From 74d7970febf7e9005375aeda0df821d2edffc9f7 Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Fri, 21 Apr 2023 16:09:01 +0900 Subject: ksmbd: fix racy issue from using ->d_parent and ->d_name Al pointed out that ksmbd has racy issue from using ->d_parent and ->d_name in ksmbd_vfs_unlink and smb2_vfs_rename(). and use new lock_rename_child() to lock stable parent while underlying rename racy. Introduce vfs_path_parent_lookup helper to avoid out of share access and export vfs functions like the following ones to use vfs_path_parent_lookup(). - rename __lookup_hash() to lookup_one_qstr_excl(). - export lookup_one_qstr_excl(). - export getname_kernel() and putname(). vfs_path_parent_lookup() is used for parent lookup of destination file using absolute pathname given from FILE_RENAME_INFORMATION request. Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- fs/namei.c | 57 +++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 45 insertions(+), 12 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 6bc1964e2214..c1d59ae5af83 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -254,6 +254,7 @@ getname_kernel(const char * filename) return result; } +EXPORT_SYMBOL(getname_kernel); void putname(struct filename *name) { @@ -271,6 +272,7 @@ void putname(struct filename *name) } else __putname(name); } +EXPORT_SYMBOL(putname); /** * check_acl - perform ACL permission checking @@ -1581,8 +1583,9 @@ static struct dentry *lookup_dcache(const struct qstr *name, * when directory is guaranteed to have no in-lookup children * at all. */ -static struct dentry *__lookup_hash(const struct qstr *name, - struct dentry *base, unsigned int flags) +struct dentry *lookup_one_qstr_excl(const struct qstr *name, + struct dentry *base, + unsigned int flags) { struct dentry *dentry = lookup_dcache(name, base, flags); struct dentry *old; @@ -1606,6 +1609,7 @@ static struct dentry *__lookup_hash(const struct qstr *name, } return dentry; } +EXPORT_SYMBOL(lookup_one_qstr_excl); static struct dentry *lookup_fast(struct nameidata *nd) { @@ -2532,16 +2536,17 @@ static int path_parentat(struct nameidata *nd, unsigned flags, } /* Note: this does not consume "name" */ -static int filename_parentat(int dfd, struct filename *name, - unsigned int flags, struct path *parent, - struct qstr *last, int *type) +static int __filename_parentat(int dfd, struct filename *name, + unsigned int flags, struct path *parent, + struct qstr *last, int *type, + const struct path *root) { int retval; struct nameidata nd; if (IS_ERR(name)) return PTR_ERR(name); - set_nameidata(&nd, dfd, name, NULL); + set_nameidata(&nd, dfd, name, root); retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); if (unlikely(retval == -ECHILD)) retval = path_parentat(&nd, flags, parent); @@ -2556,6 +2561,13 @@ static int filename_parentat(int dfd, struct filename *name, return retval; } +static int filename_parentat(int dfd, struct filename *name, + unsigned int flags, struct path *parent, + struct qstr *last, int *type) +{ + return __filename_parentat(dfd, name, flags, parent, last, type, NULL); +} + /* does lookup, returns the object with parent locked */ static struct dentry *__kern_path_locked(struct filename *name, struct path *path) { @@ -2571,7 +2583,7 @@ static struct dentry *__kern_path_locked(struct filename *name, struct path *pat return ERR_PTR(-EINVAL); } inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); - d = __lookup_hash(&last, path->dentry, 0); + d = lookup_one_qstr_excl(&last, path->dentry, 0); if (IS_ERR(d)) { inode_unlock(path->dentry->d_inode); path_put(path); @@ -2599,6 +2611,24 @@ int kern_path(const char *name, unsigned int flags, struct path *path) } EXPORT_SYMBOL(kern_path); +/** + * vfs_path_parent_lookup - lookup a parent path relative to a dentry-vfsmount pair + * @filename: filename structure + * @flags: lookup flags + * @parent: pointer to struct path to fill + * @last: last component + * @type: type of the last component + * @root: pointer to struct path of the base directory + */ +int vfs_path_parent_lookup(struct filename *filename, unsigned int flags, + struct path *parent, struct qstr *last, int *type, + const struct path *root) +{ + return __filename_parentat(AT_FDCWD, filename, flags, parent, last, + type, root); +} +EXPORT_SYMBOL(vfs_path_parent_lookup); + /** * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair * @dentry: pointer to dentry of the base directory @@ -3852,7 +3882,8 @@ static struct dentry *filename_create(int dfd, struct filename *name, if (last.name[last.len] && !want_dir) create_flags = 0; inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); - dentry = __lookup_hash(&last, path->dentry, reval_flag | create_flags); + dentry = lookup_one_qstr_excl(&last, path->dentry, + reval_flag | create_flags); if (IS_ERR(dentry)) goto unlock; @@ -4212,7 +4243,7 @@ retry: goto exit2; inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); - dentry = __lookup_hash(&last, path.dentry, lookup_flags); + dentry = lookup_one_qstr_excl(&last, path.dentry, lookup_flags); error = PTR_ERR(dentry); if (IS_ERR(dentry)) goto exit3; @@ -4345,7 +4376,7 @@ retry: goto exit2; retry_deleg: inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); - dentry = __lookup_hash(&last, path.dentry, lookup_flags); + dentry = lookup_one_qstr_excl(&last, path.dentry, lookup_flags); error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { @@ -4909,7 +4940,8 @@ retry: retry_deleg: trap = lock_rename(new_path.dentry, old_path.dentry); - old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); + old_dentry = lookup_one_qstr_excl(&old_last, old_path.dentry, + lookup_flags); error = PTR_ERR(old_dentry); if (IS_ERR(old_dentry)) goto exit3; @@ -4917,7 +4949,8 @@ retry_deleg: error = -ENOENT; if (d_is_negative(old_dentry)) goto exit4; - new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); + new_dentry = lookup_one_qstr_excl(&new_last, new_path.dentry, + lookup_flags | target_flags); error = PTR_ERR(new_dentry); if (IS_ERR(new_dentry)) goto exit4; -- cgit