From d48e81f0cda73aca49cd852212a62e879cf35b86 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Sun, 6 Jul 2008 07:00:11 +0000 Subject: mdev: do not follow symlinks in /sys (as was intended prior to rev 18811). 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 --- init/init.c | 15 +-------------- libbb/vfork_daemon_rexec.c | 9 ++++++++- util-linux/mdev.c | 17 ++++++++++++----- 3 files changed, 21 insertions(+), 20 deletions(-) diff --git a/init/init.c b/init/init.c index 232896709..4b2bd9c77 100644 --- a/init/init.c +++ b/init/init.c @@ -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"); diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c index 37d4c274e..da0dc03e5 100644 --- a/libbb/vfork_daemon_rexec.c +++ b/libbb/vfork_daemon_rexec.c @@ -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 */ diff --git a/util-linux/mdev.c b/util-linux/mdev.c index c7109373d..9c4938a70 100644 --- a/util-linux/mdev.c +++ b/util-linux/mdev.c @@ -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 { -- cgit v1.2.3