This is a note to let you know that I've just added the patch titled
cifs: protect access of TCP_Server_Info::{origin,leaf}_fullpath
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-protect-access-of-tcp_server_info-origin-leaf-_fullpath.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3dc9c433c9dde15477d02b609ccb4328e2adb6dc Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
Date: Wed, 26 Apr 2023 13:43:53 -0300
Subject: cifs: protect access of TCP_Server_Info::{origin,leaf}_fullpath
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
commit 3dc9c433c9dde15477d02b609ccb4328e2adb6dc upstream.
Protect access of TCP_Server_Info::{origin,leaf}_fullpath when
matching DFS connections, and get rid of
TCP_Server_Info::current_fullpath while we're at it.
Cc: stable@xxxxxxxxxxxxxxx # v6.2+
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/cifsglob.h | 20 +++++++++++++-------
fs/cifs/connect.c | 10 ++++++----
fs/cifs/dfs.c | 14 ++++++++------
fs/cifs/dfs.h | 13 +++++++++++--
fs/cifs/dfs_cache.c | 6 +++++-
5 files changed, 43 insertions(+), 20 deletions(-)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -736,17 +736,23 @@ struct TCP_Server_Info {
#endif
struct mutex refpath_lock; /* protects leaf_fullpath */
/*
- * Canonical DFS full paths that were used to chase referrals in mount and reconnect.
+ * origin_fullpath: Canonical copy of smb3_fs_context::source.
+ * It is used for matching existing DFS tcons.
*
- * origin_fullpath: first or original referral path
- * leaf_fullpath: last referral path (might be changed due to nested links in reconnect)
+ * leaf_fullpath: Canonical DFS referral path related to this
+ * connection.
+ * It is used in DFS cache refresher, reconnect and may
+ * change due to nested DFS links.
*
- * current_fullpath: pointer to either origin_fullpath or leaf_fullpath
- * NOTE: cannot be accessed outside cifs_reconnect() and smb2_reconnect()
+ * Both protected by @refpath_lock and @srv_lock. The @refpath_lock is
+ * mosly used for not requiring a copy of @leaf_fullpath when getting
+ * cached or new DFS referrals (which might also sleep during I/O).
+ * While @srv_lock is held for making string and NULL comparions against
+ * both fields as in mount(2) and cache refresh.
*
- * format: \\HOST\SHARE\[OPTIONAL PATH]
+ * format: \\HOST\SHARE[\OPTIONAL PATH]
*/
- char *origin_fullpath, *leaf_fullpath, *current_fullpath;
+ char *origin_fullpath, *leaf_fullpath;
};
static inline bool is_smb1(struct TCP_Server_Info *server)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -454,7 +454,6 @@ static int reconnect_target_unlocked(str
static int reconnect_dfs_server(struct TCP_Server_Info *server)
{
int rc = 0;
- const char *refpath = server->current_fullpath + 1;
struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
struct dfs_cache_tgt_iterator *target_hint = NULL;
int num_targets = 0;
@@ -467,8 +466,10 @@ static int reconnect_dfs_server(struct T
* through /proc/fs/cifs/dfscache or the target list is empty due to server settings after
* refreshing the referral, so, in this case, default it to 1.
