);
1414 }
1415
1416 seccomp_notify_free(filter);
1417 mutex_unlock(&filter->notify_lock);
1418}
1419
1420static int seccomp_notify_release(struct inode *inode, struct file *file)
1421{
1422 struct seccomp_filter *filter = file->private_data;
1423
1424 seccomp_notify_detach(filter);
1425 __put_seccomp_filter(filter);
1426 return 0;
1427}
1428
1429/* must be called with notif_lock held */
1430static inline struct seccomp_knotif *
1431find_notification(struct seccomp_filter *filter, u64 id)
1432{
1433 struct seccomp_knotif *cur;
1434
1435 lockdep_assert_held(&filter->notify_lock);
1436
1437 list_for_each_entry(cur, &filter->notif->notifications, list) {
1438 if (cur->id == id)
1439 return cur;
1440 }
1441
1442 return NULL;
1443}
1444
1445
1446static long seccomp_notify_recv(struct seccomp_filter *filter,
1447 void __user *buf)
1448{
1449 struct seccomp_knotif *knotif = NULL, *cur;
1450 struct seccomp_notif unotif;
1451 ssize_t ret;
1452
1453 /* Verify that we're not given garbage to keep struct extensible. */
1454 ret = check_zeroed_user(buf, sizeof(unotif));
1455 if (ret < 0)
1456 return ret;
1457 if (!ret)
1458 return -EINVAL;
1459
1460 memset(&unotif, 0, sizeof(unotif));
1461
1462 ret = down_interruptible(&filter->notif->request);
1463 if (ret < 0)
1464 return ret;
1465
1466 mutex_lock(&filter->notify_lock);
1467 list_for_each_entry(cur, &filter->notif->notifications, list) {
1468 if (cur->state == SECCOMP_NOTIFY_INIT) {
1469 knotif = cur;
1470 break;
1471 }
1472 }
1473
1474 /*
1475 * If we didn't find a notification, it could be that the task was
1476 * interrupted by a fatal signal between the time we were woken and
1477 * when we were able to acquire the rw lock.
1478 */
1479 if (!knotif) {
1480 ret = -ENOENT;
1481 goto out;
1482 }
1483
1484 unotif.id = knotif->id;
1485 unotif.pid = task_pid_vnr(knotif->task);
1486 unotif.data = *(knotif->data);
1487
1488 knotif->state = SECCOMP_NOTIFY_SENT;
1489 wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1490 ret = 0;
1491out:
1492 mutex_unlock(&filter->notify_lock);
1493
1494 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1495 ret = -EFAULT;
1496
1497 /*
1498 * Userspace screwed up. To make sure that we keep this
1499 * notification alive, let's reset it back to INIT. It
1500 * may have died when we released the lock, so we need to make
1501 * sure it's still around.
