From: NeilBrown <[email protected]> This requires the addition of start_creating_dentry() which is given the dentry which has already been found, and asks for it to be locked and its parent validated.
Reviewed-by: Amir Goldstein <[email protected]> Signed-off-by: NeilBrown <[email protected]> --- fs/ecryptfs/inode.c | 153 ++++++++++++++++++++---------------------- fs/namei.c | 33 +++++++++ include/linux/namei.h | 2 + 3 files changed, 107 insertions(+), 81 deletions(-) diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index ed1394da8d6b..b3702105d236 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -24,18 +24,26 @@ #include <linux/unaligned.h> #include "ecryptfs_kernel.h" -static int lock_parent(struct dentry *dentry, - struct dentry **lower_dentry, - struct inode **lower_dir) +static struct dentry *ecryptfs_start_creating_dentry(struct dentry *dentry) { - struct dentry *lower_dir_dentry; + struct dentry *parent = dget_parent(dentry->d_parent); + struct dentry *ret; - lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent); - *lower_dir = d_inode(lower_dir_dentry); - *lower_dentry = ecryptfs_dentry_to_lower(dentry); + ret = start_creating_dentry(ecryptfs_dentry_to_lower(parent), + ecryptfs_dentry_to_lower(dentry)); + dput(parent); + return ret; +} - inode_lock_nested(*lower_dir, I_MUTEX_PARENT); - return (*lower_dentry)->d_parent == lower_dir_dentry ? 0 : -EINVAL; +static struct dentry *ecryptfs_start_removing_dentry(struct dentry *dentry) +{ + struct dentry *parent = dget_parent(dentry->d_parent); + struct dentry *ret; + + ret = start_removing_dentry(ecryptfs_dentry_to_lower(parent), + ecryptfs_dentry_to_lower(dentry)); + dput(parent); + return ret; } static int ecryptfs_inode_test(struct inode *inode, void *lower_inode) @@ -141,15 +149,12 @@ static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry, struct inode *lower_dir; int rc; - rc = lock_parent(dentry, &lower_dentry, &lower_dir); - dget(lower_dentry); // don't even try to make the lower negative - if (!rc) { - if (d_unhashed(lower_dentry)) - rc = -EINVAL; - else - rc = vfs_unlink(&nop_mnt_idmap, lower_dir, lower_dentry, - NULL); - } + lower_dentry = ecryptfs_start_removing_dentry(dentry); + if (IS_ERR(lower_dentry)) + return PTR_ERR(lower_dentry); + + lower_dir = lower_dentry->d_parent->d_inode; + rc = vfs_unlink(&nop_mnt_idmap, lower_dir, lower_dentry, NULL); if (rc) { printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc); goto out_unlock; @@ -158,8 +163,7 @@ static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry, set_nlink(inode, ecryptfs_inode_to_lower(inode)->i_nlink); inode_set_ctime_to_ts(inode, inode_get_ctime(dir)); out_unlock: - dput(lower_dentry); - inode_unlock(lower_dir); + end_removing(lower_dentry); if (!rc) d_drop(dentry); return rc; @@ -186,10 +190,12 @@ ecryptfs_do_create(struct inode *directory_inode, struct inode *lower_dir; struct inode *inode; - rc = lock_parent(ecryptfs_dentry, &lower_dentry, &lower_dir); - if (!rc) - rc = vfs_create(&nop_mnt_idmap, lower_dir, - lower_dentry, mode, true); + lower_dentry = ecryptfs_start_creating_dentry(ecryptfs_dentry); + if (IS_ERR(lower_dentry)) + return ERR_CAST(lower_dentry); + lower_dir = lower_dentry->d_parent->d_inode; + rc = vfs_create(&nop_mnt_idmap, lower_dir, + lower_dentry, mode, true); if (rc) { printk(KERN_ERR "%s: Failure to create dentry in lower fs; " "rc = [%d]\n", __func__, rc); @@ -205,7 +211,7 @@ ecryptfs_do_create(struct inode *directory_inode, fsstack_copy_attr_times(directory_inode, lower_dir); fsstack_copy_inode_size(directory_inode, lower_dir); out_lock: - inode_unlock(lower_dir); + end_creating(lower_dentry, NULL); return inode; } @@ -433,10 +439,12 @@ static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir, file_size_save = i_size_read(d_inode(old_dentry)); lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry); - rc = lock_parent(new_dentry, &lower_new_dentry, &lower_dir); - if (!rc) - rc = vfs_link(lower_old_dentry, &nop_mnt_idmap, lower_dir, - lower_new_dentry, NULL); + lower_new_dentry = ecryptfs_start_creating_dentry(new_dentry); + if (IS_ERR(lower_new_dentry)) + return PTR_ERR(lower_new_dentry); + lower_dir = lower_new_dentry->d_parent->d_inode; + rc = vfs_link(lower_old_dentry, &nop_mnt_idmap, lower_dir, + lower_new_dentry, NULL); if (rc || d_really_is_negative(lower_new_dentry)) goto out_lock; rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb); @@ -448,7 +456,7 @@ static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir, ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink); i_size_write(d_inode(new_dentry), file_size_save); out_lock: - inode_unlock(lower_dir); + end_creating(lower_new_dentry, NULL); return rc; } @@ -468,9 +476,11 @@ static int ecryptfs_symlink(struct mnt_idmap *idmap, size_t encoded_symlen; struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL; - rc = lock_parent(dentry, &lower_dentry, &lower_dir); - if (rc) - goto out_lock; + lower_dentry = ecryptfs_start_creating_dentry(dentry); + if (IS_ERR(lower_dentry)) + return PTR_ERR(lower_dentry); + lower_dir = lower_dentry->d_parent->d_inode; + mount_crypt_stat = &ecryptfs_superblock_to_private( dir->i_sb)->mount_crypt_stat; rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname, @@ -490,7 +500,7 @@ static int ecryptfs_symlink(struct mnt_idmap *idmap, fsstack_copy_attr_times(dir, lower_dir); fsstack_copy_inode_size(dir, lower_dir); out_lock: - inode_unlock(lower_dir); + end_creating(lower_dentry, NULL); if (d_really_is_negative(dentry)) d_drop(dentry); return rc; @@ -501,12 +511,14 @@ static struct dentry *ecryptfs_mkdir(struct mnt_idmap *idmap, struct inode *dir, { int rc; struct dentry *lower_dentry; + struct dentry *lower_dir_dentry; struct inode *lower_dir; - rc = lock_parent(dentry, &lower_dentry, &lower_dir); - if (rc) - goto out; - + lower_dentry = ecryptfs_start_creating_dentry(dentry); + if (IS_ERR(lower_dentry)) + return lower_dentry; + lower_dir_dentry = dget(lower_dentry->d_parent); + lower_dir = lower_dir_dentry->d_inode; lower_dentry = vfs_mkdir(&nop_mnt_idmap, lower_dir, lower_dentry, mode); rc = PTR_ERR(lower_dentry); @@ -522,7 +534,7 @@ static struct dentry *ecryptfs_mkdir(struct mnt_idmap *idmap, struct inode *dir, fsstack_copy_inode_size(dir, lower_dir); set_nlink(dir, lower_dir->i_nlink); out: - inode_unlock(lower_dir); + end_creating(lower_dentry, lower_dir_dentry); if (d_really_is_negative(dentry)) d_drop(dentry); return ERR_PTR(rc); @@ -534,21 +546,18 @@ static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry) struct inode *lower_dir; int rc; - rc = lock_parent(dentry, &lower_dentry, &lower_dir); - dget(lower_dentry); // don't even try to make the lower negative - if (!rc) { - if (d_unhashed(lower_dentry)) - rc = -EINVAL; - else - rc = vfs_rmdir(&nop_mnt_idmap, lower_dir, lower_dentry); - } + lower_dentry = ecryptfs_start_removing_dentry(dentry); + if (IS_ERR(lower_dentry)) + return PTR_ERR(lower_dentry); + lower_dir = lower_dentry->d_parent->d_inode; + + rc = vfs_rmdir(&nop_mnt_idmap, lower_dir, lower_dentry); if (!rc) { clear_nlink(d_inode(dentry)); fsstack_copy_attr_times(dir, lower_dir); set_nlink(dir, lower_dir->i_nlink); } - dput(lower_dentry); - inode_unlock(lower_dir); + end_removing(lower_dentry); if (!rc) d_drop(dentry); return rc; @@ -562,10 +571,12 @@ ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir, struct dentry *lower_dentry; struct inode *lower_dir; - rc = lock_parent(dentry, &lower_dentry, &lower_dir); - if (!rc) - rc = vfs_mknod(&nop_mnt_idmap, lower_dir, - lower_dentry, mode, dev); + lower_dentry = ecryptfs_start_creating_dentry(dentry); + if (IS_ERR(lower_dentry)) + return PTR_ERR(lower_dentry); + lower_dir = lower_dentry->d_parent->d_inode; + + rc = vfs_mknod(&nop_mnt_idmap, lower_dir, lower_dentry, mode, dev); if (rc || d_really_is_negative(lower_dentry)) goto out; rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb); @@ -574,7 +585,7 @@ ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir, fsstack_copy_attr_times(dir, lower_dir); fsstack_copy_inode_size(dir, lower_dir); out: - inode_unlock(lower_dir); + end_removing(lower_dentry); if (d_really_is_negative(dentry)) d_drop(dentry); return rc; @@ -590,7 +601,6 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir, struct dentry *lower_new_dentry; struct dentry *lower_old_dir_dentry; struct dentry *lower_new_dir_dentry; - struct dentry *trap; struct inode *target_inode; struct renamedata rd = {}; @@ -605,31 +615,13 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir, target_inode = d_inode(new_dentry); - trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry); - if (IS_ERR(trap)) - return PTR_ERR(trap); - dget(lower_new_dentry); - rc = -EINVAL; - if (lower_old_dentry->d_parent != lower_old_dir_dentry) - goto out_lock; - if (lower_new_dentry->d_parent != lower_new_dir_dentry) - goto out_lock; - if (d_unhashed(lower_old_dentry) || d_unhashed(lower_new_dentry)) - goto out_lock; - /* source should not be ancestor of target */ - if (trap == lower_old_dentry) - goto out_lock; - /* target should not be ancestor of source */ - if (trap == lower_new_dentry) { - rc = -ENOTEMPTY; - goto out_lock; - } + rd.mnt_idmap = &nop_mnt_idmap; + rd.old_parent = lower_old_dir_dentry; + rd.new_parent = lower_new_dir_dentry; + rc = start_renaming_two_dentries(&rd, lower_old_dentry, lower_new_dentry); + if (rc) + return rc; - rd.mnt_idmap = &nop_mnt_idmap; - rd.old_parent = lower_old_dir_dentry; - rd.old_dentry = lower_old_dentry; - rd.new_parent = lower_new_dir_dentry; - rd.new_dentry = lower_new_dentry; rc = vfs_rename(&rd); if (rc) goto out_lock; @@ -640,8 +632,7 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir, if (new_dir != old_dir) fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry)); out_lock: - dput(lower_new_dentry); - unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry); + end_renaming(&rd); return rc; } diff --git a/fs/namei.c b/fs/namei.c index 4a4b8b96c192..8b7807cd1343 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3397,6 +3397,39 @@ struct dentry *start_removing_noperm(struct dentry *parent, } EXPORT_SYMBOL(start_removing_noperm); +/** + * start_creating_dentry - prepare to create a given dentry + * @parent: directory from which dentry should be removed + * @child: the dentry to be removed + * + * A lock is taken to protect the dentry again other dirops and + * the validity of the dentry is checked: correct parent and still hashed. + * + * If the dentry is valid and negative a reference is taken and + * returned. If not an error is returned. + * + * end_creating() should be called when creation is complete, or aborted. + * + * Returns: the valid dentry, or an error. + */ +struct dentry *start_creating_dentry(struct dentry *parent, + struct dentry *child) +{ + inode_lock_nested(parent->d_inode, I_MUTEX_PARENT); + if (unlikely(IS_DEADDIR(parent->d_inode) || + child->d_parent != parent || + d_unhashed(child))) { + inode_unlock(parent->d_inode); + return ERR_PTR(-EINVAL); + } + if (d_is_positive(child)) { + inode_unlock(parent->d_inode); + return ERR_PTR(-EEXIST); + } + return dget(child); +} +EXPORT_SYMBOL(start_creating_dentry); + /** * start_removing_dentry - prepare to remove a given dentry * @parent: directory from which dentry should be removed diff --git a/include/linux/namei.h b/include/linux/namei.h index a99ac8b7e24a..208aed1d6728 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -100,6 +100,8 @@ struct dentry *start_removing_killable(struct mnt_idmap *idmap, struct qstr *name); struct dentry *start_creating_noperm(struct dentry *parent, struct qstr *name); struct dentry *start_removing_noperm(struct dentry *parent, struct qstr *name); +struct dentry *start_creating_dentry(struct dentry *parent, + struct dentry *child); struct dentry *start_removing_dentry(struct dentry *parent, struct dentry *child); -- 2.50.0.107.gf914562f5916.dirty
