From b5b794b165956a7d213b04e51b06597b7b1f8bee Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 14 Jan 2010 12:23:27 -0500 Subject: [PATCH] statd: add IPv6 support in sm_notify_1_svc() We have all the pieces in place, so update sm_notify_1_svc() to handle SM_NOTIFY requests sent from IPv6 remotes. This also eliminates a memory leak: the strdup'd memory containing the callers' presentation address was never freed. Signed-off-by: Chuck Lever --- utils/statd/callback.c | 69 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 62 insertions(+), 7 deletions(-) diff --git a/utils/statd/callback.c b/utils/statd/callback.c index b1acd15..d1cc139 100644 --- a/utils/statd/callback.c +++ b/utils/statd/callback.c @@ -10,7 +10,7 @@ #include #endif -#include +#include #include "rpcmisc.h" #include "statd.h" @@ -20,19 +20,69 @@ /* notify_list *cbnl = NULL; ... never used */ -/* +/* * Services SM_NOTIFY requests. - * Any clients that have asked us to monitor that host are put on - * the global callback list, which is processed as soon as statd - * returns to svc_run. + * + * When NLM uses an SM_MON request to tell statd to monitor a remote, + * the request contains a "mon_name" argument. This is usually the + * "caller_name" argument of an NLMPROC_LOCK request. On Linux, the + * NLM can send statd the remote's IP address instead of its + * caller_name. The NSM protocol does not allow both the remote's + * caller_name and it's IP address to be sent in the same SM_MON + * request. + * + * The remote's caller_name is useful because it makes it simple + * to identify rebooting remotes by matching the "mon_name" argument + * they sent via an SM_NOTIFY request. + * + * The caller_name string may not be a fully qualified domain name, + * or even registered in the DNS database, however. Having the + * remote's IP address is useful because then there is no ambiguity + * about where to send an SM_NOTIFY after the local system reboots. + * + * Without the actual caller_name, however, statd must use an + * heuristic to match an incoming SM_NOTIFY request to one of the + * hosts it is currently monitoring. The incoming mon_name in an + * SM_NOTIFY address is converted to a list of IP addresses using + * DNS. Each mon_name on statd's monitor list is also converted to + * an address list, and the two lists are checked to see if there is + * a matching address. + * + * There are some risks to this strategy: + * + * 1. The external DNS database is not reliable. It can change + * over time, or the forward and reverse mappings could be + * inconsistent. + * + * 2. If statd's monitor list becomes substantial, finding a match + * can generate a not inconsequential amount of DNS traffic. + * + * 3. statd is a single-threaded service. When DNS becomes slow or + * unresponsive, statd also becomes slow or unresponsive. + * + * 4. If the remote does not have a DNS entry at all (or if the + * remote can resolve itself, but the local host can't resolve + * the remote's hostname), the remote cannot be monitored, and + * therefore NLM locking cannot be provided for that host. + * + * 5. Local DNS resolution can produce different results for the + * mon_name than the results the remote might see for the same + * query, especially if the remote did not send a caller_name + * or mon_name that is a fully qualified domain name. + * + * Note that a caller_name is passed from NFS client to server, + * but the client never knows what mon_name the server might use + * to notify it of a reboot. On Linux, the client extracts the + * server's name from the devname it was passed by the mount + * command. This is often not a fully-qualified domain name. */ void * sm_notify_1_svc(struct stat_chge *argp, struct svc_req *rqstp) { notify_list *lp, *call; static char *result = NULL; - struct sockaddr_in *sin = nfs_getrpccaller_in(rqstp->rq_xprt); - char *ip_addr = xstrdup(inet_ntoa(sin->sin_addr)); + struct sockaddr *sap = nfs_getrpccaller(rqstp->rq_xprt); + char ip_addr[INET6_ADDRSTRLEN]; xlog(D_CALL, "Received SM_NOTIFY from %s, state: %d", argp->mon_name, argp->state); @@ -44,6 +94,11 @@ sm_notify_1_svc(struct stat_chge *argp, struct svc_req *rqstp) return ((void *) &result); } + if (!statd_present_address(sap, ip_addr, sizeof(ip_addr))) { + xlog_warn("Unrecognized sender address"); + return ((void *) &result); + } + /* okir change: statd doesn't remove the remote host from its * internal monitor list when receiving an SM_NOTIFY call from * it. Lockd will want to continue monitoring the remote host -- 2.39.5