1502 */
1503 mutex_lock(&filter->notify_lock);
1504 knotif = find_notification(filter, unotif.id);
1505 if (knotif) {
1506 knotif->state = SECCOMP_NOTIFY_INIT;
1507 up(&filter->notif->request);
1508 }
1509 mutex_unlock(&filter->notify_lock);
1510 }
1511
1512 return ret;
1513}
1514
1515static long seccomp_notify_send(struct seccomp_filter *filter,
1516 void __user *buf)
1517{
1518 struct seccomp_notif_resp resp = {};
1519 struct seccomp_knotif *knotif;
1520 long ret;
1521
1522 if (copy_from_user(&resp, buf, sizeof(resp)))
1523 return -EFAULT;
1524
1525 if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1526 return -EINVAL;
1527
1528 if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1529 (resp.error || resp.val))
1530 return -EINVAL;
1531
1532 ret = mutex_lock_interruptible(&filter->notify_lock);
1533 if (ret < 0)
1534 return ret;
1535
1536 knotif = find_notification(filter, resp.id);
1537 if (!knotif) {
1538 ret = -ENOENT;
1539 goto out;
1540 }
1541
1542 /* Allow exactly one reply. */
1543 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1544 ret = -EINPROGRESS;
1545 goto out;
1546 }
1547
1548 ret = 0;
1549 knotif->state = SECCOMP_NOTIFY_REPLIED;
1550 knotif->error = resp.error;
1551 knotif->val = resp.val;
1552 knotif->flags = resp.flags;
1553 complete(&knotif->ready);
1554out:
1555 mutex_unlock(&filter->notify_lock);
1556 return ret;
1557}
1558
1559static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1560 void __user *buf)
1561{
1562 struct seccomp_knotif *knotif;
1563 u64 id;
1564 long ret;
1565
1566 if (copy_from_user(&id, buf, sizeof(id)))
1567 return -EFAULT;
1568
1569 ret = mutex_lock_interruptible(&filter->notify_lock);
1570 if (ret < 0)
1571 return ret;
1572
1573 knotif = find_notification(filter, id);
1574 if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1575 ret = 0;
1576 else
1577 ret = -ENOENT;
1578
1579 mutex_unlock(&filter->notify_lock);
1580 return ret;
1581}
1582
1583static long seccomp_notify_addfd(struct seccomp_filter *filter,
1584 struct seccomp_notif_addfd __user *uaddfd,
1585 unsigned int size)
1586{
1587 struct seccomp_notif_addfd addfd;
1588 struct seccomp_knotif *knotif;
1589 struct seccomp_kaddfd kaddfd;
1590 int ret;
1591
1592 BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1593 BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1594
1595 if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1596 return -EINVAL;
1597
1598 ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1599 if (ret)
1600 return ret;
1601
1602 if (addfd.newfd_flags & ~O_CLOEXEC)
1603 return -EINVAL;
1604
1605 if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
1606 return -EINVAL;
1607
1608 if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1609 return -EINVAL;
1610
1611 kaddfd.file = fget(addfd.srcfd);
1612 if (!kaddfd.file)
1613 return -EBADF;
1614
1615 kaddfd.ioctl_flags = addfd.flags;
1616 kaddfd.flags = addfd.newfd_flags;
1617 kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1618 kaddfd.fd = addfd.newfd;
1619 init_completion(&kaddfd.completion);
1620
1621 ret = mutex_lock_interruptible(&filter->notify_lock);
1622 if (ret < 0)
1623 goto out;
1624
1625 knotif = find_notification(filter, addfd.id);
1626 if (!knotif) {
1627 ret = -ENOENT;
1628 goto out_unlock;
1629 }
1630
1631 /*
1632 * We do not want to allow for FD injection to occur before the
1633 * notification has been picked up by a userspace handler, or after
1634 * the notification has been replied to.
1635 */
1636 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1637 ret = -EINPROGRESS;
1638 goto out_unlock;
1639 }
1640
1641 if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1642 /*
1643 * Disallow queuing an atomic addfd + send reply while there are
1644 * some addfd requests still to process.
1645 *
1646 * There is no clear reason to support it and allows us to keep
1647 * the loop on the other side straight-forward.
1648 */
1649 if (!list_empty(&knotif->addfd)) {
1650 ret = -EBUSY;
1651 goto out_unlock;
1652 }
1653
1654 /* Allow exactly only one reply */
1655 knotif->state = SECCOMP_NOTIFY_REPLIED;
1656 }
1657
1658 list_add(&kaddfd.list, &knotif->addfd);
1659 complete(&knotif->ready);
1660 mutex_unlock(&filter->notify_lock);
1661
1662 /* Now we wait for it to be processed or be interrupted */
1663 ret = wait_for_completion_interruptible(&kaddfd.completion);
1664 if (ret == 0) {
1665 /*
1666 * We had a successful completion. The other side has already
1667 * removed us from the addfd queue, and
1668 * wait_for_completion_interruptible has a memory barrier upon
1669 * success that lets us read this value directly without
1670 * locking.
