From patchwork Fri Jun 10 13:59:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12877634 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92287CCA47D for ; Fri, 10 Jun 2022 13:59:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238295AbiFJN7x (ORCPT ); Fri, 10 Jun 2022 09:59:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38246 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236558AbiFJN7i (ORCPT ); Fri, 10 Jun 2022 09:59:38 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7254203A2A; Fri, 10 Jun 2022 06:59:32 -0700 (PDT) Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4LKMtg3YYhz683Pb; Fri, 10 Jun 2022 21:55:55 +0800 (CST) Received: from roberto-ThinkStation-P620.huawei.com (10.204.63.22) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 10 Jun 2022 15:59:30 +0200 From: Roberto Sassu To: , , , CC: , , , , Roberto Sassu , kernel test robot Subject: [PATCH v3 1/2] bpf: Add bpf_verify_signature() helper Date: Fri, 10 Jun 2022 15:59:15 +0200 Message-ID: <20220610135916.1285509-2-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220610135916.1285509-1-roberto.sassu@huawei.com> References: <20220610135916.1285509-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.63.22] X-ClientProxiedBy: lhreml753-chm.china.huawei.com (10.201.108.203) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Add the bpf_verify_signature() helper, to give eBPF security modules the ability to check the validity of a signature against supplied data, by using system-provided keys as trust anchor. The new helper makes it possible to enforce mandatory policies, as eBPF programs might be allowed to make security decisions only based on data sources the system administrator approves. The caller should specify the identifier of the keyring containing the keys for signature verification: 0 for the primary keyring (immutable keyring of system keys); 1 for both the primary and secondary keyring (where keys can be added only if they are vouched for by existing keys in those keyrings); 2 for the platform keyring (primarily used by the integrity subsystem to verify a kexec'ed kerned image and, possibly, the initramfs signature); 0xffff for the session keyring (for testing purposes). The caller should also specify the type of signature. Currently only PKCS#7 is supported. Since the maximum number of parameters of an eBPF helper is 5, the keyring and signature types share one (keyring ID: low 16 bits, signature type: high 16 bits). Signed-off-by: Roberto Sassu Reported-by: kernel test robot (cast warning) --- include/uapi/linux/bpf.h | 17 +++++++++++++ kernel/bpf/bpf_lsm.c | 46 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 17 +++++++++++++ 3 files changed, 80 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f4009dbdf62d..97521857e44a 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5249,6 +5249,22 @@ union bpf_attr { * Pointer to the underlying dynptr data, NULL if the dynptr is * read-only, if the dynptr is invalid, or if the offset and length * is out of bounds. + * + * long bpf_verify_signature(u8 *data, u32 datalen, u8 *sig, u32 siglen, u32 info) + * Description + * Verify a signature of length *siglen* against the supplied data + * with length *datalen*. *info* contains the keyring identifier + * (low 16 bits) and the signature type (high 16 bits). The keyring + * identifier can have the following values (some defined in + * verification.h): 0 for the primary keyring (immutable keyring of + * system keys); 1 for both the primary and secondary keyring + * (where keys can be added only if they are vouched for by + * existing keys in those keyrings); 2 for the platform keyring + * (primarily used by the integrity subsystem to verify a kexec'ed + * kerned image and, possibly, the initramfs signature); 0xffff for + * the session keyring (for testing purposes). + * Return + * 0 on success, a negative value on error. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5455,6 +5471,7 @@ union bpf_attr { FN(dynptr_read), \ FN(dynptr_write), \ FN(dynptr_data), \ + FN(verify_signature), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index c1351df9f7ee..20bd850ea3ee 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include /* For every LSM hook that allows attachment of BPF programs, declare a nop * function where a BPF program can be attached. @@ -132,6 +134,46 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto = { .arg1_type = ARG_PTR_TO_CTX, }; +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION +BPF_CALL_5(bpf_verify_signature, u8 *, data, u32, datalen, u8 *, sig, + u32, siglen, u32, info) +{ + unsigned long keyring_id = info & U16_MAX; + enum pkey_id_type id_type = info >> 16; + const struct cred *cred = current_cred(); + struct key *keyring; + + if (keyring_id > (unsigned long)VERIFY_USE_PLATFORM_KEYRING && + keyring_id != U16_MAX) + return -EINVAL; + + keyring = (keyring_id == U16_MAX) ? + cred->session_keyring : (struct key *)keyring_id; + + switch (id_type) { + case PKEY_ID_PKCS7: + return verify_pkcs7_signature(data, datalen, sig, siglen, + keyring, + VERIFYING_UNSPECIFIED_SIGNATURE, + NULL, NULL); + default: + return -EOPNOTSUPP; + } +} + +static const struct bpf_func_proto bpf_verify_signature_proto = { + .func = bpf_verify_signature, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_PTR_TO_MEM, + .arg4_type = ARG_CONST_SIZE_OR_ZERO, + .arg5_type = ARG_ANYTHING, + .allowed = bpf_ima_inode_hash_allowed, +}; +#endif + static const struct bpf_func_proto * bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -158,6 +200,10 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return prog->aux->sleepable ? &bpf_ima_file_hash_proto : NULL; case BPF_FUNC_get_attach_cookie: return bpf_prog_has_trampoline(prog) ? &bpf_get_attach_cookie_proto : NULL; +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION + case BPF_FUNC_verify_signature: + return prog->aux->sleepable ? &bpf_verify_signature_proto : NULL; +#endif default: return tracing_prog_func_proto(func_id, prog); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index f4009dbdf62d..97521857e44a 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5249,6 +5249,22 @@ union bpf_attr { * Pointer to the underlying dynptr data, NULL if the dynptr is * read-only, if the dynptr is invalid, or if the offset and length * is out of bounds. + * + * long bpf_verify_signature(u8 *data, u32 datalen, u8 *sig, u32 siglen, u32 info) + * Description + * Verify a signature of length *siglen* against the supplied data + * with length *datalen*. *info* contains the keyring identifier + * (low 16 bits) and the signature type (high 16 bits). The keyring + * identifier can have the following values (some defined in + * verification.h): 0 for the primary keyring (immutable keyring of + * system keys); 1 for both the primary and secondary keyring + * (where keys can be added only if they are vouched for by + * existing keys in those keyrings); 2 for the platform keyring + * (primarily used by the integrity subsystem to verify a kexec'ed + * kerned image and, possibly, the initramfs signature); 0xffff for + * the session keyring (for testing purposes). + * Return + * 0 on success, a negative value on error. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5455,6 +5471,7 @@ union bpf_attr { FN(dynptr_read), \ FN(dynptr_write), \ FN(dynptr_data), \ + FN(verify_signature), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper From patchwork Fri Jun 10 13:59:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12877635 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56925CCA481 for ; Fri, 10 Jun 2022 13:59:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345011AbiFJN7y (ORCPT ); Fri, 10 Jun 2022 09:59:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349986AbiFJN7i (ORCPT ); Fri, 10 Jun 2022 09:59:38 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B73F92044C8; Fri, 10 Jun 2022 06:59:33 -0700 (PDT) Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4LKMxG4WGqz67wgF; Fri, 10 Jun 2022 21:58:10 +0800 (CST) Received: from roberto-ThinkStation-P620.huawei.com (10.204.63.22) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 10 Jun 2022 15:59:31 +0200 From: Roberto Sassu To: , , , CC: , , , , Roberto Sassu Subject: [PATCH v3 2/2] selftests/bpf: Add test for bpf_verify_signature() helper Date: Fri, 10 Jun 2022 15:59:16 +0200 Message-ID: <20220610135916.1285509-3-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220610135916.1285509-1-roberto.sassu@huawei.com> References: <20220610135916.1285509-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.63.22] X-ClientProxiedBy: lhreml753-chm.china.huawei.com (10.201.108.203) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Ensure that signature verification is performed successfully from an eBPF program, with the new bpf_verify_signature() helper. Generate a testing signature key and copy sign-file from scripts/ to the eBPF selftests directory (if exists), so that the test is selfcontained. Signed-off-by: Roberto Sassu --- tools/testing/selftests/bpf/Makefile | 11 +- tools/testing/selftests/bpf/config | 1 + .../selftests/bpf/prog_tests/verify_sig.c | 200 ++++++++++++++++++ .../selftests/bpf/progs/test_verify_sig.c | 160 ++++++++++++++ .../testing/selftests/bpf/verify_sig_setup.sh | 100 +++++++++ 5 files changed, 469 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/verify_sig.c create mode 100644 tools/testing/selftests/bpf/progs/test_verify_sig.c create mode 100755 tools/testing/selftests/bpf/verify_sig_setup.sh diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 2d3c8c8f558a..238911b4e4b4 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -75,7 +75,7 @@ TEST_PROGS := test_kmod.sh \ test_xsk.sh TEST_PROGS_EXTENDED := with_addr.sh \ - with_tunnels.sh ima_setup.sh \ + with_tunnels.sh ima_setup.sh verify_sig_setup.sh \ test_xdp_vlan.sh test_bpftool.py # Compile but not part of 'make run_tests' @@ -84,7 +84,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \ test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \ xdpxceiver xdp_redirect_multi -TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read +TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read $(OUTPUT)/sign-file # Emit succinct information message describing current building step # $1 - generic step name (e.g., CC, LINK, etc); @@ -180,6 +180,10 @@ $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_r liburandom_read.so $(LDLIBS) \ -Wl,-rpath=. -Wl,--build-id=sha1 -o $@ +$(OUTPUT)/sign-file: ../../../../scripts/sign-file + $(call msg,SIGN-FILE,,$@) + $(Q)$(shell [ -f $< ] && cp -a $< $@) + $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(wildcard bpf_testmod/Makefile bpf_testmod/*.[ch]) $(call msg,MOD,,$@) $(Q)$(RM) bpf_testmod/bpf_testmod.ko # force re-compilation @@ -502,7 +506,8 @@ TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \ cap_helpers.c TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \ $(OUTPUT)/liburandom_read.so \ - ima_setup.sh \ + $(OUTPUT)/sign-file \ + ima_setup.sh verify_sig_setup.sh \ $(wildcard progs/btf_dump_test_case_*.c) TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS) -DENABLE_ATOMICS_TESTS diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index 3b3edc0fc8a6..64b0957d7742 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -57,3 +57,4 @@ CONFIG_FPROBE=y CONFIG_IKCONFIG=y CONFIG_IKCONFIG_PROC=y CONFIG_MPTCP=y +CONFIG_MODULE_SIG=y diff --git a/tools/testing/selftests/bpf/prog_tests/verify_sig.c b/tools/testing/selftests/bpf/prog_tests/verify_sig.c new file mode 100644 index 000000000000..165ab1a8ad98 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/verify_sig.c @@ -0,0 +1,200 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "test_verify_sig.skel.h" + +#define MAX_DATA_SIZE 4096 + +struct data { + u8 payload[MAX_DATA_SIZE]; +}; + +static int _run_setup_process(const char *setup_dir, const char *cmd) +{ + int child_pid, child_status; + + child_pid = fork(); + if (child_pid == 0) { + execlp("./verify_sig_setup.sh", "./verify_sig_setup.sh", cmd, + setup_dir, NULL); + exit(errno); + + } else if (child_pid > 0) { + waitpid(child_pid, &child_status, 0); + return WEXITSTATUS(child_status); + } + + return -EINVAL; +} + +static int populate_data_item(const char *tmp_dir, struct data *data_item) +{ + struct stat st; + char signed_file_template[] = "/tmp/signed_fileXXXXXX"; + char path[PATH_MAX]; + int ret, fd, child_status, child_pid; + + fd = mkstemp(signed_file_template); + if (fd == -1) + return -errno; + + ret = write(fd, "test", 4); + + close(fd); + + if (ret != 4) { + ret = -EIO; + goto out; + } + + child_pid = fork(); + + if (child_pid == -1) { + ret = -errno; + goto out; + } + + if (child_pid == 0) { + snprintf(path, sizeof(path), "%s/signing_key.pem", tmp_dir); + + return execlp("./sign-file", "./sign-file", "sha256", + path, path, signed_file_template, NULL); + } + + waitpid(child_pid, &child_status, 0); + + ret = WEXITSTATUS(child_status); + if (ret) + goto out; + + ret = stat(signed_file_template, &st); + if (ret == -1) { + ret = -errno; + goto out; + } + + if (st.st_size > sizeof(data_item->payload) - sizeof(u32)) { + ret = -EINVAL; + goto out; + } + + *(u32 *)data_item->payload = __cpu_to_be32(st.st_size); + + fd = open(signed_file_template, O_RDONLY); + if (fd == -1) { + ret = -errno; + goto out; + } + + ret = read(fd, data_item->payload + sizeof(u32), st.st_size); + + close(fd); + + if (ret != st.st_size) { + ret = -EIO; + goto out; + } + + ret = 0; +out: + unlink(signed_file_template); + return ret; +} + +void test_verify_sig(void) +{ + char tmp_dir_template[] = "/tmp/verify_sigXXXXXX"; + char *tmp_dir; + struct test_verify_sig *skel = NULL; + struct bpf_map *map; + struct data data; + struct stat st; + u32 saved_len; + int ret, zero = 0; + + if (libbpf_probe_bpf_helper(BPF_PROG_TYPE_KPROBE, + BPF_FUNC_verify_signature, NULL) == -EOPNOTSUPP) { + printf("%s:SKIP:bpf_verify_signature() helper not supported\n", + __func__); + test__skip(); + return; + } + + if (stat("./sign-file", &st) == -1) { + printf("%s:SKIP:kernel modules are not signed\n", __func__); + test__skip(); + return; + } + + tmp_dir = mkdtemp(tmp_dir_template); + if (!ASSERT_OK_PTR(tmp_dir, "mkdtemp")) + return; + + ret = _run_setup_process(tmp_dir, "setup"); + if (!ASSERT_OK(ret, "_run_setup_process")) + goto close_prog; + + skel = test_verify_sig__open_and_load(); + if (!ASSERT_OK_PTR(skel, "test_verify_sig__open_and_load")) + goto close_prog; + + ret = test_verify_sig__attach(skel); + if (!ASSERT_OK(ret, "test_verify_sig__attach\n")) + goto close_prog; + + map = bpf_object__find_map_by_name(skel->obj, "data_input"); + if (!ASSERT_OK_PTR(map, "data_input not found")) + goto close_prog; + + ret = populate_data_item(tmp_dir, &data); + if (!ASSERT_OK(ret, "populate_data_item\n")) + goto close_prog; + + skel->bss->monitored_pid = getpid(); + skel->bss->keyring_id = 0xffff; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_OK(ret, "bpf_map_update_elem\n")) + goto close_prog; + + skel->bss->monitored_pid = getpid(); + /* Search the verification key in the primary keyring (should fail). */ + skel->bss->keyring_id = 0; + + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input\n")) + goto close_prog; + + saved_len = *(__u32 *)data.payload; + *(__u32 *)data.payload = sizeof(data.payload); + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input\n")) + goto close_prog; + + *(__u32 *)data.payload = saved_len; + data.payload[sizeof(__u32)] = 'a'; + ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY); + ASSERT_LT(ret, 0, "bpf_map_update_elem data_input\n"); +close_prog: + _run_setup_process(tmp_dir, "cleanup"); + + if (!skel) + return; + + skel->bss->monitored_pid = 0; + test_verify_sig__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_verify_sig.c b/tools/testing/selftests/bpf/progs/test_verify_sig.c new file mode 100644 index 000000000000..1c60c9b5c991 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_verify_sig.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu + */ + +#include +#include +#include +#include +#include +#include + +#define MAX_DATA_SIZE 4096 + +#ifdef __BIG_ENDIAN__ +#define be32_to_cpu(x) (x) +#else +#define be32_to_cpu(x) ___bpf_swab32(x) +#endif + +#define VERIFY_USE_SECONDARY_KEYRING (1UL) + +/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ +#define MODULE_SIG_STRING "~Module signature appended~\n" + +typedef __u8 u8; +typedef __u16 u16; +typedef __u32 u32; +typedef __u64 u64; + +enum pkey_id_type { + PKEY_ID_PGP, /* OpenPGP generated key ID */ + PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ + PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ +}; + +/* + * Module signature information block. + * + * The constituents of the signature section are, in order: + * + * - Signer's name + * - Key identifier + * - Signature data + * - Information block + */ +struct module_signature { + u8 algo; /* Public-key crypto algorithm [0] */ + u8 hash; /* Digest algorithm [0] */ + u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ + u8 signer_len; /* Length of signer's name [0] */ + u8 key_id_len; /* Length of key identifier [0] */ + u8 __pad[3]; + __be32 sig_len; /* Length of signature data */ +}; + +u32 monitored_pid; +u32 keyring_id; + +struct