[PATCH AUTOSEL 6.6 01/20] ksmbd: override fsids for share path check

From: Sasha Levin
Date: Sat Oct 12 2024 - 07:30:10 EST

From: Namjae Jeon <linkinjeon@xxxxxxxxxx>

[ Upstream commit a018c1b636e79b60149b41151ded7c2606d8606e ]

Sangsoo reported that a DAC denial error occurred when accessing
files through the ksmbd thread. This patch override fsids for share
path check.

Reported-by: Sangsoo Lee <constant.lee@xxxxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/smb/server/mgmt/share_config.c | 15 ++++++++++++---
fs/smb/server/mgmt/share_config.h | 4 +++-
fs/smb/server/mgmt/tree_connect.c | 9 +++++----
fs/smb/server/mgmt/tree_connect.h | 4 ++--
fs/smb/server/smb2pdu.c | 2 +-
fs/smb/server/smb_common.c | 9 +++++++--
fs/smb/server/smb_common.h | 2 ++
7 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/fs/smb/server/mgmt/share_config.c b/fs/smb/server/mgmt/share_config.c
index e0a6b758094fc..d8d03070ae44b 100644
--- a/fs/smb/server/mgmt/share_config.c
+++ b/fs/smb/server/mgmt/share_config.c
@@ -15,6 +15,7 @@
#include "share_config.h"
#include "user_config.h"
#include "user_session.h"
+#include "../connection.h"
#include "../transport_ipc.h"
#include "../misc.h"

@@ -120,12 +121,13 @@ static int parse_veto_list(struct ksmbd_share_config *share,
return 0;
}

-static struct ksmbd_share_config *share_config_request(struct unicode_map *um,
+static struct ksmbd_share_config *share_config_request(struct ksmbd_work *work,
const char *name)
{
struct ksmbd_share_config_response *resp;
struct ksmbd_share_config *share = NULL;
struct ksmbd_share_config *lookup;
+ struct unicode_map *um = work->conn->um;
int ret;

resp = ksmbd_ipc_share_config_request(name);
@@ -181,7 +183,14 @@ static struct ksmbd_share_config *share_config_request(struct unicode_map *um,
KSMBD_SHARE_CONFIG_VETO_LIST(resp),
resp->veto_list_sz);
if (!ret && share->path) {
+ if (__ksmbd_override_fsids(work, share)) {
+ kill_share(share);
+ share = NULL;
+ goto out;
+ }
+
ret = kern_path(share->path, 0, &share->vfs_path);
+ ksmbd_revert_fsids(work);
if (ret) {
ksmbd_debug(SMB, "failed to access '%s'\n",
share->path);
@@ -214,7 +223,7 @@ static struct ksmbd_share_config *share_config_request(struct unicode_map *um,
return share;
}

-struct ksmbd_share_config *ksmbd_share_config_get(struct unicode_map *um,
+struct ksmbd_share_config *ksmbd_share_config_get(struct ksmbd_work *work,
const char *name)
{
struct ksmbd_share_config *share;
@@ -227,7 +236,7 @@ struct ksmbd_share_config *ksmbd_share_config_get(struct unicode_map *um,

if (share)
return share;
- return share_config_request(um, name);
+ return share_config_request(work, name);
}

bool ksmbd_share_veto_filename(struct ksmbd_share_config *share,
diff --git a/fs/smb/server/mgmt/share_config.h b/fs/smb/server/mgmt/share_config.h
index 5f591751b9236..d4ac2dd4de204 100644
--- a/fs/smb/server/mgmt/share_config.h
+++ b/fs/smb/server/mgmt/share_config.h
@@ -11,6 +11,8 @@
#include <linux/path.h>
#include <linux/unicode.h>

+struct ksmbd_work;
+
struct ksmbd_share_config {
char *name;
char *path;
@@ -68,7 +70,7 @@ static inline void ksmbd_share_config_put(struct ksmbd_share_config *share)
__ksmbd_share_config_put(share);
}

-struct ksmbd_share_config *ksmbd_share_config_get(struct unicode_map *um,
+struct ksmbd_share_config *ksmbd_share_config_get(struct ksmbd_work *work,
const char *name);
bool ksmbd_share_veto_filename(struct ksmbd_share_config *share,
const char *filename);
diff --git a/fs/smb/server/mgmt/tree_connect.c b/fs/smb/server/mgmt/tree_connect.c
index d2c81a8a11dda..94a52a75014a4 100644
--- a/fs/smb/server/mgmt/tree_connect.c
+++ b/fs/smb/server/mgmt/tree_connect.c
@@ -16,17 +16,18 @@
#include "user_session.h"

struct ksmbd_tree_conn_status
-ksmbd_tree_conn_connect(struct ksmbd_conn *conn, struct ksmbd_session *sess,
- const char *share_name)
+ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name)
{
struct ksmbd_tree_conn_status status = {-ENOENT, NULL};
struct ksmbd_tree_connect_response *resp = NULL;
struct ksmbd_share_config *sc;
struct ksmbd_tree_connect *tree_conn = NULL;
struct sockaddr *peer_addr;
+ struct ksmbd_conn *conn = work->conn;
+ struct ksmbd_session *sess = work->sess;
int ret;