1671 */
1672 ret = kaddfd.ret;
1673 goto out;
1674 }
1675
1676 mutex_lock(&filter->notify_lock);
1677 /*
1678 * Even though we were woken up by a signal and not a successful
1679 * completion, a completion may have happened in the mean time.
1680 *
1681 * We need to check again if the addfd request has been handled,
1682 * and if not, we will remove it from the queue.
1683 */
1684 if (list_empty(&kaddfd.list))
1685 ret = kaddfd.ret;
1686 else
1687 list_del(&kaddfd.list);
1688
1689out_unlock:
1690 mutex_unlock(&filter->notify_lock);
1691out:
1692 fput(kaddfd.file);
1693
1694 return ret;
1695}
1696
1697static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1698 unsigned long arg)
1699{
1700 struct seccomp_filter *filter = file->private_data;
1701 void __user *buf = (void __user *)arg;
1702
1703 /* Fixed-size ioctls */
1704 switch (cmd) {
1705 case SECCOMP_IOCTL_NOTIF_RECV:
1706 return seccomp_notify_recv(filter, buf);
1707 case SECCOMP_IOCTL_NOTIF_SEND:
1708 return seccomp_notify_send(filter, buf);
1709 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1710 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1711 return seccomp_notify_id_valid(filter, buf);
1712 }
1713
1714 /* Extensible Argument ioctls */
1715#define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1716 switch (EA_IOCTL(cmd)) {
1717 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1718 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1719 default:
1720 return -EINVAL;
1721 }
1722}
1723
1724static __poll_t seccomp_notify_poll(struct file *file,
1725 struct poll_table_struct *poll_tab)
1726{
1727 struct seccomp_filter *filter = file->private_data;
1728 __poll_t ret = 0;
1729 struct seccomp_knotif *cur;
1730
1731 poll_wait(file, &filter->wqh, poll_tab);
1732
1733 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1734 return EPOLLERR;
1735
1736 list_for_each_entry(cur, &filter->notif->notifications, list) {
1737 if (cur->state == SECCOMP_NOTIFY_INIT)
1738 ret |= EPOLLIN | EPOLLRDNORM;
1739 if (cur->state == SECCOMP_NOTIFY_SENT)
1740 ret |= EPOLLOUT | EPOLLWRNORM;
1741 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1742 break;
1743 }
1744
1745 mutex_unlock(&filter->notify_lock);
1746
1747 if (refcount_read(&filter->users) == 0)
1748 ret |= EPOLLHUP;
1749
1750 return ret;
1751}
1752
1753static const struct file_operations seccomp_notify_ops = {
1754 .poll = seccomp_notify_poll,
1755 .release = seccomp_notify_release,
1756 .unlocked_ioctl = seccomp_notify_ioctl,
1757 .compat_ioctl = seccomp_notify_ioctl,
1758};
1759
1760static struct file *init_listener(struct seccomp_filter *filter)
1761{
1762 struct file *ret;
1763
1764 ret = ERR_PTR(-ENOMEM);
1765 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1766 if (!filter->notif)
1767 goto out;
1768
1769 sema_init(&filter->notif->request, 0);
1770 filter->notif->next_id = get_random_u64();
1771 INIT_LIST_HEAD(&filter->notif->notifications);
1772
1773 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1774 filter, O_RDWR);
1775 if (IS_ERR(ret))
1776 goto out_notif;
1777
1778 /* The file has a reference to it now */
1779 __get_seccomp_filter(filter);
1780
1781out_notif:
1782 if (IS_ERR(ret))
1783 seccomp_notify_free(filter);
1784out:
1785 return ret;
1786}
1787
1788/*
1789 * Does @new_child have a listener while an ancestor also has a listener?
1790 * If so, we'll want to reject this filter.
1791 * This only has to be tested for the current process, even in the TSYNC case,
1792 * because TSYNC installs @child with the same parent on all threads.
