Merge remote-tracking branch 'remotes/berrange/tags/authz-core-pull-request' into staging

Add a standard authorization framework

The current network services now support encryption via TLS and in some
cases support authentication via SASL. In cases where SASL is not
available, x509 client certificates can be used as a crude authorization
scheme, but using a sub-CA and controlling who you give certs to. In
general this is not very flexible though, so this series introduces a
new standard authorization framework.

It comes with four initial authorization mechanisms

 - Simple - an exact username match. This is useful when there is
   exactly one user that is known to connect. For example when live
   migrating from one QEMU to another with TLS, libvirt would use
   the simple scheme to whitelist the TLS cert of the source QEMU.

 - List - an full access control list, with optional regex matching.
   This is more flexible and is used to provide 100% backcompat with
   the existing HMP ACL commands. The caveat is that we can't create
   these via the CLI -object arg yet.

 - ListFile - the same as List, but with the rules stored in JSON
   format in an external file. This avoids the -object limitation
   while also allowing the admin to change list entries on the file.
   QEMU uses inotify to notice these changes and auto-reload the
   file contents. This is likely a good default choice for most
   network services, if the "simple" mechanism isn't sufficient.

 - PAM - delegate the username lookup to a PAM module, which opens
   the door to many options including things like SQL/LDAP lookups.

# gpg: Signature made Tue 26 Feb 2019 15:33:46 GMT
# gpg:                using RSA key BE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>" [full]
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>" [full]
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange/tags/authz-core-pull-request:
  authz: delete existing ACL implementation
  authz: add QAuthZPAM object type for authorizing using PAM
  authz: add QAuthZListFile object type for a file access control list
  authz: add QAuthZList object type for an access control list
  authz: add QAuthZSimple object type for easy whitelist auth checks
  authz: add QAuthZ object as an authorization base class
  hw/usb: switch MTP to use new inotify APIs
  hw/usb: fix const-ness for string params in MTP driver
  hw/usb: don't set IN_ISDIR for inotify watch in MTP driver
  qom: don't require user creatable objects to be registered
  util: add helper APIs for dealing with inotify in portable manner

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 339 insertions, 0 deletions

