From 2a02759ef5f8a34792df22b41d5e10658fd7bbd3 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 15 Oct 2019 20:25:02 -0700 Subject: bpf: Add support for BTF pointers to interpreter Pointer to BTF object is a pointer to kernel object or NULL. The memory access in the interpreter has to be done via probe_kernel_read to avoid page faults. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20191016032505.2089704-9-ast@kernel.org --- kernel/bpf/verifier.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/bpf/verifier.c') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 42a463e09761..c4b6a2cfcd47 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7581,6 +7581,7 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type) case PTR_TO_TCP_SOCK: case PTR_TO_TCP_SOCK_OR_NULL: case PTR_TO_XDP_SOCK: + case PTR_TO_BTF_ID: return false; default: return true; @@ -8722,6 +8723,13 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) case PTR_TO_XDP_SOCK: convert_ctx_access = bpf_xdp_sock_convert_ctx_access; break; + case PTR_TO_BTF_ID: + if (type == BPF_WRITE) { + verbose(env, "Writes through BTF pointers are not allowed\n"); + return -EINVAL; + } + insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); + continue; default: continue; } -- cgit v1.2.3