[20/43] vfs: Implement a filesystem superblock creation/configuration context

Message ID	155059386422.12449.6531190148715512242.stgit@warthog.procyon.org.uk (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-security-module-owner@kernel.org> Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 20/43] vfs: Implement a filesystem superblock creation/configuration context From: David Howells <dhowells@redhat.com> To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, dhowells@redhat.com, torvalds@linux-foundation.org, ebiederm@xmission.com, linux-security-module@vger.kernel.org Date: Tue, 19 Feb 2019 16:31:04 +0000 Message-ID: <155059386422.12449.6531190148715512242.stgit@warthog.procyon.org.uk> In-Reply-To: <155059366914.12449.4669870128936536848.stgit@warthog.procyon.org.uk> References: <155059366914.12449.4669870128936536848.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk
Series	VFS: Introduce filesystem context \| expand [00/43] VFS: Introduce filesystem context [01/43] fix cgroup_do_mount() handling of failure exits [02/43] cgroup: saner refcounting for cgroup_root [03/43] kill kernfs_pin_sb() [04/43] separate copying and locking mount tree on cross-userns copies [05/43] saner handling of temporary namespaces [06/43] vfs: Introduce fs_context, switch vfs_kern_mount() to it. [07/43] new helpers: vfs_create_mount(), fc_mount() [08/43] teach vfs_get_tree() to handle subtype, switch do_new_mount() to it [09/43] new helper: do_new_mount_fc() [10/43] vfs_get_tree(): evict the call of security_sb_kern_mount() [11/43] convert do_remount_sb() to fs_context [12/43] fs_context flavour for submounts [13/43] introduce fs_context methods [14/43] vfs: Introduce logging functions [15/43] vfs: Add configuration parser helpers [16/43] vfs: Add LSM hooks for the new mount API [17/43] selinux: Implement the new mount API LSM hooks [18/43] smack: Implement filesystem context security hooks [19/43] vfs: Put security flags into the fs_context struct [20/43] vfs: Implement a filesystem superblock creation/configuration context [21/43] convenience helpers: vfs_get_super() and sget_fc() [22/43] introduce cloning of fs_context [23/43] procfs: Move proc_fill_super() to fs/proc/root.c [24/43] proc: Add fs_context support to procfs [25/43] ipc: Convert mqueue fs to fs_context [26/43] cgroup: start switching to fs_context [27/43] cgroup: fold cgroup1_mount() into cgroup1_get_tree() [28/43] cgroup: take options parsing into ->parse_monolithic() [29/43] cgroup1: switch to option-by-option parsing [30/43] cgroup2: switch to option-by-option parsing [31/43] cgroup: stash cgroup_root reference into cgroup_fs_context [32/43] cgroup_do_mount(): massage calling conventions [33/43] cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper [34/43] cgroup: store a reference to cgroup_ns into cgroup_fs_context [35/43] kernfs, sysfs, cgroup, intel_rdt: Support fs_context [36/43] cpuset: Use fs_context [37/43] hugetlbfs: Convert to fs_context [38/43] vfs: Remove kern_mount_data() [39/43] vfs: Provide documentation for new mount API [40/43] vfs: Implement logging through fs_context [41/43] vfs: Add some logging to the core users of the fs_context log [42/43] afs: Add fs_context support [43/43] afs: Use fs_context to pass parameters over automount

diff --git a/fs/filesystems.c b/fs/filesystems.c index b03f57b1105b..9135646e41ac 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -16,6 +16,7 @@ #include <linux/module.h> #include <linux/slab.h> #include <linux/uaccess.h> +#include <linux/fs_parser.h> /* * Handling of filesystem drivers list. @@ -73,6 +74,9 @@ int register_filesystem(struct file_system_type * fs) int res = 0; struct file_system_type ** p; + if (fs->parameters && !fs_validate_description(fs->parameters)) + return -EINVAL; + BUG_ON(strchr(fs->name, '.')); if (fs->next) return -EBUSY; diff --git a/fs/fs_context.c b/fs/fs_context.c index 825d1b2c8807..aa7e0ffb591a 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -12,6 +12,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/fs_context.h> +#include <linux/fs_parser.h> #include <linux/fs.h> #include <linux/mount.h> #include <linux/nsproxy.h> @@ -25,13 +26,217 @@ #include "mount.h" #include "internal.h" +enum legacy_fs_param { + LEGACY_FS_UNSET_PARAMS, + LEGACY_FS_MONOLITHIC_PARAMS, + LEGACY_FS_INDIVIDUAL_PARAMS, +}; + struct legacy_fs_context { char *legacy_data; /* Data page for legacy filesystems */ size_t data_size; + enum legacy_fs_param param_type; }; static int legacy_init_fs_context(struct fs_context *fc); +static const struct constant_table common_set_sb_flag[] = { + { "dirsync", SB_DIRSYNC }, + { "lazytime", SB_LAZYTIME }, + { "mand", SB_MANDLOCK }, + { "posixacl", SB_POSIXACL }, + { "ro", SB_RDONLY }, + { "sync", SB_SYNCHRONOUS }, +}; + +static const struct constant_table common_clear_sb_flag[] = { + { "async", SB_SYNCHRONOUS }, + { "nolazytime", SB_LAZYTIME }, + { "nomand", SB_MANDLOCK }, + { "rw", SB_RDONLY }, + { "silent", SB_SILENT }, +}; + +static const char *const forbidden_sb_flag[] = { + "bind", + "dev", + "exec", + "move", + "noatime", + "nodev", + "nodiratime", + "noexec", + "norelatime", + "nostrictatime", + "nosuid", + "private", + "rec", + "relatime", + "remount", + "shared", + "slave", + "strictatime", + "suid", + "unbindable", +}; + +/* + * Check for a common mount option that manipulates s_flags. + */ +static int vfs_parse_sb_flag(struct fs_context *fc, const char *key) +{ + unsigned int token; + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++) + if (strcmp(key, forbidden_sb_flag[i]) == 0) + return -EINVAL; + + token = lookup_constant(common_set_sb_flag, key, 0); + if (token) { + fc->sb_flags |= token; + fc->sb_flags_mask |= token; + return 0; + } + + token = lookup_constant(common_clear_sb_flag, key, 0); + if (token) { + fc->sb_flags &= ~token; + fc->sb_flags_mask |= token; + return 0; + } + + return -ENOPARAM; +} + +/** + * vfs_parse_fs_param - Add a single parameter to a superblock config + * @fc: The filesystem context to modify + * @param: The parameter + * + * A single mount option in string form is applied to the filesystem context + * being set up. Certain standard options (for example "ro") are translated + * into flag bits without going to the filesystem. The active security module + * is allowed to observe and poach options. Any other options are passed over + * to the filesystem to parse. + * + * This may be called multiple times for a context. + * + * Returns 0 on success and a negative error code on failure. In the event of + * failure, supplementary error information may have been set. + */ +int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param) +{ + int ret; + + if (!param->key) + return invalf(fc, "Unnamed parameter\n"); + + ret = vfs_parse_sb_flag(fc, param->key); + if (ret != -ENOPARAM) + return ret; + + ret = security_fs_context_parse_param(fc, param); + if (ret != -ENOPARAM) + /* Param belongs to the LSM or is disallowed by the LSM; so + * don't pass to the FS. + */ + return ret; + + if (fc->ops->parse_param) { + ret = fc->ops->parse_param(fc, param); + if (ret != -ENOPARAM) + return ret; + } + + /* If the filesystem doesn't take any arguments, give it the + * default handling of source. + */ + if (strcmp(param->key, "source") == 0) { + if (param->type != fs_value_is_string) + return invalf(fc, "VFS: Non-string source"); + if (fc->source) + return invalf(fc, "VFS: Multiple sources"); + fc->source = param->string; + param->string = NULL; + return 0; + } + + return invalf(fc, "%s: Unknown parameter '%s'", + fc->fs_type->name, param->key); +} +EXPORT_SYMBOL(vfs_parse_fs_param); + +/** + * vfs_parse_fs_string - Convenience function to just parse a string. + */ +int vfs_parse_fs_string(struct fs_context *fc, const char *key, + const char *value, size_t v_size) +{ + int ret; + + struct fs_parameter param = { + .key = key, + .type = fs_value_is_string, + .size = v_size, + }; + + if (v_size > 0) { + param.string = kmemdup_nul(value, v_size, GFP_KERNEL); + if (!param.string) + return -ENOMEM; + } + + ret = vfs_parse_fs_param(fc, &param); + kfree(param.string); + return ret; +} +EXPORT_SYMBOL(vfs_parse_fs_string); + +/** + * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data + * @ctx: The superblock configuration to fill in. + * @data: The data to parse + * + * Parse a blob of data that's in key[=val][,key[=val]]* form. This can be + * called from the ->monolithic_mount_data() fs_context operation. + * + * Returns 0 on success or the error returned by the ->parse_option() fs_context + * operation on failure. + */ +int generic_parse_monolithic(struct fs_context *fc, void *data) +{ + char *options = data, *key; + int ret = 0; + + if (!options) + return 0; + + ret = security_sb_eat_lsm_opts(options, &fc->security); + if (ret) + return ret; + + while ((key = strsep(&options, ",")) != NULL) { + if (*key) { + size_t v_len = 0; + char *value = strchr(key, '='); + + if (value) { + if (value == key) + continue; + *value++ = 0; + v_len = strlen(value); + } + ret = vfs_parse_fs_string(fc, key, value, v_len); + if (ret < 0) + break; + } + } + + return ret; +} +EXPORT_SYMBOL(generic_parse_monolithic); + /** * alloc_fs_context - Create a filesystem context. * @fs_type: The filesystem type. @@ -166,7 +371,87 @@ EXPORT_SYMBOL(put_fs_context); */ static void legacy_fs_context_free(struct fs_context *fc) { - kfree(fc->fs_private); + struct legacy_fs_context *ctx = fc->fs_private; + + if (ctx) { + if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) + kfree(ctx->legacy_data); + kfree(ctx); + } +} + +/* + * Add a parameter to a legacy config. We build up a comma-separated list of + * options. + */ +static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + struct legacy_fs_context *ctx = fc->fs_private; + unsigned int size = ctx->data_size; + size_t len = 0; + + if (strcmp(param->key, "source") == 0) { + if (param->type != fs_value_is_string) + return invalf(fc, "VFS: Legacy: Non-string source"); + if (fc->source) + return invalf(fc, "VFS: Legacy: Multiple sources"); + fc->source = param->string; + param->string = NULL; + return 0; + } + + if ((fc->fs_type->fs_flags & FS_HAS_SUBTYPE) && + strcmp(param->key, "subtype") == 0) { + if (param->type != fs_value_is_string) + return invalf(fc, "VFS: Legacy: Non-string subtype"); + if (fc->subtype) + return invalf(fc, "VFS: Legacy: Multiple subtype"); + fc->subtype = param->string; + param->string = NULL; + return 0; + } + + if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS) + return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options"); + + switch (param->type) { + case fs_value_is_string: + len = 1 + param->size; + /* Fall through */ + case fs_value_is_flag: + len += strlen(param->key); + break; + default: + return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported", + param->key); + } + + if (len > PAGE_SIZE - 2 - size) + return invalf(fc, "VFS: Legacy: Cumulative options too large"); + if (strchr(param->key, ',') || + (param->type == fs_value_is_string && + memchr(param->string, ',', param->size))) + return invalf(fc, "VFS: Legacy: Option '%s' contained comma", + param->key); + if (!ctx->legacy_data) { + ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!ctx->legacy_data) + return -ENOMEM; + } + + ctx->legacy_data[size++] = ','; + len = strlen(param->key); + memcpy(ctx->legacy_data + size, param->key, len); + size += len; + if (param->type == fs_value_is_string) { + ctx->legacy_data[size++] = '='; + memcpy(ctx->legacy_data + size, param->string, param->size); + size += param->size; + } + ctx->legacy_data[size] = '\0'; + ctx->data_size = size; + ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS; + return 0; } /* @@ -175,9 +460,17 @@ static void legacy_fs_context_free(struct fs_context *fc) static int legacy_parse_monolithic(struct fs_context *fc, void *data) { struct legacy_fs_context *ctx = fc->fs_private; + + if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) { + pr_warn("VFS: Can't mix monolithic and individual options\n"); + return -EINVAL; + } + ctx->legacy_data = data; + ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS; if (!ctx->legacy_data) return 0; + if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA) return 0; return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security); @@ -221,6 +514,7 @@ static int legacy_reconfigure(struct fs_context *fc) const struct fs_context_operations legacy_fs_context_ops = { .free = legacy_fs_context_free, + .parse_param = legacy_parse_param, .parse_monolithic = legacy_parse_monolithic, .get_tree = legacy_get_tree, .reconfigure = legacy_reconfigure, @@ -242,6 +536,10 @@ static int legacy_init_fs_context(struct fs_context *fc) int parse_monolithic_mount_data(struct fs_context *fc, void *data) { int (*monolithic_mount_data)(struct fs_context *, void *); + monolithic_mount_data = fc->ops->parse_monolithic; + if (!monolithic_mount_data) + monolithic_mount_data = generic_parse_monolithic; + return monolithic_mount_data(fc, data); } diff --git a/fs/namespace.c b/fs/namespace.c index 931228d8518a..1a1ed2528f47 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -997,17 +997,15 @@ struct vfsmount *vfs_kern_mount(struct file_system_type *type, int ret = 0; if (!type) - return ERR_PTR(-ENODEV); + return ERR_PTR(-EINVAL); fc = fs_context_for_mount(type, flags); if (IS_ERR(fc)) return ERR_CAST(fc); - if (name) { - fc->source = kstrdup(name, GFP_KERNEL); - if (!fc->source) - ret = -ENOMEM; - } + if (name) + ret = vfs_parse_fs_string(fc, "source", + name, strlen(name)); if (!ret) ret = parse_monolithic_mount_data(fc, data); if (!ret) @@ -2611,16 +2609,11 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, if (IS_ERR(fc)) return PTR_ERR(fc); - if (subtype) { - fc->subtype = kstrdup(subtype, GFP_KERNEL); - if (!fc->subtype) - err = -ENOMEM; - } - if (!err && name) { - fc->source = kstrdup(name, GFP_KERNEL); - if (!fc->source) - err = -ENOMEM; - } + if (subtype) + err = vfs_parse_fs_string(fc, "subtype", + subtype, strlen(subtype)); + if (!err && name) + err = vfs_parse_fs_string(fc, "source", name, strlen(name)); if (!err) err = parse_monolithic_mount_data(fc, data); if (!err) diff --git a/include/linux/fs.h b/include/linux/fs.h index 8d578a9e1e8c..cf6e9ea161eb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -62,6 +62,7 @@ struct iov_iter; struct fscrypt_info; struct fscrypt_operations; struct fs_context; +struct fs_parameter_description; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -2175,6 +2176,7 @@ struct file_system_type { #define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */ #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */ int (*init_fs_context)(struct fs_context *); + const struct fs_parameter_description *parameters; struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); void (*kill_sb) (struct super_block *); diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h index d5ff3b0bc28d..d794b04e9fbb 100644 --- a/include/linux/fs_context.h +++ b/include/linux/fs_context.h @@ -92,6 +92,7 @@ struct fs_context { struct fs_context_operations { void (*free)(struct fs_context *fc); + int (*parse_param)(struct fs_context *fc, struct fs_parameter *param); int (*parse_monolithic)(struct fs_context *fc, void *data); int (*get_tree)(struct fs_context *fc); int (*reconfigure)(struct fs_context *fc); @@ -108,6 +109,10 @@ extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type, struct dentry *reference); +extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param); +extern int vfs_parse_fs_string(struct fs_context *fc, const char *key, + const char *value, size_t v_size); +extern int generic_parse_monolithic(struct fs_context *fc, void *data); extern int vfs_get_tree(struct fs_context *fc); extern void put_fs_context(struct fs_context *fc);

[20/43] vfs: Implement a filesystem superblock creation/configuration context

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