This patch remove symlink support that can be vulnerable and access out
of share, and we re-implement it as reparse point later.
Cc: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Cc: Ralph Böhme <slow@xxxxxxxxx>
Cc: Steve French <smfrench@xxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
---
v2:
- reorganize path lookup in smb2_open to call only one
ksmbd_vfs_kern_path().
fs/ksmbd/smb2pdu.c | 60 ++++++++++------------------------------------
fs/ksmbd/vfs.c | 50 ++++++++------------------------------
2 files changed, 22 insertions(+), 88 deletions(-)
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index e08c6b26b6f0..de044802fc5b 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2648,19 +2648,9 @@ int smb2_open(struct ksmbd_work *work)
goto err_out1;
}
- if (req->CreateOptions & FILE_DELETE_ON_CLOSE_LE) {
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS)) {
- /*
- * On delete request, instead of following up, need to
- * look the current entity
- */
- rc = ksmbd_vfs_kern_path(name, 0, &path, 1);
- } else {
- rc = ksmbd_vfs_kern_path(name, LOOKUP_NO_SYMLINKS, &path, 1);
- }
-
- if (!rc) {
+ rc = ksmbd_vfs_kern_path(name, LOOKUP_NO_SYMLINKS, &path, 1);
+ if (!rc) {
+ if (req->CreateOptions & FILE_DELETE_ON_CLOSE_LE) {
/*
* If file exists with under flags, return access
* denied error.
@@ -2679,26 +2669,10 @@ int smb2_open(struct ksmbd_work *work)
path_put(&path);
goto err_out;
}
- }
- } else {
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS)) {
- /*
- * Use LOOKUP_FOLLOW to follow the path of
- * symlink in path buildup
- */
- rc = ksmbd_vfs_kern_path(name, LOOKUP_FOLLOW, &path, 1);
- if (rc) { /* Case for broken link ?*/
- rc = ksmbd_vfs_kern_path(name, 0, &path, 1);
- }
- } else {
- rc = ksmbd_vfs_kern_path(name, LOOKUP_NO_SYMLINKS,
- &path, 1);
- if (!rc && d_is_symlink(path.dentry)) {
- rc = -EACCES;
- path_put(&path);
- goto err_out;
- }
+ } else if (d_is_symlink(path.dentry)) {
+ rc = -EACCES;
+ path_put(&path);
+ goto err_out;
}
}
@@ -4781,12 +4755,8 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
struct path path;
int rc = 0, len;
int fs_infoclass_size = 0;
- int lookup_flags = LOOKUP_NO_SYMLINKS;
-
- if (test_share_config_flag(share, KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- lookup_flags = LOOKUP_FOLLOW;
- rc = ksmbd_vfs_kern_path(share->path, lookup_flags, &path, 0);
+ rc = ksmbd_vfs_kern_path(share->path, LOOKUP_NO_SYMLINKS, &path, 0);
if (rc) {
pr_err("cannot create vfs path\n");
return -EIO;
@@ -5293,7 +5263,7 @@ static int smb2_rename(struct ksmbd_work *work,
char *pathname = NULL;
struct path path;
bool file_present = true;
- int rc, lookup_flags = LOOKUP_NO_SYMLINKS;
+ int rc;
ksmbd_debug(SMB, "setting FILE_RENAME_INFO\n");
pathname = kmalloc(PATH_MAX, GFP_KERNEL);
@@ -5362,11 +5332,8 @@ static int smb2_rename(struct ksmbd_work *work,
goto out;
}
- if (test_share_config_flag(share, KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- lookup_flags = LOOKUP_FOLLOW;
-
ksmbd_debug(SMB, "new name %s\n", new_name);
- rc = ksmbd_vfs_kern_path(new_name, lookup_flags, &path, 1);
+ rc = ksmbd_vfs_kern_path(new_name, LOOKUP_NO_SYMLINKS, &path, 1);
if (rc)
file_present = false;
else
@@ -5416,7 +5383,7 @@ static int smb2_create_link(struct ksmbd_work *work,
char *link_name = NULL, *target_name = NULL, *pathname = NULL;
struct path path;
bool file_present = true;
- int rc, lookup_flags = LOOKUP_NO_SYMLINKS;
+ int rc;
ksmbd_debug(SMB, "setting FILE_LINK_INFORMATION\n");
pathname = kmalloc(PATH_MAX, GFP_KERNEL);
@@ -5439,11 +5406,8 @@ static int smb2_create_link(struct ksmbd_work *work,
goto out;
}
- if (test_share_config_flag(share, KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- lookup_flags = LOOKUP_FOLLOW;
-
ksmbd_debug(SMB, "target name is %s\n", target_name);
