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(&current->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(&current->signal->cred_guard_mutex));
 495	assert_spin_locked(&current->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
 506		if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
 507		    (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
 508		     is_ancestor(thread->seccomp.filter,
 509				 caller->seccomp.filter)))
 510			continue;
 511
 512		/* Return the first thread that cannot be synchronized. */
 513		failed = task_pid_vnr(thread);
 514		/* If the pid cannot be resolved, then return -ESRCH */
 515		if (WARN_ON(failed == 0))
 516			failed = -ESRCH;
 517		return failed;
 518	}
 519
 520	return 0;
 521}
 522
 523static inline void seccomp_filter_free(struct seccomp_filter *filter)
 524{
 525	if (filter) {
 526		bpf_prog_destroy(filter->prog);
 527		kfree(filter);
 528	}
 529}
 530
 531static void __seccomp_filter_orphan(struct seccomp_filter *orig)
 532{
 533	while (orig && refcount_dec_and_test(&orig->users)) {
 534		if (waitqueue_active(&orig->wqh))
 535			wake_up_poll(&orig->wqh, EPOLLHUP);
 536		orig = orig->prev;
 537	}
 538}
 539
 540static void __put_seccomp_filter(struct seccomp_filter *orig)
 541{
 542	/* Clean up single-reference branches iteratively. */
 543	while (orig && refcount_dec_and_test(&orig->refs)) {
 544		struct seccomp_filter *freeme = orig;
 545		orig = orig->prev;
 546		seccomp_filter_free(freeme);
 547	}
 548}
 549
 550static void __seccomp_filter_release(struct seccomp_filter *orig)
 551{
 552	/* Notify about any unused filters in the task's former filter tree. */
 553	__seccomp_filter_orphan(orig);
 554	/* Finally drop all references to the task's former tree. */
 555	__put_seccomp_filter(orig);
 556}
 557
 558/**
 559 * seccomp_filter_release - Detach the task from its filter tree,
 560 *			    drop its reference count, and notify
 561 *			    about unused filters
 562 *
 563 * @tsk: task the filter should be released from.
 564 *
 565 * This function should only be called when the task is exiting as
 566 * it detaches it from its filter tree. As such, READ_ONCE() and
 567 * barriers are not needed here, as would normally be needed.
 568 */
 569void seccomp_filter_release(struct task_struct *tsk)
 570{
 571	struct seccomp_filter *orig = tsk->seccomp.filter;
 572
 573	/* We are effectively holding the siglock by not having any sighand. */
 574	WARN_ON(tsk->sighand != NULL);
 575
 
 
 576	/* Detach task from its filter tree. */
 577	tsk->seccomp.filter = NULL;
 
 578	__seccomp_filter_release(orig);
 579}
 580
 581/**
 582 * seccomp_sync_threads: sets all threads to use current's filter
 583 *
 584 * @flags: SECCOMP_FILTER_FLAG_* flags to set during sync.
 585 *
 586 * Expects sighand and cred_guard_mutex locks to be held, and for
 587 * seccomp_can_sync_threads() to have returned success already
 588 * without dropping the locks.
 589 *
 590 */
 591static inline void seccomp_sync_threads(unsigned long flags)
 592{
 593	struct task_struct *thread, *caller;
 594
 595	BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
 596	assert_spin_locked(&current->sighand->siglock);
 597
 598	/* Synchronize all threads. */
 599	caller = current;
 600	for_each_thread(caller, thread) {
 601		/* Skip current, since it needs no changes. */
 602		if (thread == caller)
 603			continue;
 604
 
 
 
 
 
 
 
 605		/* Get a task reference for the new leaf node. */
 606		get_seccomp_filter(caller);
 607
 608		/*
 609		 * Drop the task reference to the shared ancestor since
 610		 * current's path will hold a reference.  (This also
 611		 * allows a put before the assignment.)
 612		 */
 613		__seccomp_filter_release(thread->seccomp.filter);
 614
 615		/* Make our new filter tree visible. */
 616		smp_store_release(&thread->seccomp.filter,
 617				  caller->seccomp.filter);
 618		atomic_set(&thread->seccomp.filter_count,
 619			   atomic_read(&caller->seccomp.filter_count));
 620
 621		/*
 622		 * Don't let an unprivileged task work around
 623		 * the no_new_privs restriction by creating
 624		 * a thread that sets it up, enters seccomp,
 625		 * then dies.
 626		 */
 627		if (task_no_new_privs(caller))
 628			task_set_no_new_privs(thread);
 629
 630		/*
 631		 * Opt the other thread into seccomp if needed.
 632		 * As threads are considered to be trust-realm
 633		 * equivalent (see ptrace_may_access), it is safe to
 634		 * allow one thread to transition the other.
 635		 */
 636		if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
 637			seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
 638					    flags);
 639	}
 640}
 641
 642/**
 643 * seccomp_prepare_filter: Prepares a seccomp filter for use.
 644 * @fprog: BPF program to install
 645 *
 646 * Returns filter on success or an ERR_PTR on failure.
 647 */
 648static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
 649{
 650	struct seccomp_filter *sfilter;
 651	int ret;
 652	const bool save_orig =
 653#if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
 654		true;
 655#else
 656		false;
 657#endif
 658
 659	if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
 660		return ERR_PTR(-EINVAL);
 661
 662	BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
 663
 664	/*
 665	 * Installing a seccomp filter requires that the task has
 666	 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
 667	 * This avoids scenarios where unprivileged tasks can affect the
 668	 * behavior of privileged children.
 669	 */
 670	if (!task_no_new_privs(current) &&
 671			!ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
 672		return ERR_PTR(-EACCES);
 673
 674	/* Allocate a new seccomp_filter */
 675	sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
 676	if (!sfilter)
 677		return ERR_PTR(-ENOMEM);
 678
 679	mutex_init(&sfilter->notify_lock);
 680	ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
 681					seccomp_check_filter, save_orig);
 682	if (ret < 0) {
 683		kfree(sfilter);
 684		return ERR_PTR(ret);
 685	}
 686
 687	refcount_set(&sfilter->refs, 1);
 688	refcount_set(&sfilter->users, 1);
 689	init_waitqueue_head(&sfilter->wqh);
 690
 691	return sfilter;
 692}
 693
 694/**
 695 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
 696 * @user_filter: pointer to the user data containing a sock_fprog.
 697 *
 698 * Returns 0 on success and non-zero otherwise.
 699 */
 700static struct seccomp_filter *
 701seccomp_prepare_user_filter(const char __user *user_filter)
 702{
 703	struct sock_fprog fprog;
 704	struct seccomp_filter *filter = ERR_PTR(-EFAULT);
 705
 706#ifdef CONFIG_COMPAT
 707	if (in_compat_syscall()) {
 708		struct compat_sock_fprog fprog32;
 709		if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
 710			goto out;
 711		fprog.len = fprog32.len;
 712		fprog.filter = compat_ptr(fprog32.filter);
 713	} else /* falls through to the if below. */
 714#endif
 715	if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
 716		goto out;
 717	filter = seccomp_prepare_filter(&fprog);
 718out:
 719	return filter;
 720}
 721
 722#ifdef SECCOMP_ARCH_NATIVE
 723/**
 724 * seccomp_is_const_allow - check if filter is constant allow with given data
 725 * @fprog: The BPF programs
 726 * @sd: The seccomp data to check against, only syscall number and arch
 727 *      number are considered constant.
 728 */
 729static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
 730				   struct seccomp_data *sd)
 731{
 732	unsigned int reg_value = 0;
 733	unsigned int pc;
 734	bool op_res;
 735
 736	if (WARN_ON_ONCE(!fprog))
 737		return false;
 738
 
 
 
 
 
 
 
 
 
