From: Milan Landaverde milan@mdaverde.com
[ Upstream commit e89f3edffb860a0f54a9ed16deadb7a4a1fa3862 ]
In [0], we added the ability to bpf_prog_attach LSM programs to cgroups, but in our validation to make sure the prog is meant to be attached to BPF_LSM_CGROUP, we return too early if the check fails. This results in lack of decrementing prog's refcnt (through bpf_prog_put) leaving the LSM program alive past the point of the expected lifecycle. This fix allows for the decrement to take place.
[0] https://lore.kernel.org/all/20220628174314.1216643-4-sdf@google.com/
Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor") Signed-off-by: Milan Landaverde milan@mdaverde.com Signed-off-by: Martin KaFai Lau martin.lau@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Stanislav Fomichev sdf@google.com Link: https://lore.kernel.org/r/20221213175714.31963-1-milan@mdaverde.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/syscall.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0e758911d963..6b6fb7237ebe 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3505,9 +3505,9 @@ static int bpf_prog_attach(const union bpf_attr *attr) case BPF_PROG_TYPE_LSM: if (ptype == BPF_PROG_TYPE_LSM && prog->expected_attach_type != BPF_LSM_CGROUP) - return -EINVAL; - - ret = cgroup_bpf_prog_attach(attr, ptype, prog); + ret = -EINVAL; + else + ret = cgroup_bpf_prog_attach(attr, ptype, prog); break; default: ret = -EINVAL;