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Date: Fri, 2 Feb 2024 13:41:51 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
Kentaro Takeda <takedakn@...data.co.jp>,
Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>,
Jan Kara <jack@...e.cz>,
Eric Biederman <ebiederm@...ssion.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
linux-fsdevel@...r.kernel.org,
linux-mm@...ck.org,
Sasha Levin <sashal@...nel.org>,
mingo@...hat.com,
peterz@...radead.org,
juri.lelli@...hat.com,
vincent.guittot@...aro.org,
surenb@...gle.com,
michael.christie@...cle.com,
mst@...hat.com,
mjguzik@...il.com,
npiggin@...il.com,
zhangpeng.00@...edance.com,
hca@...ux.ibm.com
Subject: [PATCH AUTOSEL 5.10 7/8] exec: Distinguish in_execve from in_exec
From: Kees Cook <keescook@...omium.org>
[ Upstream commit 90383cc07895183c75a0db2460301c2ffd912359 ]
Just to help distinguish the fs->in_exec flag from the current->in_execve
flag, add comments in check_unsafe_exec() and copy_fs() for more
context. Also note that in_execve is only used by TOMOYO now.
Cc: Kentaro Takeda <takedakn@...data.co.jp>
Cc: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: Christian Brauner <brauner@...nel.org>
Cc: Jan Kara <jack@...e.cz>
Cc: Eric Biederman <ebiederm@...ssion.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-fsdevel@...r.kernel.org
Cc: linux-mm@...ck.org
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
fs/exec.c | 1 +
include/linux/sched.h | 2 +-
kernel/fork.c | 1 +
3 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/exec.c b/fs/exec.c
index 983295c0b8ac..b809f4a39296 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1565,6 +1565,7 @@ static void check_unsafe_exec(struct linux_binprm *bprm)
}
rcu_read_unlock();
+ /* "users" and "in_exec" locked for copy_fs() */
if (p->fs->users > n_fs)
bprm->unsafe |= LSM_UNSAFE_SHARE;
else
diff --git a/include/linux/sched.h b/include/linux/sched.h
index aa015416c569..65cfe85de8d5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -806,7 +806,7 @@ struct task_struct {
*/
unsigned sched_remote_wakeup:1;
- /* Bit to tell LSMs we're in execve(): */
+ /* Bit to tell TOMOYO we're in execve(): */
unsigned in_execve:1;
unsigned in_iowait:1;
#ifndef TIF_RESTORE_SIGMASK
diff --git a/kernel/fork.c b/kernel/fork.c
index 633b0af1d1a7..906dbaf25058 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1452,6 +1452,7 @@ static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
if (clone_flags & CLONE_FS) {
/* tsk->fs is already what we want */
spin_lock(&fs->lock);
+ /* "users" and "in_exec" locked for check_unsafe_exec() */
if (fs->in_exec) {
spin_unlock(&fs->lock);
return -EAGAIN;
--
2.43.0
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