 739	for (pc = 0; pc < fprog->len; pc++) {
 740		struct sock_filter *insn = &fprog->filter[pc];
 741		u16 code = insn->code;
 742		u32 k = insn->k;
 743
 744		switch (code) {
 745		case BPF_LD | BPF_W | BPF_ABS:
 746			switch (k) {
 747			case offsetof(struct seccomp_data, nr):
 748				reg_value = sd->nr;
 749				break;
 750			case offsetof(struct seccomp_data, arch):
 751				reg_value = sd->arch;
 752				break;
 753			default:
 754				/* can't optimize (non-constant value load) */
 755				return false;
 756			}
 757			break;
 758		case BPF_RET | BPF_K:
 759			/* reached return with constant values only, check allow */
 760			return k == SECCOMP_RET_ALLOW;
 761		case BPF_JMP | BPF_JA:
 762			pc += insn->k;
 763			break;
 764		case BPF_JMP | BPF_JEQ | BPF_K:
 765		case BPF_JMP | BPF_JGE | BPF_K:
 766		case BPF_JMP | BPF_JGT | BPF_K:
 767		case BPF_JMP | BPF_JSET | BPF_K:
 768			switch (BPF_OP(code)) {
 769			case BPF_JEQ:
 770				op_res = reg_value == k;
 771				break;
 772			case BPF_JGE:
 773				op_res = reg_value >= k;
 774				break;
 775			case BPF_JGT:
 776				op_res = reg_value > k;
 777				break;
 778			case BPF_JSET:
 779				op_res = !!(reg_value & k);
 780				break;
 781			default:
 782				/* can't optimize (unknown jump) */
 783				return false;
 784			}
 785
 786			pc += op_res ? insn->jt : insn->jf;
 787			break;
 788		case BPF_ALU | BPF_AND | BPF_K:
 789			reg_value &= k;
 790			break;
 791		default:
 792			/* can't optimize (unknown insn) */
 793			return false;
 794		}
 795	}
 796
 797	/* ran off the end of the filter?! */
 798	WARN_ON(1);
 799	return false;
 800}
 801
 802static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
 803					 void *bitmap, const void *bitmap_prev,
 804					 size_t bitmap_size, int arch)
 805{
 806	struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
 807	struct seccomp_data sd;
 808	int nr;
 809
 810	if (bitmap_prev) {
 811		/* The new filter must be as restrictive as the last. */
 812		bitmap_copy(bitmap, bitmap_prev, bitmap_size);
 813	} else {
 814		/* Before any filters, all syscalls are always allowed. */
 815		bitmap_fill(bitmap, bitmap_size);
 816	}
 817
 818	for (nr = 0; nr < bitmap_size; nr++) {
 819		/* No bitmap change: not a cacheable action. */
 820		if (!test_bit(nr, bitmap))
 821			continue;
 822
 823		sd.nr = nr;
 824		sd.arch = arch;
 825
 826		/* No bitmap change: continue to always allow. */
 827		if (seccomp_is_const_allow(fprog, &sd))
 828			continue;
 829
 830		/*
 831		 * Not a cacheable action: always run filters.
 832		 * atomic clear_bit() not needed, filter not visible yet.
 833		 */
 834		__clear_bit(nr, bitmap);
 835	}
 836}
 837
 838/**
 839 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
 840 * @sfilter: The seccomp filter
 841 *
 842 * Returns 0 if successful or -errno if error occurred.
 843 */
 844static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
 845{
 846	struct action_cache *cache = &sfilter->cache;
 847	const struct action_cache *cache_prev =
 848		sfilter->prev ? &sfilter->prev->cache : NULL;
 849
 850	seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
 851				     cache_prev ? cache_prev->allow_native : NULL,
 852				     SECCOMP_ARCH_NATIVE_NR,
 853				     SECCOMP_ARCH_NATIVE);
 854
 855#ifdef SECCOMP_ARCH_COMPAT
 856	seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
 857				     cache_prev ? cache_prev->allow_compat : NULL,
 858				     SECCOMP_ARCH_COMPAT_NR,
 859				     SECCOMP_ARCH_COMPAT);
 860#endif /* SECCOMP_ARCH_COMPAT */
 861}
 862#endif /* SECCOMP_ARCH_NATIVE */
 863
 864/**
 865 * seccomp_attach_filter: validate and attach filter
 866 * @flags:  flags to change filter behavior
 867 * @filter: seccomp filter to add to the current process
 868 *
 869 * Caller must be holding current->sighand->siglock lock.
 870 *
 871 * Returns 0 on success, -ve on error, or
 872 *   - in TSYNC mode: the pid of a thread which was either not in the correct
 873 *     seccomp mode or did not have an ancestral seccomp filter
 874 *   - in NEW_LISTENER mode: the fd of the new listener
 875 */
 876static long seccomp_attach_filter(unsigned int flags,
 877				  struct seccomp_filter *filter)
 878{
 879	unsigned long total_insns;
 880	struct seccomp_filter *walker;
 881
 882	assert_spin_locked(&current->sighand->siglock);
 883
 884	/* Validate resulting filter length. */
 885	total_insns = filter->prog->len;
 886	for (walker = current->seccomp.filter; walker; walker = walker->prev)
 887		total_insns += walker->prog->len + 4;  /* 4 instr penalty */
 888	if (total_insns > MAX_INSNS_PER_PATH)
 889		return -ENOMEM;
 890
 891	/* If thread sync has been requested, check that it is possible. */
 892	if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
 893		int ret;
 894
 895		ret = seccomp_can_sync_threads();
 896		if (ret) {
 897			if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
 898				return -ESRCH;
 899			else
 900				return ret;
 901		}
 902	}
 903
 904	/* Set log flag, if present. */
 905	if (flags & SECCOMP_FILTER_FLAG_LOG)
 906		filter->log = true;
 907
 908	/* Set wait killable flag, if present. */
 909	if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
 910		filter->wait_killable_recv = true;
 911
 912	/*
 913	 * If there is an existing filter, make it the prev and don't drop its
 914	 * task reference.
 915	 */
 916	filter->prev = current->seccomp.filter;
 917	seccomp_cache_prepare(filter);
 918	current->seccomp.filter = filter;
 919	atomic_inc(&current->seccomp.filter_count);
 920
 921	/* Now that the new filter is in place, synchronize to all threads. */
 922	if (flags & SECCOMP_FILTER_FLAG_TSYNC)
 923		seccomp_sync_threads(flags);
 924
 925	return 0;
 926}
 927
 928static void __get_seccomp_filter(struct seccomp_filter *filter)
 929{
 930	refcount_inc(&filter->refs);
 931}
 932
 933/* get_seccomp_filter - increments the reference count of the filter on @tsk */
 934void get_seccomp_filter(struct task_struct *tsk)
 935{
 936	struct seccomp_filter *orig = tsk->seccomp.filter;
 937	if (!orig)
 938		return;
 939	__get_seccomp_filter(orig);
 940	refcount_inc(&orig->users);
 941}
 942
 943#endif	/* CONFIG_SECCOMP_FILTER */
 944
 945/* For use with seccomp_actions_logged */
 946#define SECCOMP_LOG_KILL_PROCESS	(1 << 0)
 947#define SECCOMP_LOG_KILL_THREAD		(1 << 1)
 948#define SECCOMP_LOG_TRAP		(1 << 2)
 949#define SECCOMP_LOG_ERRNO		(1 << 3)
 950#define SECCOMP_LOG_TRACE		(1 << 4)
 951#define SECCOMP_LOG_LOG			(1 << 5)
 952#define SECCOMP_LOG_ALLOW		(1 << 6)
 953#define SECCOMP_LOG_USER_NOTIF		(1 << 7)
 954
 955static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
 956				    SECCOMP_LOG_KILL_THREAD  |
 957				    SECCOMP_LOG_TRAP  |
 958				    SECCOMP_LOG_ERRNO |
 959				    SECCOMP_LOG_USER_NOTIF |
 960				    SECCOMP_LOG_TRACE |
 961				    SECCOMP_LOG_LOG;
 962
 963static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
 964			       bool requested)
 965{
 966	bool log = false;
 967
 968	switch (action) {
 969	case SECCOMP_RET_ALLOW:
 970		break;
 971	case SECCOMP_RET_TRAP:
 972		log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
 973		break;
 974	case SECCOMP_RET_ERRNO:
 975		log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
 976		break;
 977	case SECCOMP_RET_TRACE:
 978		log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
 979		break;
 980	case SECCOMP_RET_USER_NOTIF:
 981		log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
 982		break;
 983	case SECCOMP_RET_LOG:
 984		log = seccomp_actions_logged & SECCOMP_LOG_LOG;
 985		break;
 986	case SECCOMP_RET_KILL_THREAD:
 987		log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
 988		break;
 989	case SECCOMP_RET_KILL_PROCESS:
 990	default:
 991		log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
 992	}
 993
 994	/*
 995	 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
 996	 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
 997	 * any action from being logged by removing the action name from the
 998	 * seccomp_actions_logged sysctl.
 999	 */
1000	if (!log)
1001		return;
1002
1003	audit_seccomp(syscall, signr, action);
1004}
1005
1006/*
1007 * Secure computing mode 1 allows only read/write/exit/sigreturn.
1008 * To be fully secure this must be combined with rlimit
1009 * to limit the stack allocations too.
1010 */
1011static const int mode1_syscalls[] = {
1012	__NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
 
