[PATCH 5.15 087/159] ksmbd: fix racy issue from using ->d_parent and ->d_name

20 Dec 2023

5.15-stable review patch.  If anyone has any objections, please let me know.
------------------
From: Namjae Jeon linkinjeon@kernel.org
[ Upstream commit 74d7970febf7e9005375aeda0df821d2edffc9f7 ]
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
Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
---
 fs/ksmbd/smb2pdu.c    |  147 +++-------------
 fs/ksmbd/vfs.c        |  439 +++++++++++++++++++++-----------------------------
 fs/ksmbd/vfs.h        |   19 --
 fs/ksmbd/vfs_cache.c  |    5 
 fs/namei.c            |   57 +++++-
 include/linux/namei.h |    6 
 6 files changed, 285 insertions(+), 388 deletions(-)

--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2456,7 +2456,7 @@ static int smb2_creat(struct ksmbd_work
    		return rc;
    }
-	rc = ksmbd_vfs_kern_path(work, name, 0, path, 0);
+	rc = ksmbd_vfs_kern_path_locked(work, name, 0, path, 0);
    if (rc) {
    	pr_err("cannot get linux path (%s), err = %d\n",
    	       name, rc);
@@ -2744,8 +2744,10 @@ int smb2_open(struct ksmbd_work *work)
    	goto err_out1;
    }
-	rc = ksmbd_vfs_kern_path(work, name, LOOKUP_NO_SYMLINKS, &path, 1);
+	rc = ksmbd_vfs_kern_path_locked(work, name, LOOKUP_NO_SYMLINKS, &path, 1);
    if (!rc) {
+		file_present = true;
+
    	if (req->CreateOptions & FILE_DELETE_ON_CLOSE_LE) {
    		/*
    		 * If file exists with under flags, return access
@@ -2754,7 +2756,6 @@ int smb2_open(struct ksmbd_work *work)
    		if (req->CreateDisposition == FILE_OVERWRITE_IF_LE ||
    		    req->CreateDisposition == FILE_OPEN_IF_LE) {
    			rc = -EACCES;
-				path_put(&path);
    			goto err_out;
    		}
@@ -2762,26 +2763,23 @@ int smb2_open(struct ksmbd_work *work)
    			ksmbd_debug(SMB,
    				    "User does not have write permission\n");
    			rc = -EACCES;
-				path_put(&path);
    			goto err_out;
    		}
    	} else if (d_is_symlink(path.dentry)) {
    		rc = -EACCES;
-			path_put(&path);
    		goto err_out;
    	}
-	}
-	if (rc) {
+		file_present = true;
+		user_ns = mnt_user_ns(path.mnt);
+	} else {
    	if (rc != -ENOENT)
    		goto err_out;
    	ksmbd_debug(SMB, "can not get linux path for %s, rc = %d\n",
    		    name, rc);
    	rc = 0;
-	} else {
-		file_present = true;
-		user_ns = mnt_user_ns(path.mnt);
    }
+
    if (stream_name) {
    	if (req->CreateOptions & FILE_DIRECTORY_FILE_LE) {
    		if (s_type == DATA_STREAM) {
@@ -2909,8 +2907,9 @@ int smb2_open(struct ksmbd_work *work)
if ((daccess & FILE_DELETE_LE) ||
    		    (req->CreateOptions & FILE_DELETE_ON_CLOSE_LE)) {
-				rc = ksmbd_vfs_may_delete(user_ns,
-							  path.dentry);
+				rc = inode_permission(user_ns,
+						      d_inode(path.dentry->d_parent),
+						      MAY_EXEC | MAY_WRITE);
    			if (rc)
    				goto err_out;
    		}
@@ -3281,10 +3280,13 @@ int smb2_open(struct ksmbd_work *work)
    }
err_out:
-	if (file_present || created)
-		path_put(&path);
+	if (file_present || created) {
+		inode_unlock(d_inode(path.dentry->d_parent));
+		dput(path.dentry);
+	}
    ksmbd_revert_fsids(work);
 err_out1:
+
    if (rc) {
    	if (rc == -EINVAL)
    		rsp->hdr.Status = STATUS_INVALID_PARAMETER;
@@ -5426,44 +5428,19 @@ int smb2_echo(struct ksmbd_work *work)
static int smb2_rename(struct ksmbd_work *work,
    	       struct ksmbd_file *fp,
-		       struct user_namespace *user_ns,
    	       struct smb2_file_rename_info *file_info,
    	       struct nls_table *local_nls)
 {
    struct ksmbd_share_config *share = fp->tcon->share_conf;
-	char *new_name = NULL, *abs_oldname = NULL, *old_name = NULL;
-	char *pathname = NULL;
-	struct path path;
-	bool file_present = true;
-	int rc;
+	char *new_name = NULL;
