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 8BA2C2DF3C6; Fri, 18 Jul 2025 15:32:03 +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=1752852725; cv=none; b=lSWkQ68yZpQ/nAZy0N9GRHdwZmXKojqb7ZznWF/JUH8LFWTX1FPpvJhfBAmASf74aXrHfhCbtE9AicQ5p3sQd4Sr8J7LRzDD9lS6xb6MidkzbldEf4g5HWtGOVoj3hqVjAlznP5WkJP3KNPu5dT0+f65dDxS462MvSn8EDWdQjo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752852725; c=relaxed/simple; bh=IGmyPMmkdO6fWAdCDA5Nezxa2nOwvHC/muUPYOvutWI=; h=From:To:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=qs7GFd1AXrcBxIDuK8uNBb4Ya4GuQBp5/YNr6OSAl/Sa7qIk8S6Lv1Az+U5/nrXj77mmzi+Efwe3HNWcUzlqz0VUsZoNyvLJoGU8s+/k9sY6Jxc05YxvpErJ21CEcqYZxaAthN74gH0H2wG056M9HSubGOUJ4CfQ4xzAH4GcGIk= 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=WgEVcxbx; 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="WgEVcxbx" Received: from narnia (unknown [40.78.13.147]) by linux.microsoft.com (Postfix) with ESMTPSA id DF3D5211FEB6; Fri, 18 Jul 2025 08:32:01 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com DF3D5211FEB6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1752852723; bh=Hbk9hC+nTouU9H02cQbs8WLgepcQKbWKNlcsWiirmIA=; h=From:To:Subject:In-Reply-To:References:Date:From; b=WgEVcxbxxHRAF6tXAFJ2J/o973BZY/RQ1S47XctjRs30rj5VP2fMgJDZoEyKJquIK +cH76RoEa+3HzV97Pm4k3MSocWMT/0bBNtd/fPMM92w2PIPTCgunlDMtngeGxmUQLB rARhPubU/lEsU2PYj02swi+l2owoCNiCImHIGUkA= From: Blaise Boscaccy To: Casey Schaufler , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Ondrej Mosnacek , John Johansen , Christian =?utf-8?Q?G=C3=B6ttsche?= , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, selinux@vger.kernel.org, bpf@vger.kernel.org, Casey Schaufler Subject: Re: [PATCH] lsm,selinux: Add LSM blob support for BPF objects In-Reply-To: References: <20250715222655.705241-1-bboscaccy@linux.microsoft.com> Date: Fri, 18 Jul 2025 08:32:00 -0700 Message-ID: <87bjph4irz.fsf@microsoft.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Casey Schaufler writes: > On 7/15/2025 3:25 PM, Blaise Boscaccy wrote: >> This patch introduces LSM blob support for BPF maps, programs, and >> tokens to enable LSM stacking and multiplexing of LSM modules that >> govern BPF objects. Additionally, the existing BPF hooks used by >> SELinux have been updated to utilize the new blob infrastructure, >> removing the assumption of exclusive ownership of the security >> pointer. >> >> Signed-off-by: Blaise Boscaccy >> --- >> include/linux/lsm_hooks.h | 3 + >> security/security.c | 120 +++++++++++++++++++++++++++++- >> security/selinux/hooks.c | 56 +++----------- >> security/selinux/include/objsec.h | 17 +++++ >> 4 files changed, 147 insertions(+), 49 deletions(-) >> >> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h >> index 090d1d3e19fed..79ec5a2bdcca7 100644 >> --- a/include/linux/lsm_hooks.h >> +++ b/include/linux/lsm_hooks.h >> @@ -116,6 +116,9 @@ struct lsm_blob_sizes { >> int lbs_xattr_count; /* number of xattr slots in new_xattrs array */ >> int lbs_tun_dev; >> int lbs_bdev; >> + int lbs_bpf_map; >> + int lbs_bpf_prog; >> + int lbs_bpf_token; >> }; >> >> /* >> diff --git a/security/security.c b/security/security.c >> index 596d418185773..8c413b84f33db 100644 >> --- a/security/security.c >> +++ b/security/security.c >> @@ -283,6 +283,9 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed) >> lsm_set_blob_size(&needed->lbs_xattr_count, >> &blob_sizes.lbs_xattr_count); >> lsm_set_blob_size(&needed->lbs_bdev, &blob_sizes.lbs_bdev); >> + lsm_set_blob_size(&needed->lbs_bpf_map, &blob_sizes.lbs_bpf_map); >> + lsm_set_blob_size(&needed->lbs_bpf_prog, &blob_sizes.lbs_bpf_prog); >> + lsm_set_blob_size(&needed->lbs_bpf_token, &blob_sizes.lbs_bpf_token); >> } >> >> /* Prepare