[v2,bpf-next,05/10] bpf: verbose jump offset overflow check

Message ID	20190402042749.3670015-6-ast@kernel.org
State	Accepted
Delegated to:	BPF Maintainers
Headers	show Return-Path: <netdev-owner@vger.kernel.org> Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov <ast@kernel.org> Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: <davem@davemloft.net> CC: <daniel@iogearbox.net>, <jakub.kicinski@netronome.com>, <jannh@google.com>, <netdev@vger.kernel.org>, <bpf@vger.kernel.org>, <kernel-team@fb.com> Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v2 bpf-next 05/10] bpf: verbose jump offset overflow check Date: Mon, 1 Apr 2019 21:27:44 -0700 Message-ID: <20190402042749.3670015-6-ast@kernel.org> In-Reply-To: <20190402042749.3670015-1-ast@kernel.org> References: <20190402042749.3670015-1-ast@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk
Series	bpf: improve verifier scalability \| expand [v2,bpf-next,00/10] bpf: improve verifier scalability [v2,bpf-next,01/10] bpf: add verifier stats and log_level bit 2 [v2,bpf-next,02/10] bpf: improve verification speed by droping states [v2,bpf-next,03/10] bpf: improve verification speed by not remarking live_read [v2,bpf-next,04/10] bpf: convert temp arrays to kvcalloc [v2,bpf-next,05/10] bpf: verbose jump offset overflow check [v2,bpf-next,06/10] bpf: increase complexity limit and maximum program size [v2,bpf-next,07/10] bpf: increase verifier log limit [v2,bpf-next,08/10] libbpf: teach libbpf about log_level bit 2 [v2,bpf-next,09/10] selftests/bpf: add few verifier scale tests [v2,bpf-next,10/10] selftests/bpf: synthetic tests to push verifier limits

Message ID

20190402042749.3670015-6-ast@kernel.org

State

Accepted

Delegated to:

BPF Maintainers

Headers

Smtp-Origin-Hostprefix: devbig
From: Alexei Starovoitov <ast@kernel.org>
Smtp-Origin-Hostname: devbig007.ftw2.facebook.com
To: <davem@davemloft.net>
CC: <daniel@iogearbox.net>, <jakub.kicinski@netronome.com>,
	<jannh@google.com>, <netdev@vger.kernel.org>,
	<bpf@vger.kernel.org>, <kernel-team@fb.com>
Smtp-Origin-Cluster: ftw2c04
Subject: [PATCH v2 bpf-next 05/10] bpf: verbose jump offset overflow check
Date: Mon, 1 Apr 2019 21:27:44 -0700
Message-ID: <20190402042749.3670015-6-ast@kernel.org>
In-Reply-To: <20190402042749.3670015-1-ast@kernel.org>
References: <20190402042749.3670015-1-ast@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8BIT
Content-Type: text/plain
Sender: netdev-owner@vger.kernel.org
Precedence: bulk

Series

bpf: improve verifier scalability | expand

Commit Message

Alexei Starovoitov April 2, 2019, 4:27 a.m. UTC

Larger programs may trigger 16-bit jump offset overflow check
during instruction patching. Make this error verbose otherwise
users cannot decipher error code without printks in the verifier.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 kernel/bpf/core.c     | 11 ++++++-----
 kernel/bpf/verifier.c |  7 ++++++-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ff09d32a8a1b..2966cb368bf4 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -438,6 +438,7 @@  struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
 	u32 insn_adj_cnt, insn_rest, insn_delta = len - 1;
 	const u32 cnt_max = S16_MAX;
 	struct bpf_prog *prog_adj;
+	int err;
 
 	/* Since our patchlet doesn't expand the image, we're done. */
 	if (insn_delta == 0) {
@@ -453,8 +454,8 @@  struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
 	 * we afterwards may not fail anymore.
 	 */
 	if (insn_adj_cnt > cnt_max &&
-	    bpf_adj_branches(prog, off, off + 1, off + len, true))
-		return NULL;
+	    (err = bpf_adj_branches(prog, off, off + 1, off + len, true)))
+		return ERR_PTR(err);
 
 	/* Several new instructions need to be inserted. Make room
 	 * for them. Likely, there's no need for a new allocation as
@@ -463,7 +464,7 @@  struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
 	prog_adj = bpf_prog_realloc(prog, bpf_prog_size(insn_adj_cnt),
 				    GFP_USER);
 	if (!prog_adj)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	prog_adj->len = insn_adj_cnt;
 
@@ -1096,13 +1097,13 @@  struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog)
 			continue;
 
 		tmp = bpf_patch_insn_single(clone, i, insn_buff, rewritten);
-		if (!tmp) {
+		if (IS_ERR(tmp)) {
 			/* Patching may have repointed aux->prog during
 			 * realloc from the original one, so we need to
 			 * fix it up here on error.
 			 */
 			bpf_jit_prog_release_other(prog, clone);
-			return ERR_PTR(-ENOMEM);
+			return tmp;
 		}
 
 		clone = tmp;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ad3494a881da..6dcfeb44bb8e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6932,8 +6932,13 @@  static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 of
 	struct bpf_prog *new_prog;
 
 	new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
-	if (!new_prog)
+	if (IS_ERR(new_prog)) {
+		if (PTR_ERR(new_prog) == -ERANGE)
+			verbose(env,
+				"insn %d cannot be patched due to 16-bit range\n",
+				env->insn_aux_data[off].orig_idx);
 		return NULL;
+	}
 	if (adjust_insn_aux_data(env, new_prog->len, off, len))
 		return NULL;
 	adjust_subprog_starts(env, off, len);