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Tue, 30 Nov 2021 16:07:12 +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 13/20] securityfs: Build securityfs_ns for namespacing support Date: Tue, 30 Nov 2021 11:06:47 -0500 Message-Id: <20211130160654.1418231-14-stefanb@linux.ibm.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211130160654.1418231-1-stefanb@linux.ibm.com> References: <20211130160654.1418231-1-stefanb@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: _sBp7DtEQu3_8VHRTdDXWoGDVysgk-s- X-Proofpoint-ORIG-GUID: m4XWq6Zh3Hjn7wqsDqx4aWWPjgKwbmG4 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-30_09,2021-11-28_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 spamscore=0 malwarescore=0 clxscore=1015 mlxlogscore=999 adultscore=0 mlxscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111300084 Precedence: bulk List-ID: Implement 'securityfs_ns' 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 shares much of the existing code of SecurityFS but requires a new API call securityfs_ns_create_mount() for creating a new instance. The API calls of securityfs_ns have the prefix securityfs_ns_ and take additional parameters struct vfsmount * and mount_count that allow for multiple instances of this filesystem to exist. The filesystem can be mounted to the usual securityfs mount point like this: mount -t securityfs_ns /sys/kernel/security /sys/kernel/security Signed-off-by: Stefan Berger --- include/linux/security.h | 18 ++++ include/uapi/linux/magic.h | 1 + security/inode.c | 197 +++++++++++++++++++++++++++++++++++-- 3 files changed, 210 insertions(+), 6 deletions(-) diff --git a/include/linux/security.h b/include/linux/security.h index 7e0ba63b5dde..8e479266f544 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1929,6 +1929,24 @@ 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, + const struct inode_operations *iops, + struct vfsmount **mount, int *mount_count); +extern struct dentry *securityfs_ns_create_dir(const char *name, struct dentry *parent, + const struct inode_operations *iops, + 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); +extern struct vfsmount *securityfs_ns_mount; + #else /* CONFIG_SECURITYFS */ static inline struct dentry *securityfs_create_dir(const char *name, diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index 35687dcb1a42..5c1cc6088dd2 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -11,6 +11,7 @@ #define CRAMFS_MAGIC_WEND 0x453dcd28 /* magic number with the wrong endianess */ #define DEBUGFS_MAGIC 0x64626720 #define SECURITYFS_MAGIC 0x73636673 +#define SECURITYFS_NS_MAGIC 0x73334473 #define SELINUX_MAGIC 0xf97cff8c #define SMACK_MAGIC 0x43415d53 /* "SMAC" */ #define RAMFS_MAGIC 0x858458f6 /* some random number */ diff --git a/security/inode.c b/security/inode.c index 429744ff4ab3..8077d1f31489 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; @@ -73,6 +74,61 @@ static struct file_system_type securityfs_type = { .kill_sb = kill_litter_super, }; +static int securityfs_ns_fill_super(struct super_block *sb, struct fs_context *fc) +{ + static const struct tree_descr files[] = {{""}}; + int error; + + error = simple_fill_super(sb, SECURITYFS_NS_MAGIC, files); + if (error) + return error; + + sb->s_op = &securityfs_super_operations; + + return 0; +} + +static int securityfs_ns_get_tree(struct fs_context *fc) +{ + return get_tree_keyed(fc, securityfs_ns_fill_super, fc->user_ns); +} + +static const struct fs_context_operations securityfs_ns_context_ops = { + .get_tree = securityfs_ns_get_tree, +}; + +static int securityfs_ns_init_fs_context(struct fs_context *fc) +{ + fc->ops = &securityfs_ns_context_ops; + return 0; +} + +static struct file_system_type securityfs_ns_type = { + .owner = THIS_MODULE, + .name = "securityfs_ns", + .init_fs_context = securityfs_ns_init_fs_context, + .kill_sb = kill_litter_super, + .fs_flags = FS_USERNS_MOUNT, +}; + +struct vfsmount *securityfs_ns_create_mount(struct user_namespace *user_ns) +{ + struct fs_context *fc; + struct vfsmount *mnt; + + fc = fs_context_for_mount(&securityfs_ns_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 * @@ -155,8 +211,8 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); inode->i_private = data; if (S_ISDIR(mode)) { - inode->i_op = &simple_dir_inode_operations; - inode->i_fop = &simple_dir_operations; + inode->i_op = iops ? iops : &simple_dir_inode_operations; + inode->i_fop = fops ? fops : &simple_dir_operations; inc_nlink(inode); inc_nlink(dir); } else if (S_ISLNK(mode)) { @@ -214,6 +270,41 @@ 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, + const struct inode_operations *iops, + struct vfsmount **mount, int *mount_count) +{ + return securityfs_create_dentry(name, mode, parent, data, fops, iops, + &securityfs_ns_type, mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_create_file); + /** * securityfs_create_dir - create a directory in the securityfs filesystem * @@ -240,6 +331,34 @@ 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, + const struct inode_operations *iops, + struct vfsmount **mount, int *mount_count) +{ + return securityfs_ns_create_file(name, S_IFDIR | 0755, parent, NULL, NULL, + iops, mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_create_dir); + struct dentry *_securityfs_create_symlink(const char *name, struct dentry *parent, const char *target, @@ -263,6 +382,7 @@ struct dentry *_securityfs_create_symlink(const char *name, return dent; } + /** * securityfs_create_symlink - create a symlink in the securityfs filesystem * @@ -300,6 +420,42 @@ 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. + * @iops: a pointer to the struct inode_operations to use for the symlink. If + * this parameter is %NULL, then the default simple_symlink_inode + * operations will be used. + * @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, + &securityfs_ns_type, mount, mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_ns_create_symlink); + void _securityfs_remove(struct dentry *dentry, struct vfsmount **mount, int *mount_count) { struct inode *dir; @@ -340,6 +496,27 @@ 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, @@ -364,14 +541,22 @@ static int __init securityfs_init(void) return retval; retval = register_filesystem(&securityfs_type); - if (retval) { - sysfs_remove_mount_point(kernel_kobj, "security"); - return retval; - } + if (retval) + goto remove_mount; + retval = register_filesystem(&securityfs_ns_type); + if (retval) + goto unregister_filesystem; #ifdef CONFIG_SECURITY lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, &lsm_ops); #endif return 0; + +unregister_filesystem: + unregister_filesystem(&securityfs_type); +remove_mount: + sysfs_remove_mount_point(kernel_kobj, "security"); + + return retval; } core_initcall(securityfs_init);