smb: client: fix DFS interlink failover

The DFS interlinks point to different DFS namespaces so make sure to
use the correct DFS root server to chase any DFS links under it by
storing the SMB session in dfs_ref_walk structure and then using it on
every referral walk.

Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index a71a988a92f9092300f9615be9948bb001c9c787..15571cf0ba632a5da1f3e5cf9cca7b5b63219b03 100644 (file)
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -821,6 +821,7 @@ struct TCP_Server_Info {
         * format: \\HOST\SHARE[\OPTIONAL PATH]
         */
        char *leaf_fullpath;
+       bool dfs_conn:1;
 };
 
 static inline bool is_smb1(struct TCP_Server_Info *server)
@@ -1059,6 +1060,7 @@ struct cifs_ses {
        struct list_head smb_ses_list;
        struct list_head rlist; /* reconnect list */
        struct list_head tcon_list;
+       struct list_head dlist; /* dfs list */
        struct cifs_tcon *tcon_ipc;
        spinlock_t ses_lock;  /* protect anything here that is not protected */
        struct mutex session_mutex;
@@ -1287,6 +1289,7 @@ struct cifs_tcon {
        /* BB add field for back pointer to sb struct(s)? */
 #ifdef CONFIG_CIFS_DFS_UPCALL
        struct delayed_work dfs_cache_work;
+       struct list_head dfs_ses_list;
 #endif
        struct delayed_work     query_interfaces; /* query interfaces workqueue job */
        char *origin_fullpath; /* canonical copy of smb3_fs_context::source */

diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index c69e3f48a60c52c88a67e77ab6c83a049364554a..68c716e6261b3abd40173dc08a30ca08183df0aa 100644 (file)
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -724,15 +724,9 @@ static inline int cifs_create_options(struct cifs_sb_info *cifs_sb, int options)
 
 int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry);
 
-/* Put references of @ses and its children */
 static inline void cifs_put_smb_ses(struct cifs_ses *ses)
 {
-       struct cifs_ses *next;
-
-       do {
-               next = ses->dfs_root_ses;
-               __cifs_put_smb_ses(ses);
-       } while ((ses = next));
+       __cifs_put_smb_ses(ses);
 }
 
 /* Get an active reference of @ses and its children.
@@ -746,9 +740,7 @@ static inline void cifs_put_smb_ses(struct cifs_ses *ses)
 static inline void cifs_smb_ses_inc_refcount(struct cifs_ses *ses)
 {
        lockdep_assert_held(&cifs_tcp_ses_lock);
-
-       for (; ses; ses = ses->dfs_root_ses)
-               ses->ses_count++;
+       ses->ses_count++;
 }
 
 static inline bool dfs_src_pathname_equal(const char *s1, const char *s2)

diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 08a41c7aaf723f5122e8b0ca53d8888936e7de31..76f02739dda5ff140c5cb8ac63fb4e51a3cbc9f4 100644 (file)
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -1530,6 +1530,9 @@ static int match_server(struct TCP_Server_Info *server,
        if (server->nosharesock)
                return 0;
 
+       if (!match_super && (ctx->dfs_conn || server->dfs_conn))
+               return 0;
+
        /* If multidialect negotiation see if existing sessions match one */
        if (strcmp(ctx->vals->version_string, SMB3ANY_VERSION_STRING) == 0) {
                if (server->vals->protocol_id < SMB30_PROT_ID)
@@ -1723,6 +1726,7 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
 
        if (ctx->nosharesock)
                tcp_ses->nosharesock = true;
+       tcp_ses->dfs_conn = ctx->dfs_conn;
 
        tcp_ses->ops = ctx->ops;
        tcp_ses->vals = ctx->vals;
@@ -1873,13 +1877,15 @@ out_err:
 }
 
 /* this function must be called with ses_lock and chan_lock held */
-static int match_session(struct cifs_ses *ses, struct smb3_fs_context *ctx)
+static int match_session(struct cifs_ses *ses,
+                        struct smb3_fs_context *ctx,
+                        bool match_super)
 {
        if (ctx->sectype != Unspecified &&
            ctx->sectype != ses->sectype)
                return 0;
 
-       if (ctx->dfs_root_ses != ses->dfs_root_ses)
+       if (!match_super && ctx->dfs_root_ses != ses->dfs_root_ses)
                return 0;
 
