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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=20H=C3=B8iland-J=C3=B8rgensen?= , "Kumar Kartikeya Dwivedi" , Florian Westphal , , Maxim Mikityanskiy Subject: [PATCH bpf-next v6 3/6] bpf: Allow helpers to accept pointers with a fixed size Date: Fri, 22 Apr 2022 20:24:19 +0300 Message-ID: <20220422172422.4037988-4-maximmi@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220422172422.4037988-1-maximmi@nvidia.com> References: <20220422172422.4037988-1-maximmi@nvidia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 3e1f77b9-89ec-4057-1411-08da248506ab X-MS-TrafficTypeDiagnostic: DM6PR12MB4268: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: mlcDUITy6TGvIl6ZleNdv7oN3NKYxFwFk8BqzUeNcsA0hYCsE7R8dKIvkdH19sog8fJC9g15AgzUNDUdNyf67Z/ZS6zl5MN/c5YHgMNgeB09YRkgWR2HpvDk9LkSC+vMnT9eAqcGkR4kHDWv+gnQJ/R83LXOCxD6DHWBn7ZT4ZYYUTXjAu8jMNuLhGG9MLVa5ynQ3d9GAJth84hXi4jVQkKtxzHVvbEtOE4I3WVw8baOgiJjqIV7Rr+SuRxO/dEXvhTT+3xJv7YZ+Nlb+uD8WrJFAokf1RYVGDR8x0rIa2pmEVgxwpgb/Yp9M+A+lqvMSOCHkA9xddfXLibJrTW4mWf0FPOTYKkKtEsYF70rf7LVg1rINaON6G0y7Q5X9BCucUOUNfqbfJ/2ssKYh5gG48PAR16ZkcCazQU2+gkbSzAS32djH9TxFSTtVBiCrsA35HSEABFp3fHgvT/EM9idD2cABhBz7sJKr/iOMLoKzIbJZdNMkwKoLUkSFrDjBGictcKjhsS1Fag8WOWTjGslvgpXvCrtGz8AEuA3iCG69ObimU6CagyOdLofenEsX41J4XoXticNyO6BsG8GR2NI+Cwxzml6SXYbsCDgE4Zel5ps8Vn9js/Kq+h0wYCBQG2D7m4wpEmwcsKQDsCNTLOtBj6be1YmqJhM20qJWX1x4HrQSm4JKubPM4uTdNKuv54WESjOcApFiQddWCYo3S2xqme+ctzdH+Urk8JcS5r/pC3Zw9PeKu8OBqPGblUH+FJjVj0zffE9+buLhCpxmXI5wA== X-Forefront-Antispam-Report: CIP:12.22.5.236;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:InfoNoRecords;CAT:NONE;SFS:(13230001)(4636009)(46966006)(36840700001)(40470700004)(81166007)(8936002)(7416002)(86362001)(5660300002)(70586007)(2906002)(70206006)(40460700003)(356005)(508600001)(47076005)(54906003)(83380400001)(186003)(8676002)(4326008)(26005)(110136005)(36756003)(426003)(336012)(6666004)(107886003)(7696005)(316002)(36860700001)(82310400005)(2616005)(1076003)(461764006)(36900700001)(309714004);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2022 17:24:58.6378 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3e1f77b9-89ec-4057-1411-08da248506ab 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: CO1NAM11FT046.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4268 Precedence: bulk List-ID: X-Mailing-List: bpf@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 Reviewed-by: Tariq Toukan --- 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 7bf441563ffc..914b571bbf3a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -465,6 +465,16 @@ 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 71827d14724a..368fab3dfca5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5602,6 +5602,11 @@ 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); @@ -5941,13 +5946,12 @@ 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) @@ -5958,11 +5962,11 @@ 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; -- 2.30.2