+	int rc, flags = 0;
ksmbd_debug(SMB, "setting FILE_RENAME_INFO\n");
-	pathname = kmalloc(PATH_MAX, GFP_KERNEL);
-	if (!pathname)
-		return -ENOMEM;
-
-	abs_oldname = file_path(fp->filp, pathname, PATH_MAX);
-	if (IS_ERR(abs_oldname)) {
-		rc = -EINVAL;
-		goto out;
-	}
-	old_name = strrchr(abs_oldname, '/');
-	if (old_name && old_name[1] != '\0') {
-		old_name++;
-	} else {
-		ksmbd_debug(SMB, "can't get last component in path %s\n",
-			    abs_oldname);
-		rc = -ENOENT;
-		goto out;
-	}
-
    new_name = smb2_get_name(file_info->FileName,
    			 le32_to_cpu(file_info->FileNameLength),
    			 local_nls);
-	if (IS_ERR(new_name)) {
-		rc = PTR_ERR(new_name);
-		goto out;
-	}
+	if (IS_ERR(new_name))
+		return PTR_ERR(new_name);
if (strchr(new_name, ':')) {
    	int s_type;
@@ -5489,7 +5466,7 @@ static int smb2_rename(struct ksmbd_work
    	if (rc)
    		goto out;
-		rc = ksmbd_vfs_setxattr(user_ns,
+		rc = ksmbd_vfs_setxattr(file_mnt_user_ns(fp->filp),
    				fp->filp->f_path.dentry,
    				xattr_stream_name,
    				NULL, 0, 0);
@@ -5504,47 +5481,18 @@ static int smb2_rename(struct ksmbd_work
    }
ksmbd_debug(SMB, "new name %s\n", new_name);
-	rc = ksmbd_vfs_kern_path(work, new_name, LOOKUP_NO_SYMLINKS, &path, 1);
-	if (rc) {
-		if (rc != -ENOENT)
-			goto out;
-		file_present = false;
-	} else {
-		path_put(&path);
-	}
-
    if (ksmbd_share_veto_filename(share, new_name)) {
    	rc = -ENOENT;
    	ksmbd_debug(SMB, "Can't rename vetoed file: %s\n", new_name);
    	goto out;
    }
-	if (file_info->ReplaceIfExists) {
-		if (file_present) {
-			rc = ksmbd_vfs_remove_file(work, new_name);
-			if (rc) {
-				if (rc != -ENOTEMPTY)
-					rc = -EINVAL;
-				ksmbd_debug(SMB, "cannot delete %s, rc %d\n",
-					    new_name, rc);
-				goto out;
-			}
-		}
-	} else {
-		if (file_present &&
-		    strncmp(old_name, path.dentry->d_name.name, strlen(old_name))) {
-			rc = -EEXIST;
-			ksmbd_debug(SMB,
-				    "cannot rename already existing file\n");
-			goto out;
-		}
-	}
+	if (!file_info->ReplaceIfExists)
+		flags = RENAME_NOREPLACE;
-	rc = ksmbd_vfs_fp_rename(work, fp, new_name);
+	rc = ksmbd_vfs_rename(work, &fp->filp->f_path, new_name, flags);
 out:
-	kfree(pathname);
-	if (!IS_ERR(new_name))
-		kfree(new_name);
+	kfree(new_name);
    return rc;
 }
@@ -5584,18 +5532,17 @@ static int smb2_create_link(struct ksmbd
    }
ksmbd_debug(SMB, "target name is %s\n", target_name);
-	rc = ksmbd_vfs_kern_path(work, link_name, LOOKUP_NO_SYMLINKS, &path, 0);
+	rc = ksmbd_vfs_kern_path_locked(work, link_name, LOOKUP_NO_SYMLINKS,
+					&path, 0);
    if (rc) {
    	if (rc != -ENOENT)
    		goto out;
    	file_present = false;
-	} else {
-		path_put(&path);
    }
if (file_info->ReplaceIfExists) {
    	if (file_present) {
-			rc = ksmbd_vfs_remove_file(work, link_name);
+			rc = ksmbd_vfs_remove_file(work, &path);
    		if (rc) {
    			rc = -EINVAL;
    			ksmbd_debug(SMB, "cannot delete %s\n",
@@ -5615,6 +5562,10 @@ static int smb2_create_link(struct ksmbd
    if (rc)
    	rc = -EINVAL;
 out:
+	if (file_present) {
+		inode_unlock(d_inode(path.dentry->d_parent));
+		path_put(&path);
+	}
    if (!IS_ERR(link_name))
    	kfree(link_name);
    kfree(pathname);
@@ -5792,12 +5743,6 @@ static int set_rename_info(struct ksmbd_
    		   struct smb2_file_rename_info *rename_info,
    		   unsigned int buf_len)
 {
-	struct user_namespace *user_ns;
-	struct ksmbd_file *parent_fp;
-	struct dentry *parent;
-	struct dentry *dentry = fp->filp->f_path.dentry;
-	int ret;
-
    if (!(fp->daccess & FILE_DELETE_LE)) {
    	pr_err("no right to delete : 0x%x\n", fp->daccess);
    	return -EACCES;
@@ -5807,32 +5752,10 @@ static int set_rename_info(struct ksmbd_
    		le32_to_cpu(rename_info->FileNameLength))