- sc = ksmbd_share_config_get(conn->um, share_name);
+ sc = ksmbd_share_config_get(work, share_name);
if (!sc)
return status;

@@ -61,7 +62,7 @@ ksmbd_tree_conn_connect(struct ksmbd_conn *conn, struct ksmbd_session *sess,
struct ksmbd_share_config *new_sc;

ksmbd_share_config_del(sc);
- new_sc = ksmbd_share_config_get(conn->um, share_name);
+ new_sc = ksmbd_share_config_get(work, share_name);
if (!new_sc) {
pr_err("Failed to update stale share config\n");
status.ret = -ESTALE;
diff --git a/fs/smb/server/mgmt/tree_connect.h b/fs/smb/server/mgmt/tree_connect.h
index 6377a70b811c8..a42cdd0510411 100644
--- a/fs/smb/server/mgmt/tree_connect.h
+++ b/fs/smb/server/mgmt/tree_connect.h
@@ -13,6 +13,7 @@
struct ksmbd_share_config;
struct ksmbd_user;
struct ksmbd_conn;
+struct ksmbd_work;

enum {
TREE_NEW = 0,
@@ -50,8 +51,7 @@ static inline int test_tree_conn_flag(struct ksmbd_tree_connect *tree_conn,
struct ksmbd_session;

struct ksmbd_tree_conn_status
-ksmbd_tree_conn_connect(struct ksmbd_conn *conn, struct ksmbd_session *sess,
- const char *share_name);
+ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name);
void ksmbd_tree_connect_put(struct ksmbd_tree_connect *tcon);

int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess,
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 592a2cdfd0670..646c874d151a8 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -1955,7 +1955,7 @@ int smb2_tree_connect(struct ksmbd_work *work)
ksmbd_debug(SMB, "tree connect request for tree %s treename %s\n",
name, treename);

- status = ksmbd_tree_conn_connect(conn, sess, name);
+ status = ksmbd_tree_conn_connect(work, name);
if (status.ret == KSMBD_TREE_CONN_STATUS_OK)
rsp->hdr.Id.SyncId.TreeId = cpu_to_le32(status.tree_conn->id);
else
diff --git a/fs/smb/server/smb_common.c b/fs/smb/server/smb_common.c
index 474dadf6b7b8b..13818ecb6e1b2 100644
--- a/fs/smb/server/smb_common.c
+++ b/fs/smb/server/smb_common.c
@@ -732,10 +732,10 @@ bool is_asterisk(char *p)
return p && p[0] == '*';
}

-int ksmbd_override_fsids(struct ksmbd_work *work)
+int __ksmbd_override_fsids(struct ksmbd_work *work,
+ struct ksmbd_share_config *share)
{
struct ksmbd_session *sess = work->sess;
- struct ksmbd_share_config *share = work->tcon->share_conf;
struct cred *cred;
struct group_info *gi;
unsigned int uid;
@@ -775,6 +775,11 @@ int ksmbd_override_fsids(struct ksmbd_work *work)
return 0;
}

+int ksmbd_override_fsids(struct ksmbd_work *work)
+{
+ return __ksmbd_override_fsids(work, work->tcon->share_conf);
+}
+
void ksmbd_revert_fsids(struct ksmbd_work *work)
{
const struct cred *cred;
diff --git a/fs/smb/server/smb_common.h b/fs/smb/server/smb_common.h
index f1092519c0c28..4a3148b0167f5 100644
--- a/fs/smb/server/smb_common.h
+++ b/fs/smb/server/smb_common.h
@@ -447,6 +447,8 @@ int ksmbd_extract_shortname(struct ksmbd_conn *conn,
int ksmbd_smb_negotiate_common(struct ksmbd_work *work, unsigned int command);

int ksmbd_smb_check_shared_mode(struct file *filp, struct ksmbd_file *curr_fp);
+int __ksmbd_override_fsids(struct ksmbd_work *work,
+ struct ksmbd_share_config *share);
int ksmbd_override_fsids(struct ksmbd_work *work);
void ksmbd_revert_fsids(struct ksmbd_work *work);

--
2.43.0