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2025-10-15ksmbd: fix recursive locking in RPC handle list accessMarios Makassikis
Since commit 305853cce3794 ("ksmbd: Fix race condition in RPC handle list access"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock. This causes hung connections / tasks when a client attempts to open a named pipe. Using Samba's rpcclient tool: $ rpcclient //192.168.1.254 -U user%password $ rpcclient $> srvinfo <connection hung here> Kernel side: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000 Workqueue: ksmbd-io handle_ksmbd_work Call trace: __schedule from schedule+0x3c/0x58 schedule from schedule_preempt_disabled+0xc/0x10 schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8 rwsem_down_read_slowpath from down_read+0x28/0x30 down_read from ksmbd_session_rpc_method+0x18/0x3c ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68 ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228 ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8 create_smb2_pipe from smb2_open+0x10c/0x27ac smb2_open from handle_ksmbd_work+0x238/0x3dc handle_ksmbd_work from process_scheduled_works+0x160/0x25c process_scheduled_works from worker_thread+0x16c/0x1e8 worker_thread from kthread+0xa8/0xb8 kthread from ret_from_fork+0x14/0x38 Exception stack(0x8529ffb0 to 0x8529fff8) The task deadlocks because the lock is already held: ksmbd_session_rpc_open down_write(&sess->rpc_lock) ksmbd_rpc_open ksmbd_session_rpc_method down_read(&sess->rpc_lock) <-- deadlock Adjust ksmbd_session_rpc_method() callers to take the lock when necessary. Fixes: 305853cce3794 ("ksmbd: Fix race condition in RPC handle list access") Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-09-30ksmbd: increase session and share hash table bitsNamjae Jeon
Increases the number of bits for the hash table from 3 to 12. The thousands of sessions and shares can be connected. So the current 3-bit size can lead to frequent hash collisions. Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-09-30ksmbd: Fix race condition in RPC handle list accessYunseong Kim
The 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd session. Access to this list is intended to be protected by 'sess->rpc_lock' (an rw_semaphore). However, the locking implementation was flawed, leading to potential race conditions. In ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock before calling xa_store() and xa_erase(). Since these operations modify the XArray structure, a write lock is required to ensure exclusive access and prevent data corruption from concurrent modifications. Furthermore, ksmbd_session_rpc_method() accessed the list using xa_load() without holding any lock at all. This could lead to reading inconsistent data or a potential use-after-free if an entry is concurrently removed and the pointer is dereferenced. Fix these issues by: 1. Using down_write() and up_write() in ksmbd_session_rpc_open() to ensure exclusive access during XArray modification, and ensuring the lock is correctly released on error paths. 2. Adding down_read() and up_read() in ksmbd_session_rpc_method() to safely protect the lookup. Fixes: a1f46c99d9ea ("ksmbd: fix use-after-free in ksmbd_session_rpc_open") Fixes: b685757c7b08 ("ksmbd: Implements sess->rpc_handle_list as xarray") Cc: stable@vger.kernel.org Signed-off-by: Yunseong Kim <ysk@kzalloc.com> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-04-22ksmbd: fix use-after-free in ksmbd_session_rpc_openNamjae Jeon
A UAF issue can occur due to a race condition between ksmbd_session_rpc_open() and __session_rpc_close(). Add rpc_lock to the session to protect it. Cc: stable@vger.kernel.org Reported-by: Norbert Szetei <norbert@doyensec.com> Tested-by: Norbert Szetei <norbert@doyensec.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-04-01ksmbd: fix null pointer dereference in alloc_preauth_hash()Namjae Jeon
The Client send malformed smb2 negotiate request. ksmbd return error response. Subsequently, the client can send smb2 session setup even thought conn->preauth_info is not allocated. This patch add KSMBD_SESS_NEED_SETUP status of connection to ignore session setup request if smb2 negotiate phase is not complete. Cc: stable@vger.kernel.org Tested-by: Steve French <stfrench@microsoft.com> Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-26505 Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-04-01ksmbd: fix session use-after-free in multichannel connectionNamjae Jeon
There is a race condition between session setup and ksmbd_sessions_deregister. The session can be freed before the connection is added to channel list of session. This patch check reference count of session before freeing it. Cc: stable@vger.kernel.org Reported-by: Sean Heelan <seanheelan@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-03-27ksmbd: fix multichannel connection failureNamjae Jeon