    	return -EINVAL;
-	user_ns = file_mnt_user_ns(fp->filp);
-	if (ksmbd_stream_fd(fp))
-		goto next;
+	if (!le32_to_cpu(rename_info->FileNameLength))
+		return -EINVAL;
-	parent = dget_parent(dentry);
-	ret = ksmbd_vfs_lock_parent(user_ns, parent, dentry);
-	if (ret) {
-		dput(parent);
-		return ret;
-	}
-
-	parent_fp = ksmbd_lookup_fd_inode(d_inode(parent));
-	inode_unlock(d_inode(parent));
-	dput(parent);
-
-	if (parent_fp) {
-		if (parent_fp->daccess & FILE_DELETE_LE) {
-			pr_err("parent dir is opened with delete access\n");
-			ksmbd_fd_put(work, parent_fp);
-			return -ESHARE;
-		}
-		ksmbd_fd_put(work, parent_fp);
-	}
-next:
-	return smb2_rename(work, fp, user_ns, rename_info,
-			   work->conn->local_nls);
+	return smb2_rename(work, fp, rename_info, work->conn->local_nls);
 }
static int set_file_disposition_info(struct ksmbd_file *fp,
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -18,6 +18,7 @@
 #include <linux/vmalloc.h>
 #include <linux/sched/xacct.h>
 #include <linux/crc32c.h>
+#include <linux/namei.h>
#include "glob.h"
 #include "oplock.h"
@@ -35,19 +36,6 @@
 #include "mgmt/user_session.h"
 #include "mgmt/user_config.h"
-static char *extract_last_component(char *path)
-{
-	char *p = strrchr(path, '/');
-
-	if (p && p[1] != '\0') {
-		*p = '\0';
-		p++;
-	} else {
-		p = NULL;
-	}
-	return p;
-}
-
 static void ksmbd_vfs_inherit_owner(struct ksmbd_work *work,
    			    struct inode *parent_inode,
    			    struct inode *inode)
@@ -61,65 +49,77 @@ static void ksmbd_vfs_inherit_owner(stru
/**
  * ksmbd_vfs_lock_parent() - lock parent dentry if it is stable
- *
- * the parent dentry got by dget_parent or @parent could be
- * unstable, we try to lock a parent inode and lookup the
- * child dentry again.
- *
- * the reference count of @parent isn't incremented.
  */
-int ksmbd_vfs_lock_parent(struct user_namespace *user_ns, struct dentry *parent,
-			  struct dentry *child)
+int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child)
 {
-	struct dentry *dentry;
-	int ret = 0;
-
    inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
-	dentry = lookup_one(user_ns, child->d_name.name, parent,
-			    child->d_name.len);
-	if (IS_ERR(dentry)) {
-		ret = PTR_ERR(dentry);
-		goto out_err;
-	}
-
-	if (dentry != child) {
-		ret = -ESTALE;
-		dput(dentry);
-		goto out_err;
+	if (child->d_parent != parent) {
+		inode_unlock(d_inode(parent));
+		return -ENOENT;
    }
-	dput(dentry);
    return 0;
-out_err:
-	inode_unlock(d_inode(parent));
-	return ret;
 }
-int ksmbd_vfs_may_delete(struct user_namespace *user_ns,
-			 struct dentry *dentry)
-{
-	struct dentry *parent;
-	int ret;
+static int ksmbd_vfs_path_lookup_locked(struct ksmbd_share_config *share_conf,
+					char *pathname, unsigned int flags,
+					struct path *path)
+{
+	struct qstr last;
+	struct filename *filename;
+	struct path *root_share_path = &share_conf->vfs_path;
+	int err, type;
+	struct path parent_path;
+	struct dentry *d;
+
+	if (pathname[0] == '\0') {
+		pathname = share_conf->path;
+		root_share_path = NULL;
+	} else {
+		flags |= LOOKUP_BENEATH;
+	}
-	parent = dget_parent(dentry);
-	ret = ksmbd_vfs_lock_parent(user_ns, parent, dentry);
-	if (ret) {
-		dput(parent);
-		return ret;
+	filename = getname_kernel(pathname);
+	if (IS_ERR(filename))
+		return PTR_ERR(filename);
+
+	err = vfs_path_parent_lookup(filename, flags,
+				     &parent_path, &last, &type,
+				     root_share_path);
+	putname(filename);
+	if (err)
+		return err;
+
+	if (unlikely(type != LAST_NORM)) {
+		path_put(&parent_path);
+		return -ENOENT;
    }
-	ret = inode_permission(user_ns, d_inode(parent),
-			       MAY_EXEC | MAY_WRITE);
+	inode_lock_nested(parent_path.dentry->d_inode, I_MUTEX_PARENT);
