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authorDenys Vlasenko2017-01-26 01:13:58 +0100
committerDenys Vlasenko2017-01-26 01:13:58 +0100
commit9967c9949e0436879354e76c2847d697c309984c (patch)
treedcd6b3707305ef43f496a6058da45c89460fda4e
parent06f20bf675cdd415c2f796ebea9fc55030ef49cc (diff)
downloadbusybox-9967c9949e0436879354e76c2847d697c309984c.zip
busybox-9967c9949e0436879354e76c2847d697c309984c.tar.gz
libbb: spawn_and_wait() fflushes before forking NOEXEC; child reinits logmode
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--docs/nofork_noexec.txt7
-rw-r--r--include/libbb.h14
-rw-r--r--libbb/vfork_daemon_rexec.c36
3 files changed, 35 insertions, 22 deletions
diff --git a/docs/nofork_noexec.txt b/docs/nofork_noexec.txt
index 2fb184a..a24dd9c 100644
--- a/docs/nofork_noexec.txt
+++ b/docs/nofork_noexec.txt
@@ -99,6 +99,13 @@ applet_name. Thus, for example, caller does not need to worry about
option_mask32 getting trashed.
+ Calling NOEXEC applets
+
+It's the same trusty spawn_and_wait(argv). If FEATURE_PREFER_APPLETS=y,
+it does NOEXEC trick. It resets xfunc_error_retval = 1 and
+logmode = LOGMODE_STDIO in the child.
+
+
Relevant CONFIG options
FEATURE_PREFER_APPLETS
diff --git a/include/libbb.h b/include/libbb.h
index 8c652e2..07fe20d 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1093,10 +1093,19 @@ pid_t wait_any_nohang(int *wstat) FAST_FUNC;
*/
int wait4pid(pid_t pid) FAST_FUNC;
int wait_for_exitstatus(pid_t pid) FAST_FUNC;
+/************************************************************************/
+/* spawn_and_wait/run_nofork_applet/run_applet_no_and_exit need to work */
+/* carefully together to reinit some global state while not disturbing */
+/* other. Be careful if you change them. Consult docs/nofork_noexec.txt */
+/************************************************************************/
/* Same as wait4pid(spawn(argv)), but with NOFORK/NOEXEC if configured: */
int spawn_and_wait(char **argv) FAST_FUNC;
/* Does NOT check that applet is NOFORK, just blindly runs it */
int run_nofork_applet(int applet_no, char **argv) FAST_FUNC;
+#ifndef BUILD_INDIVIDUAL
+extern int find_applet_by_name(const char *name) FAST_FUNC;
+extern void run_applet_no_and_exit(int a, char **argv) NORETURN FAST_FUNC;
+#endif
/* Helpers for daemonization.
*
@@ -1303,11 +1312,6 @@ const struct hwtype *get_hwtype(const char *name) FAST_FUNC;
const struct hwtype *get_hwntype(int type) FAST_FUNC;
-#ifndef BUILD_INDIVIDUAL
-extern int find_applet_by_name(const char *name) FAST_FUNC;
-extern void run_applet_no_and_exit(int a, char **argv) NORETURN FAST_FUNC;
-#endif
-
#ifdef HAVE_MNTENT_H
extern int match_fstype(const struct mntent *mt, const char *fstypes) FAST_FUNC;
extern struct mntent *find_mount_point(const char *name, int subdir_too) FAST_FUNC;
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index c192829..2e7dc2d 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -183,26 +183,28 @@ int FAST_FUNC spawn_and_wait(char **argv)
#if ENABLE_FEATURE_PREFER_APPLETS
int a = find_applet_by_name(argv[0]);
- if (a >= 0 && (APPLET_IS_NOFORK(a)
-# if BB_MMU
- || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */
-# endif
- )) {
-# if BB_MMU
+ if (a >= 0) {
if (APPLET_IS_NOFORK(a))
-# endif
- {
return run_nofork_applet(a, argv);
+# if BB_MMU /* NOEXEC needs fork(), thus this is done only on MMU machines: */
+ if (APPLET_IS_NOEXEC(a)) {
+ fflush_all();
+ rc = fork();
+ if (rc) /* parent or error */
+ return wait4pid(rc);
+
+ /* child */
+ /* reset some state and run without execing */
+
+ /* msg_eol = "\n"; - no caller needs this reinited yet */
+ logmode = LOGMODE_STDIO;
+ /* die_func = NULL; - needed if the caller is a shell,
+ * init, or a NOFORK applet. But none of those call us
+ * as of yet (and that should probably always stay true).
+ */
+ /* xfunc_error_retval and applet_name are init by: */
+ run_applet_no_and_exit(a, argv);
}
-# if BB_MMU
- /* MMU only */
- /* a->noexec is true */
- rc = fork();
- if (rc) /* parent or error */
- return wait4pid(rc);
- /* child */
- xfunc_error_retval = EXIT_FAILURE;
- run_applet_no_and_exit(a, argv);
# endif
}
#endif /* FEATURE_PREFER_APPLETS */