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-rw-r--r--fs/cifs/dfs.c544
1 files changed, 544 insertions, 0 deletions
diff --git a/fs/cifs/dfs.c b/fs/cifs/dfs.c
new file mode 100644
index 000000000000..b541e68378f6
--- /dev/null
+++ b/fs/cifs/dfs.c
@@ -0,0 +1,544 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Paulo Alcantara <palcantara@suse.de>
+ */
+
+#include <linux/namei.h>
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "dns_resolve.h"
+#include "fs_context.h"
+#include "dfs.h"
+
+/**
+ * dfs_parse_target_referral - set fs context for dfs target referral
+ *
+ * @full_path: full path in UNC format.
+ * @ref: dfs referral pointer.
+ * @ctx: smb3 fs context pointer.
+ *
+ * Return zero if dfs referral was parsed correctly, otherwise non-zero.
+ */
+int dfs_parse_target_referral(const char *full_path, const struct dfs_info3_param *ref,
+ struct smb3_fs_context *ctx)
+{
+ int rc;
+ const char *prepath = NULL;
+ char *path;
+
+ if (!full_path || !*full_path || !ref || !ctx)
+ return -EINVAL;
+
+ if (WARN_ON_ONCE(!ref->node_name || ref->path_consumed < 0))
+ return -EINVAL;
+
+ if (strlen(full_path) - ref->path_consumed) {
+ prepath = full_path + ref->path_consumed;
+ /* skip initial delimiter */
+ if (*prepath == '/' || *prepath == '\\')
+ prepath++;
+ }
+
+ path = cifs_build_devname(ref->node_name, prepath);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+
+ rc = smb3_parse_devname(path, ctx);
+ if (rc)
+ goto out;
+
+ rc = dns_resolve_server_name_to_ip(path, (struct sockaddr *)&ctx->dstaddr, NULL);
+
+out:
+ kfree(path);
+ return rc;
+}
+
+/*
+ * cifs_build_path_to_root returns full path to root when we do not have an
+ * existing connection (tcon)
+ */
+static char *build_unc_path_to_root(const struct smb3_fs_context *ctx,
+ const struct cifs_sb_info *cifs_sb, bool useppath)
+{
+ char *full_path, *pos;
+ unsigned int pplen = useppath && ctx->prepath ? strlen(ctx->prepath) + 1 : 0;
+ unsigned int unc_len = strnlen(ctx->UNC, MAX_TREE_SIZE + 1);
+
+ if (unc_len > MAX_TREE_SIZE)
+ return ERR_PTR(-EINVAL);
+
+ full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
+ if (full_path == NULL)
+ return ERR_PTR(-ENOMEM);
+
+ memcpy(full_path, ctx->UNC, unc_len);
+ pos = full_path + unc_len;
+
+ if (pplen) {
+ *pos = CIFS_DIR_SEP(cifs_sb);
+ memcpy(pos + 1, ctx->prepath, pplen);
+ pos += pplen;
+ }
+
+ *pos = '\0'; /* add trailing null */
+ convert_delimiter(full_path, CIFS_DIR_SEP(cifs_sb));
+ cifs_dbg(FYI, "%s: full_path=%s\n", __func__, full_path);
+ return full_path;
+}
+
+static int get_session(struct cifs_mount_ctx *mnt_ctx, const char *full_path)
+{
+ struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
+ int rc;
+
+ ctx->leaf_fullpath = (char *)full_path;
+ rc = cifs_mount_get_session(mnt_ctx);
+ ctx->leaf_fullpath = NULL;
+ if (!rc) {
+ struct cifs_ses *ses = mnt_ctx->ses;
+
+ mutex_lock(&ses->session_mutex);
+ ses->dfs_root_ses = mnt_ctx->root_ses;
+ mutex_unlock(&ses->session_mutex);
+ }
+ return rc;
+}
+
+static void set_root_ses(struct cifs_mount_ctx *mnt_ctx)
+{
+ if (mnt_ctx->ses) {
+ spin_lock(&cifs_tcp_ses_lock);
+ mnt_ctx->ses->ses_count++;
+ spin_unlock(&cifs_tcp_ses_lock);
+ dfs_cache_add_refsrv_session(&mnt_ctx->mount_id, mnt_ctx->ses);
+ }
+ mnt_ctx->root_ses = mnt_ctx->ses;
+}
+
+static int get_dfs_conn(struct cifs_mount_ctx *mnt_ctx, const char *ref_path, const char *full_path,
+ const struct dfs_cache_tgt_iterator *tit)
+{
+ struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
+ struct dfs_info3_param ref = {};
+ int rc;
+
+ rc = dfs_cache_get_tgt_referral(ref_path + 1, tit, &ref);
+ if (rc)
+ return rc;
+
+ rc = dfs_parse_target_referral(full_path + 1, &ref, ctx);
+ if (rc)
+ goto out;
+
+ cifs_mount_put_conns(mnt_ctx);
+ rc = get_session(mnt_ctx, ref_path);
+ if (rc)
+ goto out;
+
+ if (ref.flags & DFSREF_REFERRAL_SERVER)
+ set_root_ses(mnt_ctx);
+
+ rc = -EREMOTE;
+ if (ref.flags & DFSREF_STORAGE_SERVER) {
+ rc = cifs_mount_get_tcon(mnt_ctx);
+ if (rc)
+ goto out;
+
+ /* some servers may not advertise referral capability under ref.flags */
+ if (!(ref.flags & DFSREF_REFERRAL_SERVER) &&
+ is_tcon_dfs(mnt_ctx->tcon))
+ set_root_ses(mnt_ctx);
+
+ rc = cifs_is_path_remote(mnt_ctx);
+ }
+
+out:
+ free_dfs_info_param(&ref);
+ return rc;
+}
+
+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;
+ char *ref_path = NULL, *full_path = NULL;
+ struct dfs_cache_tgt_iterator *tit;
+ struct TCP_Server_Info *server;
+ char *origin_fullpath = NULL;
+ int num_links = 0;
+ int rc;
+
+ ref_path = dfs_get_path(cifs_sb, ctx->UNC);
+ if (IS_ERR(ref_path))
+ return PTR_ERR(ref_path);
+
+ full_path = build_unc_path_to_root(ctx, cifs_sb, true);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
+ full_path = NULL;
+ goto out;
+ }
+
+ origin_fullpath = kstrdup(full_path, GFP_KERNEL);
+ if (!origin_fullpath) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ do {
+ struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
+
+ rc = dfs_get_referral(mnt_ctx, ref_path + 1, NULL, &tl);
+ if (rc)
+ break;
+
+ tit = dfs_cache_get_tgt_iterator(&tl);
+ if (!tit) {
+ cifs_dbg(VFS, "%s: dfs referral (%s) with no targets\n", __func__,
+ ref_path + 1);
+ rc = -ENOENT;
+ dfs_cache_free_tgts(&tl);
+ break;
+ }
+
+ do {
+ rc = get_dfs_conn(mnt_ctx, ref_path, full_path, tit);
+ if (!rc)
+ break;
+ if (rc == -EREMOTE) {
+ if (++num_links > MAX_NESTED_LINKS) {
+ rc = -ELOOP;
+ break;
+ }
+ kfree(ref_path);
+ kfree(full_path);
+ ref_path = full_path = NULL;
+
+ full_path = build_unc_path_to_root(ctx, cifs_sb, true);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
+ full_path = NULL;
+ } else {
+ ref_path = dfs_get_path(cifs_sb, full_path);
+ if (IS_ERR(ref_path)) {
+ rc = PTR_ERR(ref_path);
+ ref_path = NULL;
+ }
+ }
+ break;
+ }
+ } while ((tit = dfs_cache_get_next_tgt(&tl, tit)));
+ dfs_cache_free_tgts(&tl);
+ } while (rc == -EREMOTE);
+
+ if (!rc) {
+ server = mnt_ctx->server;
+
+ mutex_lock(&server->refpath_lock);
+ server->origin_fullpath = origin_fullpath;
+ server->current_fullpath = server->leaf_fullpath;
+ mutex_unlock(&server->refpath_lock);
+ origin_fullpath = NULL;
+ }
+
+out:
+ kfree(origin_fullpath);
+ kfree(ref_path);
+ kfree(full_path);
+ return rc;
+}
+
+int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
+{
+ struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
+ struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
+ int rc;
+
+ *isdfs = false;
+
+ rc = get_session(mnt_ctx, NULL);
+ if (rc)
+ return rc;
+ mnt_ctx->root_ses = mnt_ctx->ses;
+ /*
+ * If called with 'nodfs' mount option, then skip DFS resolving. Otherwise unconditionally
+ * try to get an DFS referral (even cached) to determine whether it is an DFS mount.
+ *
+ * Skip prefix path to provide support for DFS referrals from w2k8 servers which don't seem
+ * to respond with PATH_NOT_COVERED to requests that include the prefix.