+	d = lookup_one_qstr_excl(&last, parent_path.dentry, 0);
+	if (IS_ERR(d))
+		goto err_out;
-	inode_unlock(d_inode(parent));
-	dput(parent);
-	return ret;
+	if (d_is_negative(d)) {
+		dput(d);
+		goto err_out;
+	}
+
+	path->dentry = d;
+	path->mnt = share_conf->vfs_path.mnt;
+	path_put(&parent_path);
+
+	return 0;
+
+err_out:
+	inode_unlock(parent_path.dentry->d_inode);
+	path_put(&parent_path);
+	return -ENOENT;
 }
int ksmbd_vfs_query_maximal_access(struct user_namespace *user_ns,
    			   struct dentry *dentry, __le32 *daccess)
 {
-	struct dentry *parent;
    int ret = 0;
*daccess = cpu_to_le32(FILE_READ_ATTRIBUTES | READ_CONTROL);
@@ -136,18 +136,9 @@ int ksmbd_vfs_query_maximal_access(struc
    if (!inode_permission(user_ns, d_inode(dentry), MAY_OPEN | MAY_EXEC))
    	*daccess |= FILE_EXECUTE_LE;
-	parent = dget_parent(dentry);
-	ret = ksmbd_vfs_lock_parent(user_ns, parent, dentry);
-	if (ret) {
-		dput(parent);
-		return ret;
-	}
-
-	if (!inode_permission(user_ns, d_inode(parent), MAY_EXEC | MAY_WRITE))
+	if (!inode_permission(user_ns, d_inode(dentry->d_parent), MAY_EXEC | MAY_WRITE))
    	*daccess |= FILE_DELETE_LE;
-	inode_unlock(d_inode(parent));
-	dput(parent);
    return ret;
 }
@@ -580,54 +571,32 @@ int ksmbd_vfs_fsync(struct ksmbd_work *w
  *
  * Return:	0 on success, otherwise error
  */
-int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name)
+int ksmbd_vfs_remove_file(struct ksmbd_work *work, const struct path *path)
 {
    struct user_namespace *user_ns;
-	struct path path;
-	struct dentry *parent;
+	struct dentry *parent = path->dentry->d_parent;
    int err;
if (ksmbd_override_fsids(work))
    	return -ENOMEM;
-	err = ksmbd_vfs_kern_path(work, name, LOOKUP_NO_SYMLINKS, &path, false);
-	if (err) {
-		ksmbd_debug(VFS, "can't get %s, err %d\n", name, err);
-		ksmbd_revert_fsids(work);
-		return err;
-	}
-
-	user_ns = mnt_user_ns(path.mnt);
-	parent = dget_parent(path.dentry);
-	err = ksmbd_vfs_lock_parent(user_ns, parent, path.dentry);
-	if (err) {
-		dput(parent);
-		path_put(&path);
-		ksmbd_revert_fsids(work);
-		return err;
-	}
-
-	if (!d_inode(path.dentry)->i_nlink) {
+	if (!d_inode(path->dentry)->i_nlink) {
    	err = -ENOENT;
    	goto out_err;
    }
-	if (S_ISDIR(d_inode(path.dentry)->i_mode)) {
-		err = vfs_rmdir(user_ns, d_inode(parent), path.dentry);
+	user_ns = mnt_user_ns(path->mnt);
+	if (S_ISDIR(d_inode(path->dentry)->i_mode)) {
+		err = vfs_rmdir(user_ns, d_inode(parent), path->dentry);
    	if (err && err != -ENOTEMPTY)
-			ksmbd_debug(VFS, "%s: rmdir failed, err %d\n", name,
-				    err);
+			ksmbd_debug(VFS, "rmdir failed, err %d\n", err);
    } else {
-		err = vfs_unlink(user_ns, d_inode(parent), path.dentry, NULL);
+		err = vfs_unlink(user_ns, d_inode(parent), path->dentry, NULL);
    	if (err)
-			ksmbd_debug(VFS, "%s: unlink failed, err %d\n", name,
-				    err);
+			ksmbd_debug(VFS, "unlink failed, err %d\n", err);
    }
out_err:
-	inode_unlock(d_inode(parent));
-	dput(parent);
-	path_put(&path);
    ksmbd_revert_fsids(work);
    return err;
 }
@@ -686,149 +655,114 @@ out1:
    return err;
 }
-static int ksmbd_validate_entry_in_use(struct dentry *src_dent)
+int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path,
+		     char *newname, int flags)
 {
-	struct dentry *dst_dent;
-
-	spin_lock(&src_dent->d_lock);
-	list_for_each_entry(dst_dent, &src_dent->d_subdirs, d_child) {
-		struct ksmbd_file *child_fp;
+	struct dentry *old_parent, *new_dentry, *trap;
+	struct dentry *old_child = old_path->dentry;
+	struct path new_path;
+	struct qstr new_last;
+	struct renamedata rd;
+	struct filename *to;
+	struct ksmbd_share_config *share_conf = work->tcon->share_conf;
+	struct ksmbd_file *parent_fp;
+	int new_type;