 
 
1013	-1, /* negative terminated */
1014};
1015
1016static void __secure_computing_strict(int this_syscall)
1017{
1018	const int *allowed_syscalls = mode1_syscalls;
1019#ifdef CONFIG_COMPAT
1020	if (in_compat_syscall())
1021		allowed_syscalls = get_compat_mode1_syscalls();
1022#endif
1023	do {
1024		if (*allowed_syscalls == this_syscall)
1025			return;
1026	} while (*++allowed_syscalls != -1);
1027
1028#ifdef SECCOMP_DEBUG
1029	dump_stack();
1030#endif
1031	current->seccomp.mode = SECCOMP_MODE_DEAD;
1032	seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1033	do_exit(SIGKILL);
1034}
1035
1036#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1037void secure_computing_strict(int this_syscall)
1038{
1039	int mode = current->seccomp.mode;
1040
1041	if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1042	    unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1043		return;
1044
1045	if (mode == SECCOMP_MODE_DISABLED)
1046		return;
1047	else if (mode == SECCOMP_MODE_STRICT)
1048		__secure_computing_strict(this_syscall);
1049	else
1050		BUG();
1051}
1052#else
1053
1054#ifdef CONFIG_SECCOMP_FILTER
1055static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1056{
1057	/*
1058	 * Note: overflow is ok here, the id just needs to be unique per
1059	 * filter.
1060	 */
1061	lockdep_assert_held(&filter->notify_lock);
1062	return filter->notif->next_id++;
1063}
1064
1065static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
1066{
1067	int fd;
1068
1069	/*
1070	 * Remove the notification, and reset the list pointers, indicating
1071	 * that it has been handled.
1072	 */
1073	list_del_init(&addfd->list);
1074	if (!addfd->setfd)
1075		fd = receive_fd(addfd->file, NULL, addfd->flags);
1076	else
1077		fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1078	addfd->ret = fd;
1079
1080	if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1081		/* If we fail reset and return an error to the notifier */
1082		if (fd < 0) {
1083			n->state = SECCOMP_NOTIFY_SENT;
1084		} else {
1085			/* Return the FD we just added */
1086			n->flags = 0;
1087			n->error = 0;
1088			n->val = fd;
1089		}
1090	}
1091
1092	/*
1093	 * Mark the notification as completed. From this point, addfd mem
1094	 * might be invalidated and we can't safely read it anymore.
1095	 */
1096	complete(&addfd->completion);
1097}
1098
1099static bool should_sleep_killable(struct seccomp_filter *match,
1100				  struct seccomp_knotif *n)
1101{
1102	return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
1103}
1104
1105static int seccomp_do_user_notification(int this_syscall,
1106					struct seccomp_filter *match,
1107					const struct seccomp_data *sd)
1108{
1109	int err;
1110	u32 flags = 0;
1111	long ret = 0;
1112	struct seccomp_knotif n = {};
1113	struct seccomp_kaddfd *addfd, *tmp;
1114
1115	mutex_lock(&match->notify_lock);
1116	err = -ENOSYS;
1117	if (!match->notif)
1118		goto out;
1119
1120	n.task = current;
1121	n.state = SECCOMP_NOTIFY_INIT;
1122	n.data = sd;
1123	n.id = seccomp_next_notify_id(match);
1124	init_completion(&n.ready);
1125	list_add_tail(&n.list, &match->notif->notifications);
1126	INIT_LIST_HEAD(&n.addfd);
1127
1128	atomic_inc(&match->notif->requests);
1129	if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1130		wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM);
1131	else
1132		wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1133
1134	/*
1135	 * This is where we wait for a reply from userspace.
1136	 */
1137	do {
1138		bool wait_killable = should_sleep_killable(match, &n);
1139
1140		mutex_unlock(&match->notify_lock);
1141		if (wait_killable)
1142			err = wait_for_completion_killable(&n.ready);
1143		else
1144			err = wait_for_completion_interruptible(&n.ready);
1145		mutex_lock(&match->notify_lock);
1146
1147		if (err != 0) {
1148			/*
1149			 * Check to see if the notifcation got picked up and
1150			 * whether we should switch to wait killable.
1151			 */
1152			if (!wait_killable && should_sleep_killable(match, &n))
1153				continue;
1154
1155			goto interrupted;
1156		}
1157
1158		addfd = list_first_entry_or_null(&n.addfd,
1159						 struct seccomp_kaddfd, list);
1160		/* Check if we were woken up by a addfd message */
1161		if (addfd)
1162			seccomp_handle_addfd(addfd, &n);
1163
1164	}  while (n.state != SECCOMP_NOTIFY_REPLIED);
1165
1166	ret = n.val;
1167	err = n.error;
1168	flags = n.flags;
1169
1170interrupted:
1171	/* If there were any pending addfd calls, clear them out */
1172	list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1173		/* The process went away before we got a chance to handle it */
1174		addfd->ret = -ESRCH;
1175		list_del_init(&addfd->list);
1176		complete(&addfd->completion);
1177	}
1178
1179	/*
1180	 * Note that it's possible the listener died in between the time when
1181	 * we were notified of a response (or a signal) and when we were able to
1182	 * re-acquire the lock, so only delete from the list if the
1183	 * notification actually exists.
1184	 *
1185	 * Also note that this test is only valid because there's no way to
1186	 * *reattach* to a notifier right now. If one is added, we'll need to
1187	 * keep track of the notif itself and make sure they match here.
1188	 */
1189	if (match->notif)
1190		list_del(&n.list);
1191out:
1192	mutex_unlock(&match->notify_lock);
1193
1194	/* Userspace requests to continue the syscall. */
1195	if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1196		return 0;
1197
1198	syscall_set_return_value(current, current_pt_regs(),
1199				 err, ret);
1200	return -1;
1201}
1202
1203static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1204			    const bool recheck_after_trace)
1205{
1206	u32 filter_ret, action;
1207	struct seccomp_filter *match = NULL;
1208	int data;
1209	struct seccomp_data sd_local;
1210
1211	/*
1212	 * Make sure that any changes to mode from another thread have
1213	 * been seen after SYSCALL_WORK_SECCOMP was seen.
1214	 */
1215	smp_rmb();
1216
1217	if (!sd) {
1218		populate_seccomp_data(&sd_local);
1219		sd = &sd_local;
1220	}
1221
1222	filter_ret = seccomp_run_filters(sd, &match);
1223	data = filter_ret & SECCOMP_RET_DATA;
1224	action = filter_ret & SECCOMP_RET_ACTION_FULL;
1225
1226	switch (action) {
1227	case SECCOMP_RET_ERRNO:
1228		/* Set low-order bits as an errno, capped at MAX_ERRNO. */
1229		if (data > MAX_ERRNO)
1230			data = MAX_ERRNO;
1231		syscall_set_return_value(current, current_pt_regs(),
1232					 -data, 0);
1233		goto skip;
1234
1235	case SECCOMP_RET_TRAP:
1236		/* Show the handler the original registers. */
1237		syscall_rollback(current, current_pt_regs());
1238		/* Let the filter pass back 16 bits of data. */
1239		force_sig_seccomp(this_syscall, data, false);
1240		goto skip;
1241
1242	case SECCOMP_RET_TRACE:
