libxl: prevent xl from doing operations on domains if xend is running

Prevent xl from doing any operation if xend daemon is running. That
prevents bugs that happened when xl and xend raced to close a domain.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

5 files changed, 96 insertions, 68 deletions

diff --git a/docs/man/xl.pod.1 b/docs/man/xl.pod.1
index 283c9ed2ac..b192efadf6 100644
--- a/docs/man/xl.pod.1
+++ b/docs/man/xl.pod.1
@@ -75,6 +75,12 @@ Verbose.
 
 Dry run: do not actually execute the command.
 
+=item B<-f>
+
+Force execution: xl will refuse to run some commands if it detects that xend is
+also running, this option will force the execution of those commands, even
+though it is unsafe.
+
 =back
 
 =head1 DOMAIN SUBCOMMANDS
diff --git a/tools/libxl/xl.c b/tools/libxl/xl.c
index d4db1f8b8b..750a61c54c 100644
--- a/tools/libxl/xl.c
+++ b/tools/libxl/xl.c
@@ -32,8 +32,11 @@
 #include "libxlutil.h"
 #include "xl.h"
 
+#define XEND_LOCK { "/var/lock/subsys/xend", "/var/lock/xend" }
+
 xentoollog_logger_stdiostream *logger;
 int dryrun_only;
+int force_execution;
 int autoballoon = 1;
 char *lockfile;
 char *default_vifscript = NULL;
@@ -126,8 +129,9 @@ int main(int argc, char **argv)
     char *config_file;
     void *config_data = 0;
     int config_len = 0;
+    const char *locks[] = XEND_LOCK;
 
-    while ((opt = getopt(argc, argv, "+vN")) >= 0) {
+    while ((opt = getopt(argc, argv, "+vfN")) >= 0) {
         switch (opt) {
         case 'v':
             if (minmsglevel > 0) minmsglevel--;
@@ -135,6 +139,9 @@ int main(int argc, char **argv)
         case 'N':
             dryrun_only = 1;
             break;
+        case 'f':
+            force_execution = 1;
+            break;
         default:
             fprintf(stderr, "unknown global option\n");
             exit(2);
@@ -185,6 +192,19 @@ int main(int argc, char **argv)
             ret = 1;
             goto xit;
         }
+        if (cspec->modifies && !dryrun_only) {
+            for (int i = 0; i < sizeof(locks)/sizeof(locks[0]); i++) {
+                if (!access(locks[i], F_OK) && !force_execution) {
+                    fprintf(stderr,
+"xend is running, which prevents xl from working correctly.\n"
+"If you still want to force the execution of xl please use the -f\n"
+"option.\n"
+                            );
+                    ret = 1;
+                    goto xit;
+                }
+            }
+        }
         ret = cspec->cmd_impl(argc, argv);
     } else if (!strcmp(cmd, "help")) {
         help(argv[1]);
diff --git a/tools/libxl/xl.h b/tools/libxl/xl.h
index 2b6714af36..5d0d50440f 100644
--- a/tools/libxl/xl.h
+++ b/tools/libxl/xl.h
@@ -21,6 +21,7 @@ struct cmd_spec {
     char *cmd_name;
     int (*cmd_impl)(int argc, char **argv);
     int can_dryrun;
+    int modifies;
     char *cmd_desc;
     char *cmd_usage;
     char *cmd_option;
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index efaf3de047..5fc5cde2d2 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1937,7 +1937,7 @@ void help(const char *command)
     struct cmd_spec *cmd;
 
     if (!command || !strcmp(command, "help")) {
-        printf("Usage xl [-vN] <subcommand> [args]\n\n");
+        printf("Usage xl [-vfN] <subcommand> [args]\n\n");
         printf("xl full list of subcommands:\n\n");
         for (i = 0; i < cmdtable_len; i++) {
             printf(" %-19s ", cmd_table[i].cmd_name);
@@ -1948,7 +1948,8 @@ void help(const char *command)
     } else {
         cmd = cmdtable_lookup(command);
         if (cmd) {
-            printf("Usage: xl [-v%s] %s %s\n\n%s.\n\n",
+            printf("Usage: xl [-v%s%s] %s %s\n\n%s.\n\n",
+                   cmd->modifies ? "f" : "",
                    cmd->can_dryrun ? "N" : "",
                    cmd->cmd_name,
                    cmd->cmd_usage,
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index 2796460fea..9d33707544 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -19,7 +19,7 @@
 