+ */
+ if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) ||
+ dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL)) {
+ rc = cifs_mount_get_tcon(mnt_ctx);
+ if (rc)
+ return rc;
+
+ rc = cifs_is_path_remote(mnt_ctx);
+ if (!rc || rc != -EREMOTE)
+ return rc;
+ }
+
+ *isdfs = true;
+ set_root_ses(mnt_ctx);
+
+ return __dfs_mount_share(mnt_ctx);
+}
+
+/* Update dfs referral path of superblock */
+static int update_server_fullpath(struct TCP_Server_Info *server, struct cifs_sb_info *cifs_sb,
+ const char *target)
+{
+ int rc = 0;
+ size_t len = strlen(target);
+ char *refpath, *npath;
+
+ if (unlikely(len < 2 || *target != '\\'))
+ return -EINVAL;
+
+ if (target[1] == '\\') {
+ len += 1;
+ refpath = kmalloc(len, GFP_KERNEL);
+ if (!refpath)
+ return -ENOMEM;
+
+ scnprintf(refpath, len, "%s", target);
+ } else {
+ len += sizeof("\\");
+ refpath = kmalloc(len, GFP_KERNEL);
+ if (!refpath)
+ return -ENOMEM;
+
+ scnprintf(refpath, len, "\\%s", target);
+ }
+
+ npath = dfs_cache_canonical_path(refpath, cifs_sb->local_nls, cifs_remap(cifs_sb));
+ kfree(refpath);
+
+ if (IS_ERR(npath)) {
+ rc = PTR_ERR(npath);
+ } else {
+ mutex_lock(&server->refpath_lock);
+ kfree(server->leaf_fullpath);
+ server->leaf_fullpath = npath;
+ mutex_unlock(&server->refpath_lock);
+ server->current_fullpath = server->leaf_fullpath;
+ }
+ return rc;
+}
+
+static int target_share_matches_server(struct TCP_Server_Info *server, const char *tcp_host,
+ size_t tcp_host_len, char *share, bool *target_match)
+{
+ int rc = 0;
+ const char *dfs_host;
+ size_t dfs_host_len;
+
+ *target_match = true;
+ extract_unc_hostname(share, &dfs_host, &dfs_host_len);
+
+ /* Check if hostnames or addresses match */
+ if (dfs_host_len != tcp_host_len || strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) {
+ cifs_dbg(FYI, "%s: %.*s doesn't match %.*s\n", __func__, (int)dfs_host_len,
+ dfs_host, (int)tcp_host_len, tcp_host);
+ rc = match_target_ip(server, dfs_host, dfs_host_len, target_match);
+ if (rc)
+ cifs_dbg(VFS, "%s: failed to match target ip: %d\n", __func__, rc);
+ }
+ return rc;
+}
+
+static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
+ struct cifs_sb_info *cifs_sb, char *tree, bool islink,
+ struct dfs_cache_tgt_list *tl)
+{
+ int rc;
+ struct TCP_Server_Info *server = tcon->ses->server;
+ const struct smb_version_operations *ops = server->ops;
+ struct cifs_ses *root_ses = CIFS_DFS_ROOT_SES(tcon->ses);
+ struct cifs_tcon *ipc = root_ses->tcon_ipc;
+ char *share = NULL, *prefix = NULL;
+ const char *tcp_host;
+ size_t tcp_host_len;
+ struct dfs_cache_tgt_iterator *tit;
+ bool target_match;
+
+ extract_unc_hostname(server->hostname, &tcp_host, &tcp_host_len);
+
+ tit = dfs_cache_get_tgt_iterator(tl);
+ if (!tit) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ /* Try to tree connect to all dfs targets */
+ for (; tit; tit = dfs_cache_get_next_tgt(tl, tit)) {
+ const char *target = dfs_cache_get_tgt_name(tit);
+ struct dfs_cache_tgt_list ntl = DFS_CACHE_TGT_LIST_INIT(ntl);
+
+ kfree(share);
+ kfree(prefix);
+ share = prefix = NULL;
+
+ /* Check if share matches with tcp ses */
+ rc = dfs_cache_get_tgt_share(server->current_fullpath + 1, tit, &share, &prefix);
+ if (rc) {
+ cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc);
+ break;
+ }
+
+ rc = target_share_matches_server(server, tcp_host, tcp_host_len, share,
+ &target_match);
+ if (rc)
+ break;
+ if (!target_match) {
+ rc = -EHOSTUNREACH;
+ continue;
+ }
+
+ dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit);
+
+ if (ipc->need_reconnect) {
+ scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
+ rc = ops->tree_connect(xid, ipc->ses, tree, ipc, cifs_sb->local_nls);
+ if (rc)
+ break;
+ }
+
+ scnprintf(tree, MAX_TREE_SIZE, "\\%s", share);
+ if (!islink) {
+ rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
+ break;
+ }
+ /*
+ * If no dfs referrals were returned from link target, then just do a TREE_CONNECT
+ * to it. Otherwise, cache the dfs referral and then mark current tcp ses for
+ * reconnect so either the demultiplex thread or the echo worker will reconnect to
+ * newly resolved target.
