2f0c0d0b8

Denis Vlasenko

2007-01-21

FAILED Duration: 3s

Subject

Introduce FEATURE_EXEC_PREFER_APPLETS = "re-execute our own executable if we asked to exec someting with argv[0] == known_applet" Use it in init. Also respect PATH in init, remove explicit "/sbin" etc from exec. Patch by Gabriel L. Somlo

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 →

Config.in +9 -1 init/init.c +20 -9 libbb/xfuncs.c +5 -2 scripts/defconfig +1 -0 shell/ash.c +4 -0

Config.in+9 -1

@@ -231,6 +231,14 @@ config SELINUX

	Most people will leave this set to 'N'.

+	config FEATURE_EXEC_PREFER_APPLETS
+	bool "exec prefers applets"
+	default n
+	help
+	This is an experimental option which directs applets about to
+	call 'exec' to try and find an applicable busybox applet before
+	searching the executable path for a binary or symlink to execute.
+
	config BUSYBOX_EXEC_PATH
	string "Path to BusyBox executable"
	default "/proc/self/exe"
@@ -439,7 +447,7 @@ config INSTALL_APPLET_HARDLINKS
	config INSTALL_APPLET_DONT
	bool
	prompt "not installed"
-	depends on FEATURE_INSTALLER \|\| FEATURE_SH_STANDALONE_SHELL
+	depends on FEATURE_INSTALLER \|\| FEATURE_SH_STANDALONE_SHELL \|\| FEATURE_EXEC_PREFER_APPLETS
	help
	Do not install applet links. Useful when using the -install feature
	or a standalone shell for rescue pruposes.

init/init.c+20 -9

@@ -389,6 +389,7 @@ static pid_t run(const struct init_action *a)
	#include CUSTOMIZED_BANNER
	#endif
	"\nPlease press Enter to activate this console. ";
+	char *prog;

	/* Block sigchild while forking. */
	sigemptyset(&nmask);
@@ -560,7 +561,10 @@ static pid_t run(const struct init_action *a)

	/* Now run it. The new program will take over this PID,
	* so nothing further in init.c should be run. */
-	execv(cmdpath, cmd);
+	prog = cmdpath;
+	if (ENABLE_FEATURE_EXEC_PREFER_APPLETS && find_applet_by_name(prog))
+	prog = CONFIG_BUSYBOX_EXEC_PATH;
+	execvp(prog, cmd);

	/* We're still here? Some error happened. */
	message(LOG \| CONSOLE, "Bummer, cannot run '%s': %m", cmdpath);
@@ -678,6 +682,7 @@ static void exec_signal(int sig ATTRIBUTE_UNUSED)
	{
	struct init_action a, tmp;
	sigset_t unblock_signals;
+	char *prog;

	for (a = init_action_list; a; a = tmp) {
	tmp = a->next;
@@ -713,7 +718,10 @@ static void exec_signal(int sig ATTRIBUTE_UNUSED)
	dup(0);

	messageD(CONSOLE \| LOG, "Trying to re-exec %s", a->command);
-	execl(a->command, a->command, NULL);
+	prog = a->command;
+	if (ENABLE_FEATURE_EXEC_PREFER_APPLETS && find_applet_by_name(prog))
+	prog = CONFIG_BUSYBOX_EXEC_PATH;
+	execlp(prog, a->command, NULL);

