Avoid using HOST_NAME_MAX directly and use sysconf(_SC_HOST_NAME_MAX)

instead.

MANIFEST

@@ -91,6 +91,7 @@ lib/util/fnmatch.c
 lib/util/getaddrinfo.c
 lib/util/getcwd.c
 lib/util/getgrouplist.c
+lib/util/gethostname.c
 lib/util/getline.c
 lib/util/getopt_long.c
 lib/util/gidlist.c

config.h.in

@@ -97,10 +97,6 @@
    don't. */
 #undef HAVE_DECL_GETRESUID
 
-/* Define to 1 if you have the declaration of `HOST_NAME_MAX', and to 0 if you
-   don't. */
-#undef HAVE_DECL_HOST_NAME_MAX
-
 /* Define to 1 if you have the declaration of `h_errno', and to 0 if you
    don't. */
 #undef HAVE_DECL_H_ERRNO
@@ -173,10 +169,6 @@
    don't. */
 #undef HAVE_DECL__INNETGR
 
-/* Define to 1 if you have the declaration of `_POSIX_HOST_NAME_MAX', and to 0
-   if you don't. */
-#undef HAVE_DECL__POSIX_HOST_NAME_MAX
-
 /* Define to 1 if you have the declaration of `_POSIX_PATH_MAX', and to 0 if
    you don't. */
 #undef HAVE_DECL__POSIX_PATH_MAX

configure

@@ -21337,20 +21337,6 @@ fi
 cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_PATH_MAX $ac_have_decl
 _ACEOF
-ac_fn_c_check_decl "$LINENO" "HOST_NAME_MAX" "ac_cv_have_decl_HOST_NAME_MAX" "
-#include <sys/types.h>
-#include <limits.h>
-
-"
-if test "x$ac_cv_have_decl_HOST_NAME_MAX" = xyes; then :
-  ac_have_decl=1
-else
-  ac_have_decl=0
-fi
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_DECL_HOST_NAME_MAX $ac_have_decl
-_ACEOF
 
 ac_fn_c_check_decl "$LINENO" "SIZE_MAX" "ac_cv_have_decl_SIZE_MAX" "
 #include <sys/types.h>
@@ -21457,23 +21443,6 @@ cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL__POSIX_PATH_MAX $ac_have_decl
 _ACEOF
 
-fi
-if test "$ac_cv_have_decl_HOST_NAME_MAX" != "yes"; then
-    ac_fn_c_check_decl "$LINENO" "_POSIX_HOST_NAME_MAX" "ac_cv_have_decl__POSIX_HOST_NAME_MAX" "
-#include <sys/types.h>
-#include <limits.h>
-
-"
-if test "x$ac_cv_have_decl__POSIX_HOST_NAME_MAX" = xyes; then :
-  ac_have_decl=1
-else
-  ac_have_decl=0
-fi
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_DECL__POSIX_HOST_NAME_MAX $ac_have_decl
-_ACEOF
-
 fi
 
 for ac_func in strsignal

configure.ac

@@ -3010,7 +3010,7 @@ dnl We need to add OSDEFS to CFLAGS to expose LLONG_MAX et al on glibc.
 dnl
 _CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS $OSDEFS"
-AC_CHECK_DECLS([LLONG_MAX, LLONG_MIN, ULLONG_MAX, PATH_MAX, HOST_NAME_MAX], [], [], [
+AC_CHECK_DECLS([LLONG_MAX, LLONG_MIN, ULLONG_MAX, PATH_MAX], [], [], [
 #include <sys/types.h>
 #include <limits.h>
 ])
@@ -3057,12 +3057,6 @@ if test "$ac_cv_have_decl_PATH_MAX" != "yes"; then
 #include <limits.h>
     ]])
 fi
-if test "$ac_cv_have_decl_HOST_NAME_MAX" != "yes"; then
-    AC_CHECK_DECLS([_POSIX_HOST_NAME_MAX], [], [], [[
-#include <sys/types.h>
-#include <limits.h>
-    ]])
-fi
 
