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Tsirkin" , Mateusz Guzik , Nicholas Piggin , Peng Zhang , Heiko Carstens , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] exec: Distinguish in_execve from in_exec Date: Wed, 24 Jan 2024 11:23:36 -0800 Message-Id: <20240124192336.work.346-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2067; i=keescook@chromium.org; h=from:subject:message-id; bh=VR9kpbQ0DKQJADcCvje12k4QMRw3v2j7EWNUrR5Qufc=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlsWO4+WfxI39wun33oA9LOez8cVdNcQbQe0jig /3TTk5FmSuJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZbFjuAAKCRCJcvTf3G3A JgR4EACebytLFIu8RYZJITvGsNEcqZqvOSILHoYE48QXsSIUs9g9QRKFIkJ5vh/QPgwtsmhGiIJ JnV/zDBcSQkSPdc7dZ+v+imUpKhe0fPzsBQdcUaP8UGjlJCBlA6DMd+YAeXkZF3+WG3CkKBzPMP QJhvssc4dQ4XW5o0KGGNetMWLG/mJhLpka5HJ8pZkAAcSycsLT1wJFXYgWy51n/TMAwdOfHVMiK Ivzzjiz0hWK81C8SqqaGbFhGU7+2KnIg7Zfs5bUbe/8zIjXkOQiO+VfjxLGyB9daFfbNrtXNPGK okEYC4+omNvm5517jvtuSE5N6dvcOhtF34mgDV9UBdZnc6NFYWDuDUBNv89HWXAKpHkGIChV8jB 28gO71T0qDIno9Bz00/utOA/8B84rw5srxL5+ABi/HjCxAxYIqisZym150VKYGSV5ro68qp5nLM 28X4+mbOdOHyybgFGME8CPBGkYqAVP3t28aS94mz29mU0bAIBHlErmfjKnPc7qNvEzpazZA1Jt+ B/B80aaP+TPl7Z+Rpud+gXpkVQ17jFmTjyD04rF1xIOHm941DQJ+hzZRf9F8fQWDOhafdSkSm9p xh3y/wcuEkSaGIh1mk6sYDNzpb7lnAXGJc2VDc2kPKUsrCwf5T6x+eEP/e6aHudoJHP7GNVAFCJ b1tnmrQ J0V5evIQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit 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 Cc: Tetsuo Handa Cc: Alexander Viro Cc: Christian Brauner Cc: Jan Kara Cc: Eric Biederman Cc: Andrew Morton Cc: Sebastian Andrzej Siewior Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Kees Cook --- 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 39d773021fff..d179abb78a1c 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1633,6 +1633,7 @@ 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 cdb8ea53c365..ffe8f618ab86 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -920,7 +920,7 @@ struct task_struct { unsigned sched_rt_mutex:1; #endif - /* 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 47ff3b35352e..0d944e92a43f 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1748,6 +1748,7 @@ 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; -- 2.34.1