+	int err, lookup_flags = LOOKUP_NO_SYMLINKS;
-		if (d_really_is_negative(dst_dent))
-			continue;
+	if (ksmbd_override_fsids(work))
+		return -ENOMEM;
-		child_fp = ksmbd_lookup_fd_inode(d_inode(dst_dent));
-		if (child_fp) {
-			spin_unlock(&src_dent->d_lock);
-			ksmbd_debug(VFS, "Forbid rename, sub file/dir is in use\n");
-			return -EACCES;
-		}
+	to = getname_kernel(newname);
+	if (IS_ERR(to)) {
+		err = PTR_ERR(to);
+		goto revert_fsids;
    }
-	spin_unlock(&src_dent->d_lock);
-	return 0;
-}
-
-static int __ksmbd_vfs_rename(struct ksmbd_work *work,
-			      struct user_namespace *src_user_ns,
-			      struct dentry *src_dent_parent,
-			      struct dentry *src_dent,
-			      struct user_namespace *dst_user_ns,
-			      struct dentry *dst_dent_parent,
-			      struct dentry *trap_dent,
-			      char *dst_name)
-{
-	struct dentry *dst_dent;
-	int err;
+retry:
+	err = vfs_path_parent_lookup(to, lookup_flags | LOOKUP_BENEATH,
+				     &new_path, &new_last, &new_type,
+				     &share_conf->vfs_path);
+	if (err)
+		goto out1;
-	if (!work->tcon->posix_extensions) {
-		err = ksmbd_validate_entry_in_use(src_dent);
-		if (err)
-			return err;
+	if (old_path->mnt != new_path.mnt) {
+		err = -EXDEV;
+		goto out2;
    }
-	if (d_really_is_negative(src_dent_parent))
-		return -ENOENT;
-	if (d_really_is_negative(dst_dent_parent))
-		return -ENOENT;
-	if (d_really_is_negative(src_dent))
-		return -ENOENT;
-	if (src_dent == trap_dent)
-		return -EINVAL;
+	trap = lock_rename_child(old_child, new_path.dentry);
-	if (ksmbd_override_fsids(work))
-		return -ENOMEM;
+	old_parent = dget(old_child->d_parent);
+	if (d_unhashed(old_child)) {
+		err = -EINVAL;
+		goto out3;
+	}
-	dst_dent = lookup_one(dst_user_ns, dst_name, dst_dent_parent,
-			      strlen(dst_name));
-	err = PTR_ERR(dst_dent);
-	if (IS_ERR(dst_dent)) {
-		pr_err("lookup failed %s [%d]\n", dst_name, err);
-		goto out;
+	parent_fp = ksmbd_lookup_fd_inode(d_inode(old_child->d_parent));
+	if (parent_fp) {
+		if (parent_fp->daccess & FILE_DELETE_LE) {
+			pr_err("parent dir is opened with delete access\n");
+			err = -ESHARE;
+			ksmbd_fd_put(work, parent_fp);
+			goto out3;
+		}
+		ksmbd_fd_put(work, parent_fp);
    }
-	err = -ENOTEMPTY;
-	if (dst_dent != trap_dent && !d_really_is_positive(dst_dent)) {
-		struct renamedata rd = {
-			.old_mnt_userns	= src_user_ns,
-			.old_dir	= d_inode(src_dent_parent),
-			.old_dentry	= src_dent,
-			.new_mnt_userns	= dst_user_ns,
-			.new_dir	= d_inode(dst_dent_parent),
-			.new_dentry	= dst_dent,
-		};
-		err = vfs_rename(&rd);
+	new_dentry = lookup_one_qstr_excl(&new_last, new_path.dentry,
+					  lookup_flags | LOOKUP_RENAME_TARGET);
+	if (IS_ERR(new_dentry)) {
+		err = PTR_ERR(new_dentry);
+		goto out3;
    }
-	if (err)
-		pr_err("vfs_rename failed err %d\n", err);
-	if (dst_dent)
-		dput(dst_dent);
-out:
-	ksmbd_revert_fsids(work);
-	return err;
-}
-int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
-			char *newname)
-{
-	struct user_namespace *user_ns;
-	struct path dst_path;
-	struct dentry *src_dent_parent, *dst_dent_parent;
-	struct dentry *src_dent, *trap_dent, *src_child;
-	char *dst_name;
-	int err;
+	if (d_is_symlink(new_dentry)) {
+		err = -EACCES;
+		goto out4;
+	}
-	dst_name = extract_last_component(newname);
-	if (!dst_name) {
-		dst_name = newname;
-		newname = "";
+	if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) {
+		err = -EEXIST;
+		goto out4;
    }
-	src_dent_parent = dget_parent(fp->filp->f_path.dentry);
-	src_dent = fp->filp->f_path.dentry;
-
-	err = ksmbd_vfs_kern_path(work, newname,
-				  LOOKUP_NO_SYMLINKS | LOOKUP_DIRECTORY,
-				  &dst_path, false);
-	if (err) {
-		ksmbd_debug(VFS, "Cannot get path for %s [%d]\n", newname, err);
