From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793030810; b=s6hzQMRprcAMxtRY9oUv0LdlaWG53rqhCNg0WcK1Fq3JTPUFuJ0nxXdAd7T86ibOuLFu eyxQQ0Iy52XhYgUEOqWIlTbpUho/o2bO6Wig+TBYl3qNwJ+pSGDzzVL2m9yaCpP4cTZkm dSgIAwDtRKn1xiH+x3Ftvh07NTTCvH5y2RPPlMIqonHgpd229MaAx0sB5ehbdK03V4zAS ZgXvgpMpDD3nmx/neP5HHtVl13bpbU+ZFlrUX42k3SMzc7NIzejdSMkS76/ph7zsxT+M2 izwuA2UUf7fITI5JgfhAcgnCJZ3IOoA5hu+BqZzLwEugVLI6hmYeX6MfUSegYEWsV7w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793030810; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=q2504dBjupO3FBfjQT1IaeS/YKt4BaICmOiy1i+7Ec4=; b=VQ9jjnjNez4Hhw2gVoQK8QSLJFdh3bdL+IvQWtqoNUSNW/uQ9N7UODlS5nrvmlyc3e5/ 5EcqoLl2vvyFNyqLIABIMMldLa4Iup9X4Iv8GUGW/cwc0FoMhRlofGMMn6M095RGaau44 QL3IKOufOiAqYJB5aP5UT8S64sSIGoxS9gHRXLklpT6Rvya5ibjzVUlxwqB8AoxQkvJhv RNG83WI2L32G0+Pb6d69zyglYxjCd9bbwDTRoFlSK0nOOmXiwhHuEvwLtapM3onm1tYL8 OIrLBLjGVMZHSydjEcYDRnEXBAlxsyNPNWc06PgnvCXOIiYw6ZuJI7xuJ0NEsWLo1vQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AQ20mfiG; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2816606A31F; Mon, 26 Oct 2026 16:06:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AQ20mfiG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D9921F01828; Mon, 26 Oct 2026 16:06:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793030809; bh=q2504dBjupO3FBfjQT1IaeS/YKt4BaICmOiy1i+7Ec4=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=AQ20mfiGtZB6uzWs7Kxushh1rsbLNtzWWtNTg+1AM+6Kut72rzNL++4+DmzHLg8WW AwyeO58kYaYFYkMYNboo+1owtA8IVwWGDOPsilvCrBFA/3TF0Ial9ubyvEGBLVEZC2 F5OBtjwmRwPMXzgSMbnAIqPO4ZlVB7RsLx+pkOcEDOT3nQmI1eLsH0wuijOgkK7XCs 93nkffo/f4cHeiqJUL5c0Y7zxc0LEtqJwIvLNoYhwZnzlmpQyXEc4kSskW5/rt4EmC KGYhLRDuq1HpOakJieO1oPYnoX31CeFGjkcP/ySCy7VDsmm/QF+jgEWLH5Ed2PpaiD ME69Sff6PZ0BA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH bpf-next v5 1/6] bpf: Add syscall common attrs support for link_create Reply-To: sashiko-reviews@lists.linux.dev To: "Leon Hwang" , bpf@vger.kernel.org Cc: linux-trace-kernel@vger.kernel.org In-Reply-To: <20261026154948.99408-2-leon.hwang@linux.dev> References: <20261026154948.99408-1-leon.hwang@linux.dev> <20261026154948.99408-2-leon.hwang@linux.dev> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 26 Oct 2026 16:06:48 +0000 X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Medium] bpf: inaccurate attach_type and prog_type error logging in link_= create() -- commit bc490436683f8010bb5c27c3e3a1582ddc24a909 Author: Leon Hwang bpf: Add syscall common attrs support for link_create This commit adds syscall common attributes support to link_create() in kernel/bpf/syscall.c, initializing and finalizing a bpf_verifier_log instance to report errors for invalid prog_fd, attach_type, and prog_type. Link: https://lore.kernel.org/bpf/20260514004634.3DA09C19425@smtp.kernel.or= g/ > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 90bc7230afa8a..db870e795d044 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -5862,8 +5862,11 @@ static int bpf_map_do_batch(const union bpf_attr *= attr, > } > =20 > #define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.path_fd > -static int link_create(union bpf_attr *attr, bpfptr_t uattr) > +static int link_create(union bpf_attr *attr, bpfptr_t uattr, struct bpf_= common_attr *attr_common, > + bpfptr_t uattr_common, u32 size_common) > { > + struct