 dnl
 dnl Check for strsignal() or sys_siglist

include/sudo_compat.h

@@ -160,14 +160,6 @@
 # endif
 #endif
 
-#if defined(HAVE_DECL_HOST_NAME_MAX) && !HAVE_DECL_HOST_NAME_MAX
-# if defined(HAVE_DECL__POSIX_HOST_NAME_MAX) && HAVE_DECL__POSIX_HOST_NAME_MAX
-#  define HOST_NAME_MAX		_POSIX_HOST_NAME_MAX
-# else
-#  define HOST_NAME_MAX		255
-# endif
-#endif
-
 /*
  * Posix versions for those without...
  */

include/sudo_util.h

@@ -144,6 +144,10 @@ __dso_public int aix_restoreauthdb_v1(void);
 __dso_public int aix_setauthdb_v1(char *user);
 #define aix_setauthdb(_a) aix_setauthdb_v1((_a))
 
+/* gethostname.c */
+__dso_public char *sudo_gethostname_v1(void);
+#define sudo_gethostname() sudo_gethostname_v1()
+
 /* gidlist.c */
 __dso_public int sudo_parse_gids_v1(const char *gidstr, const gid_t *basegid, GETGROUPS_T **gidsp);
 #define sudo_parse_gids(_a, _b, _c) sudo_parse_gids_v1((_a), (_b), (_c))

lib/util/Makefile.in

@@ -96,8 +96,8 @@ DEVEL = @DEVEL@
 
 SHELL = @SHELL@
 
-LTOBJS = alloc.lo event.lo fatal.lo key_val.lo gidlist.lo lbuf.lo \
-	 locking.lo parseln.lo progname.lo secure_path.lo setgroups.lo \
+LTOBJS = alloc.lo event.lo fatal.lo key_val.lo gethostname.lo gidlist.lo \
+	 lbuf.lo locking.lo parseln.lo progname.lo secure_path.lo setgroups.lo \
 	 strtobool.lo strtoid.lo strtomode.lo sudo_conf.lo sudo_debug.lo \
 	 sudo_dso.lo term.lo ttysize.lo @COMMON_OBJS@ @LTLIBOBJS@
 
@@ -361,6 +361,10 @@ getgrouplist.lo: $(srcdir)/getgrouplist.c $(incdir)/compat/nss_dbdefs.h \
                  $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \
                  $(incdir)/sudo_util.h $(top_builddir)/config.h
 	$(LIBTOOL) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(DEFS) $(srcdir)/getgrouplist.c
+gethostname.lo: $(srcdir)/gethostname.c $(incdir)/compat/stdbool.h \
+                $(incdir)/sudo_compat.h $(incdir)/sudo_util.h \
+                $(top_builddir)/config.h
+	$(LIBTOOL) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(DEFS) $(srcdir)/gethostname.c
 getline.lo: $(srcdir)/getline.c $(incdir)/sudo_compat.h $(top_builddir)/config.h
 	$(LIBTOOL) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(DEFS) $(srcdir)/getline.c
 getopt_long.lo: $(srcdir)/getopt_long.c $(incdir)/compat/getopt.h \

lib/util/gethostname.c

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2015 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#if defined(HAVE_MALLOC_H) && !defined(STDC_HEADERS)
+# include <malloc.h>
+#endif /* HAVE_MALLOC_H && !STDC_HEADERS */
+#include <unistd.h>
+
+#include "sudo_compat.h"
+#include "sudo_util.h"
+
+/*
+ * Return a malloc()ed copy of the system hostname, or NULL if 
+ * malloc() or gethostname() fails.
+ */
+char *
+sudo_gethostname_v1(void)
+{
+    char *hname;
+    size_t host_name_max;
+
+#ifdef _SC_HOST_NAME_MAX
+    host_name_max = (size_t)sysconf(_SC_HOST_NAME_MAX);
+    if (host_name_max == (size_t)-1)
+#endif
+	host_name_max = 255;	/* POSIX and historic BSD */
+
+    hname = malloc(host_name_max + 1);
+    if (hname != NULL) {
+	if (gethostname(hname, host_name_max + 1) == 0) {
+	    /* Old gethostname() may not NUL-terminate if there is no room. */
+	    hname[host_name_max] = '\0';
+	} else {
+	    free(hname);
+	    hname = NULL;
+	}
+    }
+    return hname;
+}