1793 * Note that @new_child is not hooked up to its parent at this point yet, so
1794 * we use current->seccomp.filter.
1795 */
1796static bool has_duplicate_listener(struct seccomp_filter *new_child)
1797{
1798 struct seccomp_filter *cur;
1799
1800 /* must be protected against concurrent TSYNC */
1801 lockdep_assert_held(¤t->sighand->siglock);
1802
1803 if (!new_child->notif)
1804 return false;
1805 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1806 if (cur->notif)
1807 return true;
1808 }
1809
1810 return false;
1811}
1812
1813/**
1814 * seccomp_set_mode_filter: internal function for setting seccomp filter
1815 * @flags: flags to change filter behavior
1816 * @filter: struct sock_fprog containing filter
1817 *
1818 * This function may be called repeatedly to install additional filters.
1819 * Every filter successfully installed will be evaluated (in reverse order)
1820 * for each system call the task makes.
1821 *
1822 * Once current->seccomp.mode is non-zero, it may not be changed.
1823 *
1824 * Returns 0 on success or -EINVAL on failure.
1825 */
1826static long seccomp_set_mode_filter(unsigned int flags,
1827 const char __user *filter)
1828{
1829 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1830 struct seccomp_filter *prepared = NULL;
1831 long ret = -EINVAL;
1832 int listener = -1;
1833 struct file *listener_f = NULL;
1834
1835 /* Validate flags. */
1836 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1837 return -EINVAL;
1838
1839 /*
1840 * In the successful case, NEW_LISTENER returns the new listener fd.
1841 * But in the failure case, TSYNC returns the thread that died. If you
1842 * combine these two flags, there's no way to tell whether something
1843 * succeeded or failed. So, let's disallow this combination if the user
1844 * has not explicitly requested no errors from TSYNC.
1845 */
1846 if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1847 (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1848 ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1849 return -EINVAL;
1850
1851 /* Prepare the new filter before holding any locks. */
1852 prepared = seccomp_prepare_user_filter(filter);
1853 if (IS_ERR(prepared))
1854 return PTR_ERR(prepared);
1855
1856 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1857 listener = get_unused_fd_flags(O_CLOEXEC);
1858 if (listener < 0) {
1859 ret = listener;
1860 goto out_free;
1861 }
1862
1863 listener_f = init_listener(prepared);
1864 if (IS_ERR(listener_f)) {
1865 put_unused_fd(listener);
1866 ret = PTR_ERR(listener_f);
1867 goto out_free;
1868 }
1869 }
1870
1871 /*
1872 * Make sure we cannot change seccomp or nnp state via TSYNC
1873 * while another thread is in the middle of calling exec.
1874 */
1875 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1876 mutex_lock_killable(¤t->signal->cred_guard_mutex))
1877 goto out_put_fd;
1878
1879 spin_lock_irq(¤t->sighand->siglock);
1880
1881 if (!seccomp_may_assign_mode(seccomp_mode))
1882 goto out;
1883
1884 if (has_duplicate_listener(prepared)) {
1885 ret = -EBUSY;
1886 goto out;
1887 }
1888
1889 ret = seccomp_attach_filter(flags, prepared);
1890 if (ret)
1891 goto out;
1892 /* Do not free the successfully attached filter. */
1893 prepared = NULL;
1894
1895 seccomp_assign_mode(current, seccomp_mode, flags);
1896out:
1897 spin_unlock_irq(¤t->sighand->siglock);
1898 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1899 mutex_unlock(¤t->signal->cred_guard_mutex);
1900out_put_fd:
1901 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1902 if (ret) {