diff --git a/util/filemonitor-inotify.c b/util/filemonitor-inotify.c
new file mode 100644
index 0000000000..3a72be037f
--- /dev/null
+++ b/util/filemonitor-inotify.c
@@ -0,0 +1,339 @@
+/*
+ * QEMU file monitor Linux inotify impl
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/filemonitor.h"
+#include "qemu/main-loop.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+#include "trace.h"
+
+#include <sys/inotify.h>
+
+struct QFileMonitor {
+    int fd;
+
+    QemuMutex lock; /* protects dirs & idmap */
+    GHashTable *dirs; /* dirname => QFileMonitorDir */
+    GHashTable *idmap; /* inotify ID => dirname */
+};
+
+
+typedef struct {
+    int id; /* watch ID */
+    char *filename; /* optional filter */
+    QFileMonitorHandler cb;
+    void *opaque;
+} QFileMonitorWatch;
+
+
+typedef struct {
+    char *path;
+    int id; /* inotify ID */
+    int nextid; /* watch ID counter */
+    GArray *watches; /* QFileMonitorWatch elements */
+} QFileMonitorDir;
+
+
+static void qemu_file_monitor_watch(void *arg)
+{
+    QFileMonitor *mon = arg;
+    char buf[4096]
+        __attribute__ ((aligned(__alignof__(struct inotify_event))));
+    int used = 0;
+    int len;
+
+    qemu_mutex_lock(&mon->lock);
+
+    if (mon->fd == -1) {
+        qemu_mutex_unlock(&mon->lock);
+        return;
+    }
+
+    len = read(mon->fd, buf, sizeof(buf));
+
+    if (len < 0) {
+        if (errno != EAGAIN) {
+            error_report("Failure monitoring inotify FD '%s',"
+                         "disabling events", strerror(errno));
+            goto cleanup;
+        }
+
+        /* no more events right now */
+        goto cleanup;
+    }
+
+    /* Loop over all events in the buffer */
+    while (used < len) {
+        struct inotify_event *ev =
+            (struct inotify_event *)(buf + used);
+        const char *name = ev->len ? ev->name : "";
+        QFileMonitorDir *dir = g_hash_table_lookup(mon->idmap,
+                                                   GINT_TO_POINTER(ev->wd));
+        uint32_t iev = ev->mask &
+            (IN_CREATE | IN_MODIFY | IN_DELETE | IN_IGNORED |
+             IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB);
+        int qev;
+        gsize i;
+
+        used += sizeof(struct inotify_event) + ev->len;
+
+        if (!dir) {
+            continue;
+        }
+
+        /*
+         * During a rename operation, the old name gets
+         * IN_MOVED_FROM and the new name gets IN_MOVED_TO.
+         * To simplify life for callers, we turn these into
+         * DELETED and CREATED events
+         */
+        switch (iev) {
+        case IN_CREATE:
+        case IN_MOVED_TO:
+            qev = QFILE_MONITOR_EVENT_CREATED;
+            break;
+        case IN_MODIFY:
+            qev = QFILE_MONITOR_EVENT_MODIFIED;
+            break;
+        case IN_DELETE:
+        case IN_MOVED_FROM:
+            qev = QFILE_MONITOR_EVENT_DELETED;
+            break;
+        case IN_ATTRIB:
+            qev = QFILE_MONITOR_EVENT_ATTRIBUTES;
+            break;
+        case IN_IGNORED:
+            qev = QFILE_MONITOR_EVENT_IGNORED;
+            break;
+        default:
+            g_assert_not_reached();
+        }
+
+        trace_qemu_file_monitor_event(mon, dir->path, name, ev->mask, dir->id);
+        for (i = 0; i < dir->watches->len; i++) {
+            QFileMonitorWatch *watch = &g_array_index(dir->watches,
+                                                      QFileMonitorWatch,
+                                                      i);
+
+            if (watch->filename == NULL ||
+                (name && g_str_equal(watch->filename, name))) {
+                trace_qemu_file_monitor_dispatch(mon, dir->path, name,
+                                                 qev, watch->cb,
+                                                 watch->opaque, watch->id);
+                watch->cb(watch->id, qev, name, watch->opaque);
+            }
+        }
+    }
+
+ cleanup:
+    qemu_mutex_unlock(&mon->lock);
+}
+
+
+static void
+qemu_file_monitor_dir_free(void *data)
+{
+    QFileMonitorDir *dir = data;
+    gsize i;
+
+    for (i = 0; i < dir->watches->len; i++) {
+        QFileMonitorWatch *watch = &g_array_index(dir->watches,
+                                                  QFileMonitorWatch, i);
+        g_free(watch->filename);
+    }
+    g_array_unref(dir->watches);
+    g_free(dir->path);
+    g_free(dir);
+}
+
+
+QFileMonitor *
+qemu_file_monitor_new(Error **errp)
+{
+    int fd;
+    QFileMonitor *mon;
+
+    fd = inotify_init1(IN_NONBLOCK);
