File xsa326-01.patch of Package xen.26345
From 41763ca4c788638751fb5552b60cc932c375bbb9 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Tue, 13 Sep 2022 07:35:07 +0200
Subject: tools/xenstore: split up send_reply()
Today send_reply() is used for both, normal request replies and watch
events.
Split it up into send_reply() and send_event(). This will be used to
add some event specific handling.
add_event() can be merged into send_event(), removing the need for an
intermediate memory allocation.
This is part of XSA-326.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -672,49 +672,32 @@ static void send_error(struct connection
void send_reply(struct connection *conn, enum xsd_sockmsg_type type,
const void *data, unsigned int len)
{
- struct buffered_data *bdata;
+ struct buffered_data *bdata = conn->in;
+
+ assert(type != XS_WATCH_EVENT);
if ( len > XENSTORE_PAYLOAD_MAX ) {
send_error(conn, E2BIG);
return;
}
- /* Replies reuse the request buffer, events need a new one. */
- if (type != XS_WATCH_EVENT) {
- bdata = conn->in;
- /* Drop asynchronous responses, e.g. errors for watch events. */
- if (!bdata)
- return;
- bdata->inhdr = true;
- bdata->used = 0;
- conn->in = NULL;
- } else {
- /* Message is a child of the connection for auto-cleanup. */
- bdata = new_buffer(conn);
-
- /*
- * Allocation failure here is unfortunate: we have no way to
- * tell anybody about it.
- */
- if (!bdata)
- return;
- }
+ if (!bdata)
+ return;
+ bdata->inhdr = true;
+ bdata->used = 0;
+
if (len <= DEFAULT_BUFFER_SIZE)
bdata->buffer = bdata->default_buffer;
- else
+ else {
bdata->buffer = talloc_array(bdata, char, len);
- if (!bdata->buffer) {
- if (type == XS_WATCH_EVENT) {
- /* Same as above: no way to tell someone. */
- talloc_free(bdata);
+ if (!bdata->buffer) {
+ send_error(conn, ENOMEM);
return;
}
- /* re-establish request buffer for sending ENOMEM. */
- conn->in = bdata;
- send_error(conn, ENOMEM);
- return;
}
+ conn->in = NULL;
+
/* Update relevant header fields and fill in the message body. */
bdata->hdr.msg.type = type;
bdata->hdr.msg.len = len;
@@ -722,8 +705,39 @@ void send_reply(struct connection *conn,
/* Queue for later transmission. */
list_add_tail(&bdata->list, &conn->out_list);
+}
- return;
+/*
+ * Send a watch event.
+ * As this is not directly related to the current command, errors can't be
+ * reported.
+ */
+void send_event(struct connection *conn, const char *path, const char *token)
+{
+ struct buffered_data *bdata;
+ unsigned int len;
+
+ len = strlen(path) + 1 + strlen(token) + 1;
+ /* Don't try to send over-long events. */
+ if (len > XENSTORE_PAYLOAD_MAX)
+ return;
+
+ bdata = new_buffer(conn);
+ if (!bdata)
+ return;
+
+ bdata->buffer = talloc_array(bdata, char, len);
+ if (!bdata->buffer) {
+ talloc_free(bdata);
+ return;
+ }
+ strcpy(bdata->buffer, path);
+ strcpy(bdata->buffer + strlen(path) + 1, token);
+ bdata->hdr.msg.type = XS_WATCH_EVENT;
+ bdata->hdr.msg.len = len;
+
+ /* Queue for later transmission. */
+ list_add_tail(&bdata->list, &conn->out_list);
}
/* Some routines (write, mkdir, etc) just need a non-error return */
--- a/tools/xenstore/xenstored_core.h
+++ b/tools/xenstore/xenstored_core.h
@@ -152,6 +152,7 @@ unsigned int get_strings(struct buffered
void send_reply(struct connection *conn, enum xsd_sockmsg_type type,
const void *data, unsigned int len);
+void send_event(struct connection *conn, const char *path, const char *token);
/* Some routines (write, mkdir, etc) just need a non-error return */
void send_ack(struct connection *conn, enum xsd_sockmsg_type type);
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -72,37 +72,17 @@ static bool is_child(const char *child,
return child[len] == '/' || child[len] == '\0';
}
-/*
- * Send a watch event.
- * Temporary memory allocations are done with ctx.
- */
-static void add_event(struct connection *conn,
- const void *ctx,
- struct watch *watch,
- const char *name)
+static const char *get_watch_path(const struct watch *watch, const char *name)
{
- /* Data to send (node\0token\0). */
- unsigned int len;
- char *data;
+ const char *path = name;
if (watch->relative_path) {
- name += strlen(watch->relative_path);
- if (*name == '/') /* Could be "" */
- name++;
+ path += strlen(watch->relative_path);
+ if (*path == '/') /* Could be "" */
+ path++;
}
- len = strlen(name) + 1 + strlen(watch->token) + 1;
- /* Don't try to send over-long events. */
- if (len > XENSTORE_PAYLOAD_MAX)
- return;
-
- data = talloc_array(ctx, char, len);
- if (!data)
- return;
- strcpy(data, name);
- strcpy(data + strlen(name) + 1, watch->token);
- send_reply(conn, XS_WATCH_EVENT, data, len);
- talloc_free(data);
+ return path;
}
/*
@@ -181,10 +161,14 @@ void fire_watches(struct connection *con
list_for_each_entry(watch, &i->watches, list) {
if (exact) {
if (streq(name, watch->node))
- add_event(i, ctx, watch, name);
+ send_event(i,
+ get_watch_path(watch, name),
+ watch->token);
} else {
if (is_child(name, watch->node))
- add_event(i, ctx, watch, name);
+ send_event(i,
+ get_watch_path(watch, name),
+ watch->token);
}
}
}
@@ -252,7 +236,7 @@ int do_watch(struct connection *conn, st
send_ack(conn, XS_WATCH);
/* We fire once up front: simplifies clients and restart. */
- add_event(conn, in, watch, watch->node);
+ send_event(conn, get_watch_path(watch, watch->node), watch->token);
return 0;
}