1903 listener_f->private_data = NULL;
1904 fput(listener_f);
1905 put_unused_fd(listener);
1906 seccomp_notify_detach(prepared);
1907 } else {
1908 fd_install(listener, listener_f);
1909 ret = listener;
1910 }
1911 }
1912out_free:
1913 seccomp_filter_free(prepared);
1914 return ret;
1915}
1916#else
1917static inline long seccomp_set_mode_filter(unsigned int flags,
1918 const char __user *filter)
1919{
1920 return -EINVAL;
1921}
1922#endif
1923
1924static long seccomp_get_action_avail(const char __user *uaction)
1925{
1926 u32 action;
1927
1928 if (copy_from_user(&action, uaction, sizeof(action)))
1929 return -EFAULT;
1930
1931 switch (action) {
1932 case SECCOMP_RET_KILL_PROCESS:
1933 case SECCOMP_RET_KILL_THREAD:
1934 case SECCOMP_RET_TRAP:
1935 case SECCOMP_RET_ERRNO:
1936 case SECCOMP_RET_USER_NOTIF:
1937 case SECCOMP_RET_TRACE:
1938 case SECCOMP_RET_LOG:
1939 case SECCOMP_RET_ALLOW:
1940 break;
1941 default:
1942 return -EOPNOTSUPP;
1943 }
1944
1945 return 0;
1946}
1947
1948static long seccomp_get_notif_sizes(void __user *usizes)
1949{
1950 struct seccomp_notif_sizes sizes = {
1951 .seccomp_notif = sizeof(struct seccomp_notif),
1952 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1953 .seccomp_data = sizeof(struct seccomp_data),
1954 };
1955
1956 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1957 return -EFAULT;
1958
1959 return 0;
1960}
1961
1962/* Common entry point for both prctl and syscall. */
1963static long do_seccomp(unsigned int op, unsigned int flags,
1964 void __user *uargs)
1965{
1966 switch (op) {
1967 case SECCOMP_SET_MODE_STRICT:
1968 if (flags != 0 || uargs != NULL)
1969 return -EINVAL;
1970 return seccomp_set_mode_strict();
1971 case SECCOMP_SET_MODE_FILTER:
1972 return seccomp_set_mode_filter(flags, uargs);
1973 case SECCOMP_GET_ACTION_AVAIL:
1974 if (flags != 0)
1975 return -EINVAL;
1976
1977 return seccomp_get_action_avail(uargs);
1978 case SECCOMP_GET_NOTIF_SIZES:
1979 if (flags != 0)
1980 return -EINVAL;
1981
1982 return seccomp_get_notif_sizes(uargs);
1983 default:
1984 return -EINVAL;
1985 }
1986}
1987
1988SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1989 void __user *, uargs)
1990{
1991 return do_seccomp(op, flags, uargs);
1992}
1993
1994/**
1995 * prctl_set_seccomp: configures current->seccomp.mode
1996 * @seccomp_mode: requested mode to use
1997 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1998 *
1999 * Returns 0 on success or -EINVAL on failure.
2000 */
2001long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
2002{
2003 unsigned int op;
2004 void __user *uargs;
2005
2006 switch (seccomp_mode) {
2007 case SECCOMP_MODE_STRICT:
2008 op = SECCOMP_SET_MODE_STRICT;
2009 /*
2010 * Setting strict mode through prctl always ignored filter,
2011 * so make sure it is always NULL here to pass the internal
2012 * check in do_seccomp().
2013 */
2014 uargs = NULL;
2015 break;
2016 case SECCOMP_MODE_FILTER:
2017 op = SECCOMP_SET_MODE_FILTER;
2018 uargs = filter;
2019 break;
2020 default:
2021 return -EINVAL;
2022 }
2023
2024 /* prctl interface doesn't have flags, so they are always zero. */
2025 return do_seccomp(op, 0, uargs);
2026}
2027
2028#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2029static struct seccomp_filter *get_nth_filter(struct task_struct *task,
2030 unsigned long filter_off)
2031{
2032 struct seccomp_filter *orig, *filter;
2033 unsigned long count;
2034
2035 /*
2036 * Note: this is only correct because the caller should be the (ptrace)
2037 * tracer of the task, otherwise lock_task_sighand is needed.
