On Wed, Jan 24, 2024 at 08:58:55PM +0100, Jann Horn wrote: > On Wed, Jan 24, 2024 at 8:22 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > 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. > > I think this is wrong. When CONFIG_USELIB is enabled, the uselib() > syscall will open a file with __FMODE_EXEC but without going through > execve(). From what I can tell, there are no bprm hooks on this path. Hrm, that's true. We've been trying to remove uselib for at least 10 years[1]. :( > I don't know if it _matters_ much, given that it'll only let you > read/execute stuff from files with valid ELF headers, but still. Hmpf, and frustratingly Ubuntu (and Debian) still builds with CONFIG_USELIB, even though it was reported[2] to them almost 4 years ago. -Kees [1] https://lore.kernel.org/lkml/20140221181103.GA5773@jtriplet-mobl1/ [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1879454 -- Kees Cook