Commit 2ec0616e authored May 16, 2020 by Daniel Borkmann

bpf: Fix check_return_code to only allow [0,1] in trace_iter progs

As per 15d83c4d ("bpf: Allow loading of a bpf_iter program") we only
allow a range of [0,1] for return codes. Therefore BPF_TRACE_ITER relies
on the default tnum_range(0, 1) which is set in range var. On recent merge
of net into net-next commit e92888c7 ("bpf: Enforce returning 0 for
fentry/fexit progs") got pulled in and caused a merge conflict with the
changes from 15d83c4d. The resolution had a snall hiccup in that it
removed the [0,1] range restriction again so that BPF_TRACE_ITER would
have no enforcement. Fix it by adding it back.

Fixes: da07f52d ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net"

)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>

parent da07f52d

kernel/bpf/verifier.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -7120,10 +7120,11 @@ static int check_return_code(struct bpf_verifier_env *env)
		case BPF_TRACE_FEXIT:
		range = tnum_const(0);
		break;
		case BPF_TRACE_ITER:
		case BPF_TRACE_RAW_TP:
		case BPF_MODIFY_RETURN:
		return 0;
		case BPF_TRACE_ITER:
		break;
		default:
		return -ENOTSUPP;
		}

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