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authorNamjae Jeon <linkinjeon@kernel.org>2023-04-21 16:09:01 +0900
committerSteve French <stfrench@microsoft.com>2023-04-24 00:09:20 -0500
commit74d7970febf7e9005375aeda0df821d2edffc9f7 (patch)
tree0f4dbbd9bb7a756397c8b33d17b6066200b17fc8 /fs/namei.c
parentaf36c51e0e111de4e908328d49cba49de758f66e (diff)
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 <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c57
1 files changed, 45 insertions, 12 deletions
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);
@@ -2600,6 +2612,24 @@ 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
* @mnt: pointer to vfs mount 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;