*/
- if (!dfs_cache_noreq_find(refpath, NULL, &tl))
+ mutex_lock(&server->refpath_lock);
+ if (!dfs_cache_noreq_find(server->leaf_fullpath + 1, NULL, &tl))
num_targets = dfs_cache_get_nr_tgts(&tl);
+ mutex_unlock(&server->refpath_lock);
if (!num_targets)
num_targets = 1;
@@ -512,7 +513,9 @@ static int reconnect_dfs_server(struct T
mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
} while (server->tcpStatus == CifsNeedReconnect);
- dfs_cache_noreq_update_tgthint(refpath, target_hint);
+ mutex_lock(&server->refpath_lock);
+ dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, target_hint);
+ mutex_unlock(&server->refpath_lock);
dfs_cache_free_tgts(&tl);
/* Need to set up echo worker again once connection has been established */
@@ -1579,7 +1582,6 @@ cifs_get_tcp_session(struct smb3_fs_cont
rc = -ENOMEM;
goto out_err;
}
- tcp_ses->current_fullpath = tcp_ses->leaf_fullpath;
}
if (ctx->nosharesock)
--- a/fs/cifs/dfs.c
+++ b/fs/cifs/dfs.c
@@ -248,11 +248,12 @@ static int __dfs_mount_share(struct cifs
tcon = mnt_ctx->tcon;
mutex_lock(&server->refpath_lock);
+ spin_lock(&server->srv_lock);
if (!server->origin_fullpath) {
server->origin_fullpath = origin_fullpath;
- server->current_fullpath = server->leaf_fullpath;
origin_fullpath = NULL;
}
+ spin_unlock(&server->srv_lock);
mutex_unlock(&server->refpath_lock);
if (list_empty(&tcon->dfs_ses_list)) {
@@ -366,10 +367,11 @@ static int update_server_fullpath(struct
rc = PTR_ERR(npath);
} else {
mutex_lock(&server->refpath_lock);
+ spin_lock(&server->srv_lock);
kfree(server->leaf_fullpath);
server->leaf_fullpath = npath;
+ spin_unlock(&server->srv_lock);
mutex_unlock(&server->refpath_lock);
- server->current_fullpath = server->leaf_fullpath;
}
return rc;
}
@@ -474,7 +476,7 @@ static int __tree_connect_dfs_target(con
share = prefix = NULL;
/* Check if share matches with tcp ses */
- rc = dfs_cache_get_tgt_share(server->current_fullpath + 1, tit, &share, &prefix);
+ rc = dfs_cache_get_tgt_share(server->leaf_fullpath + 1, tit, &share, &prefix);
if (rc) {
cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc);
break;
@@ -488,7 +490,7 @@ static int __tree_connect_dfs_target(con
continue;
}
- dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit);
+ dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, tit);
tree_connect_ipc(xid, tree, cifs_sb, tcon);
scnprintf(tree, MAX_TREE_SIZE, "\\%s", share);
@@ -606,8 +608,8 @@ int cifs_tree_connect(const unsigned int
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)) {
+ if (!server->leaf_fullpath ||
+ dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) {
rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls);
goto out;
}
--- a/fs/cifs/dfs.h
+++ b/fs/cifs/dfs.h
@@ -43,8 +43,12 @@ static inline char *dfs_get_automount_de
size_t len;
char *s;
- if (unlikely(!server->origin_fullpath))
+ spin_lock(&server->srv_lock);
+ if (unlikely(!server->origin_fullpath)) {
+ spin_unlock(&server->srv_lock);
return ERR_PTR(-EREMOTE);
+ }
+ spin_unlock(&server->srv_lock);
s = dentry_path_raw(dentry, page, PATH_MAX);
if (IS_ERR(s))
@@ -53,13 +57,18 @@ static inline char *dfs_get_automount_de
if (!s[1])
s++;
+ spin_lock(&server->srv_lock);
len = strlen(server->origin_fullpath);
- if (s < (char *)page + len)
+ if (s < (char *)page + len) {
+ spin_unlock(&server->srv_lock);
return ERR_PTR(-ENAMETOOLONG);
+ }
s -= len;
memcpy(s, server->origin_fullpath, len);
+ spin_unlock(&server->srv_lock);
convert_delimiter(s, '/');
+
return s;
}
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -1278,8 +1278,12 @@ static void refresh_cache_worker(struct
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
- if (!server->leaf_fullpath)
+ spin_lock(&server->srv_lock);
+ if (!server->leaf_fullpath) {
+ spin_unlock(&server->srv_lock);
continue;
+ }
+ spin_unlock(&server->srv_lock);
list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
if (ses->tcon_ipc) {
Patches currently in stable-queue which might be from pc@xxxxxxxxxxxxx are
queue-6.3/cifs-protect-access-of-tcp_server_info-origin-leaf-_fullpath.patch
queue-6.3/cifs-avoid-potential-races-when-handling-multiple-dfs-tcons.patch
queue-6.3/cifs-fix-sharing-of-dfs-connections.patch
queue-6.3/cifs-fix-potential-use-after-free-bugs-in-tcp_server_info-hostname.patch
queue-6.3/smb3-add-missing-locks-to-protect-deferred-close-fil.patch
queue-6.3/cifs-fix-potential-race-when-tree-connecting-ipc.patch
queue-6.3/cifs-protect-session-status-check-in-smb2_reconnect.patch
