From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-bc08.mail.infomaniak.ch (smtp-bc08.mail.infomaniak.ch [45.157.188.8]) (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 A3AA34963A5 for ; Fri, 5 Jun 2026 15:16:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.157.188.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780672566; cv=none; b=mH9HXiwBHCMM5A24RAWElcWhbZk38TZweLGofZs4cuYpcIC+/rG1HRJBPZ7NS3J79TAEAYOTbZWjRSFqiQB6j3vlBroGhfU7FGaazd/sasui39C2umL1p9Wu1zaObcOgAWGy86hwxUXbgtR1mpFzsEOrQq9faEoZuZv8tti74Fo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780672566; c=relaxed/simple; bh=lXG2eaND36CYrhwgwMzFGcWCKJtbEvWE+GOJ+QxVHxE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WRn52dwco60qxHI9NdMbqNIfENcXvmkRdbHk3+tpVSxnhOweUiBVqwk6GqF3hiTD71G2upI1swMKSxgLm8nxtGZ9dUV0lMmJRSoaEea/cEwvjzPCqckYKnXdgUVi59ZPtI8VqqD7iSqpfeuc+6Z5+Mw2k61MBxC1DGiiDY4iZAw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=kwx7zo+b; arc=none smtp.client-ip=45.157.188.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="kwx7zo+b" Received: from smtp-4-0000.mail.infomaniak.ch (smtp-4-0000.mail.infomaniak.ch [10.7.10.107]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4gX4Xl17GGzDq4; Fri, 5 Jun 2026 17:07:03 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1780672022; bh=qLdBr6wSUpCnPAcLYlcrVQRrZlPccPR98BWLDygtpD0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kwx7zo+bmj7YJl7ZABFGhW6ijnyp0n2yTOCXQnUWTzLyrAtwPy+DQmjPGmoCvrRPv pouLngkMxiQWTUR2ETjxjTbpNvlhCpzvkFVvsj2BwjAy+QQwzb18ajAR8bJ6WYf2sT LvVsfX1lEwx9g1FytKZ84uSOdLCKO0r9Tb+EokQo= Received: from unknown by smtp-4-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4gX4Xj34dBzbfk; Fri, 5 Jun 2026 17:07:01 +0200 (CEST) Date: Fri, 5 Jun 2026 17:06:56 +0200 From: =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= To: Paul Moore , Christian Brauner , =?utf-8?Q?G=C3=BCnther?= Noack , "Serge E . Hallyn" Cc: Daniel Durning , Jonathan Corbet , Justin Suess , Lennart Poettering , Mikhail Ivanov , Nicolas Bouchinet , Shervin Oloumi , Tingmao Wang , kernel-team@cloudflare.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v2 1/9] security: add LSM blob and hooks for namespaces Message-ID: <20260605.ieZ1hei8Ahna@digikod.net> References: <20260527181127.879771-1-mic@digikod.net> <20260527181127.879771-2-mic@digikod.net> 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; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260527181127.879771-2-mic@digikod.net> X-Infomaniak-Routing: alpha Paul, could you please take a look at this patch and the next one? I'd like to push it to linux-next to get more feedback. On Wed, May 27, 2026 at 08:11:14PM +0200, Mickaël Salaün wrote: > From: Christian Brauner > > All namespace types now share the same ns_common infrastructure. Extend > this to include a security blob so LSMs can start managing namespaces > uniformly without having to add one-off hooks or security fields to > every individual namespace type. > > Add a ns_security pointer to ns_common and the corresponding lbs_ns blob > size to lsm_blob_sizes. Allocation and freeing hooks are called from the > common __ns_common_init() and __ns_common_free() paths so every > namespace type gets covered in one go. All information about the > namespace type and the appropriate casting helpers to get at the > containing namespace are available via ns_common making it > straightforward for LSMs to differentiate when they need to. > > A namespace_install hook is called from validate_ns() during setns(2) > giving LSMs a chance to enforce policy on namespace transitions. The > LSM check runs before ns->ops->install() so the security module can deny > the operation before any type-specific installation effects. > > Individual namespace types can still have their own specialized security > hooks when needed. This is just the common baseline that makes it easy > to track and manage namespaces from the security side without requiring > every namespace type to reinvent the wheel. > > Cc: Günther