ksmbd check that the session of second channel is in the session list of first connection. If it is in session list, multichannel connection should not be allowed. Fixes: b95629435b84 ("ksmbd: fix racy issue from session lookup and expire") Reported-by: Sean Heelan <seanheelan@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-03-27ksmbd: fix use-after-free in ksmbd_sessions_deregister()Namjae Jeon
In multichannel mode, UAF issue can occur in session_deregister when the second channel sets up a session through the connection of the first channel. session that is freed through the global session table can be accessed again through ->sessions of connection. Cc: stable@vger.kernel.org Reported-by: Norbert Szetei <norbert@doyensec.com> Tested-by: Norbert Szetei <norbert@doyensec.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-12-10ksmbd: fix racy issue from session lookup and expireNamjae Jeon
Increment the session reference count within the lock for lookup to avoid racy issue with session expire. Cc: stable@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-25737 Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-25ksmbd: use __GFP_RETRY_MAYFAILNamjae Jeon
Prefer to report ENOMEM rather than incur the oom for allocations in ksmbd. __GFP_NORETRY could not achieve that, It would fail the allocations just too easily. __GFP_RETRY_MAYFAIL will keep retrying the allocation until there is no more progress and fail the allocation instead go OOM and let the caller to deal with it. Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-05ksmbd: fix slab-use-after-free in ksmbd_smb2_session_createNamjae Jeon
There is a race condition between ksmbd_smb2_session_create and ksmbd_expire_session. This patch add missing sessions_table_lock while adding/deleting session from global session table. Cc: stable@vger.kernel.org # v5.15+ Reported-by: Norbert Szetei <norbert@doyensec.com> Tested-by: Norbert Szetei <norbert@doyensec.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-28ksmbd: Fix the missing xa_store error checkJinjie Ruan
xa_store() can fail, it return xa_err(-EINVAL) if the entry cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation failed, so check error for xa_store() to fix it. Cc: stable@vger.kernel.org Fixes: b685757c7b08 ("ksmbd: Implements sess->rpc_handle_list as xarray") Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-11ksmbd: add support for supplementary groupsNamjae Jeon
Even though system user has a supplementary group, It gets NT_STATUS_ACCESS_DENIED when attempting to create file or directory. This patch add KSMBD_EVENT_LOGIN_REQUEST_EXT/RESPONSE_EXT netlink events to get supplementary groups list. The new netlink event doesn't break backward compatibility when using old ksmbd-tools. Co-developed-by: Atte Heikkilä <atteh.mailbox@gmail.com> Signed-off-by: Atte Heikkilä <atteh.mailbox@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-09ksmbd: fix user-after-free from session log offNamjae Jeon
There is racy issue between smb2 session log off and smb2 session setup. It will cause user-after-free from session log off. This add session_lock when setting SMB2_SESSION_EXPIRED and referece count to session struct not to free session while it is being used. Cc: stable@vger.kernel.org # v5.15+ Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-25282 Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-08-18ksmbd: fix race condition between destroy_previous_session() and smb2 ↵Namjae Jeon
operations() If there is ->PreviousSessionId field in the session setup request, The session of the previous connection should be destroyed. During this, if the smb2 operation requests in the previous session are being processed, a racy issue could happen with ksmbd_destroy_file_table(). This patch sets conn->status to KSMBD_SESS_NEED_RECONNECT to block incoming operations and waits until on-going operations are complete (i.e. idle) before desctorying the previous session. Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Cc: stable@vger.kernel.org # v6.6+ Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-25040 Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-08-08ksmbd: override fsids for share path checkNamjae Jeon
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@samsung.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-07-14ksmbd: add durable scavenger timerNamjae Jeon
Launch ksmbd-durable-scavenger kernel thread to scan durable fps that have not been reclaimed by a client within the configured time. Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-05-22ksmbd: ignore trailing slashes in share pathsNandor Kracser