1243		/* We've been put in this state by the ptracer already. */
1244		if (recheck_after_trace)
1245			return 0;
1246
1247		/* ENOSYS these calls if there is no tracer attached. */
1248		if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1249			syscall_set_return_value(current,
1250						 current_pt_regs(),
1251						 -ENOSYS, 0);
1252			goto skip;
1253		}
1254
1255		/* Allow the BPF to provide the event message */
1256		ptrace_event(PTRACE_EVENT_SECCOMP, data);
1257		/*
1258		 * The delivery of a fatal signal during event
1259		 * notification may silently skip tracer notification,
1260		 * which could leave us with a potentially unmodified
1261		 * syscall that the tracer would have liked to have
1262		 * changed. Since the process is about to die, we just
1263		 * force the syscall to be skipped and let the signal
1264		 * kill the process and correctly handle any tracer exit
1265		 * notifications.
1266		 */
1267		if (fatal_signal_pending(current))
1268			goto skip;
1269		/* Check if the tracer forced the syscall to be skipped. */
1270		this_syscall = syscall_get_nr(current, current_pt_regs());
1271		if (this_syscall < 0)
1272			goto skip;
1273
1274		/*
1275		 * Recheck the syscall, since it may have changed. This
1276		 * intentionally uses a NULL struct seccomp_data to force
1277		 * a reload of all registers. This does not goto skip since
1278		 * a skip would have already been reported.
1279		 */
1280		if (__seccomp_filter(this_syscall, NULL, true))
1281			return -1;
1282
1283		return 0;
1284
1285	case SECCOMP_RET_USER_NOTIF:
1286		if (seccomp_do_user_notification(this_syscall, match, sd))
1287			goto skip;
1288
1289		return 0;
1290
1291	case SECCOMP_RET_LOG:
1292		seccomp_log(this_syscall, 0, action, true);
1293		return 0;
1294
1295	case SECCOMP_RET_ALLOW:
1296		/*
1297		 * Note that the "match" filter will always be NULL for
1298		 * this action since SECCOMP_RET_ALLOW is the starting
1299		 * state in seccomp_run_filters().
1300		 */
1301		return 0;
1302
1303	case SECCOMP_RET_KILL_THREAD:
1304	case SECCOMP_RET_KILL_PROCESS:
1305	default:
1306		current->seccomp.mode = SECCOMP_MODE_DEAD;
1307		seccomp_log(this_syscall, SIGSYS, action, true);
1308		/* Dump core only if this is the last remaining thread. */
1309		if (action != SECCOMP_RET_KILL_THREAD ||
1310		    (atomic_read(&current->signal->live) == 1)) {
1311			/* Show the original registers in the dump. */
1312			syscall_rollback(current, current_pt_regs());
1313			/* Trigger a coredump with SIGSYS */
1314			force_sig_seccomp(this_syscall, data, true);
1315		} else {
1316			do_exit(SIGSYS);
1317		}
1318		return -1; /* skip the syscall go directly to signal handling */
1319	}
1320
1321	unreachable();
1322
1323skip:
1324	seccomp_log(this_syscall, 0, action, match ? match->log : false);
1325	return -1;
1326}
1327#else
1328static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1329			    const bool recheck_after_trace)
1330{
1331	BUG();
1332
1333	return -1;
1334}
1335#endif
1336
1337int __secure_computing(const struct seccomp_data *sd)
1338{
1339	int mode = current->seccomp.mode;
1340	int this_syscall;
1341
1342	if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1343	    unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1344		return 0;
1345
1346	this_syscall = sd ? sd->nr :
1347		syscall_get_nr(current, current_pt_regs());
1348
1349	switch (mode) {
1350	case SECCOMP_MODE_STRICT:
1351		__secure_computing_strict(this_syscall);  /* may call do_exit */
1352		return 0;
1353	case SECCOMP_MODE_FILTER:
1354		return __seccomp_filter(this_syscall, sd, false);
1355	/* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
1356	case SECCOMP_MODE_DEAD:
1357		WARN_ON_ONCE(1);
1358		do_exit(SIGKILL);
1359		return -1;
1360	default:
1361		BUG();
1362	}
1363}
1364#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1365
1366long prctl_get_seccomp(void)
1367{
1368	return current->seccomp.mode;
1369}
1370
1371/**
1372 * seccomp_set_mode_strict: internal function for setting strict seccomp
1373 *
1374 * Once current->seccomp.mode is non-zero, it may not be changed.
1375 *
1376 * Returns 0 on success or -EINVAL on failure.
1377 */
1378static long seccomp_set_mode_strict(void)
1379{
1380	const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1381	long ret = -EINVAL;
1382
1383	spin_lock_irq(&current->sighand->siglock);
1384
1385	if (!seccomp_may_assign_mode(seccomp_mode))
1386		goto out;
1387
1388#ifdef TIF_NOTSC
1389	disable_TSC();
1390#endif
1391	seccomp_assign_mode(current, seccomp_mode, 0);
1392	ret = 0;
1393
1394out:
1395	spin_unlock_irq(&current->sighand->siglock);
1396
1397	return ret;
1398}
1399
1400#ifdef CONFIG_SECCOMP_FILTER
1401static void seccomp_notify_free(struct seccomp_filter *filter)
1402{
1403	kfree(filter->notif);
1404	filter->notif = NULL;
1405}
1406
1407static void seccomp_notify_detach(struct seccomp_filter *filter)
1408{
1409	struct seccomp_knotif *knotif;
1410
1411	if (!filter)
1412		return;
1413
1414	mutex_lock(&filter->notify_lock);
1415
1416	/*
1417	 * If this file is being closed because e.g. the task who owned it
1418	 * died, let's wake everyone up who was waiting on us.
1419	 */
1420	list_for_each_entry(knotif, &filter->notif->notifications, list) {
1421		if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1422			continue;
1423
1424		knotif->state = SECCOMP_NOTIFY_REPLIED;
1425		knotif->error = -ENOSYS;
1426		knotif->val = 0;
1427
1428		/*
1429		 * We do not need to wake up any pending addfd messages, as
1430		 * the notifier will do that for us, as this just looks
1431		 * like a standard reply.
1432		 */
1433		complete(&knotif->ready);
1434	}
1435
1436	seccomp_notify_free(filter);
1437	mutex_unlock(&filter->notify_lock);
1438}
1439
1440static int seccomp_notify_release(struct inode *inode, struct file *file)
1441{
1442	struct seccomp_filter *filter = file->private_data;
1443
1444	seccomp_notify_detach(filter);
1445	__put_seccomp_filter(filter);
1446	return 0;
1447}
1448
1449/* must be called with notif_lock held */
1450static inline struct seccomp_knotif *
1451find_notification(struct seccomp_filter *filter, u64 id)
1452{
1453	struct seccomp_knotif *cur;
1454
1455	lockdep_assert_held(&filter->notify_lock);
1456
1457	list_for_each_entry(cur, &filter->notif->notifications, list) {
1458		if (cur->id == id)
1459			return cur;
1460	}
1461
1462	return NULL;
1463}
1464
1465static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
1466				  void *key)
1467{
1468	/* Avoid a wakeup if event not interesting for us. */
1469	if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR)))
1470		return 0;
1471	return autoremove_wake_function(wait, mode, sync, key);
1472}
1473
1474static int recv_wait_event(struct seccomp_filter *filter)
1475{
1476	DEFINE_WAIT_FUNC(wait, recv_wake_function);
1477	int ret;
1478
 
