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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 13/43] introduce fs_context methods From: David Howells 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 16:30:09 +0000 Message-ID: <155059380992.12449.10913805628701754409.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 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 19 Feb 2019 16:30:12 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: From: Al Viro Signed-off-by: Al Viro --- fs/fs_context.c | 28 ++++++++++++++++++++++------ fs/internal.h | 2 -- fs/super.c | 36 ++++++++++++++++++++++++++++-------- include/linux/fs.h | 2 ++ include/linux/fs_context.h | 13 +++++++++++++ 5 files changed, 65 insertions(+), 16 deletions(-) diff --git a/fs/fs_context.c b/fs/fs_context.c index 2bd652b6e848..825d1b2c8807 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -51,6 +51,7 @@ static struct fs_context *alloc_fs_context(struct file_system_type *fs_type, unsigned int sb_flags_mask, enum fs_context_purpose purpose) { + int (*init_fs_context)(struct fs_context *); struct fs_context *fc; int ret = -ENOMEM; @@ -81,7 +82,12 @@ static struct fs_context *alloc_fs_context(struct file_system_type *fs_type, break; } - ret = legacy_init_fs_context(fc); + /* TODO: Make all filesystems support this unconditionally */ + init_fs_context = fc->fs_type->init_fs_context; + if (!init_fs_context) + init_fs_context = legacy_init_fs_context; + + ret = init_fs_context(fc); if (ret < 0) goto err_fc; fc->need_free = true; @@ -141,8 +147,8 @@ void put_fs_context(struct fs_context *fc) deactivate_super(sb); } - if (fc->need_free) - legacy_fs_context_free(fc); + if (fc->need_free && fc->ops && fc->ops->free) + fc->ops->free(fc); security_free_mnt_opts(&fc->security); put_net(fc->net_ns); @@ -180,7 +186,7 @@ static int legacy_parse_monolithic(struct fs_context *fc, void *data) /* * Get a mountable root with the legacy mount command. */ -int legacy_get_tree(struct fs_context *fc) +static int legacy_get_tree(struct fs_context *fc) { struct legacy_fs_context *ctx = fc->fs_private; struct super_block *sb; @@ -201,7 +207,7 @@ int legacy_get_tree(struct fs_context *fc) /* * Handle remount. */ -int legacy_reconfigure(struct fs_context *fc) +static int legacy_reconfigure(struct fs_context *fc) { struct legacy_fs_context *ctx = fc->fs_private; struct super_block *sb = fc->root->d_sb; @@ -213,6 +219,13 @@ int legacy_reconfigure(struct fs_context *fc) ctx ? ctx->legacy_data : NULL); } +const struct fs_context_operations legacy_fs_context_ops = { + .free = legacy_fs_context_free, + .parse_monolithic = legacy_parse_monolithic, + .get_tree = legacy_get_tree, + .reconfigure = legacy_reconfigure, +}; + /* * Initialise a legacy context for a filesystem that doesn't support * fs_context. @@ -222,10 +235,13 @@ static int legacy_init_fs_context(struct fs_context *fc) fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL); if (!fc->fs_private) return -ENOMEM; + fc->ops = &legacy_fs_context_ops; return 0; } int parse_monolithic_mount_data(struct fs_context *fc, void *data) { - return legacy_parse_monolithic(fc, data); + int (*monolithic_mount_data)(struct fs_context *, void *); + monolithic_mount_data = fc->ops->parse_monolithic; + return monolithic_mount_data(fc, data); } diff --git a/fs/internal.h b/fs/internal.h index 016a5b8dd305..8f8d07cc433f 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -55,8 +55,6 @@ extern void __init chrdev_init(void); /* * fs_context.c */ -extern int legacy_get_tree(struct fs_context *fc); -extern int legacy_reconfigure(struct fs_context *fc); extern int parse_monolithic_mount_data(struct fs_context *, void *); extern void fc_drop_locked(struct fs_context *); diff --git a/fs/super.c b/fs/super.c index 50553233dd15..76b3181c782d 100644 --- a/fs/super.c +++ b/fs/super.c @@ -894,13 +894,15 @@ int reconfigure_super(struct fs_context *fc) } } - retval = legacy_reconfigure(fc); - if (retval) { - if (!force) - goto cancel_readonly; - /* If forced remount, go ahead despite any errors */ - WARN(1, "forced remount of a %s fs returned %i\n", - sb->s_type->name, retval); + if (fc->ops->reconfigure) { + retval = fc->ops->reconfigure(fc); + if (retval) { + if (!force) + goto cancel_readonly; + /* If forced remount, go ahead despite any errors */ + WARN(1, "forced remount of a %s fs returned %i\n", + sb->s_type->name, retval); + } } WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) | @@ -1294,10 +1296,28 @@ int vfs_get_tree(struct fs_context *fc) struct super_block *sb; int error; - error = legacy_get_tree(fc); + if (fc->fs_type->fs_flags & FS_REQUIRES_DEV && !fc->source) + return -ENOENT; + + if (fc->root) + return -EBUSY; + + /* Get the mountable root in fc->root, with a ref on the root and a ref + * on the superblock. + */ + error = fc->ops->get_tree(fc); if (error < 0) return error; + if (!fc->root) { + pr_err("Filesystem %s get_tree() didn't set fc->root\n", + fc->fs_type->name); + /* We don't know what the locking state of the superblock is - + * if there is a superblock. + */ + BUG(); + } + sb = fc->root->d_sb; WARN_ON(!sb->s_bdi); diff --git a/include/linux/fs.h b/include/linux/fs.h index c65d02c5c512..8d578a9e1e8c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -61,6 +61,7 @@ struct workqueue_struct; struct iov_iter; struct fscrypt_info; struct fscrypt_operations; +struct fs_context; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -2173,6 +2174,7 @@ struct file_system_type { #define FS_HAS_SUBTYPE 4 #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 *); 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 7feb018c7a9e..087c12954360 100644 --- a/include/linux/fs_context.h +++ b/include/linux/fs_context.h @@ -20,8 +20,13 @@ struct cred; struct dentry; struct file_operations; struct file_system_type; +struct mnt_namespace; struct net; +struct pid_namespace; +struct super_block; struct user_namespace; +struct vfsmount; +struct path; enum fs_context_purpose { FS_CONTEXT_FOR_MOUNT, /* New superblock for explicit mount */ @@ -39,6 +44,7 @@ enum fs_context_purpose { * See Documentation/filesystems/mounting.txt */ struct fs_context { + const struct fs_context_operations *ops; struct file_system_type *fs_type; void *fs_private; /* The filesystem's context */ struct dentry *root; /* The root and superblock */ @@ -54,6 +60,13 @@ struct fs_context { bool need_free:1; /* Need to call ops->free() */ }; +struct fs_context_operations { + void (*free)(struct fs_context *fc); + int (*parse_monolithic)(struct fs_context *fc, void *data); + int (*get_tree)(struct fs_context *fc); + int (*reconfigure)(struct fs_context *fc); +}; + /* * fs_context manipulation functions. */