pathtrace.c - platform/external/strace.git - Git at Google

 /*
  * Copyright (c) 2011 Comtrol Corp.
  * Copyright (c) 2011-2018 The strace developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */

 #include "defs.h"
 #include <limits.h>
 #include <poll.h>

 #include "syscall.h"
 #include "xstring.h"

 struct path_set global_path_set;

 /*
  * Return true if specified path matches one that we're tracing.
  */
 static bool
 pathmatch(const char *path, struct path_set *set)
 {
 	unsigned i;

 	for (i = 0; i < set->num_selected; ++i) {
 		if (strcmp(path, set->paths_selected[i]) == 0)
 			return true;
 	}
 	return false;
 }

 /*
  * Return true if specified path (in user-space) matches.
  */
 static bool
 upathmatch(struct tcb *const tcp, const kernel_ulong_t upath,
 	   struct path_set *set)
 {
 	char path[PATH_MAX + 1];

 	return umovestr(tcp, upath, sizeof(path), path) > 0 &&
 		pathmatch(path, set);
 }

 /*
  * Return true if specified fd maps to a path we're tracing.
  */
 static bool
 fdmatch(struct tcb *tcp, int fd, struct path_set *set)
 {
 	char path[PATH_MAX + 1];
 	int n = getfdpath(tcp, fd, path, sizeof(path));

 	return n >= 0 && pathmatch(path, set);
 }

 /*
  * Add a path to the set we're tracing.
  * Specifying NULL will delete all paths.
  */
 static void
 storepath(const char *path, struct path_set *set)
 {
 	if (pathmatch(path, set))
 		return; /* already in table */

 	if (set->num_selected >= set->size)
 		set->paths_selected =
 			xgrowarray(set->paths_selected, &set->size,
 				   sizeof(set->paths_selected[0]));

 	set->paths_selected[set->num_selected++] = path;
 }

 /*
  * Get path associated with fd.
  */
 int
 getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
 {
 	char linkpath[sizeof("/proc/%u/fd/%u") + 2 * sizeof(int)*3];
 	ssize_t n;

 	if (fd < 0)
 		return -1;

 	xsprintf(linkpath, "/proc/%u/fd/%u", tcp->pid, fd);
 	n = readlink(linkpath, buf, bufsize - 1);
 	/*
 	 * NB: if buf is too small, readlink doesn't fail,
 	 * it returns truncated result (IOW: n == bufsize - 1).
 	 */
 	if (n >= 0)
 		buf[n] = '\0';
 	return n;
 }

 /*
  * Add a path to the set we're tracing.  Also add the canonicalized
  * version of the path.  Specifying NULL will delete all paths.
  */
 void
 pathtrace_select_set(const char *path, struct path_set *set)
 {
 	char *rpath;

 	storepath(path, set);

 	rpath = realpath(path, NULL);

 	if (rpath == NULL)
 		return;

 	/* if realpath and specified path are same, we're done */
 	if (strcmp(path, rpath) == 0) {
 		free(rpath);
 		return;
 	}

 	error_msg("Requested path '%s' resolved into '%s'", path, rpath);
 	storepath(rpath, set);
 }

 static bool
 match_xselect_args(struct tcb *tcp, const kernel_ulong_t *args,
 		   struct path_set *set)
 {
 	/* Kernel truncates arg[0] to int, we do the same. */
 	int nfds = (int) args[0];
 	/* Kernel rejects negative nfds, so we don't parse it either. */
 	if (nfds <= 0)
 		return false;
 	/* Beware of select(2^31-1, NULL, NULL, NULL) and similar... */
 	if (nfds > 1024*1024)
 		nfds = 1024*1024;
 	unsigned int fdsize = (((nfds + 7) / 8) + current_wordsize-1) & -current_wordsize;
 	fd_set *fds = xmalloc(fdsize);

 	for (unsigned int i = 1; i <= 3; ++i) {
 		if (args[i] == 0)
 			continue;
 		if (umoven(tcp, args[i], fdsize, fds) < 0)
 			continue;
 		for (int j = 0;; ++j) {
 			j = next_set_bit(fds, j, nfds);
 			if (j < 0)
 				break;
 			if (fdmatch(tcp, j, set)) {
 				free(fds);
 				return true;
 			}
 		}
 	}

 	free(fds);
 	return false;
 }

 /*
  * Return true if syscall accesses a selected path
  * (or if no paths have been specified for tracing).
  */
 bool
 pathtrace_match_set(struct tcb *tcp, struct path_set *set)
 {
 	const struct_sysent *s;

 	s = tcp->s_ent;

 	if (!(s->sys_flags & (TRACE_FILE | TRACE_DESC | TRACE_NETWORK)))
 		return false;

