exec: Weaken dumpability for secureexec

This is a logical revert of commit e37fdb785a5f ("exec: Use secureexec
for setting dumpability")

This weakens dumpability back to checking only for uid/gid changes in
current (which is useless), but userspace depends on dumpability not
being tied to secureexec.

  https://bugzilla.redhat.com/show_bug.cgi?id=1528633

Reported-by: Tom Horsley <horsley1953@gmail.com>
Fixes: e37fdb785a5f ("exec: Use secureexec for setting dumpability")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/exec.c b/fs/exec.c
index 5688b5e1b9378107597a6117c8c3732889f951d2..7eb8d21bcab94b51905071d12a5205e7ac2ef194 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1349,9 +1349,14 @@ void setup_new_exec(struct linux_binprm * bprm)
 
        current->sas_ss_sp = current->sas_ss_size = 0;
 
-       /* Figure out dumpability. */
+       /*
+        * Figure out dumpability. Note that this checking only of current
+        * is wrong, but userspace depends on it. This should be testing
+        * bprm->secureexec instead.
+        */
        if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
-           bprm->secureexec)
+           !(uid_eq(current_euid(), current_uid()) &&
+             gid_eq(current_egid(), current_gid())))
                set_dumpable(current->mm, suid_dumpable);
        else
                set_dumpable(current->mm, SUID_DUMP_USER);