From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8D5A7D266 for ; Tue, 30 Jan 2024 00:06:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706573219; cv=none; b=LaFbAuRTkSWs9n64VBAxNmOLMJaD1x6C7SswnyBUAQEiAqqcIwsmPvMK/v0Gg965cxo/iQUXrA5ZQ4XByNRRmj9e5+D+lKAOcFpWrnb6+GCcH7eMN18djwT0S+aOTQJqq5fIstPfkFyMUx7cXV/bdZB2WHpk3emJyiCI2qaRZ4I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706573219; c=relaxed/simple; bh=3A7J0deHOq9ndLUf6W4Tt756O0NcriTdTq6umqVTSmE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mVbryuYGtk03Ebm8ZK51MMmFWtC13YwWL8pCbw8Nqv5eCCFwB0IgeduQgpNhFIKIsl65vUu0zti8pDNIARYQGEeVSL2+vVC4sxpuJVnruYxyIf4HsozCF7ypOFVVW0dyRZigXqiz4l0k7eC6gKqFB/hOR/yZ9lC4HKty7FkEi5M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DZT2PoWh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DZT2PoWh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39EE1C433F1; Tue, 30 Jan 2024 00:06:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706573219; bh=3A7J0deHOq9ndLUf6W4Tt756O0NcriTdTq6umqVTSmE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DZT2PoWhvsBPk0Wy83duMXGM5zDc/MUfc5AOrMywwSfNGGr/HVHJnZCNVSz85eodi gKp70g50qvpL2u04LeJ/Zs+NfvE4N0eP33raVKDTVumQcsj+PoF/eXrOn9MDvrNet7 N94r2kuGth5rkonJtUjpw2prbGBFpIXu3xLEnmUSrKH7jcEmrq7A5jxfwkWSNO0qti nroEvL1UjNkRsCX/EZcdtccCHbrBwwW/q2+g44G7MIS5gnIMhJyfVlsiYRQPnzUmql pX9W0JBDrLDglxsfoOT8JX3FSYUkweAXGcIlAu3Q5NKx7xUY1idQFLpFdtoRdEM3At WNvr//qs7WCXQ== From: Andrii Nakryiko To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@kernel.org Cc: andrii@kernel.org, kernel-team@meta.com, Eduard Zingerman Subject: [PATCH v3 bpf-next 2/4] bpf: add arg:nullable tag to be combined with trusted pointers Date: Mon, 29 Jan 2024 16:06:46 -0800 Message-Id: <20240130000648.2144827-3-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240130000648.2144827-1-andrii@kernel.org> References: <20240130000648.2144827-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add ability to mark arg:trusted arguments with optional arg:nullable tag to mark it as PTR_TO_BTF_ID_OR_NULL variant, which will allow callers to pass NULL, and subsequently will force global subprog's code to do NULL check. This allows to have "optional" PTR_TO_BTF_ID values passed into global subprogs. For now arg:nullable cannot be combined with anything else. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko --- kernel/bpf/btf.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index ed7a05815984..c8c6e6cf18e7 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7056,6 +7056,7 @@ enum btf_arg_tag { ARG_TAG_CTX = 0x1, ARG_TAG_NONNULL = 0x2, ARG_TAG_TRUSTED = 0x4, + ARG_TAG_NULLABLE = 0x8, }; /* Process BTF of a function to produce high-level expectation of function @@ -7161,6 +7162,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) tags |= ARG_TAG_TRUSTED; } else if (strcmp(tag, "nonnull") == 0) { tags |= ARG_TAG_NONNULL; + } else if (strcmp(tag, "nullable") == 0) { + tags |= ARG_TAG_NULLABLE; } else { bpf_log(log, "arg#%d has unsupported set of tags\n", i); return -EOPNOTSUPP; @@ -7210,12 +7213,19 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) return kern_type_id; sub->args[i].arg_type = ARG_PTR_TO_BTF_ID | PTR_TRUSTED; + if (tags & ARG_TAG_NULLABLE) + sub->args[i].arg_type |= PTR_MAYBE_NULL; sub->args[i].btf_id = kern_type_id; continue; } if (is_global) { /* generic user data pointer */ u32 mem_size; + if (tags & ARG_TAG_NULLABLE) { + bpf_log(log, "arg#%d has invalid combination of tags\n", i); + return -EINVAL; + } + t = btf_type_skip_modifiers(btf, t->type, NULL); ref_t = btf_resolve_size(btf, t, &mem_size); if (IS_ERR(ref_t)) { -- 2.34.1