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mdev: do not follow symlinks in /sys (as was intended prior to rev 18811).

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If this breaks things, please document why!
mdev,init: use shared code for fd sanitization

function                                             old     new   delta
bb_daemonize_or_rexec                                155     172     +17
mdev_main                                            500     505      +5
init_main                                            907     856     -51
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 22/-51)            Total: -29 bytes
This commit is contained in:
Denis Vlasenko 2008-07-06 07:00:11 +00:00
parent ff182a3d68
commit d48e81f0cd
3 changed files with 21 additions and 20 deletions
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15
init/init.c
View File

@ -221,20 +221,7 @@ static void console_init(void)
} else {
/* Make sure fd 0,1,2 are not closed
* (so that they won't be used by future opens) */
/* bb_sanitize_stdio(); - WRONG.
* It fails if "/dev/null" doesnt exist, and for init
* this is a real possibility! Open code it instead. */
int fd = open(bb_dev_null, O_RDWR);
if (fd < 0) {
/* Give me _ANY_ open descriptor! */
fd = xopen("/", O_RDONLY); /* we don't believe this can fail */
}
while ((unsigned)fd < 2)
fd = dup(fd);
if (fd > 2)
close(fd);
bb_sanitize_stdio();
}
s = getenv("TERM");

9
libbb/vfork_daemon_rexec.c
View File

@ -265,7 +265,14 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
close(2);
}
fd = xopen(bb_dev_null, O_RDWR);
fd = open(bb_dev_null, O_RDWR);
if (fd < 0) {
/* NB: we can be called as bb_sanitize_stdio() from init
* or mdev, and there /dev/null may legitimately not (yet) exist!
* Do not use xopen above, but obtain _ANY_ open descriptor,
* even bogus one as below. */
fd = xopen("/", O_RDONLY); /* don't believe this can fail */
}
while ((unsigned)fd < 2)
fd = dup(fd); /* have 0,1,2 open at least to /dev/null */

17
util-linux/mdev.c
View File

@ -19,7 +19,8 @@ struct globals {
#define root_major (G.root_major)
#define root_minor (G.root_minor)
#define MAX_SYSFS_DEPTH 3 /* prevent infinite loops in /sys symlinks */
/* Prevent infinite loops in /sys symlinks */
#define MAX_SYSFS_DEPTH 3
/* We use additional 64+ bytes in make_device() */
#define SCRATCH_SIZE 80
@ -392,11 +393,17 @@ int mdev_main(int argc, char **argv)
char *env_path;
RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
#ifdef YOU_WANT_TO_DEBUG_HOTPLUG_EVENTS
/* We can be called as hotplug helper */
/* Kernel cannot provide suitable stdio fds for us, do it ourself */
#if 1
bb_sanitize_stdio();
#else
/* Debug code */
/* Replace LOGFILE by other file or device name if you need */
#define LOGFILE "/dev/console"
xmove_fd(xopen("/dev/null", O_RDONLY), STDIN_FILENO);
/* Just making sure fd 0 is not closed,
* we don't really intend to read from it */
xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
#endif
@ -414,11 +421,11 @@ int mdev_main(int argc, char **argv)
root_minor = minor(st.st_dev);
recursive_action("/sys/block",
ACTION_RECURSE | ACTION_FOLLOWLINKS,
ACTION_RECURSE /* no ACTION_FOLLOWLINKS! */,
fileAction, dirAction, temp, 0);
recursive_action("/sys/class",
ACTION_RECURSE | ACTION_FOLLOWLINKS,
ACTION_RECURSE /* no ACTION_FOLLOWLINKS! */,
fileAction, dirAction, temp, 0);
} else {