From: Paulo Alcantara Date: Thu, 23 Oct 2025 21:59:47 +0000 (-0300) Subject: smb: client: handle lack of IPC in dfs_cache_refresh() X-Git-Tag: v6.18-rc4~15^2~1 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fac56c4651ae95f3f2b468c2cf1884cf0e6d18c1;p=thirdparty%2Fkernel%2Fstable.git smb: client: handle lack of IPC in dfs_cache_refresh() In very rare cases, DFS mounts could end up with SMB sessions without any IPC connections. These mounts are only possible when having unexpired cached DFS referrals, hence not requiring any IPC connections during the mount process. Try to establish those missing IPC connections when refreshing DFS referrals. If the server is still rejecting it, then simply ignore and leave expired cached DFS referral for any potential DFS failovers. Reported-by: Jay Shin Signed-off-by: Paulo Alcantara (Red Hat) Cc: David Howells Cc: linux-cifs@vger.kernel.org Signed-off-by: Steve French --- diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h index fb1813cbe0eb..3528c365a452 100644 --- a/fs/smb/client/cifsproto.h +++ b/fs/smb/client/cifsproto.h @@ -616,6 +616,8 @@ extern int E_md4hash(const unsigned char *passwd, unsigned char *p16, extern struct TCP_Server_Info * cifs_find_tcp_session(struct smb3_fs_context *ctx); +struct cifs_tcon *cifs_setup_ipc(struct cifs_ses *ses, bool seal); + void __cifs_put_smb_ses(struct cifs_ses *ses); extern struct cifs_ses * diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index dd12f3eb61dc..d65ab7e4b1c2 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -2015,39 +2015,31 @@ static int match_session(struct cifs_ses *ses, /** * cifs_setup_ipc - helper to setup the IPC tcon for the session * @ses: smb session to issue the request on - * @ctx: the superblock configuration context to use for building the - * new tree connection for the IPC (interprocess communication RPC) + * @seal: if encryption is requested * * A new IPC connection is made and stored in the session * tcon_ipc. The IPC tcon has the same lifetime as the session. */ -static int -cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx) +struct cifs_tcon *cifs_setup_ipc(struct cifs_ses *ses, bool seal) { int rc = 0, xid; struct cifs_tcon *tcon; char unc[SERVER_NAME_LENGTH + sizeof("//x/IPC$")] = {0}; - bool seal = false; struct TCP_Server_Info *server = ses->server; /* * If the mount request that resulted in the creation of the * session requires encryption, force IPC to be encrypted too. */ - if (ctx->seal) { - if (server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION) - seal = true; - else { - cifs_server_dbg(VFS, - "IPC: server doesn't support encryption\n"); - return -EOPNOTSUPP; - } + if (seal && !(server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION)) { + cifs_server_dbg(VFS, "IPC: server doesn't support encryption\n"); + return ERR_PTR(-EOPNOTSUPP); } /* no need to setup directory caching on IPC share, so pass in false */ tcon = tcon_info_alloc(false, netfs_trace_tcon_ref_new_ipc); if (tcon == NULL) - return -ENOMEM; + return ERR_PTR(-ENOMEM); spin_lock(&server->srv_lock); scnprintf(unc, sizeof(unc), "\\\\%s\\IPC$", server->hostname); @@ -2057,13 +2049,13 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx) tcon->ses = ses; tcon->ipc = true; tcon->seal = seal; - rc = server->ops->tree_connect(xid, ses, unc, tcon, ctx->local_nls); + rc = server->ops->tree_connect(xid, ses, unc, tcon, ses->local_nls); free_xid(xid); if (rc) { - cifs_server_dbg(VFS, "failed to connect to IPC (rc=%d)\n", rc); + cifs_server_dbg(VFS | ONCE, "failed to connect to IPC (rc=%d)\n", rc); tconInfoFree(tcon, netfs_trace_tcon_ref_free_ipc_fail); - goto