diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 119 |
1 files changed, 75 insertions, 44 deletions
diff --git a/fs/namei.c b/fs/namei.c index 71c13b2990b4..5c318d657503 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -289,7 +289,7 @@ EXPORT_SYMBOL(putname); * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ static int check_acl(struct mnt_idmap *idmap, struct inode *inode, int mask) @@ -334,7 +334,7 @@ static int check_acl(struct mnt_idmap *idmap, * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ static int acl_permission_check(struct mnt_idmap *idmap, struct inode *inode, int mask) @@ -395,7 +395,7 @@ static int acl_permission_check(struct mnt_idmap *idmap, * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int generic_permission(struct mnt_idmap *idmap, struct inode *inode, int mask) @@ -1071,7 +1071,6 @@ static struct ctl_table namei_sysctls[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_TWO, }, - { } }; static int __init init_fs_namei_sysctls(void) @@ -2467,7 +2466,7 @@ static int handle_lookup_down(struct nameidata *nd) return PTR_ERR(step_into(nd, WALK_NOFOLLOW, nd->path.dentry)); } -/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ +/* Returns 0 and nd will be valid on success; Returns error, otherwise. */ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) { const char *s = path_init(nd, flags); @@ -2522,7 +2521,7 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags, return retval; } -/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ +/* Returns 0 and nd will be valid on success; Returns error, otherwise. */ static int path_parentat(struct nameidata *nd, unsigned flags, struct path *parent) { @@ -3014,27 +3013,37 @@ static inline int may_create(struct mnt_idmap *idmap, return inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC); } +// p1 != p2, both are on the same filesystem, ->s_vfs_rename_mutex is held static struct dentry *lock_two_directories(struct dentry *p1, struct dentry *p2) { - struct dentry *p; + struct dentry *p = p1, *q = p2, *r; - p = d_ancestor(p2, p1); - if (p) { + while ((r = p->d_parent) != p2 && r != p) + p = r; + if (r == p2) { + // p is a child of p2 and an ancestor of p1 or p1 itself inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); - inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); + inode_lock_nested(p1->d_inode, I_MUTEX_PARENT2); return p; } - - p = d_ancestor(p1, p2); - if (p) { + // p is the root of connected component that contains p1 + // p2 does not occur on the path from p to p1 + while ((r = q->d_parent) != p1 && r != p && r != q) + q = r; + if (r == p1) { + // q is a child of p1 and an ancestor of p2 or p2 itself inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); - inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); - return p; + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); + return q; + } else if (likely(r == p)) { + // both p2 and p1 are descendents of p + inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); + return NULL; + } else { // no common ancestor at the time we'd been called + mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); + return ERR_PTR(-EXDEV); } - - lock_two_inodes(p1->d_inode, p2->d_inode, - I_MUTEX_PARENT, I_MUTEX_PARENT2); - return NULL; } /* @@ -3158,7 +3167,7 @@ static inline umode_t vfs_prepare_mode(struct mnt_idmap *idmap, * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_create(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, umode_t mode, bool want_excl) @@ -3646,7 +3655,7 @@ static int do_open(struct nameidata *nd, * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ static int vfs_tmpfile(struct mnt_idmap *idmap, const struct path *parentpath, @@ -3785,10 +3794,7 @@ static struct file *path_openat(struct nameidata *nd, WARN_ON(1); error = -EINVAL; } - if (unlikely(file->f_mode & FMODE_OPENED)) - fput(file); - else - release_empty_file(file); + fput(file); if (error == -EOPENSTALE) { if (flags & LOOKUP_RCU) error = -ECHILD; @@ -3954,7 +3960,7 @@ EXPORT_SYMBOL(user_path_create); * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) @@ -4080,7 +4086,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, d * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_mkdir(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, umode_t mode) @@ -4161,7 +4167,7 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry) @@ -4290,7 +4296,7 @@ SYSCALL_DEFINE1(rmdir, const char __user *, pathname) * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_unlink(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) @@ -4443,7 +4449,7 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname) * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_symlink(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, const char *oldname) @@ -4535,7 +4541,7 @@ SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newn * the vfsmount must be passed through @idmap. This function will then take * care to map the inode according to @idmap before checking permissions. * On non-idmapped mounts or if permission checking is to be performed on the - * raw inode simply passs @nop_mnt_idmap. + * raw inode simply pass @nop_mnt_idmap. */ int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap, struct inode *dir, struct dentry *new_dentry, @@ -4716,11 +4722,12 @@ SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname * * a) we can get into loop creation. * b) race potential - two innocent renames can create a loop together. - * That's where 4.4 screws up. Current fix: serialization on + * That's where 4.4BSD screws up. Current fix: serialization on * sb->s_vfs_rename_mutex. We might be more accurate, but that's another * story. - * c) we have to lock _four_ objects - parents and victim (if it exists), - * and source. + * c) we may have to lock up to _four_ objects - parents and victim (if it exists), + * and source (if it's a non-directory or a subdirectory that moves to + * different parent). * And that - after we got ->i_mutex on parents (until then we don't know * whether the target exists). Solution: try to be smart with locking * order for inodes. We rely on the fact that tree topology may change @@ -4752,6 +4759,7 @@ int vfs_rename(struct renamedata *rd) bool new_is_dir = false; unsigned max_links = new_dir->i_sb->s_max_links; struct name_snapshot old_name; + bool lock_old_subdir, lock_new_subdir; if (source == target) return 0; @@ -4805,15 +4813,32 @@ int vfs_rename(struct renamedata *rd) take_dentry_name_snapshot(&old_name, old_dentry); dget(new_dentry); /* - * Lock all moved children. Moved directories may need to change parent - * pointer so they need the lock to prevent against concurrent - * directory changes moving parent pointer. For regular files we've - * historically always done this. The lockdep locking subclasses are - * somewhat arbitrary but RENAME_EXCHANGE in particular can swap - * regular files and directories so it's difficult to tell which - * subclasses to use. + * Lock children. + * The source subdirectory needs to be locked on cross-directory + * rename or cross-directory exchange since its parent changes. + * The target subdirectory needs to be locked on cross-directory + * exchange due to parent change and on any rename due to becoming + * a victim. + * Non-directories need locking in all cases (for NFS reasons); + * they get locked after any subdirectories (in inode address order). + * + * NOTE: WE ONLY LOCK UNRELATED DIRECTORIES IN CROSS-DIRECTORY CASE. + * NEVER, EVER DO THAT WITHOUT ->s_vfs_rename_mutex. */ - lock_two_inodes(source, target, I_MUTEX_NORMAL, I_MUTEX_NONDIR2); + lock_old_subdir = new_dir != old_dir; + lock_new_subdir = new_dir != old_dir || !(flags & RENAME_EXCHANGE); + if (is_dir) { + if (lock_old_subdir) + inode_lock_nested(source, I_MUTEX_CHILD); + if (target && (!new_is_dir || lock_new_subdir)) + inode_lock(target); + } else if (new_is_dir) { + if (lock_new_subdir) + inode_lock_nested(target, I_MUTEX_CHILD); + inode_lock(source); + } else { + lock_two_nondirectories(source, target); + } error = -EPERM; if (IS_SWAPFILE(source) || (target && IS_SWAPFILE(target))) @@ -4861,8 +4886,9 @@ int vfs_rename(struct renamedata *rd) d_exchange(old_dentry, new_dentry); } out: - inode_unlock(source); - if (target) + if (!is_dir || lock_old_subdir) + inode_unlock(source); + if (target && (!new_is_dir || lock_new_subdir)) inode_unlock(target); dput(new_dentry); if (!error) { @@ -4933,6 +4959,10 @@ retry: retry_deleg: trap = lock_rename(new_path.dentry, old_path.dentry); + if (IS_ERR(trap)) { + error = PTR_ERR(trap); + goto exit_lock_rename; + } old_dentry = lookup_one_qstr_excl(&old_last, old_path.dentry, lookup_flags); @@ -5000,6 +5030,7 @@ exit4: dput(old_dentry); exit3: unlock_rename(new_path.dentry, old_path.dentry); +exit_lock_rename: if (delegated_inode) { error = break_deleg_wait(&delegated_inode); if (!error) |