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Subject[PATCH bpf 4/5] bpf: fix map permissions check
Date
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>
---
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 4e6dee19a668..5e52765161f9 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1468,7 +1468,8 @@ 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;
}
--
2.20.1
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