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8858a9864

Denys Vlasenko
Denys Vlasenko
2017-08-08
SUCCESS Duration: 142s

Subject

libbb: rearrange NOFORK/NOEXEC code, logic is not changed

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

NOFORK_NOEXEC.lst +2 -2libbb/vfork_daemon_rexec.c +69 -56
NOFORK_NOEXEC.lst+2 -2
@@ -124,7 +124,7 @@ fatattr - noexec. leaks: open+xioctl, complex
fbset - hardware, leaks: open+xfunc
fbsplash - runner, longterm
fdflush - hardware, leaks: open+ioctl_or_perror_and_die
-fdformat - hardware, needs ^C (floppy may be unresponsive), longterm
+fdformat - hardware, longterm
fdisk - interactive, longterm
fgconsole - noexec. leaks: get_console_fd_or_die() may open a new fd, or return one of stdio fds
fgrep - longterm runner ("CMD | fgrep ..." may run indefinitely, better to exec to conserve memory)
@@ -413,7 +413,7 @@ wget - longterm
which - NOFORK
who - noexec. nofork candidate(is getutxent ok?)
whoami - NOFORK
-whois - needs ^C
+whois - talks to network
xargs - noexec. spawner
xxd - noexec. runner
xz - runner
libbb/vfork_daemon_rexec.c+69 -56
@@ -14,61 +14,12 @@
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
-
#include "busybox.h" /* uses applet tables */
#include "NUM_APPLETS.h"
-/* This does a fork/exec in one call, using vfork(). Returns PID of new child,
- * -1 for failure. Runs argv[0], searching path if that has no / in it. */
-pid_t FAST_FUNC spawn(char **argv)
-{
- /* Compiler should not optimize stores here */
- volatile int failed;
- pid_t pid;
-
- fflush_all();
-
- /* Be nice to nommu machines. */
- failed = 0;
- pid = vfork();
- if (pid < 0) /* error */
- return pid;
- if (!pid) { /* child */
- /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
- BB_EXECVP(argv[0], argv);
-
- /* We are (maybe) sharing a stack with blocked parent,
- * let parent know we failed and then exit to unblock parent
- * (but don't run atexit() stuff, which would screw up parent.)
- */
- failed = errno;
- /* mount, for example, does not want the message */
- /*bb_perror_msg("can't execute '%s'", argv[0]);*/
- _exit(111);
- }
- /* parent */
- /* Unfortunately, this is not reliable: according to standards
- * vfork() can be equivalent to fork() and we won't see value
- * of 'failed'.
- * Interested party can wait on pid and learn exit code.
- * If 111 - then it (most probably) failed to exec */
- if (failed) {
- safe_waitpid(pid, NULL, 0); /* prevent zombie */
- errno = failed;
- return -1;
- }
- return pid;
-}
-
-/* Die with an error message if we can't spawn a child process. */
-pid_t FAST_FUNC xspawn(char **argv)
-{
- pid_t pid = spawn(argv);
- if (pid < 0)
- bb_simple_perror_msg_and_die(*argv);
- return pid;
-}
-
+/*
+ * NOFORK support
+ */
#if ENABLE_FEATURE_PREFER_APPLETS \
|| ENABLE_FEATURE_SH_NOFORK
static jmp_buf die_jmp;
@@ -127,10 +78,10 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
* reset the libc getopt() function, which keeps internal state.
*/
GETOPT_RESET();
+//? applet_long_options = NULL;
+//? opt_complementary = NULL;
- argc = 1;
- while (argv[argc])
- argc++;
+ argc = string_array_len(argv);
/* If xfunc "dies" in NOFORK applet, die_func longjmp's here instead */
die_func = jump;
@@ -153,11 +104,16 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
restore_nofork_data(&old);
/* Other globals can be simply reset to defaults */
GETOPT_RESET();
+//? applet_long_options = NULL;
+//? opt_complementary = NULL;
return rc & 0xff; /* don't confuse people with "exitcodes" >255 */
}
#endif /* FEATURE_PREFER_APPLETS || FEATURE_SH_NOFORK */
+/*
+ * NOEXEC support
+ */
#if (NUM_APPLETS > 1) && (ENABLE_FEATURE_PREFER_APPLETS || ENABLE_FEATURE_SH_STANDALONE)
void FAST_FUNC run_noexec_applet_and_exit(int a, const char *name, char **argv)
{
@@ -167,17 +123,74 @@ void FAST_FUNC run_noexec_applet_and_exit(int a, const char *name, char **argv)
xfunc_error_retval = EXIT_FAILURE;
die_func = NULL;
GETOPT_RESET();
+//? applet_long_options = NULL;
+//? opt_complementary = NULL;
//TODO: think pidof, pgrep, pkill!
//set_task_comm() makes our pidof find NOEXECs (e.g. "yes >/dev/null"),
//but one from procps-ng-3.3.10 needs more!
//Rewrite /proc/PID/cmdline? (need to save argv0 and length at init for this to work!)
set_task_comm(name);
- /* xfunc_error_retval and applet_name are init by: */
+ /* applet_name is set by this function: */
run_applet_no_and_exit(a, name, argv);
}
#endif
+/*
+ * Higher-level code, hiding optional NOFORK/NOEXEC trickery.
+ */
+
+/* This does a fork/exec in one call, using vfork(). Returns PID of new child,
+ * -1 for failure. Runs argv[0], searching path if that has no / in it. */
+pid_t FAST_FUNC spawn(char **argv)
+{
+ /* Compiler should not optimize stores here */
+ volatile int failed;
+ pid_t pid;
+
+ fflush_all();
+
+ /* Be nice to nommu machines. */
+ failed = 0;
+ pid = vfork();
+ if (pid < 0) /* error */
+ return pid;
+ if (!pid) { /* child */
+ /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
+ BB_EXECVP(argv[0], argv);
+
+ /* We are (maybe) sharing a stack with blocked parent,
+ * let parent know we failed and then exit to unblock parent
+ * (but don't run atexit() stuff, which would screw up parent.)
+ */
+ failed = errno;
+ /* mount, for example, does not want the message */
+ /*bb_perror_msg("can't execute '%s'", argv[0]);*/
+ _exit(111);
+ }
+ /* parent */
+ /* Unfortunately, this is not reliable: according to standards
+ * vfork() can be equivalent to fork() and we won't see value
+ * of 'failed'.
+ * Interested party can wait on pid and learn exit code.
+ * If 111 - then it (most probably) failed to exec */
+ if (failed) {
+ safe_waitpid(pid, NULL, 0); /* prevent zombie */
+ errno = failed;
+ return -1;
+ }
+ return pid;
+}
+
+/* Die with an error message if we can't spawn a child process. */
+pid_t FAST_FUNC xspawn(char **argv)
+{
+ pid_t pid = spawn(argv);
+ if (pid < 0)
+ bb_simple_perror_msg_and_die(*argv);
+ return pid;
+}
+
int FAST_FUNC spawn_and_wait(char **argv)
{
int rc;