sanlock: Introduce 'user' and 'group' conf variables

through which user set under what permissions does sanlock
daemon run so libvirt will set the same permissions for
files exposed to it.

docs/locking.html.in

@@ -120,6 +120,28 @@
       # mount /var/lib/libvirt/sanlock
     </pre>
 
+    <p>
+      If your sanlock daemon happen to run under non-root
+      privileges, you need to tell this to libvirt so it
+      chowns created files correctly. This can be done by
+      setting <code>user</code> and/or <code>group</code>
+      variables in the configuration file. Accepted values
+      range is specified in description to the same
+      variables in <code>/etc/libvirt/qemu.conf</code>. For
+      example:
+    </p>
+
+    <pre>
+      augtool -s set /files/etc/libvirt/qemu-sanlock.conf/user sanlock
+      augtool -s set /files/etc/libvirt/qemu-sanlock.conf/group sanlock
+    </pre>
+
+    <p>
+      But remember, that if this is NFS share, you need a
+      no_root_squash-ed one for chown (and chmod possibly)
+      to succeed.
+    </p>
+
     <p>
       In terms of storage requirements, if the filesystem
       uses 512 byte sectors, you need to allow for <code>1MB</code>

libvirt.spec.in

@@ -1568,6 +1568,13 @@ fi
 /bin/systemctl try-restart libvirt-guests.service >/dev/null 2>&1 || :
 %endif
 
+%post lock-sanlock
+if getent group sanlock > /dev/null ; then
+    chmod 0770 %{_localstatedir}/lib/libvirt/sanlock
+    chown root:sanlock %{_localstatedir}/lib/libvirt/sanlock
+fi
+
+
 %files
 %defattr(-, root, root)
 

src/locking/libvirt_sanlock.aug

@@ -22,6 +22,8 @@ module Libvirt_sanlock =
              | int_entry "host_id"
              | bool_entry "require_lease_for_disks"
              | bool_entry "ignore_readonly_and_shared_disks"
+             | str_entry "user"
+             | str_entry "group"
    let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]
    let empty = [ label "#empty" . eol ]
 

src/locking/lock_driver_sanlock.c

@@ -71,6 +71,10 @@ struct _virLockManagerSanlockDriver {
     int hostID;
     bool autoDiskLease;
     char *autoDiskLeasePath;
+
+    /* under which permissions does sanlock run */
+    uid_t user;
+    gid_t group;
 };
 
 static virLockManagerSanlockDriver *driver = NULL;
@@ -94,6 +98,7 @@ static int virLockManagerSanlockLoadConfig(const char *configFile)
 {
     virConfPtr conf;
     virConfValuePtr p;
+    char *tmp;
 
     if (access(configFile, R_OK) == -1) {
         if (errno != ENOENT) {
@@ -142,6 +147,39 @@ static int virLockManagerSanlockLoadConfig(const char *configFile)
     else
         driver->requireLeaseForDisks = !driver->autoDiskLease;
 
+    p = virConfGetValue(conf, "user");
+    CHECK_TYPE("user", VIR_CONF_STRING);
+    if (p) {
+        if (!(tmp = strdup(p->str))) {
+            virReportOOMError();
+            virConfFree(conf);
+            return -1;
+        }
+
+        if (virGetUserID(tmp, &driver->user) < 0) {
+            VIR_FREE(tmp);
+            virConfFree(conf);
+            return -1;
+        }
+        VIR_FREE(tmp);
+    }
+
+    p = virConfGetValue (conf, "group");
+    CHECK_TYPE ("group", VIR_CONF_STRING);
+    if (p) {
+        if (!(tmp = strdup(p->str))) {
+            virReportOOMError();
+            virConfFree(conf);
+            return -1;
+        }
+        if (virGetGroupID(tmp, &driver->group) < 0) {
+            VIR_FREE(tmp);
+            virConfFree(conf);
+            return -1;
+        }
+        VIR_FREE(tmp);
+    }
+
     virConfFree(conf);
     return 0;
 }
@@ -177,6 +215,7 @@ static int virLockManagerSanlockSetupLockspace(void)
      * space allocated for it and is initialized with lease
      */
     if (stat(path, &st) < 0) {
+        int perms = 0600;
         VIR_DEBUG("Lockspace %s does not yet exist", path);
 
         if (!(dir = mdir_name(path))) {
@@ -191,7 +230,10 @@ static int virLockManagerSanlockSetupLockspace(void)
             goto error;
         }
 