-		goto out;
+	if (old_child == trap) {
+		err = -EINVAL;
+		goto out4;
    }
-	dst_dent_parent = dst_path.dentry;
-	trap_dent = lock_rename(src_dent_parent, dst_dent_parent);
-	dget(src_dent);
-	dget(dst_dent_parent);
-	user_ns = file_mnt_user_ns(fp->filp);
-	src_child = lookup_one(user_ns, src_dent->d_name.name, src_dent_parent,
-			       src_dent->d_name.len);
-	if (IS_ERR(src_child)) {
-		err = PTR_ERR(src_child);
-		goto out_lock;
-	}
-
-	if (src_child != src_dent) {
-		err = -ESTALE;
-		dput(src_child);
-		goto out_lock;
-	}
-	dput(src_child);
-
-	err = __ksmbd_vfs_rename(work,
-				 user_ns,
-				 src_dent_parent,
-				 src_dent,
-				 mnt_user_ns(dst_path.mnt),
-				 dst_dent_parent,
-				 trap_dent,
-				 dst_name);
-out_lock:
-	dput(src_dent);
-	dput(dst_dent_parent);
-	unlock_rename(src_dent_parent, dst_dent_parent);
-	path_put(&dst_path);
-out:
-	dput(src_dent_parent);
+	if (new_dentry == trap) {
+		err = -ENOTEMPTY;
+		goto out4;
+	}
+
+	rd.old_mnt_userns	= mnt_user_ns(old_path->mnt),
+	rd.old_dir		= d_inode(old_parent),
+	rd.old_dentry		= old_child,
+	rd.new_mnt_userns	= mnt_user_ns(new_path.mnt),
+	rd.new_dir		= new_path.dentry->d_inode,
+	rd.new_dentry		= new_dentry,
+	rd.flags		= flags,
+	err = vfs_rename(&rd);
+	if (err)
+		ksmbd_debug(VFS, "vfs_rename failed err %d\n", err);
+
+out4:
+	dput(new_dentry);
+out3:
+	dput(old_parent);
+	unlock_rename(old_parent, new_path.dentry);
+out2:
+	path_put(&new_path);
+
+	if (retry_estale(err, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+out1:
+	putname(to);
+revert_fsids:
+	ksmbd_revert_fsids(work);
    return err;
 }
@@ -1079,14 +1013,16 @@ int ksmbd_vfs_remove_xattr(struct user_n
    return vfs_removexattr(user_ns, dentry, attr_name);
 }
-int ksmbd_vfs_unlink(struct user_namespace *user_ns,
-		     struct dentry *dir, struct dentry *dentry)
+int ksmbd_vfs_unlink(struct file *filp)
 {
    int err = 0;
+	struct dentry *dir, *dentry = filp->f_path.dentry;
+	struct user_namespace *user_ns = file_mnt_user_ns(filp);
-	err = ksmbd_vfs_lock_parent(user_ns, dir, dentry);
+	dir = dget_parent(dentry);
+	err = ksmbd_vfs_lock_parent(dir, dentry);
    if (err)
-		return err;
+		goto out;
    dget(dentry);
if (S_ISDIR(d_inode(dentry)->i_mode))
@@ -1098,6 +1034,8 @@ int ksmbd_vfs_unlink(struct user_namespa
    inode_unlock(d_inode(dir));
    if (err)
    	ksmbd_debug(VFS, "failed to delete, err %d\n", err);
+out:
+	dput(dir);
return err;
 }
@@ -1202,7 +1140,7 @@ static int ksmbd_vfs_lookup_in_dir(const
 }
/**
- * ksmbd_vfs_kern_path() - lookup a file and get path info
+ * ksmbd_vfs_kern_path_locked() - lookup a file and get path info
  * @name:	file path that is relative to share
  * @flags:	lookup flags
  * @path:	if lookup succeed, return path info
@@ -1210,24 +1148,20 @@ static int ksmbd_vfs_lookup_in_dir(const
  *
  * Return:	0 on success, otherwise error
  */
-int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *name,
-			unsigned int flags, struct path *path, bool caseless)
+int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,
+			       unsigned int flags, struct path *path,
+			       bool caseless)
 {
    struct ksmbd_share_config *share_conf = work->tcon->share_conf;
    int err;
+	struct path parent_path;
-	flags |= LOOKUP_BENEATH;
-	err = vfs_path_lookup(share_conf->vfs_path.dentry,
-			      share_conf->vfs_path.mnt,
-			      name,
-			      flags,
-			      path);
+	err = ksmbd_vfs_path_lookup_locked(share_conf, name, flags, path);
    if (!err)
-		return 0;
+		return err;
if (caseless) {
    	char *filepath;
-		struct path parent;
    	size_t path_len, remain_len;
filepath = kstrdup(name, GFP_KERNEL);
@@ -1237,10 +1171,10 @@ int ksmbd_vfs_kern_path(struct ksmbd_wor
