From patchwork Thu Oct 12 22:28:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13419906 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44002405FA for ; Thu, 12 Oct 2023 22:32:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01991CF for ; Thu, 12 Oct 2023 15:32:35 -0700 (PDT) Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.19/8.17.1.19) with ESMTP id 39CLuL0s022418 for ; Thu, 12 Oct 2023 15:32:35 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net (PPS) with ESMTPS id 3tpbry9abt-6 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 12 Oct 2023 15:32:35 -0700 Received: from twshared40933.03.prn6.facebook.com (2620:10d:c0a8:1b::30) by mail.thefacebook.com (2620:10d:c0a8:83::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Thu, 12 Oct 2023 15:32:31 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 7A4A139A3A544; Thu, 12 Oct 2023 15:29:25 -0700 (PDT) From: Andrii Nakryiko To: , CC: , , , , , , Subject: [PATCH v7 bpf-next 11/18] bpf,lsm: add bpf_token_create and bpf_token_free LSM hooks Date: Thu, 12 Oct 2023 15:28:03 -0700 Message-ID: <20231012222810.4120312-12-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231012222810.4120312-1-andrii@kernel.org> References: <20231012222810.4120312-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: 0q9-BgVhRTir0HiPe9x153-IViS9gDmo X-Proofpoint-ORIG-GUID: 0q9-BgVhRTir0HiPe9x153-IViS9gDmo X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-10-12_14,2023-10-12_01,2023-05-22_02 X-Spam-Status: No, score=-2.3 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_LOW,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Wire up bpf_token_create and bpf_token_free LSM hooks, which allow to allocate LSM security blob (we add `void *security` field to struct bpf_token for that), but also control who can instantiate BPF token. This follows existing pattern for BPF map and BPF prog. Signed-off-by: Andrii Nakryiko --- include/linux/bpf.h | 3 +++ include/linux/lsm_hook_defs.h | 3 +++ include/linux/security.h | 11 +++++++++++ kernel/bpf/bpf_lsm.c | 2 ++ kernel/bpf/token.c | 6 ++++++ security/security.c | 28 ++++++++++++++++++++++++++++ 6 files changed, 53 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c87af564f464..dfcac60f1857 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1585,6 +1585,9 @@ struct bpf_token { u64 allowed_maps; u64 allowed_progs; u64 allowed_attachs; +#ifdef CONFIG_SECURITY + void *security; +#endif }; struct bpf_struct_ops_value; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 0adfb136521a..d776c9b7b856 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -404,6 +404,9 @@ LSM_HOOK(void, LSM_RET_VOID, bpf_map_free, struct bpf_map *map) LSM_HOOK(int, 0, bpf_prog_load, struct bpf_prog *prog, union bpf_attr *attr, struct bpf_token *token) LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free, struct bpf_prog *prog) +LSM_HOOK(int, 0, bpf_token_create, struct bpf_token *token, union bpf_attr *attr, + struct path *path) +LSM_HOOK(void, LSM_RET_VOID, bpf_token_free, struct bpf_token *token) #endif /* CONFIG_BPF_SYSCALL */ LSM_HOOK(int, 0, locked_down, enum lockdown_reason what) diff --git a/include/linux/security.h b/include/linux/security.h index 59c5fab2c4d6..b9cb1446bb78 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2031,6 +2031,9 @@ extern void security_bpf_map_free(struct bpf_map *map); extern int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, struct bpf_token *token); extern void security_bpf_prog_free(struct bpf_prog *prog); +extern int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, + struct path *path); +extern void security_bpf_token_free(struct bpf_token *token); #else static inline int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) @@ -2065,6 +2068,14 @@ static inline int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr * static inline void security_bpf_prog_free(struct bpf_prog *prog) { } + +static inline int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, + struct path *path) +{ + return 0; +} +static inline void security_bpf_token_free(struct bpf_token *token) +{ } #endif /* CONFIG_SECURITY */ #endif /* CONFIG_BPF_SYSCALL */ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 9e4e615f11eb..2a019528953e 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -265,6 +265,8 @@ BTF_ID(func, bpf_lsm_bpf_map_free) BTF_ID(func, bpf_lsm_bpf_prog) BTF_ID(func, bpf_lsm_bpf_prog_load) BTF_ID(func, bpf_lsm_bpf_prog_free) +BTF_ID(func, bpf_lsm_bpf_token_create) +BTF_ID(func, bpf_lsm_bpf_token_free) BTF_ID(func, bpf_lsm_bprm_check_security) BTF_ID(func, bpf_lsm_bprm_committed_creds) BTF_ID(func, bpf_lsm_bprm_committing_creds) diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c index d4e0cc8075d3..18fd1e04f92d 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -7,6 +7,7 @@ #include #include #include +#include bool bpf_token_capable(const struct bpf_token *token, int cap) { @@ -28,6 +29,7 @@ void bpf_token_inc(struct bpf_token *token) static void bpf_token_free(struct bpf_token *token) { + security_bpf_token_free(token); put_user_ns(token->userns); kvfree(token); } @@ -183,6 +185,10 @@ int bpf_token_create(union bpf_attr *attr) token->allowed_progs = mnt_opts->delegate_progs; token->allowed_attachs = mnt_opts->delegate_attachs; + err = security_bpf_token_create(token, attr, &path); + if (err) + goto out_token; + fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) { err = fd; diff --git a/security/security.c b/security/security.c index 145e8082b9a6..83a2403b7261 100644 --- a/security/security.c +++ b/security/security.c @@ -5201,6 +5201,23 @@ int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, return call_int_hook(bpf_prog_load, 0, prog, attr, token); } +/** + * security_bpf_token_create() - Check if creating of BPF token is allowed + * @token BPF token object + * @attr: BPF syscall attributes used to create BPF token + * @path: path pointing to BPF FS mount point from which BPF token is created + * + * Do a check when the kernel instantiates a new BPF token object from BPF FS + * instance. This is also the point where LSM blob can be allocated for LSMs. + * + * Return: Returns 0 on success, error on failure. + */ +int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, + struct path *path) +{ + return call_int_hook(bpf_token_create, 0, token, attr, path); +} + /** * security_bpf_map_free() - Free a bpf map's LSM blob * @map: bpf map @@ -5222,6 +5239,17 @@ void security_bpf_prog_free(struct bpf_prog *prog) { call_void_hook(bpf_prog_free, prog); } + +/** + * security_bpf_token_free() - Free a BPF token's LSM blob + * @token: BPF token struct + * + * Clean up the security information stored inside BPF token. + */ +void security_bpf_token_free(struct bpf_token *token) +{ + call_void_hook(bpf_token_free, token); +} #endif /* CONFIG_BPF_SYSCALL */ /**