-        if ((fd = open(path, O_WRONLY|O_CREAT|O_EXCL, 0600)) < 0) {
+        if (driver->group != -1)
+            perms |= 0060;
+
+        if ((fd = open(path, O_WRONLY|O_CREAT|O_EXCL, perms)) < 0) {
             if (errno != EEXIST) {
                 virReportSystemError(errno,
                                      _("Unable to create lockspace %s"),
@@ -200,6 +242,17 @@ static int virLockManagerSanlockSetupLockspace(void)
             }
             VIR_DEBUG("Someone else just created lockspace %s", path);
         } else {
+            /* chown() the path to make sure sanlock can access it */
+            if ((driver->user != -1 || driver->group != -1) &&
+                (fchown(fd, driver->user, driver->group) < 0)) {
+                virReportSystemError(errno,
+                                     _("cannot chown '%s' to (%u, %u)"),
+                                     path,
+                                     (unsigned int) driver->user,
+                                     (unsigned int) driver->group);
+                goto error_unlink;
+            }
+
             if ((rv = sanlock_align(&ls.host_id_disk)) < 0) {
                 if (rv <= -200)
                     virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -242,6 +295,26 @@ static int virLockManagerSanlockSetupLockspace(void)
             }
             VIR_DEBUG("Lockspace %s has been initialized", path);
         }
+    } else if (S_ISREG(st.st_mode)) {
+        /* okay, the lease file exists. Check the permissions */
+        if (((driver->user != -1 && driver->user != st.st_uid) ||
+             (driver->group != -1 && driver->group != st.st_gid)) &&
+            (chown(path, driver->user, driver->group) < 0)) {
+            virReportSystemError(errno,
+                                 _("cannot chown '%s' to (%u, %u)"),
+                                 path,
+                                 (unsigned int) driver->user,
+                                 (unsigned int) driver->group);
+            goto error;
+        }
+
+        if ((driver->group != -1 && (st.st_mode & 0060) != 0060) &&
+            chmod(path, 0660) < 0) {
+            virReportSystemError(errno,
+                                 _("cannot chmod '%s' to 0660"),
+                                 path);
+            goto error;
+        }
     }
 
     ls.host_id = driver->hostID;
@@ -299,6 +372,7 @@ static int virLockManagerSanlockInit(unsigned int version,
     driver->requireLeaseForDisks = true;
     driver->hostID = 0;
     driver->autoDiskLease = false;
+    driver->user = driver->group = -1;
     if (!(driver->autoDiskLeasePath = strdup(LOCALSTATEDIR "/lib/libvirt/sanlock"))) {
         VIR_FREE(driver);
         virReportOOMError();

src/locking/sanlock.conf

@@ -29,7 +29,8 @@
 #
 # Recommendation is to just mount this default location as
 # an NFS volume. Uncomment this, if you would prefer the mount
-# point to be somewhere else.
+# point to be somewhere else. Moreover, please make sure
+# sanlock daemon can access the specified path.
 #
 #disk_lease_dir = "/var/lib/libvirt/sanlock"
 
@@ -52,3 +53,11 @@
 # to enabled, otherwise it defaults to disabled.
 #
 #require_lease_for_disks = 1
+
+#
+# The combination of user and group under which the sanlock
+# daemon runs. Libvirt will chown created files (like
+# content of disk_lease_dir) to make sure sanlock daemon can
+# access them. Accepted values are described in qemu.conf.
+#user = "root"
+#group = "root"

src/locking/test_libvirt_sanlock.aug.in

@@ -6,3 +6,5 @@ module Test_libvirt_sanlock =
 { "disk_lease_dir" = "/var/lib/libvirt/sanlock" }
 { "host_id" = "1" }
 { "require_lease_for_disks" = "1" }
+{ "user" = "root" }
+{ "group" = "root" }