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signals: move cred_guard_mutex from task_struct to signal_struct

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Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec
itself and we can reuse ->cred_guard_mutex for it.  Yes, concurrent
execve() has no worth.

Let's move ->cred_guard_mutex from task_struct to signal_struct.  It
naturally prevent multiple-threads-inside-exec.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro
2010-10-27 15:34:08 -07:00
committed by Linus Torvalds
parent b840115083
commit 9b1bf12d5d
8 changed files with 21 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fs/exec.c
+5 -5
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@@ -1083,14 +1083,14 @@ EXPORT_SYMBOL(setup_new_exec);
*/
int prepare_bprm_creds(struct linux_binprm *bprm)
{
if (mutex_lock_interruptible(&current->cred_guard_mutex))
if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
return -ERESTARTNOINTR;
bprm->cred = prepare_exec_creds();
if (likely(bprm->cred))
return 0;
mutex_unlock(&current->cred_guard_mutex);
mutex_unlock(&current->signal->cred_guard_mutex);
return -ENOMEM;
}
@@ -1098,7 +1098,7 @@ void free_bprm(struct linux_binprm *bprm)
{
free_arg_pages(bprm);
if (bprm->cred) {
mutex_unlock(&current->cred_guard_mutex);
mutex_unlock(&current->signal->cred_guard_mutex);
abort_creds(bprm->cred);
}
kfree(bprm);
@@ -1119,13 +1119,13 @@ void install_exec_creds(struct linux_binprm *bprm)
* credentials; any time after this it may be unlocked.
*/
security_bprm_committed_creds(bprm);
mutex_unlock(&current->cred_guard_mutex);
mutex_unlock(&current->signal->cred_guard_mutex);
}
EXPORT_SYMBOL(install_exec_creds);
/*
* determine how safe it is to execute the proposed program
* - the caller must hold current->cred_guard_mutex to protect against
* - the caller must hold ->cred_guard_mutex to protect against
* PTRACE_ATTACH
*/
int check_unsafe_exec(struct linux_binprm *bprm)