        /*
@@ -1998,7 +2004,7 @@ cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
                        continue;
                }
                spin_lock(&ses->chan_lock);
-               if (match_session(ses, ctx)) {
+               if (match_session(ses, ctx, false)) {
                        spin_unlock(&ses->chan_lock);
                        spin_unlock(&ses->ses_lock);
                        ret = ses;
@@ -2382,8 +2388,6 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
         * need to lock before changing something in the session.
         */
        spin_lock(&cifs_tcp_ses_lock);
-       if (ctx->dfs_root_ses)
-               cifs_smb_ses_inc_refcount(ctx->dfs_root_ses);
        ses->dfs_root_ses = ctx->dfs_root_ses;
        list_add(&ses->smb_ses_list, &server->smb_ses_list);
        spin_unlock(&cifs_tcp_ses_lock);
@@ -2458,6 +2462,7 @@ cifs_put_tcon(struct cifs_tcon *tcon, enum smb3_tcon_ref_trace trace)
 {
        unsigned int xid;
        struct cifs_ses *ses;
+       LIST_HEAD(ses_list);
 
        /*
         * IPC tcon share the lifetime of their session and are
@@ -2482,6 +2487,9 @@ cifs_put_tcon(struct cifs_tcon *tcon, enum smb3_tcon_ref_trace trace)
 
        list_del_init(&tcon->tcon_list);
        tcon->status = TID_EXITING;
+#ifdef CONFIG_CIFS_DFS_UPCALL
+       list_replace_init(&tcon->dfs_ses_list, &ses_list);
+#endif
        spin_unlock(&tcon->tc_lock);
        spin_unlock(&cifs_tcp_ses_lock);
 
@@ -2509,6 +2517,9 @@ cifs_put_tcon(struct cifs_tcon *tcon, enum smb3_tcon_ref_trace trace)
        cifs_fscache_release_super_cookie(tcon);
        tconInfoFree(tcon, netfs_trace_tcon_ref_free);
        cifs_put_smb_ses(ses);
+#ifdef CONFIG_CIFS_DFS_UPCALL
+       dfs_put_root_smb_sessions(&ses_list);
+#endif
 }
 
 /**
@@ -2892,7 +2903,7 @@ cifs_match_super(struct super_block *sb, void *data)
        spin_lock(&ses->chan_lock);
        spin_lock(&tcon->tc_lock);
        if (!match_server(tcp_srv, ctx, true) ||
-           !match_session(ses, ctx) ||
+           !match_session(ses, ctx, true) ||
            !match_tcon(tcon, ctx) ||
            !match_prepath(sb, tcon, mnt_data)) {
                rc = 0;
@@ -3623,13 +3634,12 @@ out:
 int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
 {
        struct cifs_mount_ctx mnt_ctx = { .cifs_sb = cifs_sb, .fs_ctx = ctx, };
-       bool isdfs;
        int rc;
 
-       rc = dfs_mount_share(&mnt_ctx, &isdfs);
+       rc = dfs_mount_share(&mnt_ctx);
        if (rc)
                goto error;
-       if (!isdfs)
+       if (!ctx->dfs_conn)
                goto out;
 
        /*
@@ -4034,7 +4044,7 @@ cifs_set_vol_auth(struct smb3_fs_context *ctx, struct cifs_ses *ses)
 }
 
 static struct cifs_tcon *
-__cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
+cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 {
        int rc;
        struct cifs_tcon *master_tcon = cifs_sb_master_tcon(cifs_sb);
@@ -4132,17 +4142,6 @@ out:
        return tcon;
 }
 
-static struct cifs_tcon *
-cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
-{
-       struct cifs_tcon *ret;
-
-       cifs_mount_lock();
-       ret = __cifs_construct_tcon(cifs_sb, fsuid);
-       cifs_mount_unlock();
-       return ret;
-}
-
 struct cifs_tcon *
 cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
 {

diff --git a/fs/smb/client/dfs.c b/fs/smb/client/dfs.c
index 3ec965547e3d4d5979da80f41681b291c29c9256..3f6077c68d68aa4a4f0c5ebe9abe157abdb170a7 100644 (file)
--- a/fs/smb/client/dfs.c
+++ b/fs/smb/client/dfs.c
@@ -69,7 +69,7 @@ static int get_session(struct cifs_mount_ctx *mnt_ctx, const char *full_path)
  * Get an active reference of @ses so that next call to cifs_put_tcon() won't
  * release it as any new DFS referrals must go through its IPC tcon.
  */
-static void add_root_smb_session(struct cifs_mount_ctx *mnt_ctx)
+static void set_root_smb_session(struct cifs_mount_ctx *mnt_ctx)
 {
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
        struct cifs_ses *ses = mnt_ctx->ses;
@@ -95,7 +95,7 @@ static inline int parse_dfs_target(struct smb3_fs_context *ctx,
        return rc;
 }
 