 	/*
 	 * Check for special cases where we need to do something
 	 * other than test arg[0].
 	 */

 	switch (s->sen) {
 	case SEN_dup2:
 	case SEN_dup3:
 	case SEN_kexec_file_load:
 	case SEN_sendfile:
 	case SEN_sendfile64:
 	case SEN_tee:
 		/* fd, fd */
 		return fdmatch(tcp, tcp->u_arg[0], set) ||
 			fdmatch(tcp, tcp->u_arg[1], set);

 	case SEN_execveat:
 	case SEN_faccessat:
 	case SEN_fchmodat:
 	case SEN_fchownat:
 	case SEN_fstatat64:
 	case SEN_futimesat:
 	case SEN_inotify_add_watch:
 	case SEN_mkdirat:
 	case SEN_mknodat:
 	case SEN_name_to_handle_at:
 	case SEN_newfstatat:
 	case SEN_openat:
 	case SEN_readlinkat:
 	case SEN_statx:
 	case SEN_unlinkat:
 	case SEN_utimensat:
 		/* fd, path */
 		return fdmatch(tcp, tcp->u_arg[0], set) ||
 			upathmatch(tcp, tcp->u_arg[1], set);

 	case SEN_link:
 	case SEN_mount:
 	case SEN_pivotroot:
 		/* path, path */
 		return upathmatch(tcp, tcp->u_arg[0], set) ||
 			upathmatch(tcp, tcp->u_arg[1], set);

 	case SEN_quotactl:
 	case SEN_symlink:
 		/* x, path */
 		return upathmatch(tcp, tcp->u_arg[1], set);

 	case SEN_linkat:
 	case SEN_renameat2:
 	case SEN_renameat:
 		/* fd, path, fd, path */
 		return fdmatch(tcp, tcp->u_arg[0], set) ||
 			fdmatch(tcp, tcp->u_arg[2], set) ||
 			upathmatch(tcp, tcp->u_arg[1], set) ||
 			upathmatch(tcp, tcp->u_arg[3], set);

 #if HAVE_ARCH_OLD_MMAP
 	case SEN_old_mmap:
 # if HAVE_ARCH_OLD_MMAP_PGOFF
 	case SEN_old_mmap_pgoff:
 # endif
 	{
 		kernel_ulong_t *args =
 			fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);

 		return args && fdmatch(tcp, args[4], set);
 	}
 #endif /* HAVE_ARCH_OLD_MMAP */

 	case SEN_mmap:
 	case SEN_mmap_4koff:
 	case SEN_mmap_pgoff:
 	case SEN_ARCH_mmap:
 		/* x, x, x, x, fd */
 		return fdmatch(tcp, tcp->u_arg[4], set);

 	case SEN_symlinkat:
 		/* x, fd, path */
 		return fdmatch(tcp, tcp->u_arg[1], set) ||
 			upathmatch(tcp, tcp->u_arg[2], set);

 	case SEN_copy_file_range:
 	case SEN_splice:
 		/* fd, x, fd, x, x, x */
 		return fdmatch(tcp, tcp->u_arg[0], set) ||
 			fdmatch(tcp, tcp->u_arg[2], set);

 	case SEN_epoll_ctl:
 		/* x, x, fd, x */
 		return fdmatch(tcp, tcp->u_arg[2], set);


 	case SEN_fanotify_mark:
 	{
 		/* x, x, mask (64 bit), fd, path */
 		unsigned long long mask = 0;
 		int argn = getllval(tcp, &mask, 2);
 		return fdmatch(tcp, tcp->u_arg[argn], set) ||
 			upathmatch(tcp, tcp->u_arg[argn + 1], set);
 	}
 #if HAVE_ARCH_OLD_SELECT
 	case SEN_oldselect:
 	{
 		kernel_ulong_t *args =
 			fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 5);