 struct cmd_spec cmd_table[] = {
     { "create",
-      &main_create, 1,
+      &main_create, 1, 1,
       "Create a domain from config file <filename>",
       "<ConfigFile> [options] [vars]",
       "-h                      Print this help.\n"
@@ -33,7 +33,7 @@ struct cmd_spec cmd_table[] = {
       "-e                      Do not wait in the background for the death of the domain."
     },
     { "config-update",
-      &main_config_update, 1,
+      &main_config_update, 1, 1,
       "Update a running domain's saved configuration, used when rebuilding "
       "the domain after reboot",
       "<Domain> <ConfigFile> [options] [vars]",
@@ -42,7 +42,7 @@ struct cmd_spec cmd_table[] = {
       "-d                      Enable debug messages.\n"
     },
     { "list",
-      &main_list, 0,
+      &main_list, 0, 0,
       "List information about all/some domains",
       "[options] [Domain]\n",
       "-l, --long              Output all VM details\n"
@@ -50,12 +50,12 @@ struct cmd_spec cmd_table[] = {
       "-Z, --context           Prints out security context"
     },
     { "destroy",
-      &main_destroy, 0,
+      &main_destroy, 0, 1,
       "Terminate a domain immediately",
       "<Domain>",
     },
     { "shutdown",
-      &main_shutdown, 0,
+      &main_shutdown, 0, 1,
       "Issue a shutdown signal to a domain",
       "[options] <Domain>",
       "-h                      Print this help.\n"
@@ -64,7 +64,7 @@ struct cmd_spec cmd_table[] = {
       "-w                      Wait for guest to shutdown.\n"
     },
     { "reboot",
-      &main_reboot, 0,
+      &main_reboot, 0, 1,
       "Issue a reboot signal to a domain",
       "[options] <Domain>",
       "-h                      Print this help.\n"
@@ -72,44 +72,44 @@ struct cmd_spec cmd_table[] = {
       "                        no PV drivers.\n"
     },
     { "pci-attach",
-      &main_pciattach, 0,
+      &main_pciattach, 0, 1,
       "Insert a new pass-through pci device",
       "<Domain> <BDF> [Virtual Slot]",
     },
     { "pci-detach",
-      &main_pcidetach, 0,
+      &main_pcidetach, 0, 1,
       "Remove a domain's pass-through pci device",
       "<Domain> <BDF>",
     },
     { "pci-list",
-      &main_pcilist, 0,
+      &main_pcilist, 0, 0,
       "List pass-through pci devices for a domain",
       "<Domain>",
     },
     { "pci-list-assignable-devices",
-      &main_pcilist_assignable, 0,
+      &main_pcilist_assignable, 0, 0,
       "List all the assignable pci devices",
       "",
     },
     { "pause",
-      &main_pause, 0,
+      &main_pause, 0, 1,
       "Pause execution of a domain",
       "<Domain>",
     },
     { "unpause",
-      &main_unpause, 0,
+      &main_unpause, 0, 1,
       "Unpause a paused domain",
       "<Domain>",
     },
     { "console",
-      &main_console, 0,
+      &main_console, 0, 0,
       "Attach to domain's console",
       "[options] <Domain>\n"
       "-t <type>       console type, pv or serial\n"
       "-n <number>     console number"
     },
     { "vncviewer",
-      &main_vncviewer, 0,
+      &main_vncviewer, 0, 0,
       "Attach to domain's VNC server.",
       "[options] <Domain>\n"
       "--autopass               Pass VNC password to viewer via stdin and\n"
@@ -117,14 +117,14 @@ struct cmd_spec cmd_table[] = {
       "--vncviewer-autopass     (consistency alias for --autopass)"
     },
     { "save",
-      &main_save, 0,
+      &main_save, 0, 1,
       "Save a domain state to restore later",
       "[options] <Domain> <CheckpointFile> [<ConfigFile>]",
       "-h  Print this help.\n"
       "-c  Leave domain running after creating the snapshot."
     },
     { "migrate",
-      &main_migrate, 0,
+      &main_migrate, 0, 1,
       "Save a domain state to restore later",
       "[options] <Domain> <host>",
       "-h              Print this help.\n"
@@ -136,12 +136,12 @@ struct cmd_spec cmd_table[] = {
       "                of the domain."
     },
     { "dump-core",
-      &main_dump_core, 0,
