From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from www62.your-server.de (www62.your-server.de [213.133.104.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B10F73C3F4B for ; Thu, 10 Sep 2026 21:35:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.133.104.62 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789076124; cv=none; b=PsiKcoPxPApjKcZAyRot8Ip2JChUohBFxGGUivAqDuniGHTRWnF3BJsKpwO2notczkhSBmWE/GXTeeMU+BC5sq5V7VNyrcIEGhJe8iPIncXCul1ZtaTpDRbKQPptUtpiDEJXgPLawK2EYG1aWKS9UIU7br4CdF0Q7YIrYLam9Do= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789076124; c=relaxed/simple; bh=qazRIji5A+0gI3RZ1IL6lIcXNK1ftLbw9Sc85Jlz9w0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XUYAn5ocTz5Ia46Z3AO6e0NBTzaltJ1lzKc0ZpaE0+H0sUWOEp7+RC5ORH4KJV0yFAkHXa2DjhTpaqmwAPhEZ4HTXwaEZLzMXIBmmZ32sCaoBXBZXOjgGPaDeUAU0J2f7JCOzU+Z5e+qcvXKjsCbx0OOmvVC24SQeTQ9qStTszs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net; spf=pass smtp.mailfrom=iogearbox.net; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b=Y0nr/HwE; arc=none smtp.client-ip=213.133.104.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b="Y0nr/HwE" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=iogearbox.net; s=default2302; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=OJhwjqwey4zGKezUYPDDBQXymqeUpEOJC4QAcSF4XM8=; b=Y0nr/HwEr+q+pLOvxSVOlyty1P e1nOV8aRX48SoeS0uNCzHU++54bBZJ0xLpoJtt1TxfDLVuYqZEH3654dhayc1q5tNmhUJcRdgLURx HMQw/CHbCVcakL5DcFoyJavXM9uXNkb+eiqP/UnDrsgetaL++5JQJ+D4ZaoP9VGUB14bsZ0UNNJ+D 7Mn/nzSe9cHY0x+Fp84z7jXev8F/lb0ZC33JE8d6r3XCAqwu3MlQ+Y05rkoBkD456C8LW8gTK68v8 E3LDGLQMeZlctFjoJG+9+RRzXoCwUzVtl6t6uE66cWmQacFLXhvzL822a+I140eVCiyWDv+nc6jRU nsJa0XUQ==; Received: from localhost ([127.0.0.1]) by www62.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1x4mQK-000H2M-1w; Thu, 10 Sep 2026 23:35:12 +0200 From: Daniel Borkmann To: ast@kernel.org Cc: memxor@gmail.com, eddyz87@gmail.com, info@starlabs.sg, bpf@vger.kernel.org Subject: [PATCH bpf v2 3/4] bpf: Require CAP_PERFMON for untrusted read-only memory reads Date: Thu, 10 Sep 2026 23:35:09 +0200 Message-ID: <20260910213510.49358-3-daniel@iogearbox.net> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260910213510.49358-1-daniel@iogearbox.net> References: <20260910213510.49358-1-daniel@iogearbox.net> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Virus-Scanned: Clear (ClamAV 1.4.3/28119/Thu Sep 10 08:24:09 2026) Marking bpf_rdonly_cast() KF_PERFMON CAP-limits one producer of PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED, but not the type itself. A global subprogram argument tagged __arg_untrusted results in the same register with no kfunc call. Reported-by: STAR Labs SG Signed-off-by: Daniel Borkmann --- v1 -> v2: - Fixed formatting bpf_diag_policy (Alexei) - Dropped Fixes tags (Alexei) kernel/bpf/verifier.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 939e535a3442..8058f684a9ea 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6453,6 +6453,15 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, struct b return -EACCES; } + if (rdonly_untrusted && !env->allow_ptr_leaks) { + verbose(env, "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + reg_type_str(env, reg->type)); + bpf_diag_policy(env, insn_idx, "read from untrusted read-only memory", + "the access requires CAP_PERFMON", + "Load the program with CAP_PERFMON, or avoid dereferencing untrusted pointers."); + return -EPERM; + } + /* * Accesses to untrusted PTR_TO_MEM are done through probe * instructions, hence no need to check bounds in that case. -- 2.43.0