 		return args && match_xselect_args(tcp, args, set);
 	}
 #endif
 	case SEN_pselect6:
 	case SEN_select:
 		return match_xselect_args(tcp, tcp->u_arg, set);
 	case SEN_poll:
 	case SEN_ppoll:
 	{
 		struct pollfd fds;
 		unsigned nfds;
 		kernel_ulong_t start, cur, end;

 		start = tcp->u_arg[0];
 		nfds = tcp->u_arg[1];

 		if (nfds > 1024 * 1024)
 			nfds = 1024 * 1024;
 		end = start + sizeof(fds) * nfds;

 		if (nfds == 0 || end < start)
 			return false;

 		for (cur = start; cur < end; cur += sizeof(fds)) {
 			if (umove(tcp, cur, &fds))
 				break;
 			if (fdmatch(tcp, fds.fd, set))
 				return true;
 		}

 		return false;
 	}

 	case SEN_accept4:
 	case SEN_accept:
 	case SEN_bpf:
 	case SEN_epoll_create:
 	case SEN_epoll_create1:
 	case SEN_eventfd2:
 	case SEN_eventfd:
 	case SEN_fanotify_init:
 	case SEN_inotify_init:
 	case SEN_inotify_init1:
 	case SEN_memfd_create:
 	case SEN_mq_getsetattr:
 	case SEN_mq_notify:
 	case SEN_mq_open:
 	case SEN_mq_timedreceive:
 	case SEN_mq_timedsend:
 	case SEN_perf_event_open:
 	case SEN_pipe:
 	case SEN_pipe2:
 	case SEN_printargs:
 	case SEN_signalfd4:
 	case SEN_signalfd:
 	case SEN_socket:
 	case SEN_socketpair:
 	case SEN_timerfd_create:
 	case SEN_timerfd_gettime:
 	case SEN_timerfd_settime:
 	case SEN_userfaultfd:
 		/*
 		 * These have TRACE_FILE or TRACE_DESCRIPTOR or TRACE_NETWORK set,
 		 * but they don't have any file descriptor or path args to test.
 		 */
 		return false;
 	}

 	/*
 	 * Our fallback position for calls that haven't already
 	 * been handled is to just check arg[0].
 	 */

 	if (s->sys_flags & TRACE_FILE)
 		return upathmatch(tcp, tcp->u_arg[0], set);

 	if (s->sys_flags & (TRACE_DESC | TRACE_NETWORK))
 		return fdmatch(tcp, tcp->u_arg[0], set);

 	return false;
 }
	/*
	* Copyright (c) 2011 Comtrol Corp.
	* Copyright (c) 2011-2018 The strace developers.
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	*/

	#include "defs.h"
	#include <limits.h>
	#include <poll.h>

	#include "syscall.h"
	#include "xstring.h"

	struct path_set global_path_set;

	/*
	* Return true if specified path matches one that we're tracing.
	*/
	static bool
	pathmatch(const char path, struct path_set set)
	{
	unsigned i;

	for (i = 0; i < set->num_selected; ++i) {
	if (strcmp(path, set->paths_selected[i]) == 0)
	return true;
	}
	return false;
	}

	/*
	* Return true if specified path (in user-space) matches.
	*/
	static bool
	upathmatch(struct tcb *const tcp, const kernel_ulong_t upath,
	struct path_set *set)
	{
	char path[PATH_MAX + 1];

	return umovestr(tcp, upath, sizeof(path), path) > 0 &&
	pathmatch(path, set);
	}

	/*
	* Return true if specified fd maps to a path we're tracing.
	*/
	static bool
	fdmatch(struct tcb tcp, int fd, struct path_set set)
	{
	char path[PATH_MAX + 1];
	int n = getfdpath(tcp, fd, path, sizeof(path));

	return n >= 0 && pathmatch(path, set);
	}

	/*
	* Add a path to the set we're tracing.
	* Specifying NULL will delete all paths.
	*/
	static void
	storepath(const char path, struct path_set set)
	{
	if (pathmatch(path, set))
	return; /* already in table */

	if (set->num_selected >= set->size)
	set->paths_selected =
	xgrowarray(set->paths_selected, &set->size,
	sizeof(set->paths_selected[0]));

	set->paths_selected[set->num_selected++] = path;
	}

	/*
	* Get path associated with fd.
	*/
	int
	getfdpath(struct tcb tcp, int fd, char buf, unsigned bufsize)
	{
	char linkpath[sizeof("/proc/%u/fd/%u") + 2 * sizeof(int)*3];
	ssize_t n;

	if (fd < 0)
	return -1;

	xsprintf(linkpath, "/proc/%u/fd/%u", tcp->pid, fd);
	n = readlink(linkpath, buf, bufsize - 1);
	/*
	* NB: if buf is too small, readlink doesn't fail,
	* it returns truncated result (IOW: n == bufsize - 1).
	*/
	if (n >= 0)
	buf[n] = '\0';
	return n;
	}

