From: Namjae Jeon linkinjeon@kernel.org
commit 2b57a4322b1b14348940744fdc02f9a86cbbdbeb upstream.
Since commit 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name"), ksmbd can not lookup cross mount points. If last component is a cross mount point during path lookup, check if it is crossed to follow it down. And allow path lookup to cross a mount point when a crossmnt parameter is set to 'yes' in smb.conf.
Cc: stable@vger.kernel.org Fixes: 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name") 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/smb/server/ksmbd_netlink.h | 3 +- fs/smb/server/smb2pdu.c | 27 +++++++++++-------- fs/smb/server/vfs.c | 58 +++++++++++++++++++++++------------------- fs/smb/server/vfs.h | 4 +- 4 files changed, 53 insertions(+), 39 deletions(-)
--- a/fs/smb/server/ksmbd_netlink.h +++ b/fs/smb/server/ksmbd_netlink.h @@ -352,7 +352,8 @@ enum KSMBD_TREE_CONN_STATUS { #define KSMBD_SHARE_FLAG_STREAMS BIT(11) #define KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS BIT(12) #define KSMBD_SHARE_FLAG_ACL_XATTR BIT(13) -#define KSMBD_SHARE_FLAG_UPDATE BIT(14) +#define KSMBD_SHARE_FLAG_UPDATE BIT(14) +#define KSMBD_SHARE_FLAG_CROSSMNT BIT(15)
/* * Tree connect request flags. --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2467,8 +2467,9 @@ static void smb2_update_xattrs(struct ks } }
-static int smb2_creat(struct ksmbd_work *work, struct path *path, char *name, - int open_flags, umode_t posix_mode, bool is_dir) +static int smb2_creat(struct ksmbd_work *work, struct path *parent_path, + struct path *path, char *name, int open_flags, + umode_t posix_mode, bool is_dir) { struct ksmbd_tree_connect *tcon = work->tcon; struct ksmbd_share_config *share = tcon->share_conf; @@ -2495,7 +2496,7 @@ static int smb2_creat(struct ksmbd_work return rc; }
- rc = ksmbd_vfs_kern_path_locked(work, name, 0, path, 0); + rc = ksmbd_vfs_kern_path_locked(work, name, 0, parent_path, path, 0); if (rc) { pr_err("cannot get linux path (%s), err = %d\n", name, rc); @@ -2565,7 +2566,7 @@ int smb2_open(struct ksmbd_work *work) struct ksmbd_tree_connect *tcon = work->tcon; struct smb2_create_req *req; struct smb2_create_rsp *rsp; - struct path path; + struct path path, parent_path; struct ksmbd_share_config *share = tcon->share_conf; struct ksmbd_file *fp = NULL; struct file *filp = NULL; @@ -2786,7 +2787,8 @@ int smb2_open(struct ksmbd_work *work) goto err_out1; }
- rc = ksmbd_vfs_kern_path_locked(work, name, LOOKUP_NO_SYMLINKS, &path, 1); + rc = ksmbd_vfs_kern_path_locked(work, name, LOOKUP_NO_SYMLINKS, + &parent_path, &path, 1); if (!rc) { file_present = true;
@@ -2908,7 +2910,8 @@ int smb2_open(struct ksmbd_work *work)
/*create file if not present */ if (!file_present) { - rc = smb2_creat(work, &path, name, open_flags, posix_mode, + rc = smb2_creat(work, &parent_path, &path, name, open_flags, + posix_mode, req->CreateOptions & FILE_DIRECTORY_FILE_LE); if (rc) { if (rc == -ENOENT) { @@ -3323,8 +3326,9 @@ int smb2_open(struct ksmbd_work *work)
err_out: if (file_present || created) { - inode_unlock(d_inode(path.dentry->d_parent)); - dput(path.dentry); + inode_unlock(d_inode(parent_path.dentry)); + path_put(&path); + path_put(&parent_path); } ksmbd_revert_fsids(work); err_out1: @@ -5547,7 +5551,7 @@ static int smb2_create_link(struct ksmbd struct nls_table *local_nls) { char *link_name = NULL, *target_name = NULL, *pathname = NULL; - struct path path; + struct path path, parent_path; bool file_present = false; int rc;
@@ -5577,7 +5581,7 @@ static int smb2_create_link(struct ksmbd
ksmbd_debug(SMB, "target name is %s\n", target_name); rc = ksmbd_vfs_kern_path_locked(work, link_name, LOOKUP_NO_SYMLINKS, - &path, 0); + &parent_path, &path, 0); if (rc) { if (rc != -ENOENT) goto out; @@ -5607,8 +5611,9 @@ static int smb2_create_link(struct ksmbd rc = -EINVAL; out: if (file_present) { - inode_unlock(d_inode(path.dentry->d_parent)); + inode_unlock(d_inode(parent_path.dentry)); path_put(&path); + path_put(&parent_path); } if (!IS_ERR(link_name)) kfree(link_name); --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -63,13 +63,13 @@ int ksmbd_vfs_lock_parent(struct dentry
