From 4759ff71f23e1a9cba001009abab68cde6dc327a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 24 Jan 2024 11:22:32 -0800 Subject: exec: Check __FMODE_EXEC instead of in_execve for LSMs After commit 978ffcbf00d8 ("execve: open the executable file before doing anything else"), current->in_execve was no longer in sync with the open(). This broke AppArmor and TOMOYO which depend on this flag to distinguish "open" operations from being "exec" operations. Instead of moving around in_execve, switch to using __FMODE_EXEC, which is where the "is this an exec?" intent is stored. Note that TOMOYO still uses in_execve around cred handling. Reported-by: Kevin Locke Closes: https://lore.kernel.org/all/ZbE4qn9_h14OqADK@kevinlocke.name Suggested-by: Linus Torvalds Fixes: 978ffcbf00d8 ("execve: open the executable file before doing anything else") Cc: Josh Triplett Cc: John Johansen Cc: Paul Moore Cc: James Morris Cc: Serge E. Hallyn 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: Cc: Cc: Cc: Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds --- security/apparmor/lsm.c | 4 +++- security/tomoyo/tomoyo.c | 3 ++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 7717354ce095..98e1150bee9d 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -469,8 +469,10 @@ static int apparmor_file_open(struct file *file) * Cache permissions granted by the previous exec check, with * implicit read and executable mmap which are required to * actually execute the image. + * + * Illogically, FMODE_EXEC is in f_flags, not f_mode. */ - if (current->in_execve) { + if (file->f_flags & __FMODE_EXEC) { fctx->allow = MAY_EXEC | MAY_READ | AA_EXEC_MMAP; return 0; } diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c index 3c3af149bf1c..04a92c3d65d4 100644 --- a/security/tomoyo/tomoyo.c +++ b/security/tomoyo/tomoyo.c @@ -328,7 +328,8 @@ static int tomoyo_file_fcntl(struct file *file, unsigned int cmd, static int tomoyo_file_open(struct file *f) { /* Don't check read permission here if called from execve(). */ - if (current->in_execve) + /* Illogically, FMODE_EXEC is in f_flags, not f_mode. */ + if (f->f_flags & __FMODE_EXEC) return 0; return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, f->f_flags); -- cgit