 
 
1479	if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1480		return 0;
1481
1482	for (;;) {
1483		ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);
1484
1485		if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1486			break;
 
 
1487
1488		if (ret)
1489			return ret;
1490
1491		schedule();
1492	}
1493	finish_wait(&filter->wqh, &wait);
1494	return 0;
1495}
1496
1497static long seccomp_notify_recv(struct seccomp_filter *filter,
1498				void __user *buf)
1499{
1500	struct seccomp_knotif *knotif = NULL, *cur;
1501	struct seccomp_notif unotif;
1502	ssize_t ret;
1503
1504	/* Verify that we're not given garbage to keep struct extensible. */
1505	ret = check_zeroed_user(buf, sizeof(unotif));
1506	if (ret < 0)
1507		return ret;
1508	if (!ret)
1509		return -EINVAL;
1510
1511	memset(&unotif, 0, sizeof(unotif));
1512
1513	ret = recv_wait_event(filter);
1514	if (ret < 0)
1515		return ret;
1516
1517	mutex_lock(&filter->notify_lock);
1518	list_for_each_entry(cur, &filter->notif->notifications, list) {
1519		if (cur->state == SECCOMP_NOTIFY_INIT) {
1520			knotif = cur;
1521			break;
1522		}
1523	}
1524
1525	/*
1526	 * If we didn't find a notification, it could be that the task was
1527	 * interrupted by a fatal signal between the time we were woken and
1528	 * when we were able to acquire the rw lock.
1529	 */
1530	if (!knotif) {
1531		ret = -ENOENT;
1532		goto out;
1533	}
1534
1535	unotif.id = knotif->id;
1536	unotif.pid = task_pid_vnr(knotif->task);
1537	unotif.data = *(knotif->data);
1538
1539	knotif->state = SECCOMP_NOTIFY_SENT;
1540	wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1541	ret = 0;
1542out:
1543	mutex_unlock(&filter->notify_lock);
1544
1545	if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1546		ret = -EFAULT;
1547
1548		/*
1549		 * Userspace screwed up. To make sure that we keep this
1550		 * notification alive, let's reset it back to INIT. It
1551		 * may have died when we released the lock, so we need to make
1552		 * sure it's still around.
1553		 */
1554		mutex_lock(&filter->notify_lock);
1555		knotif = find_notification(filter, unotif.id);
1556		if (knotif) {
1557			/* Reset the process to make sure it's not stuck */
1558			if (should_sleep_killable(filter, knotif))
1559				complete(&knotif->ready);
1560			knotif->state = SECCOMP_NOTIFY_INIT;
1561			atomic_inc(&filter->notif->requests);
1562			wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);
1563		}
1564		mutex_unlock(&filter->notify_lock);
1565	}
1566
1567	return ret;
1568}
1569
1570static long seccomp_notify_send(struct seccomp_filter *filter,
1571				void __user *buf)
1572{
1573	struct seccomp_notif_resp resp = {};
1574	struct seccomp_knotif *knotif;
1575	long ret;
1576
1577	if (copy_from_user(&resp, buf, sizeof(resp)))
1578		return -EFAULT;
1579
1580	if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1581		return -EINVAL;
1582
1583	if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1584	    (resp.error || resp.val))
1585		return -EINVAL;
1586
1587	ret = mutex_lock_interruptible(&filter->notify_lock);
1588	if (ret < 0)
1589		return ret;
1590
1591	knotif = find_notification(filter, resp.id);
1592	if (!knotif) {
1593		ret = -ENOENT;
1594		goto out;
1595	}
1596
1597	/* Allow exactly one reply. */
1598	if (knotif->state != SECCOMP_NOTIFY_SENT) {
1599		ret = -EINPROGRESS;
1600		goto out;
1601	}
1602
1603	ret = 0;
1604	knotif->state = SECCOMP_NOTIFY_REPLIED;
1605	knotif->error = resp.error;
1606	knotif->val = resp.val;
1607	knotif->flags = resp.flags;
1608	if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1609		complete_on_current_cpu(&knotif->ready);
1610	else
1611		complete(&knotif->ready);
1612out:
1613	mutex_unlock(&filter->notify_lock);
1614	return ret;
1615}
1616
1617static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1618				    void __user *buf)
1619{
1620	struct seccomp_knotif *knotif;
1621	u64 id;
1622	long ret;
1623
1624	if (copy_from_user(&id, buf, sizeof(id)))
1625		return -EFAULT;
1626
1627	ret = mutex_lock_interruptible(&filter->notify_lock);
1628	if (ret < 0)
1629		return ret;
1630
1631	knotif = find_notification(filter, id);
1632	if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1633		ret = 0;
1634	else
1635		ret = -ENOENT;
1636
1637	mutex_unlock(&filter->notify_lock);
1638	return ret;
1639}
1640
1641static long seccomp_notify_set_flags(struct seccomp_filter *filter,
1642				    unsigned long flags)
1643{
1644	long ret;
1645
1646	if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1647		return -EINVAL;
1648
1649	ret = mutex_lock_interruptible(&filter->notify_lock);
1650	if (ret < 0)
1651		return ret;
1652	filter->notif->flags = flags;
1653	mutex_unlock(&filter->notify_lock);
1654	return 0;
1655}
1656
1657static long seccomp_notify_addfd(struct seccomp_filter *filter,
1658				 struct seccomp_notif_addfd __user *uaddfd,
1659				 unsigned int size)
1660{
1661	struct seccomp_notif_addfd addfd;
1662	struct seccomp_knotif *knotif;
1663	struct seccomp_kaddfd kaddfd;
1664	int ret;
1665
1666	BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1667	BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1668
1669	if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1670		return -EINVAL;
1671
1672	ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1673	if (ret)
1674		return ret;
1675
1676	if (addfd.newfd_flags & ~O_CLOEXEC)
1677		return -EINVAL;
1678
1679	if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
1680		return -EINVAL;
1681
1682	if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1683		return -EINVAL;
1684
1685	kaddfd.file = fget(addfd.srcfd);
1686	if (!kaddfd.file)
1687		return -EBADF;
1688
1689	kaddfd.ioctl_flags = addfd.flags;
1690	kaddfd.flags = addfd.newfd_flags;
1691	kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1692	kaddfd.fd = addfd.newfd;
1693	init_completion(&kaddfd.completion);
1694
1695	ret = mutex_lock_interruptible(&filter->notify_lock);
1696	if (ret < 0)
1697		goto out;
1698
1699	knotif = find_notification(filter, addfd.id);
1700	if (!knotif) {
1701		ret = -ENOENT;
1702		goto out_unlock;
1703	}
1704
1705	/*
1706	 * We do not want to allow for FD injection to occur before the
1707	 * notification has been picked up by a userspace handler, or after
1708	 * the notification has been replied to.
1709	 */
1710	if (knotif->state != SECCOMP_NOTIFY_SENT) {
1711		ret = -EINPROGRESS;
1712		goto out_unlock;
1713	}
1714
1715	if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1716		/*
1717		 * Disallow queuing an atomic addfd + send reply while there are
1718		 * some addfd requests still to process.
1719		 *
1720		 * There is no clear reason to support it and allows us to keep
1721		 * the loop on the other side straight-forward.
1722		 */
1723		if (!list_empty(&knotif->addfd)) {
1724			ret = -EBUSY;
1725			goto out_unlock;
1726		}
1727
1728		/* Allow exactly only one reply */
1729		knotif->state = SECCOMP_NOTIFY_REPLIED;
1730	}
1731
1732	list_add(&kaddfd.list, &knotif->addfd);
1733	complete(&knotif->ready);
1734	mutex_unlock(&filter->notify_lock);
1735
1736	/* Now we wait for it to be processed or be interrupted */
1737	ret = wait_for_completion_interruptible(&kaddfd.completion);
1738	if (ret == 0) {
1739		/*
1740		 * We had a successful completion. The other side has already
1741		 * removed us from the addfd queue, and
