[Midnightbsd-cvs] src [9392] trunk/usr.sbin/gssd/gssd.c: Fix the getpwuid_r() call in the gssd daemon so that it handles

[laffer1 at midnightbsd.org]

Revision: 9392
          http://svnweb.midnightbsd.org/src/?rev=9392
Author:   laffer1
Date:     2017-03-04 16:26:28 -0500 (Sat, 04 Mar 2017)
Log Message:
-----------
Fix the getpwuid_r() call in the gssd daemon so that it handles
the ERANGE error return case. Without this fix, authentication
of users for certain system setups could fail unexpectedly.

Modified Paths:
--------------
    trunk/usr.sbin/gssd/gssd.c

Modified: trunk/usr.sbin/gssd/gssd.c
===================================================================
--- trunk/usr.sbin/gssd/gssd.c	2017-03-04 21:26:01 UTC (rev 9391)
+++ trunk/usr.sbin/gssd/gssd.c	2017-03-04 21:26:28 UTC (rev 9392)
@@ -37,6 +37,7 @@
 #include <ctype.h>
 #include <dirent.h>
 #include <err.h>
+#include <errno.h>
 #ifndef WITHOUT_KERBEROS
 #include <krb5.h>
 #endif
@@ -557,8 +558,11 @@
 {
 	gss_name_t name = gssd_find_resource(argp->pname);
 	uid_t uid;
-	char buf[128];
+	char buf[1024], *bufp;
 	struct passwd pwd, *pw;
+	size_t buflen;
+	int error;
+	static size_t buflen_hint = 1024;
 
 	memset(result, 0, sizeof(*result));
 	if (name) {
@@ -567,7 +571,24 @@
 			    name, argp->mech, &uid);
 		if (result->major_status == GSS_S_COMPLETE) {
 			result->uid = uid;
-			getpwuid_r(uid, &pwd, buf, sizeof(buf), &pw);
+			buflen = buflen_hint;
+			for (;;) {
+				pw = NULL;
+				bufp = buf;
+				if (buflen > sizeof(buf))
+					bufp = malloc(buflen);
+				if (bufp == NULL)
+					break;
+				error = getpwuid_r(uid, &pwd, bufp, buflen,
+				    &pw);
+				if (error != ERANGE)
+					break;
+				if (buflen > sizeof(buf))
+					free(bufp);
+				buflen += 1024;
+				if (buflen > buflen_hint)
+					buflen_hint = buflen;
+			}
 			if (pw) {
 				int len = NGRPS;
 				int groups[NGRPS];
@@ -584,6 +605,8 @@
 				result->gidlist.gidlist_len = 0;
 				result->gidlist.gidlist_val = NULL;
 			}
+			if (bufp != NULL && buflen > sizeof(buf))
+				free(bufp);
 		}
 	} else {
 		result->major_status = GSS_S_BAD_NAME;