    	path_len = strlen(filepath);
    	remain_len = path_len;
-		parent = share_conf->vfs_path;
-		path_get(&parent);
+		parent_path = share_conf->vfs_path;
+		path_get(&parent_path);
-		while (d_can_lookup(parent.dentry)) {
+		while (d_can_lookup(parent_path.dentry)) {
    		char *filename = filepath + path_len - remain_len;
    		char *next = strchrnul(filename, '/');
    		size_t filename_len = next - filename;
@@ -1249,12 +1183,11 @@ int ksmbd_vfs_kern_path(struct ksmbd_wor
    		if (filename_len == 0)
    			break;
-			err = ksmbd_vfs_lookup_in_dir(&parent, filename,
+			err = ksmbd_vfs_lookup_in_dir(&parent_path, filename,
    					      filename_len,
    					      work->conn->um);
-			path_put(&parent);
    		if (err)
-				goto out;
+				goto out2;
next[0] = '\0';
@@ -1262,23 +1195,31 @@ int ksmbd_vfs_kern_path(struct ksmbd_wor
    				      share_conf->vfs_path.mnt,
    				      filepath,
    				      flags,
-					      &parent);
+					      path);
    		if (err)
-				goto out;
-			else if (is_last) {
-				*path = parent;
-				goto out;
-			}
+				goto out2;
+			else if (is_last)
+				goto out1;
+			path_put(&parent_path);
+			parent_path = *path;
next[0] = '/';
    		remain_len -= filename_len + 1;
    	}
-		path_put(&parent);
    	err = -EINVAL;
-out:
+out2:
+		path_put(&parent_path);
+out1:
    	kfree(filepath);
    }
+
+	if (!err) {
+		err = ksmbd_vfs_lock_parent(parent_path.dentry, path->dentry);
+		if (err)
+			dput(path->dentry);
+		path_put(&parent_path);
+	}
    return err;
 }
--- a/fs/ksmbd/vfs.h
+++ b/fs/ksmbd/vfs.h
@@ -110,9 +110,7 @@ struct ksmbd_kstat {
    __le32			file_attributes;
 };
-int ksmbd_vfs_lock_parent(struct user_namespace *user_ns, struct dentry *parent,
-			  struct dentry *child);
-int ksmbd_vfs_may_delete(struct user_namespace *user_ns, struct dentry *dentry);
+int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child);
 int ksmbd_vfs_query_maximal_access(struct user_namespace *user_ns,
    			   struct dentry *dentry, __le32 *daccess);
 int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode);
@@ -123,12 +121,12 @@ int ksmbd_vfs_write(struct ksmbd_work *w
    	    char *buf, size_t count, loff_t *pos, bool sync,
    	    ssize_t *written);
 int ksmbd_vfs_fsync(struct ksmbd_work *work, u64 fid, u64 p_id);
-int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name);
+int ksmbd_vfs_remove_file(struct ksmbd_work *work, const struct path *path);
 int ksmbd_vfs_link(struct ksmbd_work *work,
    	   const char *oldname, const char *newname);
 int ksmbd_vfs_getattr(const struct path *path, struct kstat *stat);
-int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
-			char *newname);
+int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path,
+		     char *newname, int flags);
 int ksmbd_vfs_truncate(struct ksmbd_work *work,
    	       struct ksmbd_file *fp, loff_t size);
 struct srv_copychunk;
@@ -155,9 +153,9 @@ int ksmbd_vfs_xattr_stream_name(char *st
    			size_t *xattr_stream_name_size, int s_type);
 int ksmbd_vfs_remove_xattr(struct user_namespace *user_ns,
    		   struct dentry *dentry, char *attr_name);
-int ksmbd_vfs_kern_path(struct ksmbd_work *work,
-			char *name, unsigned int flags, struct path *path,
-			bool caseless);
+int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,
+			       unsigned int flags, struct path *path,
+			       bool caseless);
 struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,
    				  const char *name,
    				  unsigned int flags,
@@ -170,8 +168,7 @@ struct file_allocated_range_buffer;
 int ksmbd_vfs_fqar_lseek(struct ksmbd_file *fp, loff_t start, loff_t length,
    		 struct file_allocated_range_buffer *ranges,
    		 unsigned int in_count, unsigned int *out_count);