1742		 * wait_for_completion_interruptible has a memory barrier upon
1743		 * success that lets us read this value directly without
1744		 * locking.
1745		 */
1746		ret = kaddfd.ret;
1747		goto out;
1748	}
1749
1750	mutex_lock(&filter->notify_lock);
1751	/*
1752	 * Even though we were woken up by a signal and not a successful
1753	 * completion, a completion may have happened in the mean time.
1754	 *
1755	 * We need to check again if the addfd request has been handled,
1756	 * and if not, we will remove it from the queue.
1757	 */
1758	if (list_empty(&kaddfd.list))
1759		ret = kaddfd.ret;
1760	else
1761		list_del(&kaddfd.list);
1762
1763out_unlock:
1764	mutex_unlock(&filter->notify_lock);
1765out:
1766	fput(kaddfd.file);
1767
1768	return ret;
1769}
1770
1771static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1772				 unsigned long arg)
1773{
1774	struct seccomp_filter *filter = file->private_data;
1775	void __user *buf = (void __user *)arg;
1776
1777	/* Fixed-size ioctls */
1778	switch (cmd) {
1779	case SECCOMP_IOCTL_NOTIF_RECV:
1780		return seccomp_notify_recv(filter, buf);
1781	case SECCOMP_IOCTL_NOTIF_SEND:
1782		return seccomp_notify_send(filter, buf);
1783	case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1784	case SECCOMP_IOCTL_NOTIF_ID_VALID:
1785		return seccomp_notify_id_valid(filter, buf);
1786	case SECCOMP_IOCTL_NOTIF_SET_FLAGS:
1787		return seccomp_notify_set_flags(filter, arg);
1788	}
1789
1790	/* Extensible Argument ioctls */
1791#define EA_IOCTL(cmd)	((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1792	switch (EA_IOCTL(cmd)) {
1793	case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1794		return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1795	default:
1796		return -EINVAL;
1797	}
1798}
1799
1800static __poll_t seccomp_notify_poll(struct file *file,
1801				    struct poll_table_struct *poll_tab)
1802{
1803	struct seccomp_filter *filter = file->private_data;
1804	__poll_t ret = 0;
1805	struct seccomp_knotif *cur;
1806
1807	poll_wait(file, &filter->wqh, poll_tab);
1808
1809	if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1810		return EPOLLERR;
1811
1812	list_for_each_entry(cur, &filter->notif->notifications, list) {
1813		if (cur->state == SECCOMP_NOTIFY_INIT)
1814			ret |= EPOLLIN | EPOLLRDNORM;
1815		if (cur->state == SECCOMP_NOTIFY_SENT)
1816			ret |= EPOLLOUT | EPOLLWRNORM;
1817		if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1818			break;
1819	}
1820
1821	mutex_unlock(&filter->notify_lock);
1822
1823	if (refcount_read(&filter->users) == 0)
1824		ret |= EPOLLHUP;
1825
1826	return ret;
1827}
1828
1829static const struct file_operations seccomp_notify_ops = {
1830	.poll = seccomp_notify_poll,
1831	.release = seccomp_notify_release,
1832	.unlocked_ioctl = seccomp_notify_ioctl,
1833	.compat_ioctl = seccomp_notify_ioctl,
1834};
1835
1836static struct file *init_listener(struct seccomp_filter *filter)
1837{
1838	struct file *ret;
1839
1840	ret = ERR_PTR(-ENOMEM);
1841	filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1842	if (!filter->notif)
1843		goto out;
1844
1845	filter->notif->next_id = get_random_u64();
1846	INIT_LIST_HEAD(&filter->notif->notifications);
1847
1848	ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1849				 filter, O_RDWR);
1850	if (IS_ERR(ret))
1851		goto out_notif;
1852
1853	/* The file has a reference to it now */
1854	__get_seccomp_filter(filter);
1855
1856out_notif:
1857	if (IS_ERR(ret))
1858		seccomp_notify_free(filter);
1859out:
1860	return ret;
1861}
1862
1863/*
1864 * Does @new_child have a listener while an ancestor also has a listener?
1865 * If so, we'll want to reject this filter.
1866 * This only has to be tested for the current process, even in the TSYNC case,
1867 * because TSYNC installs @child with the same parent on all threads.
1868 * Note that @new_child is not hooked up to its parent at this point yet, so
1869 * we use current->seccomp.filter.
1870 */
1871static bool has_duplicate_listener(struct seccomp_filter *new_child)
1872{
1873	struct seccomp_filter *cur;
1874
1875	/* must be protected against concurrent TSYNC */
1876	lockdep_assert_held(&current->sighand->siglock);
1877
1878	if (!new_child->notif)
1879		return false;
1880	for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1881		if (cur->notif)
1882			return true;
1883	}
1884
1885	return false;
1886}
1887
1888/**
1889 * seccomp_set_mode_filter: internal function for setting seccomp filter
1890 * @flags:  flags to change filter behavior
1891 * @filter: struct sock_fprog containing filter
1892 *
1893 * This function may be called repeatedly to install additional filters.
1894 * Every filter successfully installed will be evaluated (in reverse order)
1895 * for each system call the task makes.
1896 *
1897 * Once current->seccomp.mode is non-zero, it may not be changed.
1898 *
1899 * Returns 0 on success or -EINVAL on failure.
1900 */
1901static long seccomp_set_mode_filter(unsigned int flags,
1902				    const char __user *filter)
1903{
1904	const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1905	struct seccomp_filter *prepared = NULL;
1906	long ret = -EINVAL;
1907	int listener = -1;
1908	struct file *listener_f = NULL;
1909
1910	/* Validate flags. */
1911	if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1912		return -EINVAL;
1913
1914	/*
1915	 * In the successful case, NEW_LISTENER returns the new listener fd.
1916	 * But in the failure case, TSYNC returns the thread that died. If you
1917	 * combine these two flags, there's no way to tell whether something
1918	 * succeeded or failed. So, let's disallow this combination if the user
1919	 * has not explicitly requested no errors from TSYNC.
1920	 */
1921	if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1922	    (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1923	    ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1924		return -EINVAL;
1925
1926	/*
1927	 * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
1928	 * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
1929	 */
1930	if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
1931	    ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
1932		return -EINVAL;
1933
1934	/* Prepare the new filter before holding any locks. */
1935	prepared = seccomp_prepare_user_filter(filter);
1936	if (IS_ERR(prepared))
1937		return PTR_ERR(prepared);
1938
1939	if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1940		listener = get_unused_fd_flags(O_CLOEXEC);
1941		if (listener < 0) {
1942			ret = listener;
1943			goto out_free;
1944		}
1945
1946		listener_f = init_listener(prepared);
1947		if (IS_ERR(listener_f)) {
1948			put_unused_fd(listener);
1949			ret = PTR_ERR(listener_f);
1950			goto out_free;
1951		}
1952	}
1953
1954	/*
1955	 * Make sure we cannot change seccomp or nnp state via TSYNC
1956	 * while another thread is in the middle of calling exec.
1957	 */
1958	if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1959	    mutex_lock_killable(&current->signal->cred_guard_mutex))
1960		goto out_put_fd;
1961
1962	spin_lock_irq(&current->sighand->siglock);
1963
1964	if (!seccomp_may_assign_mode(seccomp_mode))
1965		goto out;
1966
1967	if (has_duplicate_listener(prepared)) {
1968		ret = -EBUSY;
1969		goto out;
1970	}
1971
1972	ret = seccomp_attach_filter(flags, prepared);