data { + u8 payload[MAX_DATA_SIZE]; +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, struct data); +} data_input SEC(".maps"); + +char _license[] SEC("license") = "GPL"; + +static int mod_check_sig(const struct module_signature *ms, size_t file_len) +{ + if (!ms) + return -ENOENT; + + if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms)) + return -EBADMSG; + + if (ms->id_type != PKEY_ID_PKCS7) + return -ENOPKG; + + if (ms->algo != 0 || + ms->hash != 0 || + ms->signer_len != 0 || + ms->key_id_len != 0 || + ms->__pad[0] != 0 || + ms->__pad[1] != 0 || + ms->__pad[2] != 0) + return -EBADMSG; + + return 0; +} + +SEC("lsm.s/bpf") +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size) +{ + const size_t marker_len = sizeof(MODULE_SIG_STRING) - 1; + char marker[sizeof(MODULE_SIG_STRING) - 1]; + struct module_signature ms; + struct data *data_ptr; + u32 modlen; + u32 sig_len; + u64 value; + u8 *mod; + u32 pid; + int ret, zero = 0; + + pid = bpf_get_current_pid_tgid() >> 32; + if (pid != monitored_pid) + return 0; + + data_ptr = bpf_map_lookup_elem(&data_input, &zero); + if (!data_ptr) + return 0; + + bpf_probe_read(&value, sizeof(value), &attr->value); + + bpf_copy_from_user(data_ptr, sizeof(struct data), + (void *)(unsigned long)value); + + modlen = be32_to_cpu(*(u32 *)data_ptr->payload); + mod = data_ptr->payload + sizeof(u32); + + if (modlen > sizeof(struct data) - sizeof(u32)) + return -EINVAL; + + if (modlen <= marker_len) + return -ENOENT; + + modlen &= sizeof(struct data) - 1; + bpf_probe_read(marker, marker_len, (char *)mod + modlen - marker_len); + + if (bpf_strncmp(marker, marker_len, MODULE_SIG_STRING)) + return -ENOENT; + + modlen -= marker_len; + + if (modlen <= sizeof(ms)) + return -EBADMSG; + + bpf_probe_read(&ms, sizeof(ms), (char *)mod + (modlen - sizeof(ms))); + + ret = mod_check_sig(&ms, modlen); + if (ret) + return ret; + + sig_len = be32_to_cpu(ms.sig_len); + modlen -= sig_len + sizeof(ms); + + modlen &= 0x3ff; + sig_len &= 0x3ff; + + return bpf_verify_signature(mod, modlen, mod + modlen, sig_len, + keyring_id + (PKEY_ID_PKCS7 << 16)); +} diff --git a/tools/testing/selftests/bpf/verify_sig_setup.sh b/tools/testing/selftests/bpf/verify_sig_setup.sh new file mode 100755 index 000000000000..48cb55abc4a4 --- /dev/null +++ b/tools/testing/selftests/bpf/verify_sig_setup.sh @@ -0,0 +1,100 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +set -e +set -u +set -o pipefail + +VERBOSE="${SELFTESTS_VERBOSE:=0}" +LOG_FILE="$(mktemp /tmp/verify_sig_setup.XXXX.log)" + +x509_genkey_content="\ +[ req ] +default_bits = 2048 +distinguished_name = req_distinguished_name +prompt = no +string_mask = utf8only +x509_extensions = myexts + +[ req_distinguished_name ] +CN = eBPF Signature Verification Testing Key + +[ myexts ] +basicConstraints=critical,CA:FALSE +keyUsage=digitalSignature +subjectKeyIdentifier=hash +authorityKeyIdentifier=keyid +" + +usage() +{ + echo "Usage: $0 " + exit 1 +} + +setup() +{ + local tmp_dir="$1" + + echo "${x509_genkey_content}" > ${tmp_dir}/x509.genkey + + openssl req -new -nodes -utf8 -sha256 -days 36500 \ + -batch -x509 -config ${tmp_dir}/x509.genkey \ + -outform PEM -out ${tmp_dir}/signing_key.pem \ + -keyout ${tmp_dir}/signing_key.pem 2>&1 + + openssl x509 -in ${tmp_dir}/signing_key.pem -out \ + ${tmp_dir}/signing_key.der -outform der + + cat ${tmp_dir}/signing_key.der | keyctl padd asymmetric ebpf_testing_key @s +} + +cleanup() { + local tmp_dir="$1" + + keyctl unlink $(keyctl search @s asymmetric ebpf_testing_key) @s + rm -rf ${tmp_dir} +} + +catch() +{ + local exit_code="$1" + local log_file="$2" + + if [[ "${exit_code}" -ne 0 ]]; then + cat "${log_file}" >&3 + fi + + rm -f "${log_file}" + exit ${exit_code} +} + +main() +{ + [[ $# -ne 2 ]] && usage + + local action="$1" + local tmp_dir="$2" + + [[ ! -d "${tmp_dir}" ]] && echo "Directory ${tmp_dir} doesn't exist" && exit 1 + + if [[ "${action}" == "setup" ]]; then + setup "${tmp_dir}" + elif [[ "${action}" == "cleanup" ]]; then + cleanup "${tmp_dir}" + else + echo "Unknown action: ${action}" + exit 1 + fi +} + +trap 'catch "$?" "${LOG_FILE}"' EXIT + +if [[ "${VERBOSE}" -eq 0 ]]; then + # Save the stderr to 3 so that we can output back to + # it incase of an error. + exec 3>&2 1>"${LOG_FILE}" 2>&1 +fi + +main "$@" +rm -f "${LOG_FILE}"