-int ksmbd_vfs_unlink(struct user_namespace *user_ns,
-		     struct dentry *dir, struct dentry *dentry);
+int ksmbd_vfs_unlink(struct file *filp);
 void *ksmbd_vfs_init_kstat(char **p, struct ksmbd_kstat *ksmbd_kstat);
 int ksmbd_vfs_fill_dentry_attrs(struct ksmbd_work *work,
    			struct user_namespace *user_ns,
--- a/fs/ksmbd/vfs_cache.c
+++ b/fs/ksmbd/vfs_cache.c
@@ -243,7 +243,6 @@ void ksmbd_release_inode_hash(void)
static void __ksmbd_inode_close(struct ksmbd_file *fp)
 {
-	struct dentry *dir, *dentry;
    struct ksmbd_inode *ci = fp->f_ci;
    int err;
    struct file *filp;
@@ -262,11 +261,9 @@ static void __ksmbd_inode_close(struct k
    if (atomic_dec_and_test(&ci->m_count)) {
    	write_lock(&ci->m_lock);
    	if (ci->m_flags & (S_DEL_ON_CLS | S_DEL_PENDING)) {
-			dentry = filp->f_path.dentry;
-			dir = dentry->d_parent;
    		ci->m_flags &= ~(S_DEL_ON_CLS | S_DEL_PENDING);
    		write_unlock(&ci->m_lock);
-			ksmbd_vfs_unlink(file_mnt_user_ns(filp), dir, dentry);
+			ksmbd_vfs_unlink(filp);
    		write_lock(&ci->m_lock);
    	}
    	write_unlock(&ci->m_lock);
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -252,6 +252,7 @@ getname_kernel(const char * filename)
return result;
 }
+EXPORT_SYMBOL(getname_kernel);
void putname(struct filename *name)
 {
@@ -269,6 +270,7 @@ void putname(struct filename *name)
    } else
    	__putname(name);
 }
+EXPORT_SYMBOL(putname);
/**
  * check_acl - perform ACL permission checking
@@ -1539,8 +1541,9 @@ static struct dentry *lookup_dcache(cons
  * 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;
@@ -1564,6 +1567,7 @@ static struct dentry *__lookup_hash(cons
    }
    return dentry;
 }
+EXPORT_SYMBOL(lookup_one_qstr_excl);
static struct dentry *lookup_fast(struct nameidata *nd,
    			  struct inode **inode,
@@ -2508,16 +2512,17 @@ static int path_parentat(struct nameidat
 }
/* 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);
@@ -2532,6 +2537,13 @@ static int filename_parentat(int dfd, st
    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)
 {
@@ -2547,7 +2559,7 @@ static struct dentry *__kern_path_locked
    	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);
@@ -2576,6 +2588,24 @@ int kern_path(const char *name, unsigned
 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
@@ -3809,7 +3839,8 @@ static struct dentry *filename_create(in
    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;
@@ -4170,7 +4201,7 @@ 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;
@@ -4304,7 +4335,7 @@ 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)) {
    	struct user_namespace *mnt_userns;
@@ -4878,7 +4909,8 @@ 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;
@@ -4886,7 +4918,8 @@ 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;
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -57,12 +57,18 @@ static inline int user_path_at(int dfd,
    return user_path_at_empty(dfd, name, flags, path, NULL);
 }
+struct dentry *lookup_one_qstr_excl(const struct qstr *name,
+				    struct dentry *base,
+				    unsigned int flags);
 extern int kern_path(const char *, unsigned, struct path *);
extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
 extern void done_path_create(struct path *, struct dentry *);
 extern struct dentry *kern_path_locked(const char *, struct path *);
+int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
+			   struct path *parent, struct qstr *last, int *type,
+			   const struct path *root);
 int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *,
    	    unsigned int, struct path *);

    

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[PATCH 5.15 087/159] ksmbd: fix racy issue from using ->d_parent and ->d_name