1973	if (ret)
1974		goto out;
1975	/* Do not free the successfully attached filter. */
1976	prepared = NULL;
1977
1978	seccomp_assign_mode(current, seccomp_mode, flags);
1979out:
1980	spin_unlock_irq(&current->sighand->siglock);
1981	if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1982		mutex_unlock(&current->signal->cred_guard_mutex);
1983out_put_fd:
1984	if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1985		if (ret) {
1986			listener_f->private_data = NULL;
1987			fput(listener_f);
1988			put_unused_fd(listener);
1989			seccomp_notify_detach(prepared);
1990		} else {
1991			fd_install(listener, listener_f);
1992			ret = listener;
1993		}
1994	}
1995out_free:
1996	seccomp_filter_free(prepared);
1997	return ret;
1998}
1999#else
2000static inline long seccomp_set_mode_filter(unsigned int flags,
2001					   const char __user *filter)
2002{
2003	return -EINVAL;
2004}
2005#endif
2006
2007static long seccomp_get_action_avail(const char __user *uaction)
2008{
2009	u32 action;
2010
2011	if (copy_from_user(&action, uaction, sizeof(action)))
2012		return -EFAULT;
2013
2014	switch (action) {
2015	case SECCOMP_RET_KILL_PROCESS:
2016	case SECCOMP_RET_KILL_THREAD:
2017	case SECCOMP_RET_TRAP:
2018	case SECCOMP_RET_ERRNO:
2019	case SECCOMP_RET_USER_NOTIF:
2020	case SECCOMP_RET_TRACE:
2021	case SECCOMP_RET_LOG:
2022	case SECCOMP_RET_ALLOW:
2023		break;
2024	default:
2025		return -EOPNOTSUPP;
2026	}
2027
2028	return 0;
2029}
2030
2031static long seccomp_get_notif_sizes(void __user *usizes)
2032{
2033	struct seccomp_notif_sizes sizes = {
2034		.seccomp_notif = sizeof(struct seccomp_notif),
2035		.seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
2036		.seccomp_data = sizeof(struct seccomp_data),
2037	};
2038
2039	if (copy_to_user(usizes, &sizes, sizeof(sizes)))
2040		return -EFAULT;
2041
2042	return 0;
2043}
2044
2045/* Common entry point for both prctl and syscall. */
2046static long do_seccomp(unsigned int op, unsigned int flags,
2047		       void __user *uargs)
2048{
2049	switch (op) {
2050	case SECCOMP_SET_MODE_STRICT:
2051		if (flags != 0 || uargs != NULL)
2052			return -EINVAL;
2053		return seccomp_set_mode_strict();
2054	case SECCOMP_SET_MODE_FILTER:
2055		return seccomp_set_mode_filter(flags, uargs);
2056	case SECCOMP_GET_ACTION_AVAIL:
2057		if (flags != 0)
2058			return -EINVAL;
2059
2060		return seccomp_get_action_avail(uargs);
2061	case SECCOMP_GET_NOTIF_SIZES:
2062		if (flags != 0)
2063			return -EINVAL;
2064
2065		return seccomp_get_notif_sizes(uargs);
2066	default:
2067		return -EINVAL;
2068	}
2069}
2070
2071SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
2072			 void __user *, uargs)
2073{
2074	return do_seccomp(op, flags, uargs);
2075}
2076
2077/**
2078 * prctl_set_seccomp: configures current->seccomp.mode
2079 * @seccomp_mode: requested mode to use
2080 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2081 *
2082 * Returns 0 on success or -EINVAL on failure.
2083 */
2084long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
2085{
2086	unsigned int op;
2087	void __user *uargs;
2088
2089	switch (seccomp_mode) {
2090	case SECCOMP_MODE_STRICT:
2091		op = SECCOMP_SET_MODE_STRICT;
2092		/*
2093		 * Setting strict mode through prctl always ignored filter,
2094		 * so make sure it is always NULL here to pass the internal
2095		 * check in do_seccomp().
2096		 */
2097		uargs = NULL;
2098		break;
2099	case SECCOMP_MODE_FILTER:
2100		op = SECCOMP_SET_MODE_FILTER;
2101		uargs = filter;
2102		break;
2103	default:
2104		return -EINVAL;
2105	}
2106
2107	/* prctl interface doesn't have flags, so they are always zero. */
2108	return do_seccomp(op, 0, uargs);
2109}
2110
2111#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2112static struct seccomp_filter *get_nth_filter(struct task_struct *task,
2113					     unsigned long filter_off)
2114{
2115	struct seccomp_filter *orig, *filter;
2116	unsigned long count;
2117
2118	/*
2119	 * Note: this is only correct because the caller should be the (ptrace)
2120	 * tracer of the task, otherwise lock_task_sighand is needed.
2121	 */
2122	spin_lock_irq(&task->sighand->siglock);
2123
2124	if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2125		spin_unlock_irq(&task->sighand->siglock);
2126		return ERR_PTR(-EINVAL);
2127	}
2128
2129	orig = task->seccomp.filter;
2130	__get_seccomp_filter(orig);
2131	spin_unlock_irq(&task->sighand->siglock);
2132
2133	count = 0;
2134	for (filter = orig; filter; filter = filter->prev)
2135		count++;
2136
2137	if (filter_off >= count) {
2138		filter = ERR_PTR(-ENOENT);
2139		goto out;
2140	}
2141
2142	count -= filter_off;
2143	for (filter = orig; filter && count > 1; filter = filter->prev)
2144		count--;
2145
2146	if (WARN_ON(count != 1 || !filter)) {
2147		filter = ERR_PTR(-ENOENT);
2148		goto out;
2149	}
2150
2151	__get_seccomp_filter(filter);
2152
2153out:
2154	__put_seccomp_filter(orig);
2155	return filter;
2156}
2157
2158long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2159			void __user *data)
2160{
2161	struct seccomp_filter *filter;
2162	struct sock_fprog_kern *fprog;
2163	long ret;
2164
2165	if (!capable(CAP_SYS_ADMIN) ||
2166	    current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2167		return -EACCES;
2168	}
2169
2170	filter = get_nth_filter(task, filter_off);
2171	if (IS_ERR(filter))
2172		return PTR_ERR(filter);
2173
2174	fprog = filter->prog->orig_prog;
2175	if (!fprog) {
2176		/* This must be a new non-cBPF filter, since we save
2177		 * every cBPF filter's orig_prog above when
2178		 * CONFIG_CHECKPOINT_RESTORE is enabled.
2179		 */
2180		ret = -EMEDIUMTYPE;
2181		goto out;
2182	}
2183
2184	ret = fprog->len;
2185	if (!data)
2186		goto out;
2187
2188	if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2189		ret = -EFAULT;
2190
2191out:
2192	__put_seccomp_filter(filter);
2193	return ret;
2194}
2195
2196long seccomp_get_metadata(struct task_struct *task,
2197			  unsigned long size, void __user *data)
2198{
2199	long ret;
2200	struct seccomp_filter *filter;
2201	struct seccomp_metadata kmd = {};
2202
2203	if (!capable(CAP_SYS_ADMIN) ||
2204	    current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2205		return -EACCES;
2206	}
2207
2208	size = min_t(unsigned long, size, sizeof(kmd));
2209
2210	if (size < sizeof(kmd.filter_off))
2211		return -EINVAL;
2212
2213	if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2214		return -EFAULT;
2215
2216	filter = get_nth_filter(task, kmd.filter_off);
2217	if (IS_ERR(filter))
2218		return PTR_ERR(filter);
2219
2220	if (filter->log)
2221		kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2222
2223	ret = size;
2224	if (copy_to_user(data, &kmd, size))
2225		ret = -EFAULT;
2226
2227	__put_seccomp_filter(filter);
2228	return ret;
2229}
2230#endif
2231
2232#ifdef CONFIG_SYSCTL
2233
2234/* Human readable action names for friendly sysctl interaction */
2235#define SECCOMP_RET_KILL_PROCESS_NAME	"kill_process"
2236#define SECCOMP_RET_KILL_THREAD_NAME	"kill_thread"
2237#define SECCOMP_RET_TRAP_NAME		"trap"
2238#define SECCOMP_RET_ERRNO_NAME		"errno"
2239#define SECCOMP_RET_USER_NOTIF_NAME	"user_notif"
2240#define SECCOMP_RET_TRACE_NAME		"trace"
2241#define SECCOMP_RET_LOG_NAME		"log"
2242#define SECCOMP_RET_ALLOW_NAME		"allow"
2243
2244static const char seccomp_actions_avail[] =
