Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2020-05-22

The following pull-request contains BPF updates for your *net* tree.

We've added 3 non-merge commits during the last 3 day(s) which contain
a total of 5 files changed, 69 insertions(+), 11 deletions(-).

The main changes are:

1) Fix to reject mmap()'ing read-only array maps as writable since BPF verifier
   relies on such map content to be frozen, from Andrii Nakryiko.

2) Fix breaking audit from secid_to_secctx() LSM hook by avoiding to use
   call_int_hook() since this hook is not stackable, from KP Singh.

3) Fix BPF flow dissector program ref leak on netns cleanup, from Jakub Sitnicki.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 3 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2843bbba9ca1..4e6dee19a668 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -623,9 +623,20 @@ static int bpf_map_mmap(struct file *filp, struct vm_area_struct *vma)
 
 	mutex_lock(&map->freeze_mutex);
 
-	if ((vma->vm_flags & VM_WRITE) && map->frozen) {
-		err = -EPERM;
-		goto out;
+	if (vma->vm_flags & VM_WRITE) {
+		if (map->frozen) {
+			err = -EPERM;
+			goto out;
+		}
+		/* map is meant to be read-only, so do not allow mapping as
+		 * writable, because it's possible to leak a writable page
+		 * reference and allows user-space to still modify it after
+		 * freezing, while verifier will assume contents do not change
+		 */
+		if (map->map_flags & BPF_F_RDONLY_PROG) {
+			err = -EACCES;
+			goto out;
+		}
 	}
 
 	/* set default open/close callbacks */