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383 lines
8.9 KiB
383 lines
8.9 KiB
/*
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* Copyright (c) 2011 Comtrol Corp.
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* Copyright (c) 2011-2018 The strace developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include "defs.h"
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#include <limits.h>
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#include <poll.h>
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#include "syscall.h"
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#include "xstring.h"
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struct path_set global_path_set;
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/*
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* Return true if specified path matches one that we're tracing.
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*/
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static bool
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pathmatch(const char *path, struct path_set *set)
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{
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unsigned i;
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for (i = 0; i < set->num_selected; ++i) {
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if (strcmp(path, set->paths_selected[i]) == 0)
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return true;
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}
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return false;
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}
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/*
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* Return true if specified path (in user-space) matches.
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*/
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static bool
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upathmatch(struct tcb *const tcp, const kernel_ulong_t upath,
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struct path_set *set)
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{
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char path[PATH_MAX + 1];
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return umovestr(tcp, upath, sizeof(path), path) > 0 &&
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pathmatch(path, set);
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}
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/*
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* Return true if specified fd maps to a path we're tracing.
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*/
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static bool
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fdmatch(struct tcb *tcp, int fd, struct path_set *set)
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{
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char path[PATH_MAX + 1];
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int n = getfdpath(tcp, fd, path, sizeof(path));
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return n >= 0 && pathmatch(path, set);
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}
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/*
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* Add a path to the set we're tracing.
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* Specifying NULL will delete all paths.
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*/
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static void
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storepath(const char *path, struct path_set *set)
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{
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if (pathmatch(path, set))
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return; /* already in table */
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if (set->num_selected >= set->size)
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set->paths_selected =
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xgrowarray(set->paths_selected, &set->size,
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sizeof(set->paths_selected[0]));
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set->paths_selected[set->num_selected++] = path;
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}
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/*
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* Get path associated with fd.
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*/
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int
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getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
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{
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char linkpath[sizeof("/proc/%u/fd/%u") + 2 * sizeof(int)*3];
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ssize_t n;
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if (fd < 0)
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return -1;
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xsprintf(linkpath, "/proc/%u/fd/%u", tcp->pid, fd);
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n = readlink(linkpath, buf, bufsize - 1);
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/*
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* NB: if buf is too small, readlink doesn't fail,
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* it returns truncated result (IOW: n == bufsize - 1).
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*/
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if (n >= 0)
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buf[n] = '\0';
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return n;
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}
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/*
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* Add a path to the set we're tracing. Also add the canonicalized
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* version of the path. Specifying NULL will delete all paths.
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*/
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void
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pathtrace_select_set(const char *path, struct path_set *set)
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{
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char *rpath;
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storepath(path, set);
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rpath = realpath(path, NULL);
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if (rpath == NULL)
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return;
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/* if realpath and specified path are same, we're done */
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if (strcmp(path, rpath) == 0) {
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free(rpath);
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return;
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}
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error_msg("Requested path '%s' resolved into '%s'", path, rpath);
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storepath(rpath, set);
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}
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static bool
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match_xselect_args(struct tcb *tcp, const kernel_ulong_t *args,
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struct path_set *set)
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{
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/* Kernel truncates arg[0] to int, we do the same. */
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int nfds = (int) args[0];
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/* Kernel rejects negative nfds, so we don't parse it either. */
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if (nfds <= 0)
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return false;
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/* Beware of select(2^31-1, NULL, NULL, NULL) and similar... */
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if (nfds > 1024*1024)
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nfds = 1024*1024;
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unsigned int fdsize = (((nfds + 7) / 8) + current_wordsize-1) & -current_wordsize;
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fd_set *fds = xmalloc(fdsize);
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for (unsigned int i = 1; i <= 3; ++i) {
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if (args[i] == 0)
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continue;
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if (umoven(tcp, args[i], fdsize, fds) < 0)
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continue;
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for (int j = 0;; ++j) {
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j = next_set_bit(fds, j, nfds);
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if (j < 0)
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break;
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if (fdmatch(tcp, j, set)) {
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free(fds);
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return true;
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}
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}
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}
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free(fds);
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return false;
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}
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/*
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* Return true if syscall accesses a selected path
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* (or if no paths have been specified for tracing).
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*/
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bool
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pathtrace_match_set(struct tcb *tcp, struct path_set *set)
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{
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const struct_sysent *s;
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s = tcp->s_ent;
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if (!(s->sys_flags & (TRACE_FILE | TRACE_DESC | TRACE_NETWORK)))
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return false;
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/*
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* Check for special cases where we need to do something
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* other than test arg[0].