2038 */
2039 spin_lock_irq(&task->sighand->siglock);
2040
2041 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2042 spin_unlock_irq(&task->sighand->siglock);
2043 return ERR_PTR(-EINVAL);
2044 }
2045
2046 orig = task->seccomp.filter;
2047 __get_seccomp_filter(orig);
2048 spin_unlock_irq(&task->sighand->siglock);
2049
2050 count = 0;
2051 for (filter = orig; filter; filter = filter->prev)
2052 count++;
2053
2054 if (filter_off >= count) {
2055 filter = ERR_PTR(-ENOENT);
2056 goto out;
2057 }
2058
2059 count -= filter_off;
2060 for (filter = orig; filter && count > 1; filter = filter->prev)
2061 count--;
2062
2063 if (WARN_ON(count != 1 || !filter)) {
2064 filter = ERR_PTR(-ENOENT);
2065 goto out;
2066 }
2067
2068 __get_seccomp_filter(filter);
2069
2070out:
2071 __put_seccomp_filter(orig);
2072 return filter;
2073}
2074
2075long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2076 void __user *data)
2077{
2078 struct seccomp_filter *filter;
2079 struct sock_fprog_kern *fprog;
2080 long ret;
2081
2082 if (!capable(CAP_SYS_ADMIN) ||
2083 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2084 return -EACCES;
2085 }
2086
2087 filter = get_nth_filter(task, filter_off);
2088 if (IS_ERR(filter))
2089 return PTR_ERR(filter);
2090
2091 fprog = filter->prog->orig_prog;
2092 if (!fprog) {
2093 /* This must be a new non-cBPF filter, since we save
2094 * every cBPF filter's orig_prog above when
2095 * CONFIG_CHECKPOINT_RESTORE is enabled.
2096 */
2097 ret = -EMEDIUMTYPE;
2098 goto out;
2099 }
2100
2101 ret = fprog->len;
2102 if (!data)
2103 goto out;
2104
2105 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2106 ret = -EFAULT;
2107
2108out:
2109 __put_seccomp_filter(filter);
2110 return ret;
2111}
2112
2113long seccomp_get_metadata(struct task_struct *task,
2114 unsigned long size, void __user *data)
2115{
2116 long ret;
2117 struct seccomp_filter *filter;
2118 struct seccomp_metadata kmd = {};
2119
2120 if (!capable(CAP_SYS_ADMIN) ||
2121 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2122 return -EACCES;
2123 }
2124
2125 size = min_t(unsigned long, size, sizeof(kmd));
2126
2127 if (size < sizeof(kmd.filter_off))
2128 return -EINVAL;
2129
2130 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2131 return -EFAULT;
2132
2133 filter = get_nth_filter(task, kmd.filter_off);
2134 if (IS_ERR(filter))
2135 return PTR_ERR(filter);
2136
2137 if (filter->log)
2138 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2139
2140 ret = size;
2141 if (copy_to_user(data, &kmd, size))
2142 ret = -EFAULT;
2143
2144 __put_seccomp_filter(filter);
2145 return ret;
2146}
2147#endif
2148
2149#ifdef CONFIG_SYSCTL
2150
2151/* Human readable action names for friendly sysctl interaction */
2152#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2153#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2154#define SECCOMP_RET_TRAP_NAME "trap"
2155#define SECCOMP_RET_ERRNO_NAME "errno"
2156#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2157#define SECCOMP_RET_TRACE_NAME "trace"
2158#define SECCOMP_RET_LOG_NAME "log"
2159#define SECCOMP_RET_ALLOW_NAME "allow"
2160
2161static const char seccomp_actions_avail[] =
2162 SECCOMP_RET_KILL_PROCESS_NAME " "
2163 SECCOMP_RET_KILL_THREAD_NAME " "
2164 SECCOMP_RET_TRAP_NAME " "
2165 SECCOMP_RET_ERRNO_NAME " "
2166 SECCOMP_RET_USER_NOTIF_NAME " "
2167 SECCOMP_RET_TRACE_NAME " "
2168 SECCOMP_RET_LOG_NAME " "
2169 SECCOMP_RET_ALLOW_NAME;
2170
2171struct seccomp_log_name {
2172 u32 log;
2173 const char *name;
