Two modes of operation being added: Add two modes of operation: * For prog load, allow signing a program immediately before loading. This is essential for command-line testing and administration. bpftool prog load -S -k -i fentry_test.bpf.o * For gen skeleton, embed a pre-generated signature into the C skeleton file. This supports the use of signed programs in compiled applications. bpftool gen skeleton -S -k -i fentry_test.bpf.o Generation of the loader program and its metadata map is implemented in libbpf (bpf_obj__gen_loader). bpftool generates a skeleton that loads the program and automates the required steps: freezing the map, creating an exclusive map, loading, and running. Users can use standard libbpf APIs directly or integrate loader program generation into their own toolchains. Signed-off-by: KP Singh --- .../bpf/bpftool/Documentation/bpftool-gen.rst | 12 + .../bpftool/Documentation/bpftool-prog.rst | 12 + tools/bpf/bpftool/Makefile | 6 +- tools/bpf/bpftool/cgroup.c | 5 +- tools/bpf/bpftool/gen.c | 58 ++++- tools/bpf/bpftool/main.c | 21 +- tools/bpf/bpftool/main.h | 11 + tools/bpf/bpftool/prog.c | 25 +++ tools/bpf/bpftool/sign.c | 210 ++++++++++++++++++ 9 files changed, 352 insertions(+), 8 deletions(-) create mode 100644 tools/bpf/bpftool/sign.c diff --git a/tools/bpf/bpftool/Documentation/bpftool-gen.rst b/tools/bpf/bpftool/Documentation/bpftool-gen.rst index ca860fd97d8d..2997313003b1 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-gen.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-gen.rst @@ -185,6 +185,18 @@ OPTIONS For skeletons, generate a "light" skeleton (also known as "loader" skeleton). A light skeleton contains a loader eBPF program. It does not use the majority of the libbpf infrastructure, and does not need libelf. +-S, --sign + For skeletons, generate a signed skeleton. This option must be used with + **-k** and **-i**. Using this flag implicitly enables **--use-loader**. + See the "Signed Skeletons" section in the description of the + **gen skeleton** command for more details. + +-k + Path to the private key file in PEM format, required for signing. + +-i + Path to the X.509 certificate file in PEM or DER format, required for + signing. EXAMPLES ======== diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst index f69fd92df8d8..dc2ca196137e 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst @@ -248,6 +248,18 @@ OPTIONS creating the maps, and loading the programs (see **bpftool prog tracelog** as a way to dump those messages). +-S, --sign + Enable signing of the BPF program before loading. This option must be + used with **-k** and **-i**. Using this flag implicitly enables + **--use-loader**. + +-k + Path to the private key file in PEM format, required when signing. + +-i + Path to the X.509 certificate file in PEM or DER format, required when + signing. + EXAMPLES ======== **# bpftool prog show** diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 9e9a5f006cd2..586d1b2595d1 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -130,8 +130,8 @@ include $(FEATURES_DUMP) endif endif -LIBS = $(LIBBPF) -lelf -lz -LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz +LIBS = $(LIBBPF) -lelf -lz -lcrypto +LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz -lcrypto ifeq ($(feature-libelf-zstd),1) LIBS += -lzstd @@ -194,7 +194,7 @@ endif BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool -BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o) +BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o sign.o) $(BOOTSTRAP_OBJS): $(LIBBPF_BOOTSTRAP) OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index 944ebe21a216..90c9aa297806 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -1,7 +1,10 @@ // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) // Copyright (C) 2017 Facebook // Author: Roman Gushchin - +#undef GCC_VERSION +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif #define _XOPEN_SOURCE 500 #include #include diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 67a60114368f..ab6fc86598ad 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -688,10 +688,17 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name) static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard) { DECLARE_LIBBPF_OPTS(gen_loader_opts, opts); + struct bpf_load_and_run_opts sopts = {}; + char sig_buf[MAX_SIG_SIZE]; + __u8 prog_sha[SHA256_DIGEST_LENGTH]; struct bpf_map *map; + char ident[256]; int err = 0; + if (sign_progs) + opts.gen_hash = true; + err = bpf_object__gen_loader(obj, &opts); if (err) return err; @@ -701,6 +708,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h p_err("failed to load object file"); goto out; } + /* If there was no error during load then gen_loader_opts * are populated with the loader program. */ @@ -780,8 +788,51 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h print_hex(opts.insns, opts.insns_sz); codegen("\ \n\ - \"; \n\ - \n\ + \";\n"); + + if (sign_progs) { + sopts.insns = opts.insns; + sopts.insns_sz = opts.insns_sz; + sopts.excl_prog_hash = prog_sha; + sopts.excl_prog_hash_sz = sizeof(prog_sha); + sopts.signature = sig_buf; + sopts.signature_sz = MAX_SIG_SIZE; + sopts.keyring_id = KEY_SPEC_SESSION_KEYRING; + + err = bpftool_prog_sign(&sopts); + if (err < 0) + return err; + + codegen("\ + \n\ + static const char opts_sig[] __attribute__((__aligned__(8))) = \"\\\n\ + "); + print_hex((const void *)sig_buf, sopts.signature_sz); + codegen("\ + \n\ + \";\n"); + + codegen("\ + \n\ + static const char opts_excl_hash[] __attribute__((__aligned__(8))) = \"\\\n\ + "); + print_hex((const void *)prog_sha, sizeof(prog_sha)); + codegen("\ + \n\ + \";\n"); + + codegen("\ + \n\ + opts.signature = (void *)opts_sig; \n\ + opts.signature_sz = sizeof(opts_sig) - 1; \n\ + opts.excl_prog_hash = (void *)opts_excl_hash; \n\ + opts.excl_prog_hash_sz = sizeof(opts_excl_hash) - 1; \n\ + opts.keyring_id = KEY_SPEC_SESSION_KEYRING; \n\ + "); + } + + codegen("\ + \n\ opts.ctx = (struct bpf_loader_ctx *)skel; \n\ opts.data_sz = sizeof(opts_data) - 1; \n\ opts.data = (void *)opts_data; \n\ @@ -1240,7 +1291,7 @@ static int do_skeleton(int argc, char **argv) err = -errno; libbpf_strerror(err, err_buf, sizeof(err_buf)); p_err("failed to open BPF object file: %s", err_buf); - goto out; + goto out_obj; } bpf_object__for_each_map(map, obj) { @@ -1552,6 +1603,7 @@ static int do_skeleton(int argc, char **argv) err = 0; out: bpf_object__close(obj); +out_obj: if (obj_data) munmap(obj_data, mmap_sz); close(fd); diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c index 2b7f2bd3a7db..fc25bb390ec7 100644 --- a/tools/bpf/bpftool/main.c +++ b/tools/bpf/bpftool/main.c @@ -33,6 +33,9 @@ bool relaxed_maps; bool use_loader; struct btf *base_btf; struct hashmap *refs_table; +bool sign_progs; +const char *private_key_path; +const char *cert_path; static void __noreturn clean_and_exit(int i) { @@ -447,6 +450,7 @@ int main(int argc, char **argv) { "nomount", no_argument, NULL, 'n' }, { "debug", no_argument, NULL, 'd' }, { "use-loader", no_argument, NULL, 'L' }, + { "sign", required_argument, NULL, 'S'}, { "base-btf", required_argument, NULL, 'B' }, { 0 } }; @@ -473,7 +477,7 @@ int main(int argc, char **argv) bin_name = "bpftool"; opterr = 0; - while ((opt = getopt_long(argc, argv, "VhpjfLmndB:l", + while ((opt = getopt_long(argc, argv, "VhpjfLmndSi:k:B:l", options, NULL)) >= 0) { switch (opt) { case 'V': @@ -519,6 +523,16 @@ int main(int argc, char **argv) case 'L': use_loader = true; break; + case 'S': + sign_progs = true; + use_loader = true; + break; + case 