Noack > Cc: Paul Moore > Cc: Serge E. Hallyn > Signed-off-by: Christian Brauner > Link: https://lore.kernel.org/r/20260216-work-security-namespace-v1-1-075c28758e1f@kernel.org > Signed-off-by: Mickaël Salaün > --- > > Changes since v1: > https://lore.kernel.org/r/20260312100444.2609563-2-mic@digikod.net > - Move security_namespace_install() before ns->ops->install() in > validate_ns() (suggested by Christian Brauner). > - Only call proc_free_inum() on security_namespace_alloc() failure > when inum was allocated by this function (suggested by Christian > Brauner). > - Fix anonymous mount namespace blob leak: move > security_namespace_free() into __ns_common_free() and make > proc_free_inum() conditional on dynamically allocated inums > via MNT_NS_INO_SPECIAL_MAX, so free_mnt_ns() can call > ns_common_free() unconditionally (suggested by Christian > Brauner). Also reported by Daniel Durning while working on > SELinux support for these hooks: > https://lore.kernel.org/r/20260318201747.4477-1-danieldurning.work@gmail.com > - Rename security_namespace_alloc() to security_namespace_init() > to match the caller-name convention and reflect that the hook > initialises LSM state attached to a constructed ns_common rather > than allocating the ns_common itself (suggested by Paul Moore). > - Refine the security_namespace_free() kdoc to clarify that > RCU-safe blob freeing is required only if an LSM exposes data > within the blob to concurrent RCU readers, and document that > the blob memory itself is released with kfree() after the > namespace_free hooks return (suggested by Paul Moore). > - Günther Noack's v1 Reviewed-by is not carried forward to v2: > the validate_ns() reordering and the anonymous-mount-namespace > blob-leak fix are semantic changes that were not part of his > review. Cc'd instead. > --- > fs/namespace.c | 3 +- > include/linux/lsm_hook_defs.h | 3 ++ > include/linux/lsm_hooks.h | 1 + > include/linux/ns/ns_common_types.h | 3 ++ > include/linux/security.h | 20 ++++++++ > include/uapi/linux/nsfs.h | 1 + > kernel/nscommon.c | 17 ++++++- > kernel/nsproxy.c | 6 +++ > security/lsm_init.c | 2 + > security/security.c | 77 ++++++++++++++++++++++++++++++ > 10 files changed, 130 insertions(+), 3 deletions(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index fe919abd2f01..031ef3fafa48 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -4179,8 +4179,7 @@ static void dec_mnt_namespaces(struct ucounts *ucounts) > > static void free_mnt_ns(struct mnt_namespace *ns) > { > - if (!is_anon_ns(ns)) > - ns_common_free(ns); > + ns_common_free(ns); > dec_mnt_namespaces(ns->ucounts); > mnt_ns_tree_remove(ns); > } > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 2b8dfb35caed..c389ea904392 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -265,6 +265,9 @@ LSM_HOOK(int, -ENOSYS, task_prctl, int option, unsigned long arg2, > LSM_HOOK(void, LSM_RET_VOID, task_to_inode, struct task_struct *p, > struct inode *inode) > LSM_HOOK(int, 0, userns_create, const struct cred *cred) > +LSM_HOOK(int, 0, namespace_init, struct ns_common *ns) > +LSM_HOOK(void, LSM_RET_VOID, namespace_free, struct ns_common *ns) > +LSM_HOOK(int, 0, namespace_install, const struct nsset *nsset, struct ns_common *ns) > LSM_HOOK(int, 0, ipc_permission, struct kern_ipc_perm *ipcp, short flag) > LSM_HOOK(void, LSM_RET_VOID, ipc_getlsmprop, struct kern_ipc_perm *ipcp, > struct lsm_prop *prop) > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index b4f8cad53ddb..5cff13069529 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -112,6 +112,7 @@ struct lsm_blob_sizes { > unsigned int lbs_ipc; > unsigned int lbs_key; > unsigned int lbs_msg_msg; > + unsigned int lbs_ns; > unsigned int lbs_perf_event; > unsigned int lbs_task; > unsigned int lbs_xattr_count; /* num xattr slots in new_xattrs array */ > diff --git a/include/linux/ns/ns_common_types.h b/include/linux/ns/ns_common_types.h > index ea45c54e4435..5cfe0ce3c881 100644 > --- a/include/linux/ns/ns_common_types.h > +++ b/include/linux/ns/ns_common_types.h > @@ -116,6 +116,9 @@ struct ns_common { > struct dentry *stashed; > const struct proc_ns_operations *ops; > unsigned int inum; > +#ifdef CONFIG_SECURITY > + void *ns_security; > +#endif > union { > struct ns_tree; > struct rcu_head ns_rcu; > diff --git a/include/linux/security.h b/include/linux/security.h > index 41d7367cf403..8865f46cc3a9 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -67,6 +67,7 @@ enum fs_value_type; > struct watch; > struct watch_notification; > struct lsm_ctx; > +struct nsset; > > /* Default (no) options for the capable function */ > #define CAP_OPT_NONE 0x0 > @@ -80,6 +81,7 @@ struct lsm_ctx; > > struct ctl_table; > struct audit_krule; > +struct ns_common; > struct user_namespace; > struct timezone; > > @@ -540,6 +542,9 @@ int security_task_prctl(int option, unsigned long arg2, unsigned long arg3, > unsigned long arg4, unsigned long arg5); > void security_task_to_inode(struct task_struct *p, struct inode *inode); > int security_create_user_ns(const struct cred *cred); > +int security_namespace_init(struct ns_common *ns); > +void security_namespace_free(struct ns_common *ns); > +int security_namespace_install(const struct nsset *nsset, struct ns_common *ns); > int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag); > void security_ipc_getlsmprop(struct kern_ipc_perm *ipcp, struct lsm_prop *prop); > int security_msg_msg_alloc(struct msg_msg *msg); > @@ -1430,6 +1435,21 @@ static inline int security_create_user_ns(const struct cred *cred) > return 0; > } > > +static inline int security_namespace_init(struct ns_common *ns) > +{ > + return 0; > +} > + > +static inline void security_namespace_free(struct ns_common *ns) > +{ > +} > + > +static inline int security_namespace_install(const struct nsset *nsset, > + struct ns_common *ns) > +{ > + return 0; > +} > + > static inline int security_ipc_permission(struct kern_ipc_perm *ipcp, > short flag) > { > diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h > index a25e38d1c874..ea0f0267d90f 100644 > --- a/include/uapi/linux/nsfs.h > +++ b/include/uapi/linux/nsfs.h > @@ -55,6 +55,7 @@ enum init_ns_ino { > MNT_NS_INIT_INO = 0xEFFFFFF8U, > #ifdef __KERNEL__ > MNT_NS_ANON_INO = 0xEFFFFFF7U, > + MNT_NS_INO_SPECIAL_MAX = MNT_NS_ANON_INO, > #endif > }; > > diff --git a/kernel/nscommon.c b/kernel/nscommon.c > index 3166c1fd844a..e72426bba29a 100644 > --- a/kernel/nscommon.c > +++ b/kernel/nscommon.c > @@ -4,6 +4,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -59,6 +60,9 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope > > refcount_set(&ns->__ns_ref, 1); > ns->stashed = NULL; > +#ifdef CONFIG_SECURITY > + ns->ns_security = NULL; > +#endif > ns->ops = ops; > ns->ns_id = 0; > ns->ns_type = ns_type; > @@ -77,6 +81,14 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope > ret = proc_alloc_inum(&ns->inum); > if (ret) > return ret; > + > + ret = security_namespace_init(ns); > + if (ret) { > + if (!inum) > + proc_free_inum(ns->inum); > + return ret; > + } > + > /* > * Tree ref starts at 0. It's incremented when namespace enters > * active use (installed in nsproxy) and decremented when all > @@ -91,7 +103,10 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope > > void __ns_common_free(struct ns_common *ns) > { > - proc_free_inum(ns->inum); > + security_namespace_free(ns); > + > + if (ns->inum > MNT_NS_INO_SPECIAL_MAX) > + proc_free_inum(ns->inum); > } > > struct ns_common *__must_check ns_owner(struct ns_common *ns) > diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c > index d9d3d5973bf5..0f1b208d8eef 100644 > --- a/kernel/nsproxy.c > +++ b/kernel/nsproxy.c > @@ -385,6 +385,12 @@ static int prepare_nsset(unsigned flags, struct nsset *nsset) > > static inline int validate_ns(struct nsset *nsset, struct ns_common *ns) > { > + int ret; > + > + ret = security_namespace_install(nsset, ns); > + if (ret) > + return ret; > + > return ns->ops->install(nsset, ns); > } > > diff --git a/security/lsm_init.c b/security/lsm_init.c > index 7c0fd17f1601..dcd2a228c4f6 100644 > --- a/security/lsm_init.c > +++ b/security/lsm_init.c > @@ -303,6 +303,7 @@ static void __init lsm_prepare(struct lsm_info *lsm) > lsm_blob_size_update(&blobs->lbs_ipc, &blob_sizes.lbs_ipc); > lsm_blob_size_update(&blobs->lbs_key, &blob_sizes.lbs_key); > lsm_blob_size_update(&blobs->lbs_msg_msg, &blob_sizes.lbs_msg_msg); > + lsm_blob_size_update(&blobs->lbs_ns, &blob_sizes.lbs_ns); > lsm_blob_size_update(&blobs->lbs_perf_event, > &blob_sizes.lbs_perf_event); > lsm_blob_size_update(&blobs->lbs_sock, &blob_sizes.lbs_sock); > @@ -450,6 +451,7 @@ int __init security_init(void) > lsm_pr("blob(ipc) size %d\n", blob_sizes.lbs_ipc); > lsm_pr("blob(key) size %d\n", blob_sizes.lbs_key); > lsm_pr("blob(msg_msg)_size %d\n", blob_sizes.lbs_msg_msg); > + lsm_pr("blob(ns) size %d\n", blob_sizes.lbs_ns); > lsm_pr("blob(sock) size %d\n", blob_sizes.lbs_sock); > lsm_pr("blob(superblock) size %d\n", blob_sizes.lbs_superblock); > lsm_pr("blob(perf_event) size %d\n", blob_sizes.lbs_perf_event); > diff --git a/security/security.c b/security/security.c > index 4e999f023651..21cc45d4bbd0 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -26,6 +26,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -381,6 +382,19 @@ static int lsm_superblock_alloc(struct super_block *sb) > GFP_KERNEL); > } > > +/** > + * lsm_ns_alloc - allocate a composite namespace blob > + * @ns: the namespace that needs a blob > + * > + * Allocate the namespace blob for all the modules > + * > + * Returns 0, or -ENOMEM if memory can't be allocated. > + */ > +static int lsm_ns_alloc(struct ns_common *ns) > +{ > + return lsm_blob_alloc(&ns->ns_security, blob_sizes.lbs_ns, GFP_KERNEL); > +} > + > /** > * lsm_fill_user_ctx - Fill a user space lsm_ctx structure > * @uctx: a userspace LSM context to be filled > @@ -3358,6 +3372,69 @@ int security_create_user_ns(const struct cred *cred) > return call_int_hook(userns_create, cred); > } > > +/** > + * security_namespace_init() - Initialize LSM security data for a namespace > + * @ns: the namespace being initialized > + * > + * Initialize the LSM security blob attached to the namespace. The namespace type > + * is available via ns->ns_type, and the owning user namespace (if any) > + * via ns->ops->owner(ns). > + * > + * Return: Returns 0 if successful, otherwise < 0 error code. > + */ > +int security_namespace_init(struct ns_common *ns) > +{ > + int rc; > + > + rc = lsm_ns_alloc(ns); > + if (unlikely(rc)) > + return rc; > + > + rc = call_int_hook(namespace_init, ns); > + if (unlikely(rc)) > + security_namespace_free(ns); > + > + return rc; > +} > + > +/** > + * security_namespace_free() - Release LSM security data from a namespace > + * @ns: the namespace being freed > + * > + * Release security data attached to the namespace. Called before the > + * namespace structure is freed. > + * > + * Note: If an LSM exposes data within the security blob to concurrent > + * RCU readers, it must use RCU-safe freeing for that data. The blob > + * memory itself is released with kfree() after the namespace_free > + * hooks return. > + */ > +void security_namespace_free(struct ns_common *ns) > +{ > + if (!ns->ns_security) > + return; > + > + call_void_hook(namespace_free, ns); > + > + kfree(ns->ns_security); > + ns->ns_security = NULL; > +} > + > +/** > + * security_namespace_install() - Check permission to install a namespace > + * @nsset: the target nsset being configured > + * @ns: the namespace being installed > + * > + * Check permission before allowing a namespace to be installed into the > + * process's set of namespaces via setns(2). > + * > + * Return: Returns 0 if permission is granted, otherwise < 0 error code. > + */ > +int security_namespace_install(const struct nsset *nsset, struct ns_common *ns) > +{ > + return call_int_hook(namespace_install, nsset, ns); > +} > + > /** > * security_ipc_permission() - Check if sysv ipc access is allowed > * @ipcp: ipc permission structure > -- > 2.54.0 > >