BPF: make verifier 'misconfigured' errors more meaningful

Commit Message

[e-mail] April 4, 2023, 9:52 a.m. UTC

From: zhongjun <[e-mail]>

There are too many so-called 'misconfigured' errors potentially
feed back to user-space, that make it very hard to judge on
a glance the reason a verification failure occurred.
This patch make those similar error outputs more sensitive and readible.

base-commit: 738a96c4a8c36950803fdd27e7c30aca92dccefd
---
 kernel/bpf/verifier.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

Comments

Greg Kroah-Hartman April 4, 2023, 11:05 a.m. UTC | #1

On Tue, Apr 04, 2023 at 05:52:02PM +0800, [e-mail] wrote:
> From: zhongjun <[e-mail]>
> 
> There are too many so-called 'misconfigured' errors potentially
> feed back to user-space, that make it very hard to judge on
> a glance the reason a verification failure occurred.
> This patch make those similar error outputs more sensitive and readible.
> 
> base-commit: 738a96c4a8c36950803fdd27e7c30aca92dccefd
> ---
>  kernel/bpf/verifier.c | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

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If you wish to discuss this problem further, or you have questions about
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thanks,

greg k-h's patch email bot

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d517d13878cf..f19534f919c2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12684,7 +12684,8 @@  static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 			dst_reg->btf_id = aux->btf_var.btf_id;
 			break;
 		default:
-			verbose(env, "bpf verifier is misconfigured\n");
+			verbose(env, "bpf verifier is misconfigured: dst_reg->type = %d\n",
+					dst_reg->type);
 			return -EFAULT;
 		}
 		return 0;
@@ -12722,7 +12723,8 @@  static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 		   insn->src_reg == BPF_PSEUDO_MAP_IDX) {
 		dst_reg->type = CONST_PTR_TO_MAP;
 	} else {
-		verbose(env, "bpf verifier is misconfigured\n");
+		verbose(env, "bpf verifier is misconfigured: insn->src_reg = %d\n",
+				(int)insn->src_reg);
 		return -EINVAL;
 	}
 
@@ -12769,7 +12771,7 @@  static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	}
 
 	if (!env->ops->gen_ld_abs) {
-		verbose(env, "bpf verifier is misconfigured\n");
+		verbose(env, "bpf verifier is misconfigured: gen_ld_abs is NULL\n");
 		return -EINVAL;
 	}
 
@@ -15814,13 +15816,14 @@  static int convert_ctx_accesses(struct bpf_verifier_env *env)
 
 	if (ops->gen_prologue || env->seen_direct_write) {
 		if (!ops->gen_prologue) {
-			verbose(env, "bpf verifier is misconfigured\n");
+			verbose(env, "bpf verifier is misconfigured: gen_prologue is NULL\n");
 			return -EINVAL;
 		}
 		cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
 					env->prog);
 		if (cnt >= ARRAY_SIZE(insn_buf)) {
-			verbose(env, "bpf verifier is misconfigured\n");
+			verbose(env, "bpf verifier is misconfigured: cnt=%d exceeds limit@%lu\n",
+					cnt, ARRAY_SIZE(insn_buf));
 			return -EINVAL;
 		} else if (cnt) {
 			new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
@@ -15951,7 +15954,8 @@  static int convert_ctx_accesses(struct bpf_verifier_env *env)
 					 &target_size);
 		if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
 		    (ctx_field_size && !target_size)) {
-			verbose(env, "bpf verifier is misconfigured\n");
+			verbose(env, "bpf verifier is misconfigured: ins[%d] cnt=%d ctx_s=%u tg_s=%u\n",
+					i, cnt, ctx_field_size, target_size);
 			return -EINVAL;
 		}
 
@@ -16400,7 +16404,8 @@  static int do_misc_fixups(struct bpf_verifier_env *env)
 		     BPF_MODE(insn->code) == BPF_IND)) {
 			cnt = env->ops->gen_ld_abs(insn, insn_buf);
 			if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
-				verbose(env, "bpf verifier is misconfigured\n");
+				verbose(env, "bpf verifier is misconfigured: cnt=%d exceeds limit@%lu\n",
+						cnt, ARRAY_SIZE(insn_buf));
 				return -EINVAL;
 			}
 
@@ -16647,7 +16652,8 @@  static int do_misc_fixups(struct bpf_verifier_env *env)
 				if (cnt == -EOPNOTSUPP)
 					goto patch_map_ops_generic;
 				if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) {
-					verbose(env, "bpf verifier is misconfigured\n");
+					verbose(env, "bpf verifier is misconfigured: cnt=%d exceeds limit@%lu\n",
+							cnt, ARRAY_SIZE(insn_buf));
 					return -EINVAL;
 				}
 
@@ -16848,7 +16854,7 @@  static int do_misc_fixups(struct bpf_verifier_env *env)
 		if (!map_ptr->ops->map_poke_track ||
 		    !map_ptr->ops->map_poke_untrack ||
 		    !map_ptr->ops->map_poke_run) {
-			verbose(env, "bpf verifier is misconfigured\n");
+			verbose(env, "bpf verifier is misconfigured: map_poke_xxx is NULL\n");
 			return -EINVAL;
 		}