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[2001:8b0:7a5a:26ff:1913:6daa:6f2a:55c5]) by smtp.gmail.com with ESMTPSA id v17sm34177508wrr.60.2020.09.16.10.53.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2020 10:53:45 -0700 (PDT) From: Lorenz Bauer To: ast@kernel.org, yhs@fb.com, daniel@iogearbox.net, kafai@fb.com, andriin@fb.com Cc: bpf@vger.kernel.org, kernel-team@cloudflare.com, Lorenz Bauer Subject: [PATCH bpf-next v4 11/11] bpf: use a table to drive helper arg type checks Date: Wed, 16 Sep 2020 18:52:55 +0100 Message-Id: <20200916175255.192040-12-lmb@cloudflare.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200916175255.192040-1-lmb@cloudflare.com> References: <20200916175255.192040-1-lmb@cloudflare.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org The mapping between bpf_arg_type and bpf_reg_type is encoded in a big hairy if statement that is hard to follow. The debug output also leaves to be desired: if a reg_type doesn't match we only print one of the options, instead printing all the valid ones. Convert the if statement into a table which is then used to drive type checking. If none of the reg_types match we print all options, e.g.: R2 type=rdonly_buf expected=fp, pkt, pkt_meta, map_value Signed-off-by: Lorenz Bauer Acked-by: Martin KaFai Lau --- include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 183 +++++++++++++++++++++++++----------------- 2 files changed, 110 insertions(+), 74 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 732e2f144b6d..4ca817a9195c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -292,6 +292,7 @@ enum bpf_arg_type { ARG_PTR_TO_ALLOC_MEM, /* pointer to dynamically allocated memory */ ARG_PTR_TO_ALLOC_MEM_OR_NULL, /* pointer to dynamically allocated memory or NULL */ ARG_CONST_ALLOC_SIZE_OR_ZERO, /* number of allocated bytes requested */ + __BPF_ARG_TYPE_MAX, }; /* type of values returned from helper functions */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d64ac79982ad..b5c00d08f9c0 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3856,12 +3856,6 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type) type == ARG_CONST_SIZE_OR_ZERO; } -static bool arg_type_is_alloc_mem_ptr(enum bpf_arg_type type) -{ - return type == ARG_PTR_TO_ALLOC_MEM || - type == ARG_PTR_TO_ALLOC_MEM_OR_NULL; -} - static bool arg_type_is_alloc_size(enum bpf_arg_type type) { return type == ARG_CONST_ALLOC_SIZE_OR_ZERO; @@ -3910,14 +3904,115 @@ static int resolve_map_arg_type(struct bpf_verifier_env *env, return 0; } +struct bpf_reg_types { + const enum bpf_reg_type types[10]; +}; + +static const struct bpf_reg_types map_key_value_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_VALUE, + }, +}; + +static const struct bpf_reg_types sock_types = { + .types = { + PTR_TO_SOCK_COMMON, + PTR_TO_SOCKET, + PTR_TO_TCP_SOCK, + PTR_TO_XDP_SOCK, + }, +}; + +static const struct bpf_reg_types mem_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_VALUE, + PTR_TO_MEM, + PTR_TO_RDONLY_BUF, + PTR_TO_RDWR_BUF, + }, +}; + +static const struct bpf_reg_types int_ptr_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_VALUE, + }, +}; + +static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } }; +static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } }; +static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } }; +static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM } }; +static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } }; +static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } }; +static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } }; + +static const struct bpf_reg_types *compatible_reg_types[] = { + [ARG_PTR_TO_MAP_KEY] = &map_key_value_types, + [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types, + [ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types, + [ARG_PTR_TO_MAP_VALUE_OR_NULL] = &map_key_value_types, + [ARG_CONST_SIZE] = &scalar_types, + [ARG_CONST_SIZE_OR_ZERO] = &scalar_types, + [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types, + [ARG_CONST_MAP_PTR] = &const_map_ptr_types, + [ARG_PTR_TO_CTX] = &context_types, + [ARG_PTR_TO_CTX_OR_NULL] = &context_types, + [ARG_PTR_TO_SOCK_COMMON] = &sock_types, + [ARG_PTR_TO_SOCKET] = &fullsock_types, + [ARG_PTR_TO_SOCKET_OR_NULL] = &fullsock_types, + [ARG_PTR_TO_BTF_ID] = &btf_ptr_types, + [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, + [ARG_PTR_TO_MEM] = &mem_types, + [ARG_PTR_TO_MEM_OR_NULL] = &mem_types, + [ARG_PTR_TO_UNINIT_MEM] = &mem_types, + [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types, + [ARG_PTR_TO_ALLOC_MEM_OR_NULL] = &alloc_mem_types, + [ARG_PTR_TO_INT] = &int_ptr_types, + [ARG_PTR_TO_LONG] = &int_ptr_types, + [__BPF_ARG_TYPE_MAX] = NULL, +}; + +static