From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5415C350D79; Tue, 9 Sep 2025 16:24:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757435045; cv=none; b=S9I64rFZvUOd3KaGs37slYxhrD0n4kBNU6pMTsV/NOVa9bchg2BiZggFUATfzuD0tUAUc0OZpr5FhATNj2BgF7JR+13Xfm7R71QJnlHDm3LOKpn6IkZSK20N2eNlvXIS7rggTzJWWqbBKyrKwosJx475sUYD5rcM7KtQSEw6V6I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757435045; c=relaxed/simple; bh=I32WngEpEkzMhJkylrVhFdmVlSiCTuqpVVsRlHBU8v4=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OOZiOD2D6ezap3FfpgInVzJCfVwLDCqWBDLUj4w62GnhPjLSLzLUI5WG4hUIKmQZ0zzksAQ+8wabs6JAXOOA9PiTTLaN5IQuGUL9VQSDOExZDXbpbGOCwRvL1rjWjUCf97WYnvfJZfAQ6kQbrBIBwXhTZvRvBb4ew8D2Jla1UkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=d1B5gu2I; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="d1B5gu2I" Received: from narnia.corp.microsoft.com (unknown [13.88.17.9]) by linux.microsoft.com (Postfix) with ESMTPSA id DCE2B211AA25; Tue, 9 Sep 2025 09:23:56 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com DCE2B211AA25 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1757435037; bh=D4yo43ZMZEZO65LVJTXGntngPaYaKdzB0OWLprFptuE=; h=From:To:Subject:Date:In-Reply-To:References:From; b=d1B5gu2I75OIFfPD78ouwb+u+jc/4ouebRThY7a2iuKF6Xl0savLUVlnO9YnovWxx OpW3Wa1BkaEMiHLDqK4qLIvhWq71rB6VikrPdZCWKEznaysJqqNUTxiqU6wE5cIu5/ 41l5c5H9Si1h8x5oaC2KJtq4K3EVP5tGRkqbH5ys= From: Blaise Boscaccy To: bpf@vger.kernel.org, linux-security-module@vger.kernel.org, kpsingh@kernel.org, bboscaccy@linux.microsoft.com, paul@paul-moore.com, kys@microsoft.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, James.Bottomley@hansenpartnership.com, wufan@linux.microsoft.com Subject: [RFC 2/2] libbpf: Add hash chain signing support to light skeletons. Date: Tue, 9 Sep 2025 09:20:59 -0700 Message-ID: <20250909162345.569889-3-bboscaccy@linux.microsoft.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250909162345.569889-1-bboscaccy@linux.microsoft.com> References: <20250909162345.569889-1-bboscaccy@linux.microsoft.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This patch introduces a hash chain signing support for light-skeleton assets. A new flag '-M' is added which constructs a hash chain with the loader program and the target payload. Signed-off-by: Blaise Boscaccy --- tools/bpf/bpftool/gen.c | 25 +++++++++++++++++++++++++ tools/bpf/bpftool/main.c | 8 +++++++- tools/bpf/bpftool/main.h | 1 + tools/bpf/bpftool/sign.c | 17 ++++++++++++++--- tools/lib/bpf/libbpf.h | 3 ++- tools/lib/bpf/skel_internal.h | 6 +++++- 6 files changed, 54 insertions(+), 6 deletions(-) diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index ab6fc86598ad3..e660fbc701c5d 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -699,6 +699,9 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h if (sign_progs) opts.gen_hash = true; + if (sign_maps) + opts.sign_maps = true; + err = bpf_object__gen_loader(obj, &opts); if (err) return err; @@ -793,6 +796,8 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h if (sign_progs) { sopts.insns = opts.insns; sopts.insns_sz = opts.insns_sz; + sopts.data = opts.data; + sopts.data_sz = opts.data_sz; sopts.excl_prog_hash = prog_sha; sopts.excl_prog_hash_sz = sizeof(prog_sha); sopts.signature = sig_buf; @@ -821,6 +826,13 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h \n\ \";\n"); + if (sign_maps) { + codegen("\ + \n\ + static const int opts_signature_maps[1] __attribute__((__aligned__(8))) = {0}; \n\ + "); + } + codegen("\ \n\ opts.signature = (void *)opts_sig; \n\ @@ -829,6 +841,19 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h opts.excl_prog_hash_sz = sizeof(opts_excl_hash) - 1; \n\ opts.keyring_id = KEY_SPEC_SESSION_KEYRING; \n\ "); + if (sign_maps) { + codegen("\ + \n\ + opts.signature_maps = (void *)opts_signature_maps; \n\ + opts.signature_maps_sz = 1; \n\ + "); + } else { + codegen("\ + \n\ + opts.signature_maps = (void *)NULL; \n\ + opts.signature_maps_sz = 0; \n\ + "); + } } codegen("\ diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c index fc25bb390ec71..287e8205494cb 100644 --- a/tools/bpf/bpftool/main.c +++ b/tools/bpf/bpftool/main.c @@ -34,6 +34,7 @@ bool use_loader; struct btf *base_btf; struct hashmap *refs_table; bool sign_progs; +bool sign_maps; const char *private_key_path; const char *cert_path; @@ -477,7 +478,7 @@ int main(int argc, char **argv) bin_name = "bpftool"; opterr = 0; - while ((opt = getopt_long(argc, argv, "VhpjfLmndSi:k:B:l", + while ((opt = getopt_long(argc, argv, "VhpjfLmndSMi:k:B:l", options, NULL)) >= 0) { switch (opt) { case 'V': @@ -527,6 +528,11 @@ int main(int argc, char **argv) sign_progs = true; use_loader = true; break; + case 'M': + sign_maps = true; + sign_progs = true; + use_loader = true; + break; case 'k': private_key_path = optarg; break; diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h index f921af3cda87f..805c3d87a1330 100644 --- a/tools/bpf/bpftool/main.h +++ b/tools/bpf/bpftool/main.h @@ -92,6 +92,7 @@ extern bool use_loader; extern struct btf *base_btf; extern struct hashmap *refs_table; extern bool sign_progs; +extern bool sign_maps; extern const char *private_key_path; extern const char *cert_path; diff --git a/tools/bpf/bpftool/sign.c b/tools/bpf/bpftool/sign.c index f0b5dd10a46b2..d5514b7d2b82d 100644 --- a/tools/bpf/bpftool/sign.c +++ b/tools/bpf/bpftool/sign.c @@ -22,6 +22,7 @@ #include #include +#include #include "main.h" @@ -129,8 +130,18 @@ int bpftool_prog_sign(struct bpf_load_and_run_opts *opts) long actual_sig_len = 0; X509 *x509 = NULL; int err = 0; - - bd_in = BIO_new_mem_buf(opts->insns, opts->insns_sz); + unsigned char hash[SHA256_DIGEST_LENGTH * 2]; + unsigned char term[SHA256_DIGEST_LENGTH]; + + if (sign_maps) { + libbpf_sha256(opts->insns, opts->insns_sz, hash, SHA256_DIGEST_LENGTH); + libbpf_sha256(opts->data, opts->data_sz, hash + SHA256_DIGEST_LENGTH, + SHA256_DIGEST_LENGTH); + libbpf_sha256(hash, sizeof(hash), term, sizeof(term)); + bd_in = BIO_new_mem_buf(term, sizeof(term)); + } else { + bd_in = BIO_new_mem_buf(opts->insns, opts->insns_sz); + } if (!bd_in) { err = -ENOMEM; goto cleanup; @@ -171,7 +182,7 @@ int bpftool_prog_sign(struct bpf_load_and_run_opts *opts) 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()); + bd_out = BIO_new(BIO_s_mem()); if (!bd_out) { err = -ENOMEM; goto cleanup; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 7cad8470d9ebe..aad0288cd05e3 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -1827,9 +1827,10 @@ struct gen_loader_opts { __u32 data_sz; __u32 insns_sz; bool gen_hash; + bool sign_maps; }; -#define gen_loader_opts__last_field gen_hash +#define gen_loader_opts__last_field sign_maps LIBBPF_API int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts); diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h index 5b6d1b09dc8a6..c25a4f1308e44 100644 --- a/tools/lib/bpf/skel_internal.h +++ b/tools/lib/bpf/skel_internal.h @@ -74,6 +74,8 @@ struct bpf_load_and_run_opts { __u32 keyring_id; void * excl_prog_hash; __u32 excl_prog_hash_sz; + const int *signature_maps; + __u32 signature_maps_sz; }; long kern_sys_bpf(__u32 cmd, void *attr, __u32 attr_size); @@ -351,7 +353,7 @@ static inline int skel_map_freeze(int fd) static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts) { - const size_t prog_load_attr_sz = offsetofend(union bpf_attr, keyring_id); + const size_t prog_load_attr_sz = offsetofend(union bpf_attr, signature_maps_size); const size_t test_run_attr_sz = offsetofend(union bpf_attr, test); int map_fd = -1, prog_fd = -1, key = 0, err; union bpf_attr attr; @@ -394,6 +396,8 @@ static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts) #ifndef __KERNEL__ attr.signature = (long) opts->signature; attr.signature_size = opts->signature_sz; + attr.signature_maps = (long) opts->signature_maps; + attr.signature_maps_size = opts->signature_maps_sz; #else if (opts->signature || opts->signature_sz) pr_warn("signatures are not supported from bpf_preload\n"); -- 2.48.1