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authorPaulo Alcantara <pc@manguebit.com>2023-04-26 13:43:53 -0300
committerSteve French <stfrench@microsoft.com>2023-05-03 23:29:39 -0500
commit3dc9c433c9dde15477d02b609ccb4328e2adb6dc (patch)
treed097b78d406ba5b6324c3e732ce8aebfc6aa4440
parentee20d7c6100752eaf2409d783f4f1449c29ea33d (diff)
cifs: protect access of TCP_Server_Info::{origin,leaf}_fullpath
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@vger.kernel.org # v6.2+ Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
-rw-r--r--fs/cifs/cifsglob.h20
-rw-r--r--fs/cifs/connect.c10
-rw-r--r--fs/cifs/dfs.c14
-rw-r--r--fs/cifs/dfs.h13
-rw-r--r--fs/cifs/dfs_cache.c6
5 files changed, 43 insertions, 20 deletions
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 08a73dcb7786..a62447404851 100644
--- 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)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c71505a29482..9451b1023af8 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -454,7 +454,6 @@ static int reconnect_target_unlocked(struct TCP_Server_Info *server, struct dfs_
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 TCP_Server_Info *server)
* 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 TCP_Server_Info *server)
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 */
@@ -1582,7 +1585,6 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
rc = -ENOMEM;
goto out_err;
}
- tcp_ses->current_fullpath = tcp_ses->leaf_fullpath;
}
if (ctx->nosharesock)
diff --git a/fs/cifs/dfs.c b/fs/cifs/dfs.c
index 37f7da4f5c8b..c4ec5c67087b 100644
--- a/fs/cifs/dfs.c
+++ b/fs/cifs/dfs.c
@@ -248,11 +248,12 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
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)) {
@@ -342,10 +343,11 @@ static int update_server_fullpath(struct TCP_Server_Info *server, struct cifs_sb
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;
}
@@ -450,7 +452,7 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
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;
@@ -464,7 +466,7 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
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);
@@ -582,8 +584,8 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
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;
}
diff --git a/fs/cifs/dfs.h b/fs/cifs/dfs.h
index 0b8cbf721fff..1c90df5ecfbd 100644
--- a/fs/cifs/dfs.h
+++ b/fs/cifs/dfs.h
@@ -43,8 +43,12 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
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_devname(struct dentry *dentry, void *page)
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;
}
diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
index 30cbdf8514a5..6557d7b2798a 100644
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -1278,8 +1278,12 @@ static void refresh_cache_worker(struct work_struct *work)
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) {