tools/xenstore: add memory accounting for watches

Add the memory accounting for registered watches.

When a socket connection is destroyed, the associated watches are
removed, too. In order to keep memory accounting correct the watches
must be removed explicitly via a call of conn_delete_all_watches() from
destroy_conn().

This is part of XSA-326 / CVE-2022-42315.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
(cherry picked from commit 7f9978a2cc37aaffab2fb09593bc598c0712a69b)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index ecab6cfbbe159851049f9a5742439ab5f7a3d96b..d86942f5aa77cd1c6920c7577e2dc3307ae1bcc8 100644 (file)
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -463,6 +463,7 @@ static int destroy_conn(void *_conn)
        }
 
        conn_free_buffered_data(conn);
+       conn_delete_all_watches(conn);
        list_for_each_entry(req, &conn->ref_list, list)
                req->on_ref_list = false;
 

diff --git a/tools/xenstore/xenstored_watch.c b/tools/xenstore/xenstored_watch.c
index 0755ffa375baa17f9d1e1f5ce3cb1293bb3a3bb1..fdf9b2d653a01171fe70c35830c0eb83c02d0a48 100644 (file)
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -211,7 +211,7 @@ static int check_watch_path(struct connection *conn, const void *ctx,
 }
 
 static struct watch *add_watch(struct connection *conn, char *path, char *token,
-                              bool relative)
+                              bool relative, bool no_quota_check)
 {
        struct watch *watch;
 
@@ -222,6 +222,9 @@ static struct watch *add_watch(struct connection *conn, char *path, char *token,
        watch->token = talloc_strdup(watch, token);
        if (!watch->node || !watch->token)
                goto nomem;
+       if (domain_memory_add(conn->id, strlen(path) + strlen(token),
+                             no_quota_check))
+               goto nomem;
 
        if (relative)
                watch->relative_path = get_implicit_path(conn);
@@ -265,7 +268,7 @@ int do_watch(struct connection *conn, struct buffered_data *in)
        if (domain_watch(conn) > quota_nb_watch_per_domain)
                return E2BIG;
 
-       watch = add_watch(conn, vec[0], vec[1], relative);
+       watch = add_watch(conn, vec[0], vec[1], relative, false);
        if (!watch)
                return errno;
 
@@ -296,6 +299,8 @@ int do_unwatch(struct connection *conn, struct buffered_data *in)
        list_for_each_entry(watch, &conn->watches, list) {
                if (streq(watch->node, node) && streq(watch->token, vec[1])) {
                        list_del(&watch->list);
+                       domain_memory_add_nochk(conn->id, -strlen(watch->node) -
+                                                         strlen(watch->token));
                        talloc_free(watch);
                        domain_watch_dec(conn);
                        send_ack(conn, XS_UNWATCH);
@@ -311,6 +316,8 @@ void conn_delete_all_watches(struct connection *conn)
 
        while ((watch = list_top(&conn->watches, struct watch, list))) {
                list_del(&watch->list);
+               domain_memory_add_nochk(conn->id, -strlen(watch->node) -
+                                                 strlen(watch->token));
                talloc_free(watch);
                domain_watch_dec(conn);
        }
@@ -373,7 +380,7 @@ void read_state_watch(const void *ctx, const void *state)
        if (!path)
                barf("allocation error for read watch");
 
-       if (!add_watch(conn, path, token, relative))
+       if (!add_watch(conn, path, token, relative, true))
                barf("error adding watch");
 }