PATCH: removing hardcoded paths from init
Gabriel L. Somlo
somlo at cmu.edu
Sat Jan 20 23:33:01 UTC 2007
On Sat, Jan 20, 2007 at 02:13:40PM +0100, Denis Vlasenko wrote:
> - execv(cmdpath, cmd);
> + path = cmdpath;
> + if (ENABLE_FEATURE_EXEC_PREFER_APPLETS && find_applet_by_name(cmdpath))
> + path = CONFIG_BUSYBOX_EXEC_PATH;
> + execvp(path, cmd);
>
> Looks less obfuscated. (Or just reuse cmdpath instead of new 'path' ptr,
> if you can).
Long term it should all be hidden inside an execlp wrapper anyway.
BTW, is there a naming convention for busybox-specific wrappers around
library functions ? How about bb_execlp() ?
>
> Can you redo these places like this?
Sure. See below.
Cheers,
Gabriel
diff -NarU5 busybox-svn-17314.orig/Config.in busybox-svn-17314/Config.in
--- busybox-svn-17314.orig/Config.in 2007-01-15 15:18:07.000000000 -0500
+++ busybox-svn-17314/Config.in 2007-01-19 17:58:46.000000000 -0500
@@ -229,10 +229,18 @@
LDFLAGS=-L<libselinux-lib-path> \
make
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"
help
When Busybox applets need to run other busybox applets, BusyBox
@@ -437,11 +445,11 @@
on a filesystem with few inodes.
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.
endchoice
diff -NarU5 busybox-svn-17314.orig/init/init.c busybox-svn-17314/init/init.c
--- busybox-svn-17314.orig/init/init.c 2007-01-15 15:18:06.000000000 -0500
+++ busybox-svn-17314/init/init.c 2007-01-20 18:23:04.000000000 -0500
@@ -387,10 +387,11 @@
static const char press_enter[] =
#ifdef CUSTOMIZED_BANNER
#include CUSTOMIZED_BANNER
#endif
"\nPlease press Enter to activate this console. ";
+ char *prog;
/* Block sigchild while forking. */
sigemptyset(&nmask);
sigaddset(&nmask, SIGCHLD);
sigprocmask(SIG_BLOCK, &nmask, &omask);
@@ -558,11 +559,14 @@
}
#endif
/* 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);
_exit(-1);
}
@@ -676,10 +680,11 @@
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;
if (a->action & RESTART) {
shutdown_system();
@@ -711,11 +716,14 @@
/* Setup stdout, stderr on the supplied terminal */
dup(0);
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);
sync();
sleep(2);
@@ -850,17 +858,17 @@
file = fopen(INITTAB, "r");
if (file == NULL) {
/* 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);
new_init_action(ASKFIRST, bb_default_login_shell, VC_3);
new_init_action(ASKFIRST, bb_default_login_shell, VC_4);
@@ -1037,13 +1045,13 @@
if (!sysinfo(&info) &&
(info.mem_unit ? : 1) * (long long)info.totalram < 1024*1024)
{
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 */
}
}
/* Check if we are supposed to be in single user mode */
@@ -1066,11 +1074,14 @@
if (getenv("SELINUX_INIT") == NULL) {
int enforce = 0;
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 */
message(CONSOLE,"Unable to load SELinux Policy. Machine is in enforcing mode. Halting now.");
exit(1);
diff -NarU5 busybox-svn-17314.orig/libbb/xfuncs.c busybox-svn-17314/libbb/xfuncs.c
--- busybox-svn-17314.orig/libbb/xfuncs.c 2007-01-15 15:18:04.000000000 -0500
+++ busybox-svn-17314/libbb/xfuncs.c 2007-01-20 18:17:02.000000000 -0500
@@ -181,18 +181,21 @@
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
// would screw up parent.)
diff -NarU5 busybox-svn-17314.orig/scripts/defconfig busybox-svn-17314/scripts/defconfig
--- busybox-svn-17314.orig/scripts/defconfig 2007-01-15 15:17:59.000000000 -0500
+++ busybox-svn-17314/scripts/defconfig 2007-01-19 18:10:04.000000000 -0500
@@ -25,10 +25,11 @@
CONFIG_FEATURE_SUID=y
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"
#
# Build Options
#
More information about the busybox
mailing list