Date: Sat, 6 Sep 2003 13:28:13 -0400 From: Jonathan Lennox <lennox@cs.columbia.edu> To: FreeBSD-gnats-submit@FreeBSD.org, freebsd-bugs@FreeBSD.org Subject: Re: bin/56500: rpc.lockd needs to use reserved ports Message-ID: <16218.6445.294271.622770@cnr.cs.columbia.edu> In-Reply-To: <200309051730.h85HUDxE019269@freefall.freebsd.org> References: <200309051722.h85HMPbj085465@cnr.cs.columbia.edu> <200309051730.h85HUDxE019269@freefall.freebsd.org>
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After a day or so of untangling how RPC code works, I've worked out a patch. I'm pretty sure that this patch regains root privileges for the absolute minimum amount of time necessary to bind to a reserved port. I've tested this, and it does (along with the patch in kern/56461) allow me to sucessfully lock files from a Linux server -- and thus to invoke movemail on my mailspool, and thus to read my mail on my FreeBSD machine, which was the whole motivation. --- usr.sbin/rpc.lockd/lock_proc.c.orig Sat Sep 6 12:48:10 2003 +++ usr.sbin/rpc.lockd/lock_proc.c Sat Sep 6 13:18:08 2003 @@ -197,6 +197,8 @@ const char *netid; struct netconfig *nconf; char host[NI_MAXHOST]; + uid_t old_euid; + int clnt_fd; gettimeofday(&time_now, NULL); @@ -270,6 +272,22 @@ syslog(LOG_ERR, "Unable to return result to %s", host); return NULL; } + + /* Get the FD of the client, for bindresvport. */ + clnt_control(client, CLGET_FD, &clnt_fd); + + /* Regain root privileges, for bindresvport. */ + old_euid = geteuid(); + seteuid(0); + + /* + * Bind the client FD to a reserved port. + * Some NFS servers reject any NLM request from a non-reserved port. + */ + bindresvport(clnt_fd, NULL); + + /* Drop root privileges again. */ + seteuid(old_euid); /* Success - update the cache entry */ clnt_cache_ptr[clnt_cache_next_to_use] = client;
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