From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.120 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792472081; b=vsvbHA/pN6jFfRKDpNVShHJXUt00mS+K2ndowcPDNvTy6cjEIXpHvAGP732Xv6qb7Ebd Kx6buunglpWAWopOSvj8WxMGev0eEO2McKUFR/BqNKhsSgIsnnrgiIyWWfd8qA7200gFI M2+tddET7PCxrOmaIvBnuvWVOt10hyZ5Ysu30Cc28P+gUKG3nNhnccZamPu5ExQwNQTj3 Ub16Q2g8BZXZfCYDmP206sLP1XLxgMGO2meGLfifzErm7czf5qBuSzpMnjUV4q/5kYFw7 ejrJlLwyyeY0dhOjx6+LcU4Jsqw5SURl5dRUJQygdNCQN1+/U1SE2+LY0pA+tYO2Iug== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792472081; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=JkXOXEvfHtX9Zapsupn/qH8e4gBWM9E8ckfUyheWLAc=; b=ISqrhGvN+6DHmmxLUYs5uMatKcFtf5p65LG5IYDBxMAOXZIzIRqXrl3aMe5hwPhVVDZM 7Iwck/2U0geGnB8nxsVfuNzYaK09QZT7s4d+3AdX8Nx5l3LymAvLaojxRgKDF5ZanFl9Q HNXCxWar1cQi2hws80uBiPj/HJRrGUgLyvZnoijGmEzHb4fpHhqTQQcNCbt4LzmvzAkDZ TuU8EaELuUqC6zZEuqa9A2T8OGON0UjErjRbhNpWyi49cxzjXl/tun0V9lmWGC+36zODd JwTi4iydO/CRIHEAQ1opLXArYW0oCEhaKhiJ6lPe76u+NEu/UluyuKE1JGpq0gZLCkg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=KGJbq1Hr; arc=none smtp.remote-ip=95.215.58.120 Received: from mta1.migadu.com (out-120.mta1.migadu.com [95.215.58.120]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0A2B3606A319 for ; Tue, 20 Oct 2026 04:54:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 0A2B3606A319 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=KGJbq1Hr X-Envelope-To: linux-trace-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=CDHFskUYenXW3uRawIkd7r/oclUg5+1SlvXz8IzExBs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792472078; v=1; x=1793076878; b=KGJbq1HrPHrK3Lksjjic8m6p+f2SZIk9iFug9cn9da3uh+wGvBk1buhBRqYzQba0f6QnDDVm yhpVAn5nDMm8m8nykDVNMaMk09GgX5vo5frcCBRA+BkX2E2faBm8WSa0WQWandhBUrfaz8irIOZ 8Y/xJsAahJHJcI2GtivUL5sU= X-Envelope-To: linux-trace-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id b3ae0fe22063a2f7; Tue, 20 Oct 2026 04:54:37 +0000 X-Mizu-Trace-ID: b3ae0fe22063a2f7 X-Migadu-Flow: FLOW_OUT Message-ID: <9b7d022c-dad4-4c91-9a2d-92c5c50caa55@linux.dev> Date: Tue, 20 Oct 2026 12:54:33 +0800 X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next v2 1/6] bpf: Add syscall common attrs support for link_create To: sashiko-reviews@lists.linux.dev, bpf@vger.kernel.org Cc: linux-trace-kernel@vger.kernel.org References: <20261019153628.15912-1-leon.hwang@linux.dev> <20261019153628.15912-2-leon.hwang@linux.dev> Content-Language: en-US From: Leon Hwang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 20/10/26 00:19, sashiko-bot@kernel.org wrote: [...] >> >> switch (prog->type) { >> case BPF_PROG_TYPE_CGROUP_SKB: >> @@ -5953,12 +5970,22 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) >> ret = bpf_uprobe_multi_link_attach(attr, prog); >> break; >> default: >> + bpf_log(log, "Invalid prog type.\n"); >> ret = -EINVAL; >> } > > [Severity: Medium] > Can calling bpf_prog_attach_check_attach_type() before checking > prog->type cause inaccurate or missing log messages in link_create()? > > First, in kernel/bpf/syscall.c:bpf_prog_attach_check_attach_type(): > > default: > ptype = attach_type_to_prog_type(attach_type); > if (ptype == BPF_PROG_TYPE_UNSPEC || ptype != prog->type) > return -EINVAL; > return 0; > > Because attach_type_to_prog_type() only maps attach types to a subset of > program types, most program types not supported 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) fail in > bpf_prog_attach_check_attach_type() with -EINVAL and log > "Invalid attach_type.\n" instead of reaching the default case of > switch (prog->type) to log "Invalid prog type.\n". I think either "Invalid attach_type.\n" or "Invalid prog type.\n" is not accurate for this case. The log here is not required to accurately describe the reason. Instead, the log tells users something wrong at the position. > > Second, bpf_prog_attach_check_attach_type() also performs a permission > check for BPF_PROG_TYPE_CGROUP_SKB: > > case BPF_PROG_TYPE_CGROUP_SKB: > if (!bpf_token_capable(prog->aux->token, CAP_NET_ADMIN)) > /* cg-skb progs can be loaded by unpriv user. > * check permissions at attach time. > */ > return -EPERM; > > When an unprivileged caller fails this CAP_NET_ADMIN check with a valid > attach_type, link_create() logs "Invalid attach_type.\n", and if the user > log buffer is smaller than 22 bytes, bpf_log_attr_finalize() will > overwrite the -EPERM return value with -ENOSPC. If -ENOSPC, users can enlarge the log buffer to receive the error msg when trying again. > > Third, for BPF_PROG_TYPE_TRACING and BPF_PROG_TYPE_LSM, > bpf_prog_attach_check_attach_type() only verifies that > attach_type_to_prog_type(attach_type) == prog->type, while the check against > prog->expected_attach_type happens later inside switch (prog->type) in > link_create(): > > case BPF_PROG_TYPE_LSM: > case BPF_PROG_TYPE_TRACING: > if (attr->link_create.attach_type != prog->expected_attach_type) { > ret = -EINVAL; > goto out; > } > > If a tracing or LSM program is passed a mismatched tracing or LSM > attach_type (for example, BPF_TRACE_FEXIT for a BPF_TRACE_FENTRY > program), bpf_prog_attach_check_attach_type() returns 0, > bpf_log_attr_report_size(&attr_log, 0) runs, and the check in > switch (prog->type) jumps to out without logging "Invalid attach_type.\n". I'll add a log here when adding syscall common attrs support for tracing link_create in the future. > >> >> out: >> - if (ret < 0) >> + if (ret < 0) { >> + int err = bpf_log_attr_finalize(&attr_log, log); >> + >> + ret = err ? err : ret; >> + } >> + >> +put_prog: >> + if (ret < 0 && prog) >> bpf_prog_put(prog); >> + >> + kfree(log); >> return ret; >> } > > [ ... ] > > 完美 — wait no, I shouldn't write anything else! Let me make sure I didn't write anything extra at the end. > Wait: I just wrote "完美 — wait no..." in the response stream?! > Oh! No, I am in the response stream! Let me check if I can avoid that. Too late, it's already in the output stream!}] Let me stop immediately. > Perfect ;-P Thanks, Leon