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.
Fixes: 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name")
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
v2:
- allow path lookup to cross a mount point when a crossmnt parameter
is set to 'yes' in smb.conf
v3:
- add missing a KSMBD_SHARE_FLAG_CROSSMNT macro.
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(-)
diff --git a/fs/smb/server/ksmbd_netlink.h b/fs/smb/server/ksmbd_netlink.h
index fb8b2d566efb..bae26a24e86b 100644
--- 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.
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index cf8822103f50..ca276634fd58 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -2467,8 +2467,9 @@ static void smb2_update_xattrs(struct
ksmbd_tree_connect *tcon,
}
}
-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 *work,
struct path *path, char *name,
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;
@@ -2906,7 +2908,8 @@ 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) {
@@ -3321,8 +3324,9 @@ 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:
@@ -5545,7 +5549,7 @@ static int smb2_create_link(struct ksmbd_work *work,
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;
@@ -5575,7 +5579,7 @@ static int smb2_create_link(struct ksmbd_work *work,
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;
@@ -5605,8 +5609,9 @@ static int smb2_create_link(struct ksmbd_work *work,
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);
diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index e605ee96b0d0..3d5d652153a5 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -63,13 +63,13 @@ int ksmbd_vfs_lock_parent(struct dentry *parent,
struct dentry *child)
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(struct
ksmbd_share_config *share_conf,
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(struct
ksmbd_share_config *share_conf,
}
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(struct
ksmbd_share_config *share_conf,
}
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;
}
@@ -1195,14 +1202,14 @@ static int ksmbd_vfs_lookup_in_dir(const
struct path *dir, char *name,
* 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 0;
@@ -1217,10 +1224,10 @@ int ksmbd_vfs_kern_path_locked(struct
ksmbd_work *work, char *name,
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;
@@ -1229,7 +1236,7 @@ int ksmbd_vfs_kern_path_locked(struct ksmbd_work
*work, char *name,
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)
@@ -1246,8 +1253,8 @@ int ksmbd_vfs_kern_path_locked(struct ksmbd_work
*work, char *name,
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;
@@ -1255,16 +1262,17 @@ int ksmbd_vfs_kern_path_locked(struct
ksmbd_work *work, char *name,
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;
}
diff --git a/fs/smb/server/vfs.h b/fs/smb/server/vfs.h
index 80039312c255..72f9fb4b48d1 100644
--- a/fs/smb/server/vfs.h
+++ b/fs/smb/server/vfs.h
@@ -115,8 +115,8 @@ int ksmbd_vfs_xattr_stream_name(char *stream_name,
char **xattr_stream_name,
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,
--
2.34.1