-static int set_ref_paths(struct cifs_mount_ctx *mnt_ctx,
+static int setup_dfs_ref(struct cifs_mount_ctx *mnt_ctx,
                         struct dfs_info3_param *tgt,
                         struct dfs_ref_walk *rw)
 {
@@ -120,6 +120,7 @@ static int set_ref_paths(struct cifs_mount_ctx *mnt_ctx,
        }
        ref_walk_path(rw) = ref_path;
        ref_walk_fpath(rw) = full_path;
+       ref_walk_ses(rw) = ctx->dfs_root_ses;
        return 0;
 }
 
@@ -128,11 +129,11 @@ static int __dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx,
 {
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
        struct dfs_info3_param tgt = {};
-       bool is_refsrv;
        int rc = -ENOENT;
 
 again:
        do {
+               ctx->dfs_root_ses = ref_walk_ses(rw);
                if (ref_walk_empty(rw)) {
                        rc = dfs_get_referral(mnt_ctx, ref_walk_path(rw) + 1,
                                              NULL, ref_walk_tl(rw));
@@ -158,10 +159,7 @@ again:
                        if (rc)
                                continue;
 
-                       is_refsrv = tgt.server_type == DFS_TYPE_ROOT ||
-                               DFS_INTERLINK(tgt.flags);
                        ref_walk_set_tgt_hint(rw);
-
                        if (tgt.flags & DFSREF_STORAGE_SERVER) {
                                rc = cifs_mount_get_tcon(mnt_ctx);
                                if (!rc)
@@ -172,12 +170,10 @@ again:
                                        continue;
                        }
 
-                       if (is_refsrv)
-                               add_root_smb_session(mnt_ctx);
-
+                       set_root_smb_session(mnt_ctx);
                        rc = ref_walk_advance(rw);
                        if (!rc) {
-                               rc = set_ref_paths(mnt_ctx, &tgt, rw);
+                               rc = setup_dfs_ref(mnt_ctx, &tgt, rw);
                                if (!rc) {
                                        rc = -EREMOTE;
                                        goto again;
@@ -193,20 +189,22 @@ out:
        return rc;
 }
 
-static int dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx)
+static int dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx,
+                            struct dfs_ref_walk **rw)
 {
-       struct dfs_ref_walk *rw;
        int rc;
 
-       rw = ref_walk_alloc();
-       if (IS_ERR(rw))
-               return PTR_ERR(rw);
+       *rw = ref_walk_alloc();
+       if (IS_ERR(*rw)) {
+               rc = PTR_ERR(*rw);
+               *rw = NULL;
+               return rc;
+       }
 
-       ref_walk_init(rw);
-       rc = set_ref_paths(mnt_ctx, NULL, rw);
+       ref_walk_init(*rw);
+       rc = setup_dfs_ref(mnt_ctx, NULL, *rw);
        if (!rc)
-               rc = __dfs_referral_walk(mnt_ctx, rw);
-       ref_walk_free(rw);
+               rc = __dfs_referral_walk(mnt_ctx, *rw);
        return rc;
 }
 
@@ -214,16 +212,16 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 {
        struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
+       struct dfs_ref_walk *rw = NULL;
        struct cifs_tcon *tcon;
        char *origin_fullpath;
-       bool new_tcon = true;
        int rc;
 
        origin_fullpath = dfs_get_path(cifs_sb, ctx->source);
        if (IS_ERR(origin_fullpath))
                return PTR_ERR(origin_fullpath);
 
