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Improve fd filtering

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* pathtrace.c (fdmatch_fd_func): New function.
(match_fd_common): Likewise.
(pathtrace_match_set): Move fd matching to match_fd_common.
* filter.h (match_fd_common): Add new declaration.
* basic_filters.c (is_fd_in_set): New function.
(run_fd_filter): Use match_fd_common for fd filter.

[ldv: cleanup run_fd_filter]
This commit is contained in:
Nikolay Marchuk
2017-08-23 16:26:28 +07:00
committed by Dmitry V. Levin
parent c411e208bd
commit a732d730b7
3 changed files with 130 additions and 94 deletions
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14
basic_filters.c
View File

@ -342,19 +342,21 @@ parse_fd_filter(const char *str)
return set;
}
static bool
is_fd_in_set(struct tcb *tcp, int fd, void *data) {
return fd < 0 ? false : is_number_in_set(fd, data);
}
bool
run_fd_filter(struct tcb *tcp, void *priv_data)
{
int fd = tcp->u_arg[0];
return fd < 0 ? false : is_number_in_set(fd, priv_data);
return match_fd_common(tcp, &is_fd_in_set, priv_data);
}
void
free_fd_filter(void *priv_data)
{
free_number_set_array(priv_data, 1);
return;
}
void *
@ -369,9 +371,7 @@ parse_path_filter(const char *path)
bool
run_path_filter(struct tcb *tcp, void *priv_data)
{
struct path_set *set = priv_data;
return pathtrace_match_set(tcp, set);
return pathtrace_match_set(tcp, priv_data);
}
void

3
filter.h
View File

@ -47,6 +47,9 @@ void parse_inject_common_args(char *, struct inject_opts *,
bool is_traced(struct tcb *);
bool not_injected(struct tcb *);
typedef bool (*match_fd_func)(struct tcb *, int, void *);
int match_fd_common(struct tcb *, match_fd_func, void *);
/* filter api */
struct filter* add_filter_to_array(struct filter **, unsigned int *nfilters,
const char *name);

207
pathtrace.c
View File

@ -70,6 +70,8 @@ upathmatch(struct tcb *const tcp, const kernel_ulong_t upath,
static bool
fdmatch(struct tcb *tcp, int fd, struct path_set *set)
{
if (fd < 0)
return false;
char path[PATH_MAX + 1];
int n = getfdpath(tcp, fd, path, sizeof(path));
@ -143,9 +145,17 @@ pathtrace_select_set(const char *path, struct path_set *set)
storepath(rpath, set);
}
typedef bool (*match_fd_func)(struct tcb *, int, void *);
static
bool fdmatch_fd_func(struct tcb *tcp, int fd, void *data)
{
return fdmatch(tcp, fd, (struct path_set *) data);
}
static bool
match_xselect_args(struct tcb *tcp, const kernel_ulong_t *args,
struct path_set *set)
match_xselect_args(struct tcb *tcp, match_fd_func func,
const kernel_ulong_t *args, struct path_set *set)
{
/* Kernel truncates arg[0] to int, we do the same. */
int nfds = (int) args[0];
@ -167,7 +177,7 @@ match_xselect_args(struct tcb *tcp, const kernel_ulong_t *args,
j = next_set_bit(fds, j, nfds);
if (j < 0)
break;
if (fdmatch(tcp, j, set)) {
if (func(tcp, j, set)) {
free(fds);
return true;
}
@ -178,25 +188,15 @@ match_xselect_args(struct tcb *tcp, const kernel_ulong_t *args,
return false;
}
/*
* Return true if syscall accesses a selected path
* (or if no paths have been specified for tracing).
*/
/* Match fd with func. */
bool
pathtrace_match_set(struct tcb *tcp, struct path_set *set)
match_fd_common(struct tcb *tcp, match_fd_func func, void *data)
{
const struct_sysent *s;
const struct_sysent *s = tcp->s_ent;
s = tcp->s_ent;
if (!(s->sys_flags & (TRACE_FILE | TRACE_DESC | TRACE_NETWORK)))
if (!(s->sys_flags & (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:
@ -205,49 +205,17 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
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);
return func(tcp, tcp->u_arg[0], data) ||
func(tcp, tcp->u_arg[1], data);
case SEN_copy_file_range:
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);
case SEN_splice:
/* fd, x, fd */
return func(tcp, tcp->u_arg[0], data) ||
func(tcp, tcp->u_arg[2], data);
#if HAVE_ARCH_OLD_MMAP
case SEN_old_mmap:
@ -258,7 +226,7 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
kernel_ulong_t *args =
fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);
return args && fdmatch(tcp, args[4], set);
return args && func(tcp, args[4], data);
}
#endif /* HAVE_ARCH_OLD_MMAP */
@ -267,22 +235,15 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
case SEN_mmap_pgoff:
case SEN_ARCH_mmap:
/* x, x, x, x, fd */
return fdmatch(tcp, tcp->u_arg[4], set);
return func(tcp, tcp->u_arg[4], data);
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);
/* x, fd, x */
return func(tcp, tcp->u_arg[1], data);
case SEN_epoll_ctl:
/* x, x, fd, x */
return fdmatch(tcp, tcp->u_arg[2], set);
return func(tcp, tcp->u_arg[2], data);
case SEN_fanotify_mark:
@ -290,21 +251,22 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
/* 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);
return func(tcp, tcp->u_arg[argn], data);
}
#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);
return args && match_xselect_args(tcp, func, args, data);
}
#endif
case SEN_pselect6:
case SEN_select:
return match_xselect_args(tcp, tcp->u_arg, set);
return match_xselect_args(tcp, func, tcp->u_arg, data);
case SEN_poll:
case SEN_ppoll:
{
@ -325,16 +287,21 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
for (cur = start; cur < end; cur += sizeof(fds)) {
if (umove(tcp, cur, &fds))
break;
if (fdmatch(tcp, fds.fd, set))
if (func(tcp, fds.fd, data))
return true;
}
return false;
}
/*
* These have TRACE_DESCRIPTOR or TRACE_NETWORK set,
* but they don't have any file descriptor to test.
*/
case SEN_accept4:
case SEN_accept:
case SEN_bpf:
case SEN_creat:
case SEN_epoll_create:
case SEN_epoll_create1:
case SEN_eventfd2:
@ -346,8 +313,7 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
case SEN_mq_getsetattr:
case SEN_mq_notify:
case SEN_mq_open:
case SEN_mq_timedreceive:
case SEN_mq_timedsend:
case SEN_open:
case SEN_perf_event_open:
case SEN_pipe:
case SEN_pipe2:
@ -360,10 +326,84 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
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;
}
return func(tcp, tcp->u_arg[0], data);
}
/*
* 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;
if (match_fd_common(tcp, fdmatch_fd_func, set))
return true;
if (!(s->sys_flags & TRACE_FILE))
return false;
/*
* Check for special cases where we need to do something
* other than test arg[0].
*/
switch (s->sen) {
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_quotactl:
case SEN_readlinkat:
case SEN_symlink:
case SEN_statx:
case SEN_unlinkat:
case SEN_utimensat:
/* x, path */
return 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_linkat:
case SEN_renameat2:
case SEN_renameat:
/* x, path, x, path */
return upathmatch(tcp, tcp->u_arg[1], set) ||
upathmatch(tcp, tcp->u_arg[3], set);
case SEN_symlinkat:
/* x, x, path */
return upathmatch(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 upathmatch(tcp, tcp->u_arg[argn + 1], set);
}
case SEN_printargs:
return false;
}
@ -371,12 +411,5 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
* 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;
return upathmatch(tcp, tcp->u_arg[0], set);
}