From: Lorenz Bauer <lmb@cloudflare.com>
Date: Mon, 21 Sep 2020 12:12:23 +0000 (+0100)
Subject: bpf: Make context access check generic
X-Git-Tag: v5.15~2655^2~169^2~5^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=feec70401672bd9b0268ae59ec5efd15d86ae138;p=platform%2Fkernel%2Flinux-starfive.git

bpf: Make context access check generic

Always check context access if the register we're operating on is
PTR_TO_CTX, rather than relying on ARG_PTR_TO_CTX. This allows
simplifying the arg_type checking section of the function.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-8-lmb@cloudflare.com
---

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a4549b2..fc795ba 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4021,9 +4021,6 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		      arg_type == ARG_PTR_TO_CTX_OR_NULL)) {
 			if (type != expected_type)
 				goto err_type;
-			err = check_ctx_reg(env, reg, regno);
-			if (err < 0)
-				return err;
 		}
 	} else if (arg_type == ARG_PTR_TO_SOCK_COMMON) {
 		expected_type = PTR_TO_SOCK_COMMON;
@@ -4107,6 +4104,10 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 				regno);
 			return -EACCES;
 		}
+	} else if (type == PTR_TO_CTX) {
+		err = check_ctx_reg(env, reg, regno);
+		if (err < 0)
+			return err;
 	}
 
 	if (reg->ref_obj_id) {