sm-notify: Use my_name when sending SM_NOTIFY requests

The mon_name argument of an SM_NOTIFY request is a string that
identifies the rebooting host.

sm-notify should send the my_name provided by the local lockd at the
time the remote was monitored, rather than cocking up a mon_name
argument based on the present return value of gethostname(3).  If the
local system's hostname happened to change after the last reboot, then
the string returned by gethostname(3) will not be recognized by the
remote.  Thus the remote will never initiate lock recovery for the
original named host, possibly leaving stale locks.

The existing behavior of using the -v command line option as the
mon_name argument is preserved, but we now prevent sending an IP
presentation address, as some non-Linux implementations don't
recognize addresses as valid mon_names.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
index 3259a3e973d774de310f93065fcc1c867a026124..2d146687f706dca0a8cc70dc38ebd80405ddcdac 100644 (file)
--- a/utils/statd/sm-notify.c
+++ b/utils/statd/sm-notify.c
@@ -54,7 +54,7 @@ struct nsm_host {
        uint32_t                xid;
 };
 
-static char            nsm_hostname[256];
+static char            nsm_hostname[SM_MAXSTRLEN + 1];
 static int             nsm_state;
 static int             nsm_family = AF_INET;
 static int             opt_debug = 0;
@@ -412,12 +412,33 @@ usage:            fprintf(stderr,
                }
        }
 
-       if (opt_srcaddr) {
-               strncpy(nsm_hostname, opt_srcaddr, sizeof(nsm_hostname)-1);
-       } else
-       if (gethostname(nsm_hostname, sizeof(nsm_hostname)) < 0) {
-               xlog(L_ERROR, "Failed to obtain name of local host: %m");
-               exit(1);
+       if (opt_srcaddr != NULL) {
+               struct addrinfo *ai = NULL;
+               struct addrinfo hint = {
+                       .ai_family      = AF_UNSPEC,
+                       .ai_flags       = AI_NUMERICHOST,
+               };
+
+               if (getaddrinfo(opt_srcaddr, NULL, &hint, &ai))
+                       /* not a presentation address - use it */
+                       strncpy(nsm_hostname, opt_srcaddr, sizeof(nsm_hostname));
+               else {
+                       /* was a presentation address - look it up in
+                        * /etc/hosts, so it can be used for my_name */
+                       int error;
+
+                       freeaddrinfo(ai);
+                       hint.ai_flags = AI_CANONNAME;
+                       error = getaddrinfo(opt_srcaddr, NULL, &hint, &ai);
+                       if (error != 0) {
+                               xlog(L_ERROR, "Bind address %s is unusable: %s",
+                                               opt_srcaddr, gai_strerror(error));
+                               exit(1);
+                       }
+                       strncpy(nsm_hostname, ai->ai_canonname,
+                                                       sizeof(nsm_hostname));
+                       freeaddrinfo(ai);
+               }
        }
 
        (void)nsm_retire_monitored_hosts();
@@ -535,6 +556,8 @@ notify(const int sock)
 static int
 notify_host(int sock, struct nsm_host *host)
 {
+       const char *my_name = (opt_srcaddr != NULL ?
+                                       nsm_hostname : host->my_name);
        struct sockaddr *sap;
        socklen_t salen;
 
@@ -580,8 +603,8 @@ notify_host(int sock, struct nsm_host *host)
                host->xid = nsm_xmit_rpcbind(sock, sap, SM_PROG, SM_VERS);
        else
                host->xid = nsm_xmit_notify(sock, sap, salen,
-                               SM_PROG, nsm_hostname, nsm_state);
-       
+                                       SM_PROG, my_name, nsm_state);
+
        return 0;
 }
 

diff --git a/utils/statd/sm-notify.man b/utils/statd/sm-notify.man
index 163713ebe5963f7af0d7dc2cff0020f958e43f18..7a1cbfae998f0ed517368e250e377d3d00c709b2 100644 (file)
--- a/utils/statd/sm-notify.man
+++ b/utils/statd/sm-notify.man
@@ -97,11 +97,9 @@ It uses the
 string as the destination.
 To identify which host has rebooted, the
 .B sm-notify
-command normally sends the results of
-.BR gethostname (3)
-as the
+command normally sends
 .I my_name
-string.
+string recorded when that remote was monitored.
 The remote
 .B rpc.statd
 matches incoming SM_NOTIFY requests using this string,
@@ -202,15 +200,22 @@ argument to use when sending SM_NOTIFY requests.
 If this option is not specified,
 .B sm-notify
 uses a wildcard address as the transport bind address,
-and uses the results of
-.BR gethostname (3)
-as the
+and uses the
+.I my_name
+recorded when the remote was monitored as the
 .I mon_name
-argument.
+argument when sending SM_NOTIFY requests.
 .IP
 The
 .I ipaddr
 form can be expressed as either an IPv4 or an IPv6 presentation address.
+If the
+.I ipaddr
+form is used, the
+.B sm-notify
+command converts this address to a hostname for use as the
+.I mon_name
+argument when sending SM_NOTIFY requests.
 .IP
 This option can be useful in multi-homed configurations where
 the remote requires notification from a specific network address.
@@ -252,13 +257,6 @@ consistent
 The hostname the client uses to mount the server should match the server's
 .I mon_name
 in SM_NOTIFY requests it sends
-.IP
-The use of network addresses as a
-.I mon_name
-or a
-.I my_name
-string should be avoided when
-interoperating with non-Linux NFS implementations.
 .PP
 Unmounting an NFS file system does not necessarily stop
 either the NFS client or server from monitoring each other.

diff --git a/utils/statd/statd.man b/utils/statd/statd.man
index ffc5e950990c5f7f0b7c1c0b9d06199aed030a41..ca00e24af6ede8cc68aca9c17aea27528aea54d2 100644 (file)
--- a/utils/statd/statd.man
+++ b/utils/statd/statd.man
@@ -100,11 +100,9 @@ It uses the
 string as the destination.
 To identify which host has rebooted, the
 .B sm-notify
-command normally sends the results of
-.BR gethostname (3)
-as the
+command sends the
 .I my_name
-string.
+string recorded when that remote was monitored.
 The remote
 .B rpc.statd
 matches incoming SM_NOTIFY requests using this string,
@@ -292,7 +290,6 @@ man pages.
 .SH ADDITIONAL NOTES
 Lock recovery after a reboot is critical to maintaining data integrity
 and preventing unnecessary application hangs.
-.PP
 To help
 .B rpc.statd
 match SM_NOTIFY requests to NLM requests, a number of best practices
@@ -309,13 +306,6 @@ consistent
 The hostname the client uses to mount the server should match the server's
 .I mon_name
 in SM_NOTIFY requests it sends
-.IP
-The use of network addresses as a
-.I mon_name
-or a
-.I my_name
-string should be avoided when
-interoperating with non-Linux NFS implementations.
 .PP
 Unmounting an NFS file system does not necessarily stop
 either the NFS client or server from monitoring each other.