LSM for initialization. */ >> @@ -480,6 +483,9 @@ static void __init ordered_lsm_init(void) >> init_debug("tun device blob size = %d\n", blob_sizes.lbs_tun_dev); >> init_debug("xattr slots = %d\n", blob_sizes.lbs_xattr_count); >> init_debug("bdev blob size = %d\n", blob_sizes.lbs_bdev); >> + init_debug("bpf map blob size = %d\n", blob_sizes.lbs_bpf_map); >> + init_debug("bpf prog blob size = %d\n", blob_sizes.lbs_bpf_prog); >> + init_debug("bpf token blob size = %d\n", blob_sizes.lbs_bpf_token); >> >> /* >> * Create any kmem_caches needed for blobs >> @@ -835,6 +841,72 @@ static int lsm_bdev_alloc(struct block_device *bdev) >> return 0; >> } >> >> +/** >> + * lsm_bpf_map_alloc - allocate a composite bpf_map blob >> + * @map: the bpf_map that needs a blob >> + * >> + * Allocate the bpf_map blob for all the modules >> + * >> + * Returns 0, or -ENOMEM if memory can't be allocated. >> + */ >> +static int lsm_bpf_map_alloc(struct bpf_map *map) >> +{ >> + if (blob_sizes.lbs_bpf_map == 0) { >> + map->security = NULL; >> + return 0; >> + } >> + >> + map->security = kzalloc(blob_sizes.lbs_bpf_map, GFP_KERNEL); > > Some of the blobs use kmem_cache_alloc(). You should consider if that > might be right for you. > I looked into that, allocation numbers for this are going to very low in volume compared to something like inodes. I think we are okay for the time being using kzalloc. If this turns out to be a bottleneck, we can totally switch to that. -blaise >> + if (!map->security) >> + return -ENOMEM; >> + >> + return 0; >> +} >> + >> +/** >> + * lsm_bpf_prog_alloc - allocate a composite bpf_prog blob >> + * @prog: the bpf_prog that needs a blob >> + * >> + * Allocate the bpf_prog blob for all the modules >> + * >> + * Returns 0, or -ENOMEM if memory can't be allocated. >> + */ >> +static int lsm_bpf_prog_alloc(struct bpf_prog *prog) >> +{ >> + if (blob_sizes.lbs_bpf_prog == 0) { >> + prog->aux->security = NULL; >> + return 0; >> + } >> + >> + prog->aux->security = kzalloc(blob_sizes.lbs_bpf_prog, GFP_KERNEL); >> + if (!prog->aux->security) >> + return -ENOMEM; >> + >> + return 0; >> +} >> + >> +/** >> + * lsm_bpf_token_alloc - allocate a composite bpf_token blob >> + * @token: the bpf_token that needs a blob >> + * >> + * Allocate the bpf_token blob for all the modules >> + * >> + * Returns 0, or -ENOMEM if memory can't be allocated. >> + */ >> +static int lsm_bpf_token_alloc(struct bpf_token *token) >> +{ >> + if (blob_sizes.lbs_bpf_token == 0) { >> + token->security = NULL; >> + return 0; >> + } >> + >> + token->security = kzalloc(blob_sizes.lbs_bpf_token, GFP_KERNEL); >> + if (!token->security) >> + return -ENOMEM; >> + >> + return 0; >> +} >> + >> /** >> * lsm_early_task - during initialization allocate a composite task blob >> * @task: the task that needs a blob >> @@ -5684,7 +5756,16 @@ int security_bpf_prog(struct bpf_prog *prog) >> int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, >> struct bpf_token *token, bool kernel) >> { >> - return call_int_hook(bpf_map_create, map, attr, token, kernel); >> + int rc = 0; >> + >> + rc = lsm_bpf_map_alloc(map); >> + if (unlikely(rc)) >> + return rc; >> + >> + rc = call_int_hook(bpf_map_create, map, attr, token, kernel); >> + if (unlikely(rc)) >> + security_bpf_map_free(map); >> + return rc; >> } >> >> /** >> @@ -5703,7 +5784,16 @@ int