+    if (fd < 0) {
+        error_setg_errno(errp, errno,
+                         "Unable to initialize inotify");
+        return NULL;
+    }
+
+    mon = g_new0(QFileMonitor, 1);
+    qemu_mutex_init(&mon->lock);
+    mon->fd = fd;
+
+    mon->dirs = g_hash_table_new_full(g_str_hash, g_str_equal, NULL,
+                                      qemu_file_monitor_dir_free);
+    mon->idmap = g_hash_table_new(g_direct_hash, g_direct_equal);
+
+    trace_qemu_file_monitor_new(mon, mon->fd);
+
+    return mon;
+}
+
+static gboolean
+qemu_file_monitor_free_idle(void *opaque)
+{
+    QFileMonitor *mon = opaque;
+
+    if (!mon) {
+        return G_SOURCE_REMOVE;
+    }
+
+    qemu_mutex_lock(&mon->lock);
+
+    g_hash_table_unref(mon->idmap);
+    g_hash_table_unref(mon->dirs);
+
+    qemu_mutex_unlock(&mon->lock);
+
+    qemu_mutex_destroy(&mon->lock);
+    g_free(mon);
+
+    return G_SOURCE_REMOVE;
+}
+
+void
+qemu_file_monitor_free(QFileMonitor *mon)
+{
+    if (!mon) {
+        return;
+    }
+
+    qemu_mutex_lock(&mon->lock);
+    if (mon->fd != -1) {
+        qemu_set_fd_handler(mon->fd, NULL, NULL, NULL);
+        close(mon->fd);
+        mon->fd = -1;
+    }
+    qemu_mutex_unlock(&mon->lock);
+
+    /*
+     * Can't free it yet, because another thread
+     * may be running event loop, so the inotify
+     * callback might be pending. Using an idle
+     * source ensures we'll only free after the
+     * pending callback is done
+     */
+    g_idle_add((GSourceFunc)qemu_file_monitor_free_idle, mon);
+}
+
+int
+qemu_file_monitor_add_watch(QFileMonitor *mon,
+                            const char *dirpath,
+                            const char *filename,
+                            QFileMonitorHandler cb,
+                            void *opaque,
+                            Error **errp)
+{
+    QFileMonitorDir *dir;
+    QFileMonitorWatch watch;
+    int ret = -1;
+
+    qemu_mutex_lock(&mon->lock);
+    dir = g_hash_table_lookup(mon->dirs, dirpath);
+    if (!dir) {
+        int rv = inotify_add_watch(mon->fd, dirpath,
+                                   IN_CREATE | IN_DELETE | IN_MODIFY |
+                                   IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB);
+
+        if (rv < 0) {
+            error_setg_errno(errp, errno, "Unable to watch '%s'", dirpath);
+            goto cleanup;
+        }
+
+        trace_qemu_file_monitor_enable_watch(mon, dirpath, rv);
+
+        dir = g_new0(QFileMonitorDir, 1);
+        dir->path = g_strdup(dirpath);
+        dir->id = rv;
+        dir->watches = g_array_new(FALSE, TRUE, sizeof(QFileMonitorWatch));
+
+        g_hash_table_insert(mon->dirs, dir->path, dir);
+        g_hash_table_insert(mon->idmap, GINT_TO_POINTER(rv), dir);
+
+        if (g_hash_table_size(mon->dirs) == 1) {
+            qemu_set_fd_handler(mon->fd, qemu_file_monitor_watch, NULL, mon);
+        }
+    }
+
+    watch.id = dir->nextid++;
+    watch.filename = g_strdup(filename);
+    watch.cb = cb;
+    watch.opaque = opaque;
+
+    g_array_append_val(dir->watches, watch);
+
+    trace_qemu_file_monitor_add_watch(mon, dirpath,
+                                      filename ? filename : "<none>",
+                                      cb, opaque, watch.id);
+
+    ret = watch.id;
+
+ cleanup:
+    qemu_mutex_unlock(&mon->lock);
+    return ret;
+}
+
+
+void qemu_file_monitor_remove_watch(QFileMonitor *mon,
+                                    const char *dirpath,
+                                    int id)
+{
+    QFileMonitorDir *dir;
+    gsize i;
+
+    qemu_mutex_lock(&mon->lock);
+
+    trace_qemu_file_monitor_remove_watch(mon, dirpath, id);
+
+    dir = g_hash_table_lookup(mon->dirs, dirpath);
+    if (!dir) {
+        goto cleanup;
+    }
+
+    for (i = 0; i < dir->watches->len; i++) {
+        QFileMonitorWatch *watch = &g_array_index(dir->watches,
+                                                  QFileMonitorWatch, i);
+        if (watch->id == id) {
+            g_free(watch->filename);
+            g_array_remove_index(dir->watches, i);
+            break;
+        }
+    }
+
+    if (dir->watches->len == 0) {
+        inotify_rm_watch(mon->fd, dir->id);
+        trace_qemu_file_monitor_disable_watch(mon, dir->path, dir->id);
+
+        g_hash_table_remove(mon->idmap, GINT_TO_POINTER(dir->id));
+        g_hash_table_remove(mon->dirs, dir->path);
+
+        if (g_hash_table_size(mon->dirs) == 0) {
+            qemu_set_fd_handler(mon->fd, NULL, NULL, NULL);
+        }
+    }
+
+ cleanup:
+    qemu_mutex_unlock(&mon->lock);
+}