diff options
| author | Alan Cox <alan@lxorguk.ukuu.org.uk> | 2007-04-16 22:53:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-04-17 16:36:26 -0700 |
| commit | c4bbafda70a0fc95c6595bffd6825ef264050d01 (patch) | |
| tree | 92860180bea4f2e1fd515432bb165c7ae628d2af /fs | |
| parent | c4b7e8754e3198eb5392568e523da6440143c2cd (diff) | |
| download | lwn-c4bbafda70a0fc95c6595bffd6825ef264050d01.tar.gz lwn-c4bbafda70a0fc95c6595bffd6825ef264050d01.zip | |
exec.c: fix coredump to pipe problem and obscure "security hole"
The patch checks for "|" in the pattern not the output and doesn't nail a
pid on to a piped name (as it is a program name not a file)
Also fixes a very very obscure security corner case. If you happen to have
decided on a core pattern that starts with the program name then the user
can run a program called "|myevilhack" as it stands. I doubt anyone does
this.
Signed-off-by: Alan Cox <alan@redhat.com>
Confirmed-by: Christopher S. Aker <caker@theshore.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/exec.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/fs/exec.c b/fs/exec.c index 7e36c6f6f538..3155e915307a 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1244,13 +1244,17 @@ EXPORT_SYMBOL(set_binfmt); * name into corename, which must have space for at least * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. */ -static void format_corename(char *corename, const char *pattern, long signr) +static int format_corename(char *corename, const char *pattern, long signr) { const char *pat_ptr = pattern; char *out_ptr = corename; char *const out_end = corename + CORENAME_MAX_SIZE; int rc; int pid_in_pattern = 0; + int ispipe = 0; + + if (*pattern == '|') + ispipe = 1; /* Repeat as long as we have more pattern to process and more output space */ @@ -1341,8 +1345,8 @@ static void format_corename(char *corename, const char *pattern, long signr) * * If core_pattern does not include a %p (as is the default) * and core_uses_pid is set, then .%pid will be appended to - * the filename */ - if (!pid_in_pattern + * the filename. Do not do this for piped commands. */ + if (!ispipe && !pid_in_pattern && (core_uses_pid || atomic_read(¤t->mm->mm_users) != 1)) { rc = snprintf(out_ptr, out_end - out_ptr, ".%d", current->tgid); @@ -1350,8 +1354,9 @@ static void format_corename(char *corename, const char *pattern, long signr) goto out; out_ptr += rc; } - out: +out: *out_ptr = 0; + return ispipe; } static void zap_process(struct task_struct *start) @@ -1502,16 +1507,15 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) * uses lock_kernel() */ lock_kernel(); - format_corename(corename, core_pattern, signr); + ispipe = format_corename(corename, core_pattern, signr); unlock_kernel(); - if (corename[0] == '|') { + if (ispipe) { /* SIGPIPE can happen, but it's just never processed */ if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) { printk(KERN_INFO "Core dump to %s pipe failed\n", corename); goto fail_unlock; } - ispipe = 1; } else file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, |