	message(CONSOLE \| LOG, "exec of '%s' failed: %m",
	a->command);
@@ -852,13 +860,13 @@ static void parse_inittab(void)
	/* No inittab file -- set up some default behavior */
	#endif
	/* Reboot on Ctrl-Alt-Del */
-	new_init_action(CTRLALTDEL, "/sbin/reboot", "");
+	new_init_action(CTRLALTDEL, "reboot", "");
	/* Umount all filesystems on halt/reboot */
-	new_init_action(SHUTDOWN, "/bin/umount -a -r", "");
+	new_init_action(SHUTDOWN, "umount -a -r", "");
	/* Swapoff on halt/reboot */
-	if(ENABLE_SWAPONOFF) new_init_action(SHUTDOWN, "/sbin/swapoff -a", "");
+	if(ENABLE_SWAPONOFF) new_init_action(SHUTDOWN, "swapoff -a", "");
	/* Prepare to restart init when a HUP is received */
-	new_init_action(RESTART, "/sbin/init", "");
+	new_init_action(RESTART, "init", "");
	/* Askfirst shell on tty1-4 */
	new_init_action(ASKFIRST, bb_default_login_shell, "");
	new_init_action(ASKFIRST, bb_default_login_shell, VC_2);
@@ -1039,9 +1047,9 @@ int init_main(int argc, char **argv)
	{
	message(CONSOLE,"Low memory: forcing swapon.");
	/* swapon -a requires /proc typically */
-	new_init_action(SYSINIT, "/bin/mount -t proc proc /proc", "");
+	new_init_action(SYSINIT, "mount -t proc proc /proc", "");
	/* Try to turn on swap */
-	new_init_action(SYSINIT, "/sbin/swapon -a", "");
+	new_init_action(SYSINIT, "swapon -a", "");
	run_actions(SYSINIT); /* wait and removing */
	}
	}
@@ -1068,7 +1076,10 @@ int init_main(int argc, char **argv)

	putenv("SELINUX_INIT=YES");
	if (selinux_init_load_policy(&enforce) == 0) {
-	execv(argv[0], argv);
+	char *prog = argv[0];
+	if (ENABLE_FEATURE_EXEC_PREFER_APPLETS && find_applet_by_name(prog))
+	prog = CONFIG_BUSYBOX_EXEC_PATH;
+	execvp(prog, argv);
	} else if (enforce > 0) {
	/* SELinux in enforcing mode but load_policy failed */
	/* At this point, we probably can't open /dev/console, so log() won't work */

libbb/xfuncs.c+5 -2

@@ -183,14 +183,17 @@ pid_t spawn(char **argv)
	/* Why static? */
	static int failed;
	pid_t pid;
-	void *app = ENABLE_FEATURE_SH_STANDALONE_SHELL ? find_applet_by_name(argv[0]) : 0;
+	char *prog;

	// Be nice to nommu machines.
	failed = 0;
	pid = vfork();
	if (pid < 0) return pid;
	if (!pid) {
-	execvp(app ? CONFIG_BUSYBOX_EXEC_PATH : *argv, argv);
+	prog = argv[0];
+	if (ENABLE_FEATURE_EXEC_PREFER_APPLETS && find_applet_by_name(prog))
+	prog = CONFIG_BUSYBOX_EXEC_PATH;
+	execvp(prog, argv);

	// We're sharing a stack with blocked parent, let parent know we failed
	// and then exit to unblock parent (but don't run atexit() stuff, which

scripts/defconfig+1 -0

@@ -27,6 +27,7 @@ CONFIG_FEATURE_SYSLOG=y
	CONFIG_FEATURE_SUID_CONFIG=y
	CONFIG_FEATURE_SUID_CONFIG_QUIET=y
	# CONFIG_SELINUX is not set
+	#CONFIG_FEATURE_EXEC_PREFER_APPLETS is not set
	CONFIG_BUSYBOX_EXEC_PATH="/proc/self/exe"

	#

shell/ash.c+4 -0

@@ -6528,6 +6528,10 @@ setjobctl(int on)
	int ofd;
	ofd = fd = open(_PATH_TTY, O_RDWR);
	if (fd < 0) {
+	/* BTW, bash will try to open(ttyname(0)) if open("/dev/tty") fails.
+	* That sometimes helps to acquire controlling tty.
+	* Obviously, a workaround for bugs when someone
+	* failed to provide a controlling tty to bash! :) */
	fd += 3;
	while (!isatty(fd) && --fd >= 0)
	;