out; + return ERR_PTR(rc); } cifs_dbg(FYI, "IPC tcon rc=%d ipc tid=0x%x\n", rc, tcon->tid); @@ -2071,9 +2063,7 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx) spin_lock(&tcon->tc_lock); tcon->status = TID_GOOD; spin_unlock(&tcon->tc_lock); - ses->tcon_ipc = tcon; -out: - return rc; + return tcon; } static struct cifs_ses * @@ -2347,6 +2337,7 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx) { struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&server->dstaddr; struct sockaddr_in *addr = (struct sockaddr_in *)&server->dstaddr; + struct cifs_tcon *ipc; struct cifs_ses *ses; unsigned int xid; int retries = 0; @@ -2525,7 +2516,12 @@ retry_new_session: list_add(&ses->smb_ses_list, &server->smb_ses_list); spin_unlock(&cifs_tcp_ses_lock); - cifs_setup_ipc(ses, ctx); + ipc = cifs_setup_ipc(ses, ctx->seal); + spin_lock(&cifs_tcp_ses_lock); + spin_lock(&ses->ses_lock); + ses->tcon_ipc = !IS_ERR(ipc) ? ipc : NULL; + spin_unlock(&ses->ses_lock); + spin_unlock(&cifs_tcp_ses_lock); free_xid(xid); diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c index 4dada26d56b5..f2ad0ccd08a7 100644 --- a/fs/smb/client/dfs_cache.c +++ b/fs/smb/client/dfs_cache.c @@ -1120,24 +1120,63 @@ static bool target_share_equal(struct cifs_tcon *tcon, const char *s1) return match; } -static bool is_ses_good(struct cifs_ses *ses) +static bool is_ses_good(struct cifs_tcon *tcon, struct cifs_ses *ses) { struct TCP_Server_Info *server = ses->server; - struct cifs_tcon *tcon = ses->tcon_ipc; + struct cifs_tcon *ipc = NULL; bool ret; + spin_lock(&cifs_tcp_ses_lock); spin_lock(&ses->ses_lock); spin_lock(&ses->chan_lock); + ret = !cifs_chan_needs_reconnect(ses, server) && - ses->ses_status == SES_GOOD && - !tcon->need_reconnect; + ses->ses_status == SES_GOOD; + spin_unlock(&ses->chan_lock); + + if (!ret) + goto out; + + if (likely(ses->tcon_ipc)) { + if (ses->tcon_ipc->need_reconnect) { + ret = false; + goto out; + } + } else { + spin_unlock(&ses->ses_lock); + spin_unlock(&cifs_tcp_ses_lock); + + ipc = cifs_setup_ipc(ses, tcon->seal); + + spin_lock(&cifs_tcp_ses_lock); + spin_lock(&ses->ses_lock); + if (!IS_ERR(ipc)) { + if (!ses->tcon_ipc) { + ses->tcon_ipc = ipc; + ipc = NULL; + } + } else { + ret = false; + ipc = NULL; + } + } + +out: spin_unlock(&ses->ses_lock); + spin_unlock(&cifs_tcp_ses_lock); + if (ipc && server->ops->tree_disconnect) { + unsigned int xid = get_xid(); + + (void)server->ops->tree_disconnect(xid, ipc); + _free_xid(xid); + } + tconInfoFree(ipc, netfs_trace_tcon_ref_free_ipc); return ret; } /* Refresh dfs referral of @ses */ -static void refresh_ses_referral(struct cifs_ses *ses) +static void refresh_ses_referral(struct cifs_tcon *tcon, struct cifs_ses *ses) { struct cache_entry *ce; unsigned int xid; @@ -1153,7 +1192,7 @@ static void refresh_ses_referral(struct cifs_ses *ses) } ses = CIFS_DFS_ROOT_SES(ses); - if (!is_ses_good(ses)) { + if (!is_ses_good(tcon, ses)) { cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", __func__); goto out; @@ -1241,7 +1280,7 @@ static void refresh_tcon_referral(struct cifs_tcon *tcon, bool force_refresh) up_read(&htable_rw_lock); ses = CIFS_DFS_ROOT_SES(ses); - if (!is_ses_good(ses)) { + if (!is_ses_good(tcon, ses)) { cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", __func__); goto out; @@ -1309,7 +1348,7 @@ void dfs_cache_refresh(struct work_struct *work) tcon = container_of(work, struct cifs_tcon, dfs_cache_work.work); list_for_each_entry(ses, &tcon->dfs_ses_list, dlist) - refresh_ses_referral(ses); + refresh_ses_referral(tcon, ses); refresh_tcon_referral(tcon, false); queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,