- rc = ksmbd_vfs_kern_path(link_name, lookup_flags, &path, 0);
+ rc = ksmbd_vfs_kern_path(link_name, LOOKUP_NO_SYMLINKS, &path, 0);
if (rc)
file_present = false;
else
diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c
index 53047f013371..3733e4944c1d 100644
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -164,13 +164,9 @@ int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode)
{
struct path path;
struct dentry *dentry;
- int err, lookup_flags = LOOKUP_NO_SYMLINKS;
-
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- lookup_flags = LOOKUP_FOLLOW;
+ int err;
- dentry = kern_path_create(AT_FDCWD, name, &path, lookup_flags);
+ dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_NO_SYMLINKS);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
if (err != -ENOENT)
@@ -205,14 +201,10 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode)
struct user_namespace *user_ns;
struct path path;
struct dentry *dentry;
- int err, lookup_flags = LOOKUP_NO_SYMLINKS;
-
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- lookup_flags = LOOKUP_FOLLOW;
+ int err;
dentry = kern_path_create(AT_FDCWD, name, &path,
- lookup_flags | LOOKUP_DIRECTORY);
+ LOOKUP_NO_SYMLINKS | LOOKUP_DIRECTORY);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
if (err != -EEXIST)
@@ -597,16 +589,11 @@ int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name)
struct path path;
struct dentry *parent;
int err;
- int flags = LOOKUP_NO_SYMLINKS;
if (ksmbd_override_fsids(work))
return -ENOMEM;
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- flags = LOOKUP_FOLLOW;
-
- err = kern_path(name, flags, &path);
+ err = kern_path(name, LOOKUP_NO_SYMLINKS, &path);
if (err) {
ksmbd_debug(VFS, "can't get %s, err %d\n", name, err);
ksmbd_revert_fsids(work);
@@ -661,16 +648,11 @@ int ksmbd_vfs_link(struct ksmbd_work *work, const char *oldname,
struct path oldpath, newpath;
struct dentry *dentry;
int err;
- int flags = LOOKUP_NO_SYMLINKS;
if (ksmbd_override_fsids(work))
return -ENOMEM;
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- flags = LOOKUP_FOLLOW;
-
- err = kern_path(oldname, flags, &oldpath);
+ err = kern_path(oldname, LOOKUP_NO_SYMLINKS, &oldpath);
if (err) {
pr_err("cannot get linux path for %s, err = %d\n",
oldname, err);
@@ -678,7 +660,7 @@ int ksmbd_vfs_link(struct ksmbd_work *work, const char *oldname,
}
dentry = kern_path_create(AT_FDCWD, newname, &newpath,
- flags | LOOKUP_REVAL);
+ LOOKUP_NO_SYMLINKS | LOOKUP_REVAL);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
pr_err("path create err for %s, err %d\n", newname, err);
@@ -797,7 +779,6 @@ int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
struct dentry *src_dent, *trap_dent, *src_child;
char *dst_name;
int err;
- int flags = LOOKUP_NO_SYMLINKS;
dst_name = extract_last_component(newname);
if (!dst_name)
@@ -806,13 +787,8 @@ int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
src_dent_parent = dget_parent(fp->filp->f_path.dentry);
src_dent = fp->filp->f_path.dentry;
- flags = LOOKUP_DIRECTORY;
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- flags = LOOKUP_FOLLOW;
- flags |= LOOKUP_DIRECTORY;
-
- err = kern_path(newname, flags, &dst_path);
+ err = kern_path(newname, LOOKUP_NO_SYMLINKS | LOOKUP_DIRECTORY,
+ &dst_path);
if (err) {
ksmbd_debug(VFS, "Cannot get path for %s [%d]\n", newname, err);
goto out;
@@ -871,13 +847,7 @@ int ksmbd_vfs_truncate(struct ksmbd_work *work, const char *name,
int err = 0;
if (name) {
- int flags = LOOKUP_NO_SYMLINKS;
-
- if (test_share_config_flag(work->tcon->share_conf,
- KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
- flags = LOOKUP_FOLLOW;
-
- err = kern_path(name, flags, &path);
+ err = kern_path(name, LOOKUP_NO_SYMLINKS, &path);
if (err) {
pr_err("cannot get linux path for %s, err %d\n",
name, err);
--
2.25.1