int check_reg_type(struct bpf_verifier_env *env, u32 regno, + const struct bpf_reg_types *compatible) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + enum bpf_reg_type expected, type = reg->type; + int i, j; + + for (i = 0; i < ARRAY_SIZE(compatible->types); i++) { + expected = compatible->types[i]; + if (expected == NOT_INIT) + break; + + if (type == expected) + return 0; + } + + verbose(env, "R%d type=%s expected=", regno, reg_type_str[type]); + for (j = 0; j + 1 < i; j++) + verbose(env, "%s, ", reg_type_str[compatible->types[j]]); + verbose(env, "%s\n", reg_type_str[compatible->types[j]]); + return -EACCES; +} + static int check_func_arg(struct bpf_verifier_env *env, u32 arg, struct bpf_call_arg_meta *meta, const struct bpf_func_proto *fn) { u32 regno = BPF_REG_1 + arg; struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; - enum bpf_reg_type expected_type, type = reg->type; enum bpf_arg_type arg_type = fn->arg_type[arg]; + const struct bpf_reg_types *compatible; + enum bpf_reg_type type = reg->type; int err = 0; if (arg_type == ARG_DONTCARE) @@ -3956,72 +4051,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, */ goto skip_type_check; - if (arg_type == ARG_PTR_TO_MAP_KEY || - arg_type == ARG_PTR_TO_MAP_VALUE || - arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE || - arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) { - expected_type = PTR_TO_STACK; - if (!type_is_pkt_pointer(type) && - type != PTR_TO_MAP_VALUE && - type != expected_type) - goto err_type; - } else if (arg_type == ARG_CONST_SIZE || - arg_type == ARG_CONST_SIZE_OR_ZERO || - arg_type == ARG_CONST_ALLOC_SIZE_OR_ZERO) { - expected_type = SCALAR_VALUE; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_CONST_MAP_PTR) { - expected_type = CONST_PTR_TO_MAP; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_PTR_TO_CTX || - arg_type == ARG_PTR_TO_CTX_OR_NULL) { - expected_type = PTR_TO_CTX; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_PTR_TO_SOCK_COMMON) { - expected_type = PTR_TO_SOCK_COMMON; - /* Any sk pointer can be ARG_PTR_TO_SOCK_COMMON */ - if (!type_is_sk_pointer(type)) - goto err_type; - } else if (arg_type == ARG_PTR_TO_SOCKET || - arg_type == ARG_PTR_TO_SOCKET_OR_NULL) { - expected_type = PTR_TO_SOCKET; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_PTR_TO_BTF_ID) { - expected_type = PTR_TO_BTF_ID; - if (type != expected_type) - goto err_type; - } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) { - expected_type = PTR_TO_MAP_VALUE; - if (type != expected_type) - goto err_type; - } else if (arg_type_is_mem_ptr(arg_type)) { - expected_type = PTR_TO_STACK; - if (!type_is_pkt_pointer(type) && - type != PTR_TO_MAP_VALUE && - type != PTR_TO_MEM && - type != PTR_TO_RDONLY_BUF && - type != PTR_TO_RDWR_BUF && - type != expected_type) - goto err_type; - } else if (arg_type_is_alloc_mem_ptr(arg_type)) { - expected_type = PTR_TO_MEM; - if (type != expected_type) - goto err_type; - } else if (arg_type_is_int_ptr(arg_type)) { - expected_type = PTR_TO_STACK; - if (!type_is_pkt_pointer(type) && - type != PTR_TO_MAP_VALUE && - type != expected_type) - goto err_type; - } else { - verbose(env, "unsupported arg_type %d\n", arg_type); + compatible = compatible_reg_types[arg_type]; + if (!compatible) { + verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type); return -EFAULT; } + err = check_reg_type(env, regno, compatible); + if (err) + return err; + if (type == PTR_TO_BTF_ID) { const u32 *btf_id = fn->arg_btf_id[arg]; @@ -4174,10 +4213,6 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, } return err; -err_type: - verbose(env, "R%d type=%s expected=%s\n", regno, - reg_type_str[type], reg_type_str[expected_type]); - return -EACCES; } static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) -- 2.25.1