-       rc = dfs_referral_walk(mnt_ctx);
+       rc = dfs_referral_walk(mnt_ctx, &rw);
        if (!rc) {
                /*
                 * Prevent superblock from being created with any missing
@@ -241,21 +239,16 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 
        tcon = mnt_ctx->tcon;
        spin_lock(&tcon->tc_lock);
-       if (!tcon->origin_fullpath) {
-               tcon->origin_fullpath = origin_fullpath;
-               origin_fullpath = NULL;
-       } else {
-               new_tcon = false;
-       }
+       tcon->origin_fullpath = origin_fullpath;
+       origin_fullpath = NULL;
+       ref_walk_set_tcon(rw, tcon);
        spin_unlock(&tcon->tc_lock);
-
-       if (new_tcon) {
-               queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,
-                                  dfs_cache_get_ttl() * HZ);
-       }
+       queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,
+                          dfs_cache_get_ttl() * HZ);
 
 out:
        kfree(origin_fullpath);
+       ref_walk_free(rw);
        return rc;
 }
 
@@ -279,7 +272,7 @@ static int update_fs_context_dstaddr(struct smb3_fs_context *ctx)
        return rc;
 }
 
-int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
+int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 {
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
        bool nodfs = ctx->nodfs;
@@ -289,7 +282,6 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
        if (rc)
                return rc;
 
-       *isdfs = false;
        rc = get_session(mnt_ctx, NULL);
        if (rc)
                return rc;
@@ -317,10 +309,15 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
                return rc;
        }
 
-       *isdfs = true;
-       add_root_smb_session(mnt_ctx);
-       rc = __dfs_mount_share(mnt_ctx);
-       dfs_put_root_smb_sessions(mnt_ctx);
+       if (!ctx->dfs_conn) {
+               ctx->dfs_conn = true;
+               cifs_mount_put_conns(mnt_ctx);
+               rc = get_session(mnt_ctx, NULL);
+       }
+       if (!rc) {
+               set_root_smb_session(mnt_ctx);
+               rc = __dfs_mount_share(mnt_ctx);
+       }
        return rc;
 }
 

diff --git a/fs/smb/client/dfs.h b/fs/smb/client/dfs.h
index e5c4dcf837503aa2851f9b01680b6f5b7eb8874d..1aa2bc65b3bc2c43f953d01f753ff26a42f0511d 100644 (file)
--- a/fs/smb/client/dfs.h
+++ b/fs/smb/client/dfs.h
@@ -19,6 +19,7 @@
 struct dfs_ref {
        char *path;
        char *full_path;
+       struct cifs_ses *ses;
        struct dfs_cache_tgt_list tl;
        struct dfs_cache_tgt_iterator *tit;
 };
@@ -38,6 +39,7 @@ struct dfs_ref_walk {
 #define ref_walk_path(w)       (ref_walk_cur(w)->path)
 #define ref_walk_fpath(w)      (ref_walk_cur(w)->full_path)
 #define ref_walk_tl(w)         (&ref_walk_cur(w)->tl)
+#define ref_walk_ses(w)        (ref_walk_cur(w)->ses)
 
 static inline struct dfs_ref_walk *ref_walk_alloc(void)
 {
@@ -60,14 +62,19 @@ static inline void __ref_walk_free(struct dfs_ref *ref)
        kfree(ref->path);
        kfree(ref->full_path);
        dfs_cache_free_tgts(&ref->tl);
+       if (ref->ses)
+               cifs_put_smb_ses(ref->ses);
        memset(ref, 0, sizeof(*ref));
 }
 
 static inline void ref_walk_free(struct dfs_ref_walk *rw)
 {
-       struct dfs_ref *ref = ref_walk_start(rw);
+       struct dfs_ref *ref;
 
-       for (; ref <= ref_walk_end(rw); ref++)
+       if (!rw)
+               return;
+
+       for (ref = ref_walk_start(rw); ref <= ref_walk_end(rw); ref++)
                __ref_walk_free(ref);
        kfree(rw);
 }
@@ -116,9 +123,22 @@ static inline void ref_walk_set_tgt_hint(struct dfs_ref_walk *rw)
                                       ref_walk_tit(rw));
 }
 