	/*
	* Add a path to the set we're tracing. Also add the canonicalized
	* version of the path. Specifying NULL will delete all paths.
	*/
	void
	pathtrace_select_set(const char path, struct path_set set)
	{
	char *rpath;

	storepath(path, set);

	rpath = realpath(path, NULL);

	if (rpath == NULL)
	return;

	/* if realpath and specified path are same, we're done */
	if (strcmp(path, rpath) == 0) {
	free(rpath);
	return;
	}

	error_msg("Requested path '%s' resolved into '%s'", path, rpath);
	storepath(rpath, set);
	}

	static bool
	match_xselect_args(struct tcb tcp, const kernel_ulong_t args,
	struct path_set *set)
	{
	/* Kernel truncates arg[0] to int, we do the same. */
	int nfds = (int) args[0];
	/* Kernel rejects negative nfds, so we don't parse it either. */
	if (nfds <= 0)
	return false;
	/* Beware of select(2^31-1, NULL, NULL, NULL) and similar... */
	if (nfds > 1024*1024)
	nfds = 1024*1024;
	unsigned int fdsize = (((nfds + 7) / 8) + current_wordsize-1) & -current_wordsize;
	fd_set *fds = xmalloc(fdsize);

	for (unsigned int i = 1; i <= 3; ++i) {
	if (args[i] == 0)
	continue;
	if (umoven(tcp, args[i], fdsize, fds) < 0)
	continue;
	for (int j = 0;; ++j) {
	j = next_set_bit(fds, j, nfds);
	if (j < 0)
	break;
	if (fdmatch(tcp, j, set)) {
	free(fds);
	return true;
	}
	}
	}

	free(fds);
	return false;
	}

	/*
	* Return true if syscall accesses a selected path
	* (or if no paths have been specified for tracing).
	*/
	bool
	pathtrace_match_set(struct tcb tcp, struct path_set set)
	{
	const struct_sysent *s;

	s = tcp->s_ent;

	if (!(s->sys_flags & (TRACE_FILE \| TRACE_DESC \| TRACE_NETWORK)))
	return false;

	/*
	* Check for special cases where we need to do something
	* other than test arg[0].
	*/

	switch (s->sen) {
	case SEN_dup2:
	case SEN_dup3:
	case SEN_kexec_file_load:
	case SEN_sendfile:
	case SEN_sendfile64:
	case SEN_tee:
	/* fd, fd */
	return fdmatch(tcp, tcp->u_arg[0], set) \|\|
	fdmatch(tcp, tcp->u_arg[1], set);

	case SEN_execveat:
	case SEN_faccessat:
	case SEN_fchmodat:
	case SEN_fchownat:
	case SEN_fstatat64:
	case SEN_futimesat:
	case SEN_inotify_add_watch:
	case SEN_mkdirat:
	case SEN_mknodat:
	case SEN_name_to_handle_at:
	case SEN_newfstatat:
	case SEN_openat:
	case SEN_readlinkat:
	case SEN_statx:
	case SEN_unlinkat:
	case SEN_utimensat:
	/* fd, path */
	return fdmatch(tcp, tcp->u_arg[0], set) \|\|
	upathmatch(tcp, tcp->u_arg[1], set);

	case SEN_link:
	case SEN_mount:
	case SEN_pivotroot:
	/* path, path */
	return upathmatch(tcp, tcp->u_arg[0], set) \|\|
	upathmatch(tcp, tcp->u_arg[1], set);

	case SEN_quotactl:
	case SEN_symlink:
	/* x, path */
	return upathmatch(tcp, tcp->u_arg[1], set);

	case SEN_linkat:
	case SEN_renameat2:
	case SEN_renameat:
	/* fd, path, fd, path */
	return fdmatch(tcp, tcp->u_arg[0], set) \|\|
	fdmatch(tcp, tcp->u_arg[2], set) \|\|
	upathmatch(tcp, tcp->u_arg[1], set) \|\|
	upathmatch(tcp, tcp->u_arg[3], set);

