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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>
This commit is contained in:
Paulo Alcantara 2023-04-26 13:43:53 -03:00 committed by Steve French
parent ee20d7c610
commit 3dc9c433c9
5 changed files with 43 additions and 20 deletions
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20
fs/cifs/cifsglob.h
View File

@ -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)

10
fs/cifs/connect.c
View File

@ -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)

14
fs/cifs/dfs.c
View File

@ -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;
}

13
fs/cifs/dfs.h
View File

@ -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;
}

6
fs/cifs/dfs_cache.c
View File

@ -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) {