+      &main_dump_core, 0, 1,
       "Core dump a domain",
       "<Domain> <filename>"
     },
     { "restore",
-      &main_restore, 0,
+      &main_restore, 0, 1,
       "Restore a domain from a saved state",
       "[options] [<ConfigFile>] <CheckpointFile>",
       "-h  Print this help.\n"
@@ -150,68 +150,68 @@ struct cmd_spec cmd_table[] = {
       "-d  Enable debug messages."
     },
     { "migrate-receive",
-      &main_migrate_receive, 0,
+      &main_migrate_receive, 0, 1,
       "Restore a domain from a saved state",
       "- for internal use only",
     },
     { "cd-insert",
-      &main_cd_insert, 0,
+      &main_cd_insert, 0, 1,
       "Insert a cdrom into a guest's cd drive",
       "<Domain> <VirtualDevice> <type:path>",
     },
     { "cd-eject",
-      &main_cd_eject, 0,
+      &main_cd_eject, 0, 1,
       "Eject a cdrom from a guest's cd drive",
       "<Domain> <VirtualDevice>",
     },
     { "mem-max",
-      &main_memmax, 0,
+      &main_memmax, 0, 1,
       "Set the maximum amount reservation for a domain",
       "<Domain> <MemMB['b'[bytes]|'k'[KB]|'m'[MB]|'g'[GB]|'t'[TB]]>",
     },
     { "mem-set",
-      &main_memset, 0,
+      &main_memset, 0, 1,
       "Set the current memory usage for a domain",
       "<Domain> <MemMB['b'[bytes]|'k'[KB]|'m'[MB]|'g'[GB]|'t'[TB]]>",
     },
     { "button-press",
-      &main_button_press, 0,
+      &main_button_press, 0, 1,
       "Indicate an ACPI button press to the domain",
       "<Domain> <Button>",
       "<Button> may be 'power' or 'sleep'."
     },
     { "vcpu-list",
-      &main_vcpulist, 0,
+      &main_vcpulist, 0, 0,
       "List the VCPUs for all/some domains",
       "[Domain, ...]",
     },
     { "vcpu-pin",
-      &main_vcpupin, 0,
+      &main_vcpupin, 0, 1,
       "Set which CPUs a VCPU can use",
       "<Domain> <VCPU|all> <CPUs|all>",
     },
     { "vcpu-set",
-      &main_vcpuset, 0,
+      &main_vcpuset, 0, 1,
       "Set the number of active VCPUs allowed for the domain",
       "<Domain> <vCPUs>",
     },
     { "list-vm",
-      &main_list_vm, 0,
+      &main_list_vm, 0, 0,
       "List the VMs,without DOM0",
       "",
     },
     { "info",
-      &main_info, 0,
+      &main_info, 0, 0,
       "Get information about Xen host",
       "-n, --numa         List host NUMA topology information",
     },
     { "sharing",
-      &main_sharing, 0,
+      &main_sharing, 0, 0,
       "Get information about page sharing",
       "[Domain]", 
     },
     { "sched-credit",
-      &main_sched_credit, 0,
+      &main_sched_credit, 0, 1,
       "Get/set credit scheduler parameters",
       "[-d <Domain> [-w[=WEIGHT]|-c[=CAP]]] [-s [-t TSLICE] [-r RATELIMIT]] [-p CPUPOOL]",
       "-d DOMAIN, --domain=DOMAIN        Domain to modify\n"
@@ -223,7 +223,7 @@ struct cmd_spec cmd_table[] = {
       "-p CPUPOOL, --cpupool=CPUPOOL     Restrict output to CPUPOOL"
     },
     { "sched-credit2",
-      &main_sched_credit2, 0,
+      &main_sched_credit2, 0, 1,
       "Get/set credit2 scheduler parameters",
       "[-d <Domain> [-w[=WEIGHT]]] [-p CPUPOOL]",
       "-d DOMAIN, --domain=DOMAIN     Domain to modify\n"
@@ -231,7 +231,7 @@ struct cmd_spec cmd_table[] = {
       "-p CPUPOOL, --cpupool=CPUPOOL  Restrict output to CPUPOOL"
     },
     { "sched-sedf",
-      &main_sched_sedf, 0,
+      &main_sched_sedf, 0, 1,
       "Get/set sedf scheduler parameters",
       "[options]",
       "-d DOMAIN, --domain=DOMAIN     Domain to modify\n"
@@ -247,103 +247,103 @@ struct cmd_spec cmd_table[] = {
       "-c CPUPOOL, --cpupool=CPUPOOL  Restrict output to CPUPOOL"
     },
     { "domid",
-      &main_domid, 0,
+      &main_domid, 0, 0,
       "Convert a domain name to domain id",
       "<DomainName>",
     },
     { "domname",
-      &main_domname, 0,
+      &main_domname, 0, 0,
       "Convert a domain id to domain name",
       "<DomainId>",
     },
     { "rename",
-      &main_rename, 0,
+      &main_rename, 0, 1,
       "Rename a domain",