'k': + private_key_path = optarg; + break; + case 'i': + cert_path = optarg; + break; default: p_err("unrecognized option '%s'", argv[optind - 1]); if (json_output) @@ -533,6 +547,11 @@ int main(int argc, char **argv) if (argc < 0) usage(); + if (sign_progs && (private_key_path == NULL || cert_path == NULL)) { + p_err("-i and -k key must be supplied with -S for signing"); + return -EINVAL; + } + if (version_requested) ret = do_version(argc, argv); else diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h index 6db704fda5c0..f921af3cda87 100644 --- a/tools/bpf/bpftool/main.h +++ b/tools/bpf/bpftool/main.h @@ -6,9 +6,14 @@ /* BFD and kernel.h both define GCC_VERSION, differently */ #undef GCC_VERSION +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif #include #include +#include #include +#include #include #include #include @@ -52,6 +57,7 @@ static inline void *u64_to_ptr(__u64 ptr) }) #define ERR_MAX_LEN 1024 +#define MAX_SIG_SIZE 4096 #define BPF_TAG_FMT "%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx" @@ -85,6 +91,9 @@ extern bool relaxed_maps; extern bool use_loader; extern struct btf *base_btf; extern struct hashmap *refs_table; +extern bool sign_progs; +extern const char *private_key_path; +extern const char *cert_path; void __printf(1, 2) p_err(const char *fmt, ...); void __printf(1, 2) p_info(const char *fmt, ...); @@ -274,4 +283,6 @@ int pathname_concat(char *buf, int buf_sz, const char *path, /* print netfilter bpf_link info */ void netfilter_dump_plain(const struct bpf_link_info *info); void netfilter_dump_json(const struct bpf_link_info *info, json_writer_t *wtr); +int bpftool_prog_sign(struct bpf_load_and_run_opts *opts); +__u32 register_session_key(const char *key_der_path); #endif diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index 9722d841abc0..0b67612a2ce8 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -1930,6 +1931,8 @@ static int try_loader(struct gen_loader_opts *gen) { struct bpf_load_and_run_opts opts = {}; struct bpf_loader_ctx *ctx; + char sig_buf[MAX_SIG_SIZE]; + __u8 prog_sha[SHA256_DIGEST_LENGTH]; int ctx_sz = sizeof(*ctx) + 64 * max(sizeof(struct bpf_map_desc), sizeof(struct bpf_prog_desc)); int log_buf_sz = (1u << 24) - 1; @@ -1953,6 +1956,24 @@ static int try_loader(struct gen_loader_opts *gen) opts.insns = gen->insns; opts.insns_sz = gen->insns_sz; fds_before = count_open_fds(); + + if (sign_progs) { + opts.excl_prog_hash = prog_sha; + opts.excl_prog_hash_sz = sizeof(prog_sha); + opts.signature = sig_buf; + opts.signature_sz = MAX_SIG_SIZE; + opts.keyring_id = KEY_SPEC_SESSION_KEYRING; + + err = bpftool_prog_sign(&opts); + if (err < 0) + return err; + + err = register_session_key(cert_path); + if (err < 0) { + p_err("failed to add session key"); + goto out; + } + } err = bpf_load_and_run(&opts); fd_delta = count_open_fds() - fds_before; if (err < 0 || verifier_logs) { @@ -1961,6 +1982,7 @@ static int try_loader(struct gen_loader_opts *gen) fprintf(stderr, "loader prog leaked %d FDs\n", fd_delta); } +out: free(log_buf); return err; } @@ -1988,6 +2010,9 @@ static int do_loader(int argc, char **argv) goto err_close_obj; } + if (sign_progs) + gen.gen_hash = true; + err = bpf_object__gen_loader(obj, &gen); if (err) goto err_close_obj; diff --git a/tools/bpf/bpftool/sign.c b/tools/bpf/bpftool/sign.c new file mode 100644 index 000000000000..f0b5dd10a46b --- /dev/null +++ b/tools/bpf/bpftool/sign.c @@ -0,0 +1,210 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2022 Google LLC. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "main.h" + +#define OPEN_SSL_ERR_BUF_LEN 256 + +static void display_openssl_errors(int l) +{ + char buf[OPEN_SSL_ERR_BUF_LEN]; + const char *file; + const char *data; + unsigned long e; + int flags; + int line; + + while ((e = ERR_get_error_all(&file, &line, NULL, &data, &flags))) { + ERR_error_string_n(e, buf, sizeof(buf)); + if (data && (flags & ERR_TXT_STRING)) { + p_err("OpenSSL %s: %s:%d: %s\n", buf, file, line, data); + } else { + p_err("OpenSSL %s: %s:%d\n", buf, file, line); + } + } +} + +#define DISPLAY_OSSL_ERR(cond) \ + do { \ + bool __cond = (cond); \ + if (__cond && ERR_peek_error()) \ + display_openssl_errors(__LINE__);\ + } while (0) + +static EVP_PKEY *read_private_key(const char *pkey_path) +{ + EVP_PKEY *private_key = NULL; + BIO *b; + + b = BIO_new_file(pkey_path, "rb"); + private_key = PEM_read_bio_PrivateKey(b, NULL, NULL, NULL); + BIO_free(b); + DISPLAY_OSSL_ERR(!private_key); + return private_key; +} + +static X509 *read_x509(const char *x509_name) +{ + unsigned char buf[2]; + X509 *x509 = NULL; + BIO *b; + int n; + + b = BIO_new_file(x509_name, "rb"); + if (!b) + goto cleanup; + + /* Look at the first two bytes of the file to determine the encoding */ + n = BIO_read(b, buf, 2); + if (n != 2) + goto cleanup; + + if (BIO_reset(b) != 0) + goto cleanup; + + if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84) + /* Assume raw DER encoded X.509 */ + x509 = d2i_X509_bio(b, NULL); + else + /* Assume PEM encoded X.509 */ + x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); + +cleanup: + BIO_free(b); + DISPLAY_OSSL_ERR(!x509); + return x509; +} + +__u32 register_session_key(const char *key_der_path) +{ + unsigned char *der_buf = NULL; + X509 *x509 = NULL; + int key_id = -1; + int der_len; + + if (!key_der_path) + return key_id; + x509 = read_x509(key_der_path); + if (!x509) + goto cleanup; + der_len = i2d_X509(x509, &der_buf); + if (der_len < 0) + goto cleanup; + key_id = syscall(__NR_add_key, "asymmetric", key_der_path, der_buf, + (size_t)der_len, KEY_SPEC_SESSION_KEYRING); +cleanup: + X509_free(x509); + OPENSSL_free(der_buf); + DISPLAY_OSSL_ERR(key_id == -1); + return key_id; +} + +int bpftool_prog_sign(struct bpf_load_and_run_opts *opts) +{ + BIO *bd_in = NULL, *bd_out = NULL; + EVP_PKEY *private_key = NULL; + CMS_ContentInfo *cms = NULL; + long actual_sig_len = 0; + X509 *x509 = NULL; + int err = 0; + + bd_in = BIO_new_mem_buf(opts->insns, opts->insns_sz); + if (!bd_in) { + err = -ENOMEM; + goto cleanup; + } + + private_key = read_private_key(private_key_path); + if (!private_key) { + err = -EINVAL; + goto cleanup; + } + + x509 = read_x509(cert_path); + if (!x509) { + err = -EINVAL; + goto cleanup; + } + + cms = CMS_sign(NULL, NULL, NULL, NULL, + CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED | + CMS_STREAM); + if (!cms) { + err = -EINVAL; + goto cleanup; + } + + if (!CMS_add1_signer(cms, x509, private_key, EVP_sha256(), + CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP | + CMS_USE_KEYID | CMS_NOATTR)) { + err = -EINVAL; + goto cleanup; + } + + if (CMS_final(cms, bd_in, NULL, CMS_NOCERTS | CMS_BINARY) != 1) { + err = -EIO; + goto cleanup; + } + + EVP_Digest(opts->insns, opts->insns_sz, opts->excl_prog_hash, + &opts->excl_prog_hash_sz, EVP_sha256(), NULL); + + bd_out = BIO_new(BIO_s_mem()); + if (!bd_out) { + err = -ENOMEM; + goto cleanup; + } + + if (!i2d_CMS_bio_stream(bd_out, cms, NULL, 0)) { + err = -EIO; + goto cleanup; + } + + actual_sig_len = BIO_get_mem_data(bd_out, NULL); + if (actual_sig_len <= 0) { + err = -EIO; + goto cleanup; + } + + if ((size_t)actual_sig_len > opts->signature_sz) { + err = -ENOSPC; + goto cleanup; + } + + if (BIO_read(bd_out, opts->signature, actual_sig_len) != actual_sig_len) { + err = -EIO; + goto cleanup; + } + + opts->signature_sz = actual_sig_len; +cleanup: + BIO_free(bd_out); + CMS_ContentInfo_free(cms); + X509_free(x509); + EVP_PKEY_free(private_key); + BIO_free(bd_in); + DISPLAY_OSSL_ERR(err < 0); + return err; +} -- 2.43.0