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*/
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switch (s->sen) {
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case SEN_dup2:
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case SEN_dup3:
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case SEN_kexec_file_load:
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case SEN_sendfile:
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case SEN_sendfile64:
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case SEN_tee:
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/* fd, fd */
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return fdmatch(tcp, tcp->u_arg[0], set) ||
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fdmatch(tcp, tcp->u_arg[1], set);
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case SEN_execveat:
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case SEN_faccessat:
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case SEN_fchmodat:
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case SEN_fchownat:
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case SEN_fstatat64:
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case SEN_futimesat:
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case SEN_inotify_add_watch:
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case SEN_mkdirat:
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case SEN_mknodat:
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case SEN_name_to_handle_at:
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case SEN_newfstatat:
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case SEN_openat:
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case SEN_readlinkat:
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case SEN_statx:
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case SEN_unlinkat:
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case SEN_utimensat:
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/* fd, path */
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return fdmatch(tcp, tcp->u_arg[0], set) ||
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upathmatch(tcp, tcp->u_arg[1], set);
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case SEN_link:
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case SEN_mount:
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case SEN_pivotroot:
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/* path, path */
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return upathmatch(tcp, tcp->u_arg[0], set) ||
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upathmatch(tcp, tcp->u_arg[1], set);
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case SEN_quotactl:
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case SEN_symlink:
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/* x, path */
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return upathmatch(tcp, tcp->u_arg[1], set);
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case SEN_linkat:
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case SEN_renameat2:
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case SEN_renameat:
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/* fd, path, fd, path */
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return fdmatch(tcp, tcp->u_arg[0], set) ||
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fdmatch(tcp, tcp->u_arg[2], set) ||
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upathmatch(tcp, tcp->u_arg[1], set) ||
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upathmatch(tcp, tcp->u_arg[3], set);
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#if HAVE_ARCH_OLD_MMAP
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case SEN_old_mmap:
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# if HAVE_ARCH_OLD_MMAP_PGOFF
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case SEN_old_mmap_pgoff:
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# endif
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{
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kernel_ulong_t *args =
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fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);
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return args && fdmatch(tcp, args[4], set);
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}
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#endif /* HAVE_ARCH_OLD_MMAP */
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case SEN_mmap:
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case SEN_mmap_4koff:
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case SEN_mmap_pgoff:
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case SEN_ARCH_mmap:
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/* x, x, x, x, fd */
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return fdmatch(tcp, tcp->u_arg[4], set);
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case SEN_symlinkat:
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/* x, fd, path */
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return fdmatch(tcp, tcp->u_arg[1], set) ||
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upathmatch(tcp, tcp->u_arg[2], set);
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case SEN_copy_file_range:
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case SEN_splice:
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/* fd, x, fd, x, x, x */
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return fdmatch(tcp, tcp->u_arg[0], set) ||
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fdmatch(tcp, tcp->u_arg[2], set);
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case SEN_epoll_ctl:
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/* x, x, fd, x */
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return fdmatch(tcp, tcp->u_arg[2], set);
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case SEN_fanotify_mark:
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{
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/* x, x, mask (64 bit), fd, path */
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unsigned long long mask = 0;
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int argn = getllval(tcp, &mask, 2);
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return fdmatch(tcp, tcp->u_arg[argn], set) ||
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upathmatch(tcp, tcp->u_arg[argn + 1], set);
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}
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#if HAVE_ARCH_OLD_SELECT
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case SEN_oldselect:
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{
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kernel_ulong_t *args =
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fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 5);
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return args && match_xselect_args(tcp, args, set);
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}
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#endif
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case SEN_pselect6:
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case SEN_select:
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return match_xselect_args(tcp, tcp->u_arg, set);
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case SEN_poll:
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case SEN_ppoll:
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{
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struct pollfd fds;
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unsigned nfds;
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kernel_ulong_t start, cur, end;
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start = tcp->u_arg[0];
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nfds = tcp->u_arg[1];
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if (nfds > 1024 * 1024)
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nfds = 1024 * 1024;
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end = start + sizeof(fds) * nfds;
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if (nfds == 0 || end < start)
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return false;
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for (cur = start; cur < end; cur += sizeof(fds)) {
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if (umove(tcp, cur, &fds))
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break;
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if (fdmatch(tcp, fds.fd, set))
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return true;
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}
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return false;
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}
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case SEN_accept4:
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case SEN_accept:
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case SEN_bpf:
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case SEN_epoll_create:
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case SEN_epoll_create1:
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case SEN_eventfd2:
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case SEN_eventfd:
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case SEN_fanotify_init:
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case SEN_inotify_init:
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case SEN_inotify_init1:
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case SEN_memfd_create:
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case SEN_mq_getsetattr:
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case SEN_mq_notify:
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case SEN_mq_open:
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case SEN_mq_timedreceive:
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case SEN_mq_timedsend:
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case SEN_perf_event_open:
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case SEN_pipe:
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case SEN_pipe2:
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case SEN_printargs:
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case SEN_signalfd4:
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case SEN_signalfd:
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case SEN_socket:
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case SEN_socketpair:
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case SEN_timerfd_create:
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case SEN_timerfd_gettime:
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case SEN_timerfd_settime:
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case SEN_userfaultfd:
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/*
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* These have TRACE_FILE or TRACE_DESCRIPTOR or TRACE_NETWORK set,
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* but they don't have any file descriptor or path args to test.
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*/
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return false;
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}
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/*
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* Our fallback position for calls that haven't already
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* been handled is to just check arg[0].
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*/
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if (s->sys_flags & TRACE_FILE)
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return upathmatch(tcp, tcp->u_arg[0], set);
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if (s->sys_flags & (TRACE_DESC | TRACE_NETWORK))
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return fdmatch(tcp, tcp->u_arg[0], set);
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return false;
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}
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