security_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, >> int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, >> struct bpf_token *token, bool kernel) >> { >> - return call_int_hook(bpf_prog_load, prog, attr, token, kernel); >> + int rc = 0; >> + >> + rc = lsm_bpf_prog_alloc(prog); >> + if (unlikely(rc)) >> + return rc; >> + >> + rc = call_int_hook(bpf_prog_load, prog, attr, token, kernel); >> + if (unlikely(rc)) >> + security_bpf_prog_free(prog); >> + return rc; >> } >> >> /** >> @@ -5720,7 +5810,16 @@ int security_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, >> int security_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, >> const struct path *path) >> { >> - return call_int_hook(bpf_token_create, token, attr, path); >> + int rc = 0; >> + >> + rc = lsm_bpf_token_alloc(token); >> + if (unlikely(rc)) >> + return rc; >> + >> + rc = call_int_hook(bpf_token_create, token, attr, path); >> + if (unlikely(rc)) >> + security_bpf_token_free(token); >> + return rc; >> } >> >> /** >> @@ -5763,7 +5862,12 @@ int security_bpf_token_capable(const struct bpf_token *token, int cap) >> */ >> void security_bpf_map_free(struct bpf_map *map) >> { >> + if (!map->security) >> + return; >> + >> call_void_hook(bpf_map_free, map); >> + kfree(map->security); >> + map->security = NULL; >> } >> >> /** >> @@ -5774,7 +5878,12 @@ void security_bpf_map_free(struct bpf_map *map) >> */ >> void security_bpf_prog_free(struct bpf_prog *prog) >> { >> + if (!prog->aux->security) >> + return; >> + >> call_void_hook(bpf_prog_free, prog); >> + kfree(prog->aux->security); >> + prog->aux->security = NULL; >> } >> >> /** >> @@ -5785,7 +5894,12 @@ void security_bpf_prog_free(struct bpf_prog *prog) >> */ >> void security_bpf_token_free(struct bpf_token *token) >> { >> + if (!token->security) >> + return; >> + >> call_void_hook(bpf_token_free, token); >> + kfree(token->security); >> + token->security = NULL; >> } >> #endif /* CONFIG_BPF_SYSCALL */ >> >> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >> index 595ceb314aeb3..8052fb5fafc4d 100644 >> --- a/security/selinux/hooks.c >> +++ b/security/selinux/hooks.c >> @@ -7038,14 +7038,14 @@ static int bpf_fd_pass(const struct file *file, u32 sid) >> >> if (file->f_op == &bpf_map_fops) { >> map = file->private_data; >> - bpfsec = map->security; >> + bpfsec = selinux_bpf_map_security(map); >> ret = avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, >> bpf_map_fmode_to_av(file->f_mode), NULL); >> if (ret) >> return ret; >> } else if (file->f_op == &bpf_prog_fops) { >> prog = file->private_data; >> - bpfsec = prog->aux->security; >> + bpfsec = selinux_bpf_prog_security(prog); >> ret = avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, >> BPF__PROG_RUN, NULL); >> if (ret) >> @@ -7059,7 +7059,7 @@ static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) >> u32 sid = current_sid(); >> struct bpf_security_struct *bpfsec; >> >> - bpfsec = map->security; >> + bpfsec = selinux_bpf_map_security(map); >> return avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, >> bpf_map_fmode_to_av(fmode), NULL); >> } >> @@ -7069,7 +7069,7 @@ static int selinux_bpf_prog(struct bpf_prog *prog) >> u32 sid = current_sid(); >> struct bpf_security_struct *bpfsec; >> >> - bpfsec = prog->aux->security; >> + bpfsec = selinux_bpf_prog_security(prog); >> return avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, >> BPF__PROG_RUN, NULL); >> } >> @@ -7079,69 +7079,33 @@ static int selinux_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, >> { >> struct bpf_security_struct *bpfsec; >> >> - bpfsec = kzalloc(sizeof(*bpfsec), GFP_KERNEL); >> - if (!bpfsec) >> - return -ENOMEM; >> - >> + bpfsec = selinux_bpf_map_security(map); >> bpfsec->sid = current_sid(); >> - map->security = bpfsec; >> >> return 0; >> } >> >> -static void selinux_bpf_map_free(struct bpf_map *map) >> -{ >> - struct bpf_security_struct *bpfsec = map->security; >> - >> - map->security = NULL; >> - kfree(bpfsec); >> -} >> - >> static int selinux_bpf_prog_load(struct bpf_prog *prog, union bpf_attr *attr, >> struct bpf_token *token, bool kernel) >> { >> struct bpf_security_struct *bpfsec; >> >> - bpfsec = kzalloc(sizeof(*bpfsec), GFP_KERNEL); >> - if (!bpfsec) >> - return -ENOMEM; >> - >> + bpfsec = selinux_bpf_prog_security(prog); >> bpfsec->sid = current_sid(); >> - prog->aux->security = bpfsec; >> >> return 0; >> } >> >> -static void selinux_bpf_prog_free(struct bpf_prog *prog) >> -{ >> - struct bpf_security_struct *bpfsec = prog->aux->security; >> - >> - prog->aux->security = NULL; >> - kfree(bpfsec); >> -} >> - >> static int selinux_bpf_token_create(struct bpf_token *token, union bpf_attr *attr, >> const struct path *path) >> { >> struct bpf_security_struct *bpfsec; >> >> - bpfsec = kzalloc(sizeof(*bpfsec), GFP_KERNEL); >> - if (!bpfsec) >> - return -ENOMEM; >> - >> + bpfsec = selinux_bpf_token_security(token); >> bpfsec->sid = current_sid(); >> - token->security = bpfsec; >> >> return 0; >> } >> - >> -static void selinux_bpf_token_free(struct bpf_token *token) >> -{ >> - struct bpf_security_struct *bpfsec = token->security; >> - >> - token->security = NULL; >> - kfree(bpfsec); >> -} >> #endif >> >> struct lsm_blob_sizes selinux_blob_sizes __ro_after_init = { >> @@ -7159,6 +7123,9 @@ struct lsm_blob_sizes selinux_blob_sizes __ro_after_init = { >> .lbs_xattr_count = SELINUX_INODE_INIT_XATTRS, >> .lbs_tun_dev = sizeof(struct tun_security_struct), >> .lbs_ib = sizeof(struct ib_security_struct), >> + .lbs_bpf_map = sizeof(struct bpf_security_struct), >> + .lbs_bpf_prog = sizeof(struct bpf_security_struct), >> + .lbs_bpf_token = sizeof(struct bpf_security_struct), >> }; >> >> #ifdef CONFIG_PERF_EVENTS >> @@ -7510,9 +7477,6 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { >> LSM_HOOK_INIT(bpf, selinux_bpf), >> LSM_HOOK_INIT(bpf_map, selinux_bpf_map), >> LSM_HOOK_INIT(bpf_prog, selinux_bpf_prog), >> - LSM_HOOK_INIT(bpf_map_free, selinux_bpf_map_free), >> - LSM_HOOK_INIT(bpf_prog_free, selinux_bpf_prog_free), >> - LSM_HOOK_INIT(bpf_token_free, selinux_bpf_token_free), >> #endif >> >> #ifdef CONFIG_PERF_EVENTS >> diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h >> index 6ee7dc4dfd6e0..9f935ed9a761f 100644 >> --- a/security/selinux/include/objsec.h >> +++ b/security/selinux/include/objsec.h >> @@ -26,6 +26,7 @@ >> #include >> #include >> #include >> +#include >> #include "flask.h" >> #include "avc.h" >> >> @@ -237,4 +238,20 @@ selinux_perf_event(void *perf_event) >> return perf_event + selinux_blob_sizes.lbs_perf_event; >> } >> >> +#ifdef CONFIG_BPF_SYSCALL >> +static inline struct bpf_security_struct *selinux_bpf_map_security(struct bpf_map *map) >> +{ >> + return map->security + selinux_blob_sizes.lbs_bpf_map; >> +} >> + >> +static inline struct bpf_security_struct *selinux_bpf_prog_security(struct bpf_prog *prog) >> +{ >> + return prog->aux->security + selinux_blob_sizes.lbs_bpf_prog; >> +} >> + >> +static inline struct bpf_security_struct *selinux_bpf_token_security(struct bpf_token *token) >> +{ >> + return token->security + selinux_blob_sizes.lbs_bpf_token; >> +} >> +#endif /* CONFIG_BPF_SYSCALL */ >> #endif /* _SELINUX_OBJSEC_H_ */