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Thu, 24 Feb 2022 15:12:48 +0000 Received: from rnnvmail203.nvidia.com (10.129.68.9) by rnnvmail203.nvidia.com (10.129.68.9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.9; Thu, 24 Feb 2022 07:12:46 -0800 Received: from vdi.nvidia.com (10.127.8.12) by mail.nvidia.com (10.129.68.9) with Microsoft SMTP Server id 15.2.986.9 via Frontend Transport; Thu, 24 Feb 2022 07:12:39 -0800 From: Maxim Mikityanskiy To: , Alexei Starovoitov , "Daniel Borkmann" , Andrii Nakryiko , CC: Tariq Toukan , Martin KaFai Lau , "Song Liu" , Yonghong Song , John Fastabend , KP Singh , "David S. Miller" , Jakub Kicinski , Petar Penkov , Lorenz Bauer , Eric Dumazet , Hideaki YOSHIFUJI , "David Ahern" , Shuah Khan , "Jesper Dangaard Brouer" , Nathan Chancellor , "Nick Desaulniers" , Joe Stringer , "Florent Revest" , , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , "Kumar Kartikeya Dwivedi" , Florian Westphal , "Maxim Mikityanskiy" Subject: [PATCH bpf-next v3 3/5] bpf: Allow helpers to accept pointers with a fixed size Date: Thu, 24 Feb 2022 17:11:43 +0200 Message-ID: <20220224151145.355355-4-maximmi@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220224151145.355355-1-maximmi@nvidia.com> References: <20220224151145.355355-1-maximmi@nvidia.com> MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 062c68ff-6fb6-4fd0-abf0-08d9f7a81f17 X-MS-TrafficTypeDiagnostic: MN2PR12MB3758:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:12.22.5.236; CTRY:US; LANG:en; SCL:1; SRV:; IPV:CAL; SFV:NSPM; H:mail.nvidia.com; PTR:InfoNoRecords; CAT:NONE; SFS:(13230001)(4636009)(46966006)(36840700001)(40470700004)(2906002)(26005)(36756003)(40460700003)(186003)(1076003)(4326008)(316002)(70586007)(2616005)(107886003)(356005)(81166007)(86362001)(70206006)(8676002)(8936002)(54906003)(36860700001)(47076005)(7416002)(5660300002)(110136005)(82310400004)(7696005)(508600001)(6666004)(83380400001)(336012)(426003)(461764006)(36900700001)(309714004); DIR:OUT; SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Feb 2022 15:12:49.5659 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 062c68ff-6fb6-4fd0-abf0-08d9f7a81f17 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a; Ip=[12.22.5.236]; Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT006.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB3758 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Before this commit, the BPF verifier required ARG_PTR_TO_MEM arguments to be followed by ARG_CONST_SIZE holding the size of the memory region. The helpers had to check that size in runtime. There are cases where the size expected by a helper is a compile-time constant. Checking it in runtime is an unnecessary overhead and waste of BPF registers. This commit allows helpers to accept ARG_PTR_TO_MEM arguments without the corresponding ARG_CONST_SIZE, given that they define the memory region size in struct bpf_func_proto. Signed-off-by: Maxim Mikityanskiy --- include/linux/bpf.h | 10 ++++++++++ kernel/bpf/verifier.c | 26 +++++++++++++++----------- 2 files changed, 25 insertions(+), 11 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f19abc59b6cd..19715994f919 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -457,6 +457,16 @@ struct bpf_func_proto { }; u32 *arg_btf_id[5]; }; + union { + struct { + size_t arg1_size; + size_t arg2_size; + size_t arg3_size; + size_t arg4_size; + size_t arg5_size; + }; + size_t arg_size[5]; + }; int *ret_btf_id; /* return value btf_id */ bool (*allowed)(const struct bpf_prog *prog); }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d7473fee247c..f00e516acbbe 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5529,6 +5529,11 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, * next is_mem_size argument below. */ meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM); + if (fn->arg_size[arg]) { + err = check_helper_mem_access(env, regno, + fn->arg_size[arg], false, + meta); + } } else if (arg_type_is_mem_size(arg_type)) { bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); @@ -5868,13 +5873,12 @@ static bool check_raw_mode_ok(const struct bpf_func_proto *fn) return count <= 1; } -static bool check_args_pair_invalid(enum bpf_arg_type arg_curr, - enum bpf_arg_type arg_next) +static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg) { - return (arg_type_is_mem_ptr(arg_curr) && - !arg_type_is_mem_size(arg_next)) || - (!arg_type_is_mem_ptr(arg_curr) && - arg_type_is_mem_size(arg_next)); + if (arg_type_is_mem_ptr(fn->arg_type[arg])) + return arg_type_is_mem_size(fn->arg_type[arg + 1]) == + !!fn->arg_size[arg]; + return arg_type_is_mem_size(fn->arg_type[arg + 1]) || fn->arg_size[arg]; } static bool check_arg_pair_ok(const struct bpf_func_proto *fn) @@ -5885,11 +5889,11 @@ static bool check_arg_pair_ok(const struct bpf_func_proto *fn) * helper function specification. */ if (arg_type_is_mem_size(fn->arg1_type) || - arg_type_is_mem_ptr(fn->arg5_type) || - check_args_pair_invalid(fn->arg1_type, fn->arg2_type) || - check_args_pair_invalid(fn->arg2_type, fn->arg3_type) || - check_args_pair_invalid(fn->arg3_type, fn->arg4_type) || - check_args_pair_invalid(fn->arg4_type, fn->arg5_type)) + (arg_type_is_mem_ptr(fn->arg5_type) && !fn->arg5_size) || + check_args_pair_invalid(fn, 1) || + check_args_pair_invalid(fn, 2) || + check_args_pair_invalid(fn, 3) || + check_args_pair_invalid(fn, 4)) return false; return true;