       "<Domain> <NewDomainName>",
     },
     { "trigger",
-      &main_trigger, 0,
+      &main_trigger, 0, 1,
       "Send a trigger to a domain",
       "<Domain> <nmi|reset|init|power|sleep|s3resume> [<VCPU>]",
     },
     { "sysrq",
-      &main_sysrq, 0,
+      &main_sysrq, 0, 1,
       "Send a sysrq to a domain",
       "<Domain> <letter>",
     },
     { "debug-keys",
-      &main_debug_keys, 0,
+      &main_debug_keys, 0, 1,
       "Send debug keys to Xen",
       "<Keys>",
     },
     { "dmesg",
-      &main_dmesg, 0,
+      &main_dmesg, 0, 0,
       "Read and/or clear dmesg buffer",
       "[-c]",
       "  -c                        Clear dmesg buffer as well as printing it",
     },
     { "top",
-      &main_top, 0,
+      &main_top, 0, 0,
       "Monitor a host and the domains in real time",
       "",
     },
     { "network-attach",
-      &main_networkattach, 1,
+      &main_networkattach, 1, 1,
       "Create a new virtual network device",
       "<Domain> [type=<type>] [mac=<mac>] [bridge=<bridge>] "
       "[ip=<ip>] [script=<script>] [backend=<BackDomain>] [vifname=<name>] "
       "[rate=<rate>] [model=<model>] [accel=<accel>]",
     },
     { "network-list",
-      &main_networklist, 0,
+      &main_networklist, 0, 0,
       "List virtual network interfaces for a domain",
       "<Domain(s)>",
     },
     { "network-detach",
-      &main_networkdetach, 0,
+      &main_networkdetach, 0, 1,
       "Destroy a domain's virtual network device",
       "<Domain> <DevId|mac>",
     },
     { "block-attach",
-      &main_blockattach, 1,
+      &main_blockattach, 1, 1,
       "Create a new virtual block device",
       "<Domain> <disk-spec-component(s)>...",
     },
     { "block-list",
-      &main_blocklist, 0,
+      &main_blocklist, 0, 0,
       "List virtual block devices for a domain",
       "<Domain(s)>",
     },
     { "block-detach",
-      &main_blockdetach, 0,
+      &main_blockdetach, 0, 1,
       "Destroy a domain's virtual block device",
       "<Domain> <DevId>",
     },
     { "uptime",
-      &main_uptime, 0,
+      &main_uptime, 0, 0,
       "Print uptime for all/some domains",
       "[-s] [Domain]",
     },
     { "tmem-list",
-      &main_tmem_list, 0,
+      &main_tmem_list, 0, 0,
       "List tmem pools",
       "[-l] [<Domain>|-a]",
       "  -l                             List tmem stats",
     },
     { "tmem-freeze",
-      &main_tmem_freeze, 0,
+      &main_tmem_freeze, 0, 1,
       "Freeze tmem pools",
       "[<Domain>|-a]",
       "  -a                             Freeze all tmem",
     },
     { "tmem-thaw",
-      &main_tmem_thaw, 0,
+      &main_tmem_thaw, 0, 1,
       "Thaw tmem pools",
       "[<Domain>|-a]",
       "  -a                             Thaw all tmem",
     },
     { "tmem-set",
-      &main_tmem_set, 0,
+      &main_tmem_set, 0, 1,
       "Change tmem settings",
       "[<Domain>|-a] [-w[=WEIGHT]|-c[=CAP]|-p[=COMPRESS]]",
       "  -a                             Operate on all tmem\n"
@@ -352,7 +352,7 @@ struct cmd_spec cmd_table[] = {
       "  -p COMPRESS                    Compress (int)",
     },
     { "tmem-shared-auth",
-      &main_tmem_shared_auth, 0,
+      &main_tmem_shared_auth, 0, 1,
       "De/authenticate shared tmem pool",
       "[<Domain>|-a] [-u[=UUID] [-A[=AUTH]",
       "  -a                             Authenticate for all tmem pools\n"
@@ -361,12 +361,12 @@ struct cmd_spec cmd_table[] = {
       "  -A AUTH                        0=auth,1=deauth",
     },
     { "tmem-freeable",
-      &main_tmem_freeable, 0,
+      &main_tmem_freeable, 0, 0,
       "Get information about how much freeable memory (MB) is in-use by tmem",
       "",
     },
     { "cpupool-create",
-      &main_cpupoolcreate, 1,
+      &main_cpupoolcreate, 1, 1,
       "Create a new CPU pool",
       "[options] [<ConfigFile>] [Variable=value ...]",
       "-h, --help                   Print this help.\n"
@@ -377,53 +377,53 @@ struct cmd_spec cmd_table[] = {
 
