From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6298E3D5645; Fri, 24 Apr 2026 13:41:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038112; cv=none; b=bTkuMSs35PmtZFkZC2U7RWyl3Y5szqx4vnABD8f5lmMpJQOLGbefJOw1mVdjAIgikUmdOAqtySkAo6fplJhIbUYX79nJxtLguCB5x5yA59/Re2/JoUv+EfNdmY0W1FRE9CmxZi73AblIDiIVMBHyG7RAt7AJP3MROIAwldm24pU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038112; c=relaxed/simple; bh=QAR4SSkDTe1BcFo2DdU4Bg+fG16soJwT2YSm3q/Ipb4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iiU2g1ZVgsRvATHk2pw9mvP0FTGSUfFoJRM7a61TJgcvLK5EgXo0kZ1KqKiB8mIMs/kAQBFWDoLTATNaniaP+1zuUjUQGYBVL8FzMvt6jQB6F3xqTq5ahUWits6uwYpmYMXoi3Iuy/e5iv77kBiErO1FTP4ze7wVgDDktotbiXk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YrRBumsM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YrRBumsM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBDFFC19425; Fri, 24 Apr 2026 13:41:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038112; bh=QAR4SSkDTe1BcFo2DdU4Bg+fG16soJwT2YSm3q/Ipb4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YrRBumsM8XEYY/xg8fOnzy5NSbJXz9UObQsp4ZwsVcn+BDyJ6ANoK0ZDrTxlzSdPi GvVxM8LXHqDxdC73rJ6nXzfsUcJj1bniN65xwiM45PsaNZ24JpSgtSaf/ZXII+jSNh bWCQAA7JkhJKciqlUu0htBnfN65ehbSUkuS6tjVY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Davide Ornaghi , Navaneeth K , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.18 09/55] ksmbd: validate owner of durable handle on reconnect Date: Fri, 24 Apr 2026 15:30:48 +0200 Message-ID: <20260424132431.999743575@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424132430.006424517@linuxfoundation.org> References: <20260424132430.006424517@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon [ Upstream commit 49110a8ce654bbe56bef7c5e44cce31f4b102b8a ] Currently, ksmbd does not verify if the user attempting to reconnect to a durable handle is the same user who originally opened the file. This allows any authenticated user to hijack an orphaned durable handle by predicting or brute-forcing the persistent ID. According to MS-SMB2, the server MUST verify that the SecurityContext of the reconnect request matches the SecurityContext associated with the existing open. Add a durable_owner structure to ksmbd_file to store the original opener's UID, GID, and account name. and catpure the owner information when a file handle becomes orphaned. and implementing ksmbd_vfs_compare_durable_owner() to validate the identity of the requester during SMB2_CREATE (DHnC). Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Reported-by: Davide Ornaghi Reported-by: Navaneeth K Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/mgmt/user_session.c | 7 +-- fs/smb/server/oplock.c | 7 +++ fs/smb/server/oplock.h | 1 fs/smb/server/smb2pdu.c | 3 - fs/smb/server/vfs_cache.c | 87 ++++++++++++++++++++++++++++++++++---- fs/smb/server/vfs_cache.h | 12 ++++- 6 files changed, 102 insertions(+), 15 deletions(-) --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -161,11 +161,10 @@ void ksmbd_session_destroy(struct ksmbd_ if (!sess) return; + ksmbd_tree_conn_session_logoff(sess); + ksmbd_destroy_file_table(sess); if (sess->user) ksmbd_free_user(sess->user); - - ksmbd_tree_conn_session_logoff(sess); - ksmbd_destroy_file_table(&sess->file_table); ksmbd_launch_ksmbd_durable_scavenger(); ksmbd_session_rpc_clear_list(sess); free_channel_list(sess); @@ -396,7 +395,7 @@ void destroy_previous_session(struct ksm goto out; } - ksmbd_destroy_file_table(&prev_sess->file_table); + ksmbd_destroy_file_table(prev_sess); prev_sess->state = SMB2_SESSION_EXPIRED; ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_SETUP); ksmbd_launch_ksmbd_durable_scavenger(); --- a/fs/smb/server/oplock.c +++ b/fs/smb/server/oplock.c @@ -1841,6 +1841,7 @@ int smb2_check_durable_oplock(struct ksm struct ksmbd_share_config *share, struct ksmbd_file *fp, struct lease_ctx_info *lctx, + struct ksmbd_user *user, char *name) { struct oplock_info *opinfo = opinfo_get(fp); @@ -1849,6 +1850,12 @@ int smb2_check_durable_oplock(struct ksm if (!opinfo) return 0; + if (ksmbd_vfs_compare_durable_owner(fp, user) == false) { + ksmbd_debug(SMB, "Durable handle reconnect failed: owner mismatch\n"); + ret = -EBADF; + goto out; + } + if (opinfo->is_lease == false) { if (lctx) { pr_err("create context include lease\n"); --- a/fs/smb/server/oplock.h +++ b/fs/smb/server/oplock.h @@ -126,5 +126,6 @@ int smb2_check_durable_oplock(struct ksm struct ksmbd_share_config *share, struct ksmbd_file *fp, struct lease_ctx_info *lctx, + struct ksmbd_user *user, char *name); #endif /* __KSMBD_OPLOCK_H */ --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -3022,7 +3022,8 @@ int smb2_open(struct ksmbd_work *work) } if (dh_info.reconnected == true) { - rc = smb2_check_durable_oplock(conn, share, dh_info.fp, lc, name); + rc = smb2_check_durable_oplock(conn, share, dh_info.fp, + lc, sess->user, name); if (rc) { ksmbd_put_durable_fd(dh_info.fp); goto err_out2; --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -18,6 +18,7 @@ #include "connection.h" #include "mgmt/tree_connect.h" #include "mgmt/user_session.h" +#include "mgmt/user_config.h" #include "smb_common.h" #include "server.h" @@ -383,6 +384,8 @@ static void __ksmbd_close_fd(struct ksmb if (ksmbd_stream_fd(fp)) kfree(fp->stream.name); + kfree(fp->owner.name); + kmem_cache_free(filp_cache, fp); } @@ -694,11 +697,13 @@ void ksmbd_update_fstate(struct ksmbd_fi } static int -__close_file_table_ids(struct ksmbd_file_table *ft, +__close_file_table_ids(struct ksmbd_session *sess, struct ksmbd_tree_connect *tcon, bool (*skip)(struct ksmbd_tree_connect *tcon, - struct ksmbd_file *fp)) + struct ksmbd_file *fp, + struct ksmbd_user *user)) { + struct ksmbd_file_table *ft = &sess->file_table; struct ksmbd_file *fp; unsigned int id = 0; int num = 0; @@ -711,7 +716,7 @@ __close_file_table_ids(struct ksmbd_file break; } - if (skip(tcon, fp) || + if (skip(tcon, fp, sess->user) || !atomic_dec_and_test(&fp->refcount)) { id++; write_unlock(&ft->lock); @@ -763,7 +768,8 @@ static inline bool is_reconnectable(stru } static bool tree_conn_fd_check(struct ksmbd_tree_connect *tcon, - struct ksmbd_file *fp) + struct ksmbd_file *fp, + struct ksmbd_user *user) { return fp->tcon != tcon; } @@ -898,8 +904,62 @@ void ksmbd_stop_durable_scavenger(void) kthread_stop(server_conf.dh_task); } +/* + * ksmbd_vfs_copy_durable_owner - Copy owner info for durable reconnect + * @fp: ksmbd file pointer to store owner info + * @user: user pointer to copy from + * + * This function binds the current user's identity to the file handle + * to satisfy MS-SMB2 Step 8 (SecurityContext matching) during reconnect. + * + * Return: 0 on success, or negative error code on failure + */ +static int ksmbd_vfs_copy_durable_owner(struct ksmbd_file *fp, + struct ksmbd_user *user) +{ + if (!user) + return -EINVAL; + + /* Duplicate the user name to ensure identity persistence */ + fp->owner.name = kstrdup(user->name, GFP_KERNEL); + if (!fp->owner.name) + return -ENOMEM; + + fp->owner.uid = user->uid; + fp->owner.gid = user->gid; + + return 0; +} + +/** + * ksmbd_vfs_compare_durable_owner - Verify if the requester is original owner + * @fp: existing ksmbd file pointer + * @user: user pointer of the reconnect requester + * + * Compares the UID, GID, and name of the current requester against the + * original owner stored in the file handle. + * + * Return: true if the user matches, false otherwise + */ +bool ksmbd_vfs_compare_durable_owner(struct ksmbd_file *fp, + struct ksmbd_user *user) +{ + if (!user || !fp->owner.name) + return false; + + /* Check if the UID and GID match first (fast path) */ + if (fp->owner.uid != user->uid || fp->owner.gid != user->gid) + return false; + + /* Validate the account name to ensure the same SecurityContext */ + if (strcmp(fp->owner.name, user->name)) + return false; + + return true; +} + static bool session_fd_check(struct ksmbd_tree_connect *tcon, - struct ksmbd_file *fp) + struct ksmbd_file *fp, struct ksmbd_user *user) { struct ksmbd_inode *ci; struct oplock_info *op; @@ -909,6 +969,9 @@ static bool session_fd_check(struct ksmb if (!is_reconnectable(fp)) return false; + if (ksmbd_vfs_copy_durable_owner(fp, user)) + return false; + conn = fp->conn; ci = fp->f_ci; down_write(&ci->m_lock); @@ -940,7 +1003,7 @@ static bool session_fd_check(struct ksmb void ksmbd_close_tree_conn_fds(struct ksmbd_work *work) { - int num = __close_file_table_ids(&work->sess->file_table, + int num = __close_file_table_ids(work->sess, work->tcon, tree_conn_fd_check); @@ -949,7 +1012,7 @@ void ksmbd_close_tree_conn_fds(struct ks void ksmbd_close_session_fds(struct ksmbd_work *work) { - int num = __close_file_table_ids(&work->sess->file_table, + int num = __close_file_table_ids(work->sess, work->tcon, session_fd_check); @@ -1046,6 +1109,10 @@ int ksmbd_reopen_durable_fd(struct ksmbd } up_write(&ci->m_lock); + fp->owner.uid = fp->owner.gid = 0; + kfree(fp->owner.name); + fp->owner.name = NULL; + return 0; } @@ -1060,12 +1127,14 @@ int ksmbd_init_file_table(struct ksmbd_f return 0; } -void ksmbd_destroy_file_table(struct ksmbd_file_table *ft) +void ksmbd_destroy_file_table(struct ksmbd_session *sess) { + struct ksmbd_file_table *ft = &sess->file_table; + if (!ft->idr) return; - __close_file_table_ids(ft, NULL, session_fd_check); + __close_file_table_ids(sess, NULL, session_fd_check); idr_destroy(ft->idr); kfree(ft->idr); ft->idr = NULL; --- a/fs/smb/server/vfs_cache.h +++ b/fs/smb/server/vfs_cache.h @@ -68,6 +68,13 @@ enum { FP_CLOSED }; +/* Owner information for durable handle reconnect */ +struct durable_owner { + unsigned int uid; + unsigned int gid; + char *name; +}; + struct ksmbd_file { struct file *filp; u64 persistent_id; @@ -114,6 +121,7 @@ struct ksmbd_file { bool is_resilient; bool is_posix_ctxt; + struct durable_owner owner; }; static inline void set_ctx_actor(struct dir_context *ctx, @@ -140,7 +148,7 @@ static inline bool ksmbd_stream_fd(struc } int ksmbd_init_file_table(struct ksmbd_file_table *ft); -void ksmbd_destroy_file_table(struct ksmbd_file_table *ft); +void ksmbd_destroy_file_table(struct ksmbd_session *sess); int ksmbd_close_fd(struct ksmbd_work *work, u64 id); struct ksmbd_file *ksmbd_lookup_fd_fast(struct ksmbd_work *work, u64 id); struct ksmbd_file *ksmbd_lookup_foreign_fd(struct ksmbd_work *work, u64 id); @@ -166,6 +174,8 @@ void ksmbd_free_global_file_table(void); void ksmbd_set_fd_limit(unsigned long limit); void ksmbd_update_fstate(struct ksmbd_file_table *ft, struct ksmbd_file *fp, unsigned int state); +bool ksmbd_vfs_compare_durable_owner(struct ksmbd_file *fp, + struct ksmbd_user *user); /* * INODE hash