bpf_verifier_log *log; > + struct bpf_log_attr attr_log; > struct bpf_prog *prog; > int ret; > =20 > @@ -5873,14 +5876,24 @@ static int link_create(union bpf_attr *attr, bpfp= tr_t uattr) > if (attr->link_create.attach_type =3D=3D BPF_STRUCT_OPS) > return bpf_struct_ops_link_create(attr); > =20 > + log =3D bpf_log_attr_create_vlog(&attr_log, attr_common, uattr_common, = size_common); > + if (IS_ERR(log)) > + return PTR_ERR(log); > + > prog =3D bpf_prog_get(attr->link_create.prog_fd); > - if (IS_ERR(prog)) > - return PTR_ERR(prog); > + if (IS_ERR(prog)) { > + bpf_log(log, "Invalid prog_fd.\n"); > + ret =3D PTR_ERR(prog); > + prog =3D NULL; > + goto out; > + } > =20 > ret =3D bpf_prog_attach_check_attach_type(prog, > attr->link_create.attach_type); > - if (ret) > + if (ret) { > + bpf_log(log, "Invalid attach_type.\n"); > goto out; > + } > =20 > switch (prog->type) { > case BPF_PROG_TYPE_CGROUP_SKB: > @@ -5959,12 +5972,20 @@ static int link_create(union bpf_attr *attr, bpfp= tr_t uattr) > ret =3D bpf_uprobe_multi_link_attach(attr, prog); > break; > default: > + bpf_log(log, "Invalid prog type.\n"); > ret =3D -EINVAL; > } [Severity: Medium] Does calling bpf_prog_attach_check_attach_type() before switch (prog->type) in kernel/bpf/syscall.c:link_create() cause misleading or missing log messages in a few cases? First, for almost all program types that are unsupported by link_create() (such as BPF_PROG_TYPE_SOCKET_FILTER, BPF_PROG_TYPE_SCHED_ACT, BPF_PROG_TYPE_RAW_TRACEPOINT, or BPF_PROG_TYPE_SYSCALL), link_create() -> bpf_prog_attach_check_attach_type() hits the default branch: kernel/bpf/syscall.c:bpf_prog_attach_check_attach_type() { ... default: ptype =3D attach_type_to_prog_type(attach_type); if (ptype =3D=3D BPF_PROG_TYPE_UNSPEC || ptype !=3D prog->type) return -EINVAL; return 0; } Because attach_type_to_prog_type() never returns those program types for any attach_type, bpf_prog_attach_check_attach_type() returns -EINVAL and link_create() logs "Invalid attach_type.\n" instead of reaching the default branch of switch (prog->type) to log "Invalid prog type.\n". Second, for BPF_PROG_TYPE_CGROUP_SKB, bpf_prog_attach_check_attach_type() also performs a capability check: case BPF_PROG_TYPE_CGROUP_SKB: if (!bpf_token_capable(prog->aux->token, CAP_NET_ADMIN)) return -EPERM; When this check fails with -EPERM, link_create() still logs "Invalid attach_type.\n" even when attach_type is valid. Third, for BPF_PROG_TYPE_LSM and BPF_PROG_TYPE_TRACING, bpf_prog_attach_check_attach_type() only checks that attach_type maps to the general program type. The stricter expected_attach_type check happens inside switch (prog->type) in link_create(): case BPF_PROG_TYPE_LSM: case BPF_PROG_TYPE_TRACING: if (attr->link_create.attach_type !=3D prog->expected_attach_type) { ret =3D -EINVAL; goto out; } If a caller passes an attach_type of the same program type that does not match prog->expected_attach_type, link_create() jumps to out without logging "Invalid attach_type.\n". Should the program type validation and attach_type logging be ordered so that unsupported program types, -EPERM failures, and expected_attach_type mismatches report accurate messages? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261026154948.9940= 8-1-leon.hwang@linux.dev?part=3D1