Trailing slashes in share paths (like: /home/me/Share/) caused permission issues with shares for clients on iOS and on Android TV for me, but otherwise they work fine with plain old Samba. Cc: stable@vger.kernel.org Signed-off-by: Nandor Kracser <bonifaido@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-04-02ksmbd: validate payload size in ipc responseNamjae Jeon
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>
2024-03-12ksmbd: add support for durable handles v1/v2Namjae Jeon
Durable file handles allow reopening a file preserved on a short network outage and transparent client reconnection within a timeout. i.e. Durable handles aren't necessarily cleaned up when the opening process terminates. This patch add support for durable handle version 1 and 2. To prove durable handles work on ksmbd, I have tested this patch with the following smbtorture tests: smb2.durable-open.open-oplock smb2.durable-open.open-lease smb2.durable-open.reopen1 smb2.durable-open.reopen1a smb2.durable-open.reopen1a-lease smb2.durable-open.reopen2 smb2.durable-open.reopen2a smb2.durable-open.reopen2-lease smb2.durable-open.reopen2-lease-v2 smb2.durable-open.reopen3 smb2.durable-open.reopen4 smb2.durable-open.delete_on_close2 smb2.durable-open.file-position smb2.durable-open.lease smb2.durable-open.alloc-size smb2.durable-open.read-only smb2.durable-v2-open.create-blob smb2.durable-v2-open.open-oplock smb2.durable-v2-open.open-lease smb2.durable-v2-open.reopen1 smb2.durable-v2-open.reopen1a smb2.durable-v2-open.reopen1a-lease smb2.durable-v2-open.reopen2 smb2.durable-v2-open.reopen2b Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-12ksmbd: mark SMB2_SESSION_EXPIRED to session when destroying previous sessionNamjae Jeon
Currently ksmbd exit connection as well destroying previous session. When testing durable handle feaure, I found that destroy_previous_session() should destroy only session, i.e. the connection should be still alive. This patch mark SMB2_SESSION_EXPIRED on the previous session to be destroyed later and not used anymore. Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-01-09ksmbd: Remove usage of the deprecated ida_simple_xx() APIChristophe JAILLET
ida_alloc() and ida_free() should be preferred to the deprecated ida_simple_get() and ida_simple_remove(). This is less verbose. Note that the upper limit of ida_simple_get() is exclusive, but the one of ida_alloc_range() is inclusive. So change a 0xFFFFFFFF into a 0xFFFFFFFE in order to keep the same behavior. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-10-22ksmbd: Remove unused field in ksmbd_user structCheng-Han Wu
fs/smb/server/mgmt/user_config.h:21: Remove the unused field 'failed_login_count' from the ksmbd_user struct. Signed-off-by: Cheng-Han Wu <hank20010209@gmail.com> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-10-04ksmbd: fix race condition between tree conn lookup and disconnectNamjae Jeon
if thread A in smb2_write is using work-tcon, other thread B use smb2_tree_disconnect free the tcon, then thread A will use free'd tcon. Time + Thread A | Thread A smb2_write | smb2_tree_disconnect | | | kfree(tree_conn) | // UAF! | work->tcon->share_conf | + This patch add state, reference count and lock for tree conn to fix race condition issue. Reported-by: luosili <rootlab@huawei.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-10-04ksmbd: fix race condition between session lookup and expireNamjae Jeon
Thread A + Thread B ksmbd_session_lookup | smb2_sess_setup sess = xa_load | | | xa_erase(&conn->sessions, sess->id); | | ksmbd_session_destroy(sess) --> kfree(sess) | // UAF! | sess->last_active = jiffies | + This patch add rwsem to fix race condition between ksmbd_session_lookup and ksmbd_expire_session. Reported-by: luosili <rootlab@huawei.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-08-29ksmbd: fix `force create mode' and `force directory mode'Atte Heikkilä
`force create mode' and `force directory mode' should be bitwise ORed with the perms after `create mask' and `directory mask' have been applied, respectively. Signed-off-by: Atte Heikkilä <atteh.mailbox@gmail.com> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-06-26ksmbd: remove unused ksmbd_tree_conn_share functionNamjae Jeon
Remove unused ksmbd_tree_conn_share function. Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-05-24smb: move client and server files to common directory fs/smbSteve French
Move CIFS/SMB3 related client and server files (cifs.ko and ksmbd.ko and helper modules) to new fs/smb subdirectory: fs/cifs --> fs/smb/client fs/ksmbd --> fs/smb/server fs/smbfs_common --> fs/smb/common Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
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