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bpf: Fix map permissions check 

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: bd513cd08f ("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>
This commit is contained in:
Anton Protopopov 2020-05-27 18:56:59 +00:00 committed by Alexei Starovoitov
parent efbc3b8fe1
commit 1ea0f9120c
1 changed files with 2 additions and 1 deletions
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3
kernel/bpf/syscall.c
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@ -1472,7 +1472,8 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
map = __bpf_map_get(f); map = __bpf_map_get(f);
if (IS_ERR(map)) if (IS_ERR(map))
return PTR_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; err = -EPERM;
goto err_put; goto err_put;
} }