+ */
+ if (dfs_cache_find(xid, root_ses, cifs_sb->local_nls, cifs_remap(cifs_sb), target,
+ NULL, &ntl)) {
+ rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
+ if (rc)
+ continue;
+
+ rc = cifs_update_super_prepath(cifs_sb, prefix);
+ } else {
+ /* Target is another dfs share */
+ rc = update_server_fullpath(server, cifs_sb, target);
+ dfs_cache_free_tgts(tl);
+
+ if (!rc) {
+ rc = -EREMOTE;
+ list_replace_init(&ntl.tl_list, &tl->tl_list);
+ } else
+ dfs_cache_free_tgts(&ntl);
+ }
+ break;
+ }
+
+out:
+ kfree(share);
+ kfree(prefix);
+
+ return rc;
+}
+
+static int tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
+ struct cifs_sb_info *cifs_sb, char *tree, bool islink,
+ struct dfs_cache_tgt_list *tl)
+{
+ int rc;
+ int num_links = 0;
+ struct TCP_Server_Info *server = tcon->ses->server;
+ char *old_fullpath = server->leaf_fullpath;
+
+ do {
+ rc = __tree_connect_dfs_target(xid, tcon, cifs_sb, tree, islink, tl);
+ if (!rc || rc != -EREMOTE)
+ break;
+ } while (rc = -ELOOP, ++num_links < MAX_NESTED_LINKS);
+ /*
+ * If we couldn't tree connect to any targets from last referral path, then
+ * retry it from newly resolved dfs referral.
+ */
+ if (rc && server->leaf_fullpath != old_fullpath)
+ cifs_signal_cifsd_for_reconnect(server, true);
+
+ dfs_cache_free_tgts(tl);
+ return rc;
+}
+
+int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc)
+{
+ int rc;
+ struct TCP_Server_Info *server = tcon->ses->server;
+ const struct smb_version_operations *ops = server->ops;
+ struct super_block *sb = NULL;
+ struct cifs_sb_info *cifs_sb;
+ struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
+ char *tree;
+ struct dfs_info3_param ref = {0};
+
+ /* only send once per connect */
+ spin_lock(&tcon->tc_lock);
+ if (tcon->ses->ses_status != SES_GOOD ||
+ (tcon->status != TID_NEW &&
+ tcon->status != TID_NEED_TCON)) {
+ spin_unlock(&tcon->tc_lock);
+ return 0;
+ }
+ tcon->status = TID_IN_TCON;
+ spin_unlock(&tcon->tc_lock);
+
+ tree = kzalloc(MAX_TREE_SIZE, GFP_KERNEL);
+ if (!tree) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ if (tcon->ipc) {
+ scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
+ rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc);
+ goto out;
+ }
+
+ sb = cifs_get_tcp_super(server);
+ if (IS_ERR(sb)) {
+ rc = PTR_ERR(sb);
+ cifs_dbg(VFS, "%s: could not find superblock: %d\n", __func__, rc);
+ goto out;
+ }
+
+ cifs_sb = CIFS_SB(sb);
+
+ /* If it is not dfs or there was no cached dfs referral, then reconnect to same share */
+ if (!server->current_fullpath ||
+ dfs_cache_noreq_find(server->current_fullpath + 1, &ref, &tl)) {
+ rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls);
+ goto out;
+ }
+
+ rc = tree_connect_dfs_target(xid, tcon, cifs_sb, tree, ref.server_type == DFS_TYPE_LINK,
+ &tl);
+ free_dfs_info_param(&ref);
+
+out:
+ kfree(tree);
+ cifs_put_tcp_super(sb);
+
+ if (rc) {
+ spin_lock(&tcon->tc_lock);
+ if (tcon->status == TID_IN_TCON)
+ tcon->status = TID_NEED_TCON;
+ spin_unlock(&tcon->tc_lock);
+ } else {
+ spin_lock(&tcon->tc_lock);
+ if (tcon->status == TID_IN_TCON)
+ tcon->status = TID_GOOD;
+ spin_unlock(&tcon->tc_lock);
+ tcon->need_reconnect = false;
+ }
+
+ return rc;
+}