     },
     { "cpupool-list",
-      &main_cpupoollist, 0,
+      &main_cpupoollist, 0, 0,
       "List CPU pools on host",
       "[-c|--cpus] [<CPU Pool>]",
       "-c, --cpus                     Output list of CPUs used by a pool"
     },
     { "cpupool-destroy",
-      &main_cpupooldestroy, 0,
+      &main_cpupooldestroy, 0, 1,
       "Deactivates a CPU pool",
       "<CPU Pool>",
     },
     { "cpupool-rename",
-      &main_cpupoolrename, 0,
+      &main_cpupoolrename, 0, 1,
       "Renames a CPU pool",
       "<CPU Pool> <new name>",
     },
     { "cpupool-cpu-add",
-      &main_cpupoolcpuadd, 0,
+      &main_cpupoolcpuadd, 0, 1,
       "Adds a CPU to a CPU pool",
       "<CPU Pool> <CPU nr>|node:<node nr>",
     },
     { "cpupool-cpu-remove",
-      &main_cpupoolcpuremove, 0,
+      &main_cpupoolcpuremove, 0, 1,
       "Removes a CPU from a CPU pool",
       "<CPU Pool> <CPU nr>|node:<node nr>",
     },
     { "cpupool-migrate",
-      &main_cpupoolmigrate, 0,
+      &main_cpupoolmigrate, 0, 1,
       "Moves a domain into a CPU pool",
       "<Domain> <CPU Pool>",
     },
     { "cpupool-numa-split",
-      &main_cpupoolnumasplit, 0,
+      &main_cpupoolnumasplit, 0, 1,
       "Splits up the machine into one CPU pool per NUMA node",
       "",
     },
     { "getenforce",
-      &main_getenforce, 0,
+      &main_getenforce, 0, 0,
       "Returns the current enforcing mode of the Flask Xen security module",
       "",
     },
     { "setenforce",
-      &main_setenforce, 0,
+      &main_setenforce, 0, 1,
       "Sets the current enforcing mode of the Flask Xen security module",
       "<1|0|Enforcing|Permissive>",
     },
     { "loadpolicy",
-      &main_loadpolicy, 0,
+      &main_loadpolicy, 0, 1,
       "Loads a new policy int the Flask Xen security module",
       "<policy file>",
     },