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Fri, 3 Dec 2021 02:31:40 +0000 (GMT) Received: from sbct-3.pok.ibm.com (unknown [9.47.158.153]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Fri, 3 Dec 2021 02:31:40 +0000 (GMT) From: Stefan Berger To: linux-integrity@vger.kernel.org Cc: zohar@linux.ibm.com, serge@hallyn.com, christian.brauner@ubuntu.com, containers@lists.linux.dev, dmitry.kasatkin@gmail.com, ebiederm@xmission.com, krzysztof.struczynski@huawei.com, roberto.sassu@huawei.com, mpeters@redhat.com, lhinds@redhat.com, lsturman@redhat.com, puiterwi@redhat.com, jejb@linux.ibm.com, jamjoom@us.ibm.com, linux-kernel@vger.kernel.org, paul@paul-moore.com, rgb@redhat.com, linux-security-module@vger.kernel.org, jmorris@namei.org, Stefan Berger Subject: [RFC v2 13/19] securityfs: Extend securityfs with namespacing support Date: Thu, 2 Dec 2021 21:31:12 -0500 Message-Id: <20211203023118.1447229-14-stefanb@linux.ibm.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211203023118.1447229-1-stefanb@linux.ibm.com> References: <20211203023118.1447229-1-stefanb@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: ywihtBwY22VVeTFTVpOXGP6QjjX8GRef X-Proofpoint-ORIG-GUID: 5m5nWm2oxzEsq6P-gZSDe7WmeaWvASff X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-02_16,2021-12-02_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxlogscore=999 mlxscore=0 bulkscore=0 impostorscore=0 adultscore=0 malwarescore=0 spamscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112030012 Precedence: bulk List-ID: Extend 'securityfs' for support of IMA namespacing so that each IMA (user) namespace can have its own front-end for showing the currently active policy, the measurement list, number of violations and so on. This filesystem adds a new API call securityfs_ns_create_mount() for creating a new instance of the filesystem. The API calls the namespaced SecurityFS have the prefix securityfs_ns_ and take additional parameters struct vfsmount ** and int *mount_count that allow for access to different instances of this filesystem. The filesystem can be mounted to the usual securityfs mount point like this: mount -t securityfs /sys/kernel/security /sys/kernel/security Signed-off-by: Stefan Berger --- include/linux/security.h | 15 ++++ security/inode.c | 145 ++++++++++++++++++++++++++++++++++++++- 2 files changed, 159 insertions(+), 1 deletion(-) diff --git a/include/linux/security.h b/include/linux/security.h index 7e0ba63b5dde..13fdb09d86b2 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1929,6 +1929,21 @@ struct dentry *securityfs_create_symlink(const char *name, const struct inode_operations *iops); extern void securityfs_remove(struct dentry *dentry); +extern struct dentry *securityfs_ns_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops, + struct vfsmount **mount, int *mount_count); +extern struct dentry *securityfs_ns_create_dir(const char *name, struct dentry *parent, + struct vfsmount **mount, int *mount_count); +struct dentry *securityfs_ns_create_symlink(const char *name, + struct dentry *parent, + const char *target, + const struct inode_operations *iops, + struct vfsmount **mount, int *mount_count); +extern void securityfs_ns_remove(struct dentry *dentry, + struct vfsmount **mount, int *mount_count); +struct vfsmount *securityfs_ns_create_mount(struct user_namespace *user_ns); + #else /* CONFIG_SECURITYFS */ static inline struct dentry *securityfs_create_dir(const char *name, diff --git a/security/inode.c b/security/inode.c index 9299f134877f..2738a7b31469 100644 --- a/security/inode.c +++ b/security/inode.c @@ -21,6 +21,7 @@ #include #include #include +#include static struct vfsmount *securityfs_mount; static int securityfs_mount_count; @@ -53,7 +54,7 @@ static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc) static int securityfs_get_tree(struct fs_context *fc) { - return get_tree_single(fc, securityfs_fill_super); + return get_tree_keyed(fc, securityfs_fill_super, fc->user_ns); } static const struct fs_context_operations securityfs_context_ops = { @@ -71,8 +72,34 @@ static struct file_system_type fs_type = { .name = "securityfs", .init_fs_context = securityfs_init_fs_context, .kill_sb = kill_litter_super, + .fs_flags = FS_USERNS_MOUNT, }; +/** + * securityfs_ns_create_mount - create instance of securityfs in given user namespace + * + * @user_ns: the user namespace to create the vfsmount in + * + * This function returns a pointer to the vfsmount or an error code. The vfsmount + * has to be used when creating or removing filesystem dentries. + */ +struct vfsmount *securityfs_ns_create_mount(struct user_namespace *user_ns) +{ + struct fs_context *fc; + struct vfsmount *mnt; + + fc = fs_context_for_mount(&fs_type, SB_KERNMOUNT); + if (IS_ERR(fc)) + return ERR_CAST(fc); + + put_user_ns(fc->user_ns); + fc->user_ns = get_user_ns(user_ns); + + mnt = fc_mount(fc); + put_fs_context(fc); + return mnt; +} + /** * securityfs_create_dentry - create a dentry in the securityfs filesystem * @@ -213,6 +240,40 @@ struct dentry *securityfs_create_file(const char *name, umode_t mode, } EXPORT_SYMBOL_GPL(securityfs_create_file); +/** + * securityfs_ns_create_file - create a file in the securityfs_ns filesystem + * + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is %NULL, then the + * file will be created in the root of the securityfs_ns filesystem. