[PATCH 5.15 02/71] ksmbd: validate payload size in ipc response

Greg Kroah-Hartman
2024-04-23T21:46:15Z

From: Namjae Jeon <linkinjeon@kernel.org>

[ Upstream commit a677ebd8ca2f2632ccdecbad7b87641274e15aac ]

If installing malicious ksmbd-tools, ksmbd.mountd can return invalid ipc
response to ksmbd kernel server. ksmbd should validate payload size of
ipc response from ksmbd.mountd to avoid memory overrun or
slab-out-of-bounds. This patch validate 3 ipc response that has payload.

Cc: stable@vger.kernel.org
Reported-by: Chao Ma <machao2019@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ksmbd/ksmbd_netlink.h | 3 ++-
fs/ksmbd/mgmt/share_config.c | 7 ++++++-
fs/ksmbd/transport_ipc.c | 37 ++++++++++++++++++++++++++++++++++++
3 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/fs/ksmbd/ksmbd_netlink.h b/fs/ksmbd/ksmbd_netlink.h
index ecffcb8a1557a..dc30cd0f6acd0 100644
--- a/fs/ksmbd/ksmbd_netlink.h
+++ b/fs/ksmbd/ksmbd_netlink.h
@@ -166,7 +166,8 @@ struct ksmbd_share_config_response {
__u16 force_uid;
__u16 force_gid;
__s8 share_name[KSMBD_REQ_MAX_SHARE_NAME];
- __u32 reserved[112]; /* Reserved room */
+ __u32 reserved[111]; /* Reserved room */
+ __u32 payload_sz;
__u32 veto_list_sz;
__s8 ____payload[];
};
diff --git a/fs/ksmbd/mgmt/share_config.c b/fs/ksmbd/mgmt/share_config.c
index 328a412259dc1..a2f0a2edceb8a 100644
--- a/fs/ksmbd/mgmt/share_config.c
+++ b/fs/ksmbd/mgmt/share_config.c
@@ -158,7 +158,12 @@ static struct ksmbd_share_config *share_config_request(struct unicode_map *um,
share->name = kstrdup(name, GFP_KERNEL);

if (!test_share_config_flag(share, KSMBD_SHARE_FLAG_PIPE)) {
- share->path = kstrdup(ksmbd_share_config_path(resp),
+ int path_len = PATH_MAX;
+
+ if (resp->payload_sz)
+ path_len = resp->payload_sz - resp->veto_list_sz;
+
+ share->path = kstrndup(ksmbd_share_config_path(resp), path_len,
GFP_KERNEL);
if (share->path)
share->path_sz = strlen(share->path);
diff --git a/fs/ksmbd/transport_ipc.c b/fs/ksmbd/transport_ipc.c
index 2c9662e327990..d62ebbff1e0f4 100644
--- a/fs/ksmbd/transport_ipc.c
+++ b/fs/ksmbd/transport_ipc.c
@@ -65,6 +65,7 @@ struct ipc_msg_table_entry {
struct hlist_node ipc_table_hlist;

void *response;
+ unsigned int msg_sz;
};

static struct delayed_work ipc_timer_work;
@@ -274,6 +275,7 @@ static int handle_response(int type, void *payload, size_t sz)
}

memcpy(entry->response, payload, sz);
+ entry->msg_sz = sz;
wake_up_interruptible(&entry->wait);
ret = 0;
break;
@@ -452,6 +454,34 @@ static int ipc_msg_send(struct ksmbd_ipc_msg *msg)
return ret;
}

+static int ipc_validate_msg(struct ipc_msg_table_entry *entry)
+{
+ unsigned int msg_sz = entry->msg_sz;
+
+ if (entry->type == KSMBD_EVENT_RPC_REQUEST) {
+ struct ksmbd_rpc_command *resp = entry->response;
+
+ msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;
+ } else if (entry->type == KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST) {
+ struct ksmbd_spnego_authen_response *resp = entry->response;
+
+ msg_sz = sizeof(struct ksmbd_spnego_authen_response) +
+ resp->session_key_len + resp->spnego_blob_len;
+ } else if (entry->type == KSMBD_EVENT_SHARE_CONFIG_REQUEST) {
+ struct ksmbd_share_config_response *resp = entry->response;
+
+ if (resp->payload_sz) {
+ if (resp->payload_sz < resp->veto_list_sz)
+ return -EINVAL;
+
+ msg_sz = sizeof(struct ksmbd_share_config_response) +
+ resp->payload_sz;
+ }
+ }
+
+ return entry->msg_sz != msg_sz ? -EINVAL : 0;
+}
+
static void *ipc_msg_send_request(struct ksmbd_ipc_msg *msg, unsigned int handle)
{
struct ipc_msg_table_entry entry;
@@ -476,6 +506,13 @@ static void *ipc_msg_send_request(struct ksmbd_ipc_msg *msg, unsigned int handle
ret = wait_event_interruptible_timeout(entry.wait,
entry.response != NULL,
IPC_WAIT_TIMEOUT);
+ if (entry.response) {
+ ret = ipc_validate_msg(&entry);
+ if (ret) {
+ kvfree(entry.response);
+ entry.response = NULL;
+ }
+ }
out:
down_write(&ipc_msg_table_lock);
hash_del(&entry.ipc_table_hlist);
--
2.43.0