[PATCH AUTOSEL 5.4 169/175] bpf: Fix map permissions check

Sasha Levin
2020-06-09T00:01:21Z

From: Anton Protopopov <a.s.protopopov@gmail.com>

[ Upstream commit 1ea0f9120c8ce105ca181b070561df5cbd6bc049 ]

The map_lookup_and_delete_elem() function should check for both FMODE_CAN_WRITE
and FMODE_CAN_READ permissions because it returns a map element to user space.

Fixes: bd513cd08f10 ("bpf: add MAP_LOOKUP_AND_DELETE_ELEM syscall")
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200527185700.14658-5-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/syscall.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 946cfdd3b2cc..e7af1ac69d75 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1118,7 +1118,8 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
map = __bpf_map_get(f);
if (IS_ERR(map))
return PTR_ERR(map);
- if (!(map_get_sys_perms(map, f) & FMODE_CAN_WRITE)) {
+ if (!(map_get_sys_perms(map, f) & FMODE_CAN_READ) ||
+ !(map_get_sys_perms(map, f) & FMODE_CAN_WRITE)) {
err = -EPERM;
goto err_put;
}
--
2.25.1