coredump: kill MMF_DUMPABLE and MMF_DUMP_SECURELY
Nobody actually needs MMF_DUMPABLE/MMF_DUMP_SECURELY, they are only used
to enforce the encoding of SUID_DUMP_* enum in mm->flags &
MMF_DUMPABLE_MASK.
Now that set_dumpable() updates both bits atomically we can kill them and
simply store the value "as is" in 2 lower bits.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Alex Kelly <alex.page.kelly@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: Vasily Kulikov <segoon@openwall.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/exec.c b/fs/exec.c
index f039386..f798da0 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1613,33 +1613,24 @@
EXPORT_SYMBOL(set_binfmt);
/*
- * set_dumpable converts traditional three-value dumpable to two flags and
- * stores them into mm->flags.
+ * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
*/
void set_dumpable(struct mm_struct *mm, int value)
{
unsigned long old, new;
+ if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
+ return;
+
do {
old = ACCESS_ONCE(mm->flags);
- new = old & ~MMF_DUMPABLE_MASK;
-
- switch (value) {
- case SUID_DUMP_ROOT:
- new |= (1 << MMF_DUMP_SECURELY);
- case SUID_DUMP_USER:
- new |= (1<< MMF_DUMPABLE);
- }
-
+ new = (old & ~MMF_DUMPABLE_MASK) | value;
} while (cmpxchg(&mm->flags, old, new) != old);
}
int __get_dumpable(unsigned long mm_flags)
{
- int ret;
-
- ret = mm_flags & MMF_DUMPABLE_MASK;
- return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret;
+ return mm_flags & MMF_DUMPABLE_MASK;
}
/*
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 485234d..124430b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -400,10 +400,8 @@
#define SUID_DUMP_ROOT 2 /* Dump as root */
/* mm flags */
-/* dumpable bits */
-#define MMF_DUMPABLE 0 /* core dump is permitted */
-#define MMF_DUMP_SECURELY 1 /* core file is readable only by root */
+/* for SUID_DUMP_* above */
#define MMF_DUMPABLE_BITS 2
#define MMF_DUMPABLE_MASK ((1 << MMF_DUMPABLE_BITS) - 1)
