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qmp: Don't let malformed in-band commands jump the queue 

handle_qmp_command() reports certain errors right away.  This is wrong
when OOB is enabled, because the errors can "jump the queue" then, as
the previous commit demonstrates.

To fix, we need to delay errors until dispatch.  Do that for semantic
errors, mostly by reverting ill-advised parts of commit cf869d5317
"qmp: support out-of-band (oob) execution".  Bonus: doesn't run
qmp_dispatch_check_obj() twice, once in handle_qmp_command(), and
again in do_qmp_dispatch().  That's also due to commit cf869d5317.

The next commit will fix queue jumping for syntax errors.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180703085358.13941-18-armbru@redhat.com>
This commit is contained in:
Markus Armbruster 2018-07-03 10:53:43 +02:00
parent e8f4a22168
commit 69240fe62d
4 changed files with 30 additions and 67 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/qapi/qmp/dispatch.h
View File

@ -48,8 +48,6 @@ bool qmp_command_is_enabled(const QmpCommand *cmd);
const char *qmp_command_name(const QmpCommand *cmd);
bool qmp_has_success_response(const QmpCommand *cmd);
QObject *qmp_build_error_object(Error *err);
QDict *qmp_dispatch_check_obj(const QObject *request, bool allow_oob,
Error **errp);
QObject *qmp_dispatch(QmpCommandList *cmds, QObject *request,
bool allow_oob);
bool qmp_is_oob(QDict *dict);

79
monitor.c
View File

@ -1290,48 +1290,6 @@ static void qmp_caps_apply(Monitor *mon, QMPCapabilityList *list)
}
}
/*
* Return true if check successful, or false otherwise. When false is
* returned, detailed error will be in errp if provided.
*/
static bool qmp_cmd_oob_check(Monitor *mon, QDict *req, Error **errp)
{
const char *command;
QmpCommand *cmd;
command = qdict_get_try_str(req, "execute");
if (!command) {
command = qdict_get_try_str(req, "exec-oob");
}
if (!command) {
error_setg(errp, "Command field 'execute' missing");
return false;
}
cmd = qmp_find_command(mon->qmp.commands, command);
if (!cmd) {
if (mon->qmp.commands == &qmp_cap_negotiation_commands) {
error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
"Expecting capabilities negotiation "
"with 'qmp_capabilities'");
} else {
error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
"The command %s has not been found", command);
}
return false;
}
if (qmp_is_oob(req)) {
if (!(cmd->options & QCO_ALLOW_OOB)) {
error_setg(errp, "The command %s does not support OOB",
command);
return false;
}
}
return true;
}
void qmp_qmp_capabilities(bool has_enable, QMPCapabilityList *enable,
Error **errp)
{
@ -4171,6 +4129,7 @@ static void monitor_qmp_dispatch(Monitor *mon, QObject *req, QObject *id)
{
Monitor *old_mon;
QObject *rsp;
QDict *error;
old_mon = cur_mon;
cur_mon = mon;
@ -4179,6 +4138,19 @@ static void monitor_qmp_dispatch(Monitor *mon, QObject *req, QObject *id)
cur_mon = old_mon;
if (mon->qmp.commands == &qmp_cap_negotiation_commands) {
error = qdict_get_qdict(qobject_to(QDict, rsp), "error");
if (error
&& !g_strcmp0(qdict_get_try_str(error, "class"),
QapiErrorClass_str(ERROR_CLASS_COMMAND_NOT_FOUND))) {
/* Provide a more useful error message */
qdict_del(error, "desc");
qdict_put_str(error, "desc", "Expecting capabilities negotiation"
" with 'qmp_capabilities'");
}
}
/* Respond if necessary */
monitor_qmp_respond(mon, rsp, NULL, qobject_ref(id));
}
@ -4256,7 +4228,9 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens)
error_setg(&err, QERR_JSON_PARSING);
}
if (err) {
goto err;
assert(!req);
monitor_qmp_respond(mon, NULL, err, NULL);
return;
}
qdict = qobject_to(QDict, req);
@ -4271,18 +4245,7 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens)
qobject_unref(req_json);
}
/* Check against the request in general layout */
qdict = qmp_dispatch_check_obj(req, qmp_oob_enabled(mon), &err);
if (!qdict) {
goto err;
}
/* Check against OOB specific */
if (!qmp_cmd_oob_check(mon, qdict, &err)) {
goto err;
}
if (qmp_is_oob(qdict)) {
if (qdict && qmp_is_oob(qdict)) {
/* Out-of-band (OOB) requests are executed directly in parser. */
trace_monitor_qmp_cmd_out_of_band(qobject_get_try_str(id)
?: "");
@ -4336,12 +4299,6 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens)
/* Kick the dispatcher routine */
qemu_bh_schedule(mon_global.qmp_dispatcher_bh);
return;
err:
/* FIXME overtakes queued in-band commands, wrong when !qmp_is_oob() */
monitor_qmp_respond(mon, NULL, err, NULL);
qobject_unref(req);
}
static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size)

12
qapi/qmp-dispatch.c
View File

@ -20,8 +20,8 @@
#include "qapi/qmp/qbool.h"
#include "sysemu/sysemu.h"
QDict *qmp_dispatch_check_obj(const QObject *request, bool allow_oob,
Error **errp)
static QDict *qmp_dispatch_check_obj(const QObject *request, bool allow_oob,
Error **errp)
{
const char *exec_key = NULL;
const QDictEntry *ent;
@ -78,6 +78,7 @@ static QObject *do_qmp_dispatch(QmpCommandList *cmds, QObject *request,
bool allow_oob, Error **errp)
{
Error *local_err = NULL;
bool oob;
const char *command;
QDict *args, *dict;
QmpCommand *cmd;
@ -89,9 +90,11 @@ static QObject *do_qmp_dispatch(QmpCommandList *cmds, QObject *request,
}
command = qdict_get_try_str(dict, "execute");
oob = false;
if (!command) {
assert(allow_oob);
command = qdict_get_str(dict, "exec-oob");
oob = true;
}
cmd = qmp_find_command(cmds, command);
if (cmd == NULL) {
@ -104,6 +107,11 @@ static QObject *do_qmp_dispatch(QmpCommandList *cmds, QObject *request,
command);
return NULL;
}
if (oob && !(cmd->options & QCO_ALLOW_OOB)) {
error_setg(errp, "The command %s does not support OOB",
command);
return false;
}
if (runstate_check(RUN_STATE_PRECONFIG) &&
!(cmd->options & QCO_ALLOW_PRECONFIG)) {

4
tests/qmp-test.c
View File

@ -242,12 +242,12 @@ static void test_qmp_oob(void)
recv_cmd_id(qts, "ib-blocks-1");
recv_cmd_id(qts, "ib-quick-1");
/* FIXME certain in-band errors overtake slow in-band command */
/* Even malformed in-band command fails in-band */
send_cmd_that_blocks(qts, "blocks-2");
qtest_async_qmp(qts, "{ 'id': 'err-2' }");
recv_cmd_id(qts, NULL);
unblock_blocked_cmd();
recv_cmd_id(qts, "blocks-2");
recv_cmd_id(qts, "err-2");
cleanup_blocking_cmd();
qtest_quit(qts);