From patchwork Wed Jan 24 02:21:08 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13528383 X-Patchwork-Delegate: paul@paul-moore.com Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7AA28523F; Wed, 24 Jan 2024 02:22:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706062932; cv=none; b=Chrxkl9UyqpNljBagIe2HBavKo+lSZ8G669Z3Mv5HqkduZmxf/G3nEdvzb9EV1XN6DncJg+jEc9siRuYkB0463nYflXHuL53Wc1AiiRBg4MoFRtLNCCBuuZJUYM7vfrEcZ72b0oD77LWO7qdIKoDp+ajgQoii537P0fFyQbJQVs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706062932; c=relaxed/simple; bh=Xtw+UTgOwWFnQXcFlbGdeQXEJ5jODRqkakY4v5A1ZFc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ineEV9qEBh2m0cZ9IZKygzk67xiGDrfI2Op4wt0KzFYMesdqqFWJ1n+PXzDn1xdnzbG4QKaAc6sTSNTjrK0mg/D9RTurCI13cWJT3cIVNcAlZwV/AIS/F35xZw0FbsxxpsKofJHcskE3NrD8MPNCuhhW5PXkfrg6JBH3blWWgXc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=agI5NkaZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="agI5NkaZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 157F5C433C7; Wed, 24 Jan 2024 02:22:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706062932; bh=Xtw+UTgOwWFnQXcFlbGdeQXEJ5jODRqkakY4v5A1ZFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=agI5NkaZfR6nOAHaWEaIWMbPLUZBJUDsDK/ws92KSOmcdT1At6jbU4he3Vnu5tG5E rHXVvm+S2tbzWIIgWwTNOMgRahuLBfkmth/8esNxZXrE4Fdavl4UFBePBEwXSZgrGV 04m+JsI6HJoNT1Y2vinxDXP0QXqDA1+6ZtroiW0mz56P+oEtjQxAuU43gNu1AmoUGv +Zbw/KvjnbE7VD7+JKZMVtGGaaLG7mPhQB+BGTaHyLLtsw7eTN1f8KiCPgNatIllvw aJIuLJKk7QknK+k2nD/efOfB/2bNjJCtwlQbjHfZSu2a1wkUh7fjEPOxbl/WY3SiI/ un/uc6DjXZJxw== From: Andrii Nakryiko To: bpf@vger.kernel.org, netdev@vger.kernel.org, paul@paul-moore.com, brauner@kernel.org Cc: torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v2 bpf-next 11/30] bpf,lsm: add BPF token LSM hooks Date: Tue, 23 Jan 2024 18:21:08 -0800 Message-Id: <20240124022127.2379740-12-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240124022127.2379740-1-andrii@kernel.org> References: <20240124022127.2379740-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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. Also add security_bpf_token_allow_cmd() and security_bpf_token_capable() LSM hooks that allow LSM implementation to control and negate (if necessary) BPF token's delegation of a specific bpf_cmd and capability, respectively. Acked-by: Paul Moore Signed-off-by: Andrii Nakryiko --- include/linux/bpf.h | 3 ++ include/linux/lsm_hook_defs.h | 5 +++ include/linux/security.h | 25 +++++++++++++++ kernel/bpf/bpf_lsm.c | 4 +++ kernel/bpf/token.c | 12 ++++++- security/security.c | 60 +++++++++++++++++++++++++++++++++++ 6 files changed, 108 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1b556c74f43f..2a184a847381 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1634,6 +1634,9 @@ 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 1be4d3ca6efb..cd6fbc7af3f8 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -410,6 +410,11 @@ 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) +LSM_HOOK(int, 0, bpf_token_cmd, const struct bpf_token *token, enum bpf_cmd cmd) +LSM_HOOK(int, 0, bpf_token_capable, const struct bpf_token *token, int cap) #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 83fcdc974116..15804af54f37 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -32,6 +32,7 @@ #include #include #include +#include #include struct linux_binprm; @@ -2075,6 +2076,11 @@ 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); +extern int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd); +extern int security_bpf_token_capable(const struct bpf_token *token, int cap); #else static inline int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) @@ -2109,6 +2115,25 @@ 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) +{ } + +static inline int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd) +{ + return 0; +} + +static inline int security_bpf_token_capable(const struct bpf_token *token, int cap) +{ + return 0; +} #endif /* CONFIG_SECURITY */ #endif /* CONFIG_BPF_SYSCALL */ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 76976908b302..63b4dc495125 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -265,6 +265,10 @@ 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_bpf_token_cmd) +BTF_ID(func, bpf_lsm_bpf_token_capable) 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 c13c73788d8c..64c568f47f69 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -7,6 +7,7 @@ #include #include #include +#include static bool bpf_ns_capable(struct user_namespace *ns, int cap) { @@ -21,6 +22,8 @@ bool bpf_token_capable(const struct bpf_token *token, int cap) userns = token ? token->userns : &init_user_ns; if (!bpf_ns_capable(userns, cap)) return false; + if (token && security_bpf_token_capable(token, cap) < 0) + return false; return true; } @@ -31,6 +34,7 @@ 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); kfree(token); } @@ -193,6 +197,10 @@ 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; @@ -237,7 +245,9 @@ bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd) { if (!token) return false; - return token->allowed_cmds & (1ULL << cmd); + if (!(token->allowed_cmds & (1ULL << cmd))) + return false; + return security_bpf_token_cmd(token, cmd) == 0; } bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type) diff --git a/security/security.c b/security/security.c index 26fcab35b6cd..73e009e3d937 100644 --- a/security/security.c +++ b/security/security.c @@ -5444,6 +5444,55 @@ 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_token_cmd() - Check if BPF token is allowed to delegate + * requested BPF syscall command + * @token: BPF token object + * @cmd: BPF syscall command requested to be delegated by BPF token + * + * Do a check when the kernel decides whether provided BPF token should allow + * delegation of requested BPF syscall command. + * + * Return: Returns 0 on success, error on failure. + */ +int security_bpf_token_cmd(const struct bpf_token *token, enum bpf_cmd cmd) +{ + return call_int_hook(bpf_token_cmd, 0, token, cmd); +} + +/** + * security_bpf_token_capable() - Check if BPF token is allowed to delegate + * requested BPF-related capability + * @token: BPF token object + * @cap: capabilities requested to be delegated by BPF token + * + * Do a check when the kernel decides whether provided BPF token should allow + * delegation of requested BPF-related capabilities. + * + * Return: Returns 0 on success, error on failure. + */ +int security_bpf_token_capable(const struct bpf_token *token, int cap) +{ + return call_int_hook(bpf_token_capable, 0, token, cap); +} + /** * security_bpf_map_free() - Free a bpf map's LSM blob * @map: bpf map @@ -5465,6 +5514,17 @@ 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 */ /**