2174};
2175
2176static const struct seccomp_log_name seccomp_log_names[] = {
2177 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2178 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2179 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2180 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2181 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2182 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2183 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2184 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2185 { }
2186};
2187
2188static bool seccomp_names_from_actions_logged(char *names, size_t size,
2189 u32 actions_logged,
2190 const char *sep)
2191{
2192 const struct seccomp_log_name *cur;
2193 bool append_sep = false;
2194
2195 for (cur = seccomp_log_names; cur->name && size; cur++) {
2196 ssize_t ret;
2197
2198 if (!(actions_logged & cur->log))
2199 continue;
2200
2201 if (append_sep) {
2202 ret = strscpy(names, sep, size);
2203 if (ret < 0)
2204 return false;
2205
2206 names += ret;
2207 size -= ret;
2208 } else
2209 append_sep = true;
2210
2211 ret = strscpy(names, cur->name, size);
2212 if (ret < 0)
2213 return false;
2214
2215 names += ret;
2216 size -= ret;
2217 }
2218
2219 return true;
2220}
2221
2222static bool seccomp_action_logged_from_name(u32 *action_logged,
2223 const char *name)
2224{
2225 const struct seccomp_log_name *cur;
2226
2227 for (cur = seccomp_log_names; cur->name; cur++) {
2228 if (!strcmp(cur->name, name)) {
2229 *action_logged = cur->log;
2230 return true;
2231 }
2232 }
2233
2234 return false;
2235}
2236
2237static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2238{
2239 char *name;
2240
2241 *actions_logged = 0;
2242 while ((name = strsep(&names, " ")) && *name) {
2243 u32 action_logged = 0;
2244
2245 if (!seccomp_action_logged_from_name(&action_logged, name))
2246 return false;
2247
2248 *actions_logged |= action_logged;
2249 }
2250
2251 return true;
2252}
2253
2254static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
2255 size_t *lenp, loff_t *ppos)
2256{
2257 char names[sizeof(seccomp_actions_avail)];
2258 struct ctl_table table;
2259
2260 memset(names, 0, sizeof(names));
2261
2262 if (!seccomp_names_from_actions_logged(names, sizeof(names),
2263 seccomp_actions_logged, " "))
2264 return -EINVAL;
2265
2266 table = *ro_table;
2267 table.data = names;
2268 table.maxlen = sizeof(names);
2269 return proc_dostring(&table, 0, buffer, lenp, ppos);
2270}
2271
2272static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
2273 size_t *lenp, loff_t *ppos, u32 *actions_logged)
2274{
2275 char names[sizeof(seccomp_actions_avail)];
2276 struct ctl_table table;
2277 int ret;
2278
2279 if (!capable(CAP_SYS_ADMIN))
2280 return -EPERM;
2281
2282 memset(names, 0, sizeof(names));
2283
2284 table = *ro_table;
2285 table.data = names;
2286 table.maxlen = sizeof(names);
2287 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2288 if (ret)
2289 return ret;
2290
2291 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2292 return -EINVAL;
2293
2294 if (*actions_logged & SECCOMP_LOG_ALLOW)
2295 return -EINVAL;
2296
2297 seccomp_actions_logged = *actions_logged;
2298 return 0;
2299}
2300
2301static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2302 int ret)
2303{
2304 char names[sizeof(seccomp_actions_avail)];
2305 char old_names[sizeof(seccomp_actions_avail)];
2306 const char *new = names;
2307 const char *old = old_names;
2308
2309 if (!audit_enabled)
2310 return;