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fops: a pointer to a struct file_operations that should be used for + * this file. + * @mount: Pointer to a pointer of a an existing vfsmount + * @mount_count: The mount_count that goes along with the @mount + * + * This function creates a file in securityfs_ns with the given @name. + * + * This function returns a pointer to a dentry if it succeeds. This + * pointer must be passed to the securityfs_ns_remove() function when the file + * is to be removed (no automatic cleanup happens if your module is unloaded, + * you are responsible here). If an error occurs, the function will return + * the error value (via ERR_PTR). + */ +struct dentry *securityfs_ns_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops, + struct vfsmount **mount, int *mount_count) +{ + return securityfs_create_dentry(name, mode, parent, data, fops, NULL, + mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_create_file); + /** * securityfs_create_dir - create a directory in the securityfs filesystem * @@ -239,6 +300,33 @@ struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) } EXPORT_SYMBOL_GPL(securityfs_create_dir); +/** + * securityfs_ns_create_dir - create a directory in the securityfs_ns filesystem + * + * @name: a pointer to a string containing the name of the directory to + * create. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is %NULL, then the + * directory will be created in the root of the securityfs_ns filesystem. + * @mount: Pointer to a pointer of a an existing vfsmount + * @mount_count: The mount_count that goes along with the @mount + * + * This function creates a directory in securityfs_ns with the given @name. + * + * This function returns a pointer to a dentry if it succeeds. This + * pointer must be passed to the securityfs_ns_remove() function when the file + * is to be removed (no automatic cleanup happens if your module is unloaded, + * you are responsible here). If an error occurs, the function will return + * the error value (via ERR_PTR). + */ +struct dentry *securityfs_ns_create_dir(const char *name, struct dentry *parent, + struct vfsmount **mount, int *mount_count) +{ + return securityfs_ns_create_file(name, S_IFDIR | 0755, parent, NULL, NULL, + mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_create_dir); + static struct dentry *_securityfs_create_symlink(const char *name, struct dentry *parent, const char *target, @@ -260,6 +348,7 @@ static struct dentry *_securityfs_create_symlink(const char *name, return dent; } + /** * securityfs_create_symlink - create a symlink in the securityfs filesystem * @@ -296,6 +385,39 @@ struct dentry *securityfs_create_symlink(const char *name, } EXPORT_SYMBOL_GPL(securityfs_create_symlink); +/** + * securityfs_ns_create_symlink - create a symlink in the securityfs_ns filesystem + * + * @name: a pointer to a string containing the name of the symlink to + * create. + * @parent: a pointer to the parent dentry for the symlink. This should be a + * directory dentry if set. If this parameter is %NULL, then the + * directory will be created in the root of the securityfs_ns filesystem. + * @target: a pointer to a string containing the name of the symlink's target. + * If this parameter is %NULL, then the @iops parameter needs to be + * setup to handle .readlink and .get_link inode_operations. + * @mount: Pointer to a pointer of a an existing vfsmount + * @mount_count: The mount_count that goes along with the @mount + * + * This function creates a symlink in securityfs_ns with the given @name. + * + * This function returns a pointer to a dentry if it succeeds. This + * pointer must be passed to the securityfs_ns_remove() function when the file + * is to be removed (no automatic cleanup happens if your module is unloaded, + * you are responsible here). If an error occurs, the function will return + * the error value (via ERR_PTR). + */ +struct dentry *securityfs_ns_create_symlink(const char *name, + struct dentry *parent, + const char *target, + const struct inode_operations *iops, + struct vfsmount **mount, int *mount_count) +{ + return _securityfs_create_symlink(name, parent, target, iops, + mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_create_symlink); + static void _securityfs_remove(struct dentry *dentry, struct vfsmount **mount, int *mount_count) { @@ -337,6 +459,27 @@ void securityfs_remove(struct dentry *dentry) EXPORT_SYMBOL_GPL(securityfs_remove); +/** + * securityfs_ns_remove - removes a file or directory from the securityfs_ns filesystem + * + * @dentry: a pointer to a the dentry of the file or directory to be removed. + * @mount: Pointer to a pointer of a an existing vfsmount + * @mount_count: The mount_count that goes along with the @mount + * + * This function removes a file or directory in securityfs_ns that was previously + * created with a call to another securityfs_ns function (like + * securityfs_ns_create_file() or variants thereof.) + * + * This function is required to be called in order for the file to be + * removed. No automatic cleanup of files will happen when a module is + * removed; you are responsible here. + */ +void securityfs_ns_remove(struct dentry *dentry, struct vfsmount **mount, int *mount_count) +{ + _securityfs_remove(dentry, mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_remove); + #ifdef CONFIG_SECURITY static struct dentry *lsm_dentry; static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,