+static inline void ref_walk_set_tcon(struct dfs_ref_walk *rw,
+                                    struct cifs_tcon *tcon)
+{
+       struct dfs_ref *ref = ref_walk_start(rw);
+
+       for (; ref <= ref_walk_cur(rw); ref++) {
+               if (WARN_ON_ONCE(!ref->ses))
+                       continue;
+               list_add(&ref->ses->dlist, &tcon->dfs_ses_list);
+               ref->ses = NULL;
+       }
+}
+
 int dfs_parse_target_referral(const char *full_path, const struct dfs_info3_param *ref,
                              struct smb3_fs_context *ctx);
-int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs);
+int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx);
 
 static inline char *dfs_get_path(struct cifs_sb_info *cifs_sb, const char *path)
 {
@@ -142,20 +162,14 @@ static inline int dfs_get_referral(struct cifs_mount_ctx *mnt_ctx, const char *p
  * references of all DFS root sessions that were used across the mount process
  * in dfs_mount_share().
  */
-static inline void dfs_put_root_smb_sessions(struct cifs_mount_ctx *mnt_ctx)
+static inline void dfs_put_root_smb_sessions(struct list_head *head)
 {
-       const struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
-       struct cifs_ses *ses = ctx->dfs_root_ses;
-       struct cifs_ses *cur;
-
-       if (!ses)
-               return;
+       struct cifs_ses *ses, *n;
 
-       for (cur = ses; cur; cur = cur->dfs_root_ses) {
-               if (cur->dfs_root_ses)
-                       cifs_put_smb_ses(cur->dfs_root_ses);
+       list_for_each_entry_safe(ses, n, head, dlist) {
+               list_del_init(&ses->dlist);
+               cifs_put_smb_ses(ses);
        }
-       cifs_put_smb_ses(ses);
 }
 
 #endif /* _CIFS_DFS_H */

diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c
index e496dbf8c6228f03c1733c9695e190677b5b4109..110f03df012a00b8a53150e6e20fb159302782a1 100644 (file)
--- a/fs/smb/client/dfs_cache.c
+++ b/fs/smb/client/dfs_cache.c
@@ -1334,9 +1334,8 @@ void dfs_cache_refresh(struct work_struct *work)
        struct cifs_ses *ses;
 
        tcon = container_of(work, struct cifs_tcon, dfs_cache_work.work);
-       ses = tcon->ses->dfs_root_ses;
 
-       for (; ses; ses = ses->dfs_root_ses)
+       list_for_each_entry(ses, &tcon->dfs_ses_list, dlist)
                refresh_ses_referral(ses);
        refresh_tcon_referral(tcon, false);
 

diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h
index cf577ec0dd0ac4a8f5a3131e8ed0c3ce9574a4d7..69f9d938b336a7599f951fde4502ad86d69fd60e 100644 (file)
--- a/fs/smb/client/fs_context.h
+++ b/fs/smb/client/fs_context.h
@@ -284,6 +284,7 @@ struct smb3_fs_context {
        struct cifs_ses *dfs_root_ses;
        bool dfs_automount:1; /* set for dfs automount only */
        enum cifs_reparse_type reparse_type;
+       bool dfs_conn:1; /* set for dfs mounts */
 };
 
 extern const struct fs_parameter_spec smb3_fs_parameters[];

diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
index dab526191b07425747b92cacfbb0a45bd048e58f..47b861517bed53f18e981eb903576520b5f5eb14 100644 (file)
--- a/fs/smb/client/misc.c
+++ b/fs/smb/client/misc.c
@@ -145,6 +145,9 @@ tcon_info_alloc(bool dir_leases_enabled, enum smb3_tcon_ref_trace trace)
        mutex_init(&ret_buf->fscache_lock);
 #endif
        trace_smb3_tcon_ref(ret_buf->debug_id, ret_buf->tc_count, trace);
+#ifdef CONFIG_CIFS_DFS_UPCALL
+       INIT_LIST_HEAD(&ret_buf->dfs_ses_list);
+#endif
 
        return ret_buf;
 }

diff --git a/fs/smb/client/namespace.c b/fs/smb/client/namespace.c
index 4a517b280f2b79a2c1395a1c627b496def7392a7..0f788031b7405f3366cf7764eff23c3e0142c39b 100644 (file)
--- a/fs/smb/client/namespace.c
+++ b/fs/smb/client/namespace.c
@@ -240,7 +240,7 @@ static struct vfsmount *cifs_do_automount(struct path *path)
                ctx->source = NULL;
                goto out;
        }
-       ctx->dfs_automount = is_dfs_mount(mntpt);
+       ctx->dfs_automount = ctx->dfs_conn = is_dfs_mount(mntpt);
        cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s dfs_automount=%d\n",
                 __func__, ctx->source, ctx->UNC, ctx->prepath, ctx->dfs_automount);