2311
2312 memset(names, 0, sizeof(names));
2313 memset(old_names, 0, sizeof(old_names));
2314
2315 if (ret)
2316 new = "?";
2317 else if (!actions_logged)
2318 new = "(none)";
2319 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2320 actions_logged, ","))
2321 new = "?";
2322
2323 if (!old_actions_logged)
2324 old = "(none)";
2325 else if (!seccomp_names_from_actions_logged(old_names,
2326 sizeof(old_names),
2327 old_actions_logged, ","))
2328 old = "?";
2329
2330 return audit_seccomp_actions_logged(new, old, !ret);
2331}
2332
2333static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
2334 void *buffer, size_t *lenp,
2335 loff_t *ppos)
2336{
2337 int ret;
2338
2339 if (write) {
2340 u32 actions_logged = 0;
2341 u32 old_actions_logged = seccomp_actions_logged;
2342
2343 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2344 &actions_logged);
2345 audit_actions_logged(actions_logged, old_actions_logged, ret);
2346 } else
2347 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2348
2349 return ret;
2350}
2351
2352static struct ctl_path seccomp_sysctl_path[] = {
2353 { .procname = "kernel", },
2354 { .procname = "seccomp", },
2355 { }
2356};
2357
2358static struct ctl_table seccomp_sysctl_table[] = {
2359 {
2360 .procname = "actions_avail",
2361 .data = (void *) &seccomp_actions_avail,
2362 .maxlen = sizeof(seccomp_actions_avail),
2363 .mode = 0444,
2364 .proc_handler = proc_dostring,
2365 },
2366 {
2367 .procname = "actions_logged",
2368 .mode = 0644,
2369 .proc_handler = seccomp_actions_logged_handler,
2370 },
2371 { }
2372};
2373
2374static int __init seccomp_sysctl_init(void)
2375{
2376 struct ctl_table_header *hdr;
2377
2378 hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
2379 if (!hdr)
2380 pr_warn("sysctl registration failed\n");
2381 else
2382 kmemleak_not_leak(hdr);
2383
2384 return 0;
2385}
2386
2387device_initcall(seccomp_sysctl_init)
2388
2389#endif /* CONFIG_SYSCTL */
2390
2391#ifdef CONFIG_SECCOMP_CACHE_DEBUG
2392/* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2393static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2394 const void *bitmap, size_t bitmap_size)
2395{
2396 int nr;
2397
2398 for (nr = 0; nr < bitmap_size; nr++) {
2399 bool cached = test_bit(nr, bitmap);
2400 char *status = cached ? "ALLOW" : "FILTER";
2401
2402 seq_printf(m, "%s %d %s\n", name, nr, status);
2403 }
2404}
2405
2406int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2407 struct pid *pid, struct task_struct *task)
2408{
2409 struct seccomp_filter *f;
2410 unsigned long flags;
2411
2412 /*
2413 * We don't want some sandboxed process to know what their seccomp
2414 * filters consist of.
2415 */
2416 if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2417 return -EACCES;
2418
2419 if (!lock_task_sighand(task, &flags))
2420 return -ESRCH;
2421
2422 f = READ_ONCE(task->seccomp.filter);
2423 if (!f) {
2424 unlock_task_sighand(task, &flags);
2425 return 0;
2426 }
2427
2428 /* prevent filter from being freed while we are printing it */
2429 __get_seccomp_filter(f);
2430 unlock_task_sighand(task, &flags);
2431
2432 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2433 f->cache.allow_native,
2434 SECCOMP_ARCH_NATIVE_NR);
2435
2436#ifdef SECCOMP_ARCH_COMPAT
2437 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2438 f->cache.allow_compat,
2439 SECCOMP_ARCH_COMPAT_NR);
2440#endif /* SECCOMP_ARCH_COMPAT */
2441
2442 __put_seccomp_filter(f);
2443 return 0;
2444}
2445#endif /* CONFIG_SECCOMP_CACHE_DEBUG */