	#if HAVE_ARCH_OLD_MMAP
	case SEN_old_mmap:
	# if HAVE_ARCH_OLD_MMAP_PGOFF
	case SEN_old_mmap_pgoff:
	# endif
	{
	kernel_ulong_t *args =
	fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);

	return args && fdmatch(tcp, args[4], set);
	}
	#endif /* HAVE_ARCH_OLD_MMAP */

	case SEN_mmap:
	case SEN_mmap_4koff:
	case SEN_mmap_pgoff:
	case SEN_ARCH_mmap:
	/* x, x, x, x, fd */
	return fdmatch(tcp, tcp->u_arg[4], set);

	case SEN_symlinkat:
	/* x, fd, path */
	return fdmatch(tcp, tcp->u_arg[1], set) \|\|
	upathmatch(tcp, tcp->u_arg[2], set);

	case SEN_copy_file_range:
	case SEN_splice:
	/* fd, x, fd, x, x, x */
	return fdmatch(tcp, tcp->u_arg[0], set) \|\|
	fdmatch(tcp, tcp->u_arg[2], set);

	case SEN_epoll_ctl:
	/* x, x, fd, x */
	return fdmatch(tcp, tcp->u_arg[2], set);


	case SEN_fanotify_mark:
	{
	/* x, x, mask (64 bit), fd, path */
	unsigned long long mask = 0;
	int argn = getllval(tcp, &mask, 2);
	return fdmatch(tcp, tcp->u_arg[argn], set) \|\|
	upathmatch(tcp, tcp->u_arg[argn + 1], set);
	}
	#if HAVE_ARCH_OLD_SELECT
	case SEN_oldselect:
	{
	kernel_ulong_t *args =
	fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 5);

	return args && match_xselect_args(tcp, args, set);
	}
	#endif
	case SEN_pselect6:
	case SEN_select:
	return match_xselect_args(tcp, tcp->u_arg, set);
	case SEN_poll:
	case SEN_ppoll:
	{
	struct pollfd fds;
	unsigned nfds;
	kernel_ulong_t start, cur, end;

	start = tcp->u_arg[0];
	nfds = tcp->u_arg[1];

	if (nfds > 1024 * 1024)
	nfds = 1024 * 1024;
	end = start + sizeof(fds) * nfds;

	if (nfds == 0 \|\| end < start)
	return false;

	for (cur = start; cur < end; cur += sizeof(fds)) {
	if (umove(tcp, cur, &fds))
	break;
	if (fdmatch(tcp, fds.fd, set))
	return true;
	}

	return false;
	}

	case SEN_accept4:
	case SEN_accept:
	case SEN_bpf:
	case SEN_epoll_create:
	case SEN_epoll_create1:
	case SEN_eventfd2:
	case SEN_eventfd:
	case SEN_fanotify_init:
	case SEN_inotify_init:
	case SEN_inotify_init1:
	case SEN_memfd_create:
	case SEN_mq_getsetattr:
	case SEN_mq_notify:
	case SEN_mq_open:
	case SEN_mq_timedreceive:
	case SEN_mq_timedsend:
	case SEN_perf_event_open:
	case SEN_pipe:
	case SEN_pipe2:
	case SEN_printargs:
	case SEN_signalfd4:
	case SEN_signalfd:
	case SEN_socket:
	case SEN_socketpair:
	case SEN_timerfd_create:
	case SEN_timerfd_gettime:
	case SEN_timerfd_settime:
	case SEN_userfaultfd:
	/*
	* These have TRACE_FILE or TRACE_DESCRIPTOR or TRACE_NETWORK set,
	* but they don't have any file descriptor or path args to test.
	*/
	return false;
	}

	/*
	* Our fallback position for calls that haven't already
	* been handled is to just check arg[0].
	*/

	if (s->sys_flags & TRACE_FILE)
	return upathmatch(tcp, tcp->u_arg[0], set);

	if (s->sys_flags & (TRACE_DESC \| TRACE_NETWORK))
	return fdmatch(tcp, tcp->u_arg[0], set);

	return false;
	}