2245				SECCOMP_RET_KILL_PROCESS_NAME	" "
2246				SECCOMP_RET_KILL_THREAD_NAME	" "
2247				SECCOMP_RET_TRAP_NAME		" "
2248				SECCOMP_RET_ERRNO_NAME		" "
2249				SECCOMP_RET_USER_NOTIF_NAME     " "
2250				SECCOMP_RET_TRACE_NAME		" "
2251				SECCOMP_RET_LOG_NAME		" "
2252				SECCOMP_RET_ALLOW_NAME;
2253
2254struct seccomp_log_name {
2255	u32		log;
2256	const char	*name;
2257};
2258
2259static const struct seccomp_log_name seccomp_log_names[] = {
2260	{ SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2261	{ SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2262	{ SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2263	{ SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2264	{ SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2265	{ SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2266	{ SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2267	{ SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2268	{ }
2269};
2270
2271static bool seccomp_names_from_actions_logged(char *names, size_t size,
2272					      u32 actions_logged,
2273					      const char *sep)
2274{
2275	const struct seccomp_log_name *cur;
2276	bool append_sep = false;
2277
2278	for (cur = seccomp_log_names; cur->name && size; cur++) {
2279		ssize_t ret;
2280
2281		if (!(actions_logged & cur->log))
2282			continue;
2283
2284		if (append_sep) {
2285			ret = strscpy(names, sep, size);
2286			if (ret < 0)
2287				return false;
2288
2289			names += ret;
2290			size -= ret;
2291		} else
2292			append_sep = true;
2293
2294		ret = strscpy(names, cur->name, size);
2295		if (ret < 0)
2296			return false;
2297
2298		names += ret;
2299		size -= ret;
2300	}
2301
2302	return true;
2303}
2304
2305static bool seccomp_action_logged_from_name(u32 *action_logged,
2306					    const char *name)
2307{
2308	const struct seccomp_log_name *cur;
2309
2310	for (cur = seccomp_log_names; cur->name; cur++) {
2311		if (!strcmp(cur->name, name)) {
2312			*action_logged = cur->log;
2313			return true;
2314		}
2315	}
2316
2317	return false;
2318}
2319
2320static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2321{
2322	char *name;
2323
2324	*actions_logged = 0;
2325	while ((name = strsep(&names, " ")) && *name) {
2326		u32 action_logged = 0;
2327
2328		if (!seccomp_action_logged_from_name(&action_logged, name))
2329			return false;
2330
2331		*actions_logged |= action_logged;
2332	}
2333
2334	return true;
2335}
2336
2337static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
2338			       size_t *lenp, loff_t *ppos)
2339{
2340	char names[sizeof(seccomp_actions_avail)];
2341	struct ctl_table table;
2342
2343	memset(names, 0, sizeof(names));
2344
2345	if (!seccomp_names_from_actions_logged(names, sizeof(names),
2346					       seccomp_actions_logged, " "))
2347		return -EINVAL;
2348
2349	table = *ro_table;
2350	table.data = names;
2351	table.maxlen = sizeof(names);
2352	return proc_dostring(&table, 0, buffer, lenp, ppos);
2353}
2354
2355static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
2356				size_t *lenp, loff_t *ppos, u32 *actions_logged)
2357{
2358	char names[sizeof(seccomp_actions_avail)];
2359	struct ctl_table table;
2360	int ret;
2361
2362	if (!capable(CAP_SYS_ADMIN))
2363		return -EPERM;
2364
2365	memset(names, 0, sizeof(names));
2366
2367	table = *ro_table;
2368	table.data = names;
2369	table.maxlen = sizeof(names);
2370	ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2371	if (ret)
2372		return ret;
2373
2374	if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2375		return -EINVAL;
2376
2377	if (*actions_logged & SECCOMP_LOG_ALLOW)
2378		return -EINVAL;
2379
2380	seccomp_actions_logged = *actions_logged;
2381	return 0;
2382}
2383
2384static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2385				 int ret)
2386{
2387	char names[sizeof(seccomp_actions_avail)];
2388	char old_names[sizeof(seccomp_actions_avail)];
2389	const char *new = names;
2390	const char *old = old_names;
2391
2392	if (!audit_enabled)
2393		return;
2394
2395	memset(names, 0, sizeof(names));
2396	memset(old_names, 0, sizeof(old_names));
2397
2398	if (ret)
2399		new = "?";
2400	else if (!actions_logged)
2401		new = "(none)";
2402	else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2403						    actions_logged, ","))
2404		new = "?";
2405
2406	if (!old_actions_logged)
2407		old = "(none)";
2408	else if (!seccomp_names_from_actions_logged(old_names,
2409						    sizeof(old_names),
2410						    old_actions_logged, ","))
2411		old = "?";
2412
2413	return audit_seccomp_actions_logged(new, old, !ret);
2414}
2415
2416static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
2417					  void *buffer, size_t *lenp,
2418					  loff_t *ppos)
2419{
2420	int ret;
2421
2422	if (write) {
2423		u32 actions_logged = 0;
2424		u32 old_actions_logged = seccomp_actions_logged;
2425
2426		ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2427					   &actions_logged);
2428		audit_actions_logged(actions_logged, old_actions_logged, ret);
2429	} else
2430		ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2431
2432	return ret;
2433}
2434
2435static struct ctl_table seccomp_sysctl_table[] = {
2436	{
2437		.procname	= "actions_avail",
2438		.data		= (void *) &seccomp_actions_avail,
2439		.maxlen		= sizeof(seccomp_actions_avail),
2440		.mode		= 0444,
2441		.proc_handler	= proc_dostring,
2442	},
2443	{
2444		.procname	= "actions_logged",
2445		.mode		= 0644,
2446		.proc_handler	= seccomp_actions_logged_handler,
2447	},
2448	{ }
2449};
2450
2451static int __init seccomp_sysctl_init(void)
2452{
2453	register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
2454	return 0;
2455}
2456
2457device_initcall(seccomp_sysctl_init)
2458
2459#endif /* CONFIG_SYSCTL */
2460
2461#ifdef CONFIG_SECCOMP_CACHE_DEBUG
2462/* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2463static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2464					const void *bitmap, size_t bitmap_size)
2465{
2466	int nr;
2467
2468	for (nr = 0; nr < bitmap_size; nr++) {
2469		bool cached = test_bit(nr, bitmap);
2470		char *status = cached ? "ALLOW" : "FILTER";
2471
2472		seq_printf(m, "%s %d %s\n", name, nr, status);
2473	}
2474}
2475
2476int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2477			   struct pid *pid, struct task_struct *task)
2478{
2479	struct seccomp_filter *f;
2480	unsigned long flags;
2481
2482	/*
2483	 * We don't want some sandboxed process to know what their seccomp
2484	 * filters consist of.
2485	 */
2486	if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2487		return -EACCES;
2488
2489	if (!lock_task_sighand(task, &flags))
2490		return -ESRCH;
2491
2492	f = READ_ONCE(task->seccomp.filter);
2493	if (!f) {
2494		unlock_task_sighand(task, &flags);
2495		return 0;
2496	}
2497
2498	/* prevent filter from being freed while we are printing it */
2499	__get_seccomp_filter(f);
2500	unlock_task_sighand(task, &flags);
2501
2502	proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2503				    f->cache.allow_native,
2504				    SECCOMP_ARCH_NATIVE_NR);
2505
2506#ifdef SECCOMP_ARCH_COMPAT
2507	proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2508				    f->cache.allow_compat,
2509				    SECCOMP_ARCH_COMPAT_NR);
2510#endif /* SECCOMP_ARCH_COMPAT */
2511
2512	__put_seccomp_filter(f);
2513	return 0;
2514}
2515#endif /* CONFIG_SECCOMP_CACHE_DEBUG */