From: Namjae Jeon Date: Sat, 13 Jun 2026 13:00:00 +0000 (+0900) Subject: ksmbd: use opener credentials for delete-on-close X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=52e2f21911158ec961cd5aae19c56460db382af0;p=thirdparty%2Flinux.git ksmbd: use opener credentials for delete-on-close Delete-on-close can be completed by deferred or durable handle teardown, where no request work is available. Both the base-file unlink and the ADS xattr removal consequently run with the ksmbd worker credentials and can bypass filesystem permission checks. Run both operations with the credentials captured in struct file when the handle was opened. This preserves the authenticated user's fsuid, fsgid, supplementary groups and capability restrictions at final close. Cc: stable@vger.kernel.org Reported-by: Musaab Khan Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c index e865ae91650a1..c002cc4b1c026 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -1001,13 +1001,15 @@ int ksmbd_vfs_remove_xattr(struct mnt_idmap *idmap, int ksmbd_vfs_unlink(struct file *filp) { + const struct cred *saved_cred; int err = 0; struct dentry *dir, *dentry = filp->f_path.dentry; struct mnt_idmap *idmap = file_mnt_idmap(filp); + saved_cred = override_creds(filp->f_cred); err = mnt_want_write(filp->f_path.mnt); if (err) - return err; + goto out_revert; dir = dget_parent(dentry); dentry = start_removing_dentry(dir, dentry); @@ -1026,7 +1028,8 @@ int ksmbd_vfs_unlink(struct file *filp) out: dput(dir); mnt_drop_write(filp->f_path.mnt); - +out_revert: + revert_creds(saved_cred); return err; } diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index 4daccc77f9eca..8c556e46cc102 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -385,10 +385,14 @@ static void __ksmbd_inode_close(struct ksmbd_file *fp) up_write(&ci->m_lock); if (remove_stream_xattr) { + const struct cred *saved_cred; + + saved_cred = override_creds(filp->f_cred); err = ksmbd_vfs_remove_xattr(file_mnt_idmap(filp), &filp->f_path, fp->stream.name, true); + revert_creds(saved_cred); if (err) pr_err("remove xattr failed : %s\n", fp->stream.name);