static int ksmbd_vfs_path_lookup_locked(struct ksmbd_share_config *share_conf, char *pathname, unsigned int flags, + struct path *parent_path, 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') { @@ -84,7 +84,7 @@ static int ksmbd_vfs_path_lookup_locked( return PTR_ERR(filename);
err = vfs_path_parent_lookup(filename, flags, - &parent_path, &last, &type, + parent_path, &last, &type, root_share_path); if (err) { putname(filename); @@ -92,13 +92,13 @@ static int ksmbd_vfs_path_lookup_locked( }
if (unlikely(type != LAST_NORM)) { - path_put(&parent_path); + path_put(parent_path); putname(filename); return -ENOENT; }
- inode_lock_nested(parent_path.dentry->d_inode, I_MUTEX_PARENT); - d = lookup_one_qstr_excl(&last, parent_path.dentry, 0); + 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;
@@ -108,15 +108,22 @@ static int ksmbd_vfs_path_lookup_locked( }
path->dentry = d; - path->mnt = share_conf->vfs_path.mnt; - path_put(&parent_path); - putname(filename); + path->mnt = mntget(parent_path->mnt); + + if (test_share_config_flag(share_conf, KSMBD_SHARE_FLAG_CROSSMNT)) { + err = follow_down(path, 0); + if (err < 0) { + path_put(path); + goto err_out; + } + }
+ putname(filename); return 0;
err_out: - inode_unlock(parent_path.dentry->d_inode); - path_put(&parent_path); + inode_unlock(d_inode(parent_path->dentry)); + path_put(parent_path); putname(filename); return -ENOENT; } @@ -1198,14 +1205,14 @@ static int ksmbd_vfs_lookup_in_dir(const * Return: 0 on success, otherwise error */ int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name, - unsigned int flags, struct path *path, - bool caseless) + unsigned int flags, struct path *parent_path, + struct path *path, bool caseless) { struct ksmbd_share_config *share_conf = work->tcon->share_conf; int err; - struct path parent_path;
- err = ksmbd_vfs_path_lookup_locked(share_conf, name, flags, path); + err = ksmbd_vfs_path_lookup_locked(share_conf, name, flags, parent_path, + path); if (!err) return err;
@@ -1220,10 +1227,10 @@ int ksmbd_vfs_kern_path_locked(struct ks path_len = strlen(filepath); remain_len = path_len;
- parent_path = share_conf->vfs_path; - path_get(&parent_path); + *parent_path = share_conf->vfs_path; + path_get(parent_path);
- while (d_can_lookup(parent_path.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; @@ -1232,7 +1239,7 @@ int ksmbd_vfs_kern_path_locked(struct ks if (filename_len == 0) break;
- err = ksmbd_vfs_lookup_in_dir(&parent_path, filename, + err = ksmbd_vfs_lookup_in_dir(parent_path, filename, filename_len, work->conn->um); if (err) @@ -1249,8 +1256,8 @@ int ksmbd_vfs_kern_path_locked(struct ks goto out2; else if (is_last) goto out1; - path_put(&parent_path); - parent_path = *path; + path_put(parent_path); + *parent_path = *path;
next[0] = '/'; remain_len -= filename_len + 1; @@ -1258,16 +1265,17 @@ int ksmbd_vfs_kern_path_locked(struct ks
err = -EINVAL; out2: - path_put(&parent_path); + 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); + err = ksmbd_vfs_lock_parent(parent_path->dentry, path->dentry); + if (err) { + path_put(path); + path_put(parent_path); + } } return err; } --- a/fs/smb/server/vfs.h +++ b/fs/smb/server/vfs.h @@ -115,8 +115,8 @@ int ksmbd_vfs_xattr_stream_name(char *st int ksmbd_vfs_remove_xattr(struct mnt_idmap *idmap, const struct path *path, char *attr_name); int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name, - unsigned int flags, struct path *path, - bool caseless); + unsigned int flags, struct path *parent_path, + struct path *path, bool caseless); struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work, const char *name, unsigned int flags,