lib/util/util.exp.in

@@ -65,6 +65,7 @@ sudo_fatal_callback_register_v1
 sudo_fatal_nodebug_v1
 sudo_fatalx_nodebug_v1
 sudo_get_ttysize_v1
+sudo_gethostname_v1
 sudo_lbuf_append_quoted_v1
 sudo_lbuf_append_v1
 sudo_lbuf_destroy_v1

plugins/sudoers/match.c

@@ -911,40 +911,57 @@ done:
 /*
  * Get NIS-style domain name and copy from static storage or NULL if none.
  */
+#if defined(HAVE_GETDOMAINNAME) || defined(SI_SRPC_DOMAIN)
 const char *
 sudo_getdomainname(void)
 {
-    char *domain = NULL;
-#if defined(HAVE_GETDOMAINNAME) || defined(SI_SRPC_DOMAIN)
-    static char buf[HOST_NAME_MAX + 1];
+    static char *domain;
     static bool initialized;
+    debug_decl(sudo_getdomainname, SUDOERS_DEBUG_MATCH)
 
     if (!initialized) {
+	size_t host_name_max;
 	int rval;
 
-# ifdef SI_SRPC_DOMAIN
-	buf[0] = '\0';
-	rval = sysinfo(SI_SRPC_DOMAIN, buf, sizeof(buf));
-# else
-	rval = getdomainname(buf, sizeof(buf));
+# ifdef _SC_HOST_NAME_MAX
+	host_name_max = (size_t)sysconf(_SC_HOST_NAME_MAX);
+	if (host_name_max == (size_t)-1)
 # endif
-	if (rval != -1 && buf[0] != '\0') {
-	    char *cp;
+	    host_name_max = 255;    /* POSIX and historic BSD */
 
-	    domain = buf;
-	    for (cp = buf; *cp != '\0'; cp++) {
+	domain = malloc(host_name_max + 1);
+	if (domain != NULL) {
+# ifdef SI_SRPC_DOMAIN
+	    domain[0] = '\0';
+	    rval = sysinfo(SI_SRPC_DOMAIN, domain, host_name_max + 1);
+# else
+	    rval = getdomainname(domain, host_name_max + 1);
+# endif
+	    if (rval != -1 && domain[0] != '\0') {
+		const char *cp;
+
+		for (cp = domain; *cp != '\0'; cp++) {
 		    /* Check for illegal characters, Linux may use "(none)". */
 		    if (*cp == '(' || *cp == ')' || *cp == ',' || *cp == ' ') {
+			sudo_efree(domain);
 			domain = NULL;
 			break;
 		    }
 		}
 	    }
+	}
 	initialized = true;
     }
-#endif /* HAVE_GETDOMAINNAME || SI_SRPC_DOMAIN */
-    return domain;
+    debug_return_str(domain);
 }
+#else
+const char *
+sudo_getdomainname(void)
+{
+    debug_decl(sudo_getdomainname, SUDOERS_DEBUG_MATCH)
+    debug_return_ptr(NULL);
+}
+#endif /* HAVE_GETDOMAINNAME || SI_SRPC_DOMAIN */
 
 /*
  * Returns true if "host" and "user" belong to the netgroup "netgr",

plugins/sudoers/testsudoers.c

@@ -119,7 +119,6 @@ main(int argc, char *argv[])
     struct privilege *priv;
     struct userspec *us;
     char *p, *grfile, *pwfile;
-    char hbuf[HOST_NAME_MAX + 1];
     const char *errstr;
     int match, host_match, runas_match, cmnd_match;
     int ch, dflag, exitcode = 0;
@@ -212,10 +211,8 @@ main(int argc, char *argv[])
 	sudo_fatalx(U_("unknown user: %s"), user_name);
 
     if (user_host == NULL) {
-	if (gethostname(hbuf, sizeof(hbuf)) != 0)
+	if ((user_host = sudo_gethostname()) == NULL)
 	    sudo_fatal("gethostname");
-	hbuf[sizeof(hbuf) - 1] = '\0';
-	user_host = hbuf;
     }
     if ((p = strchr(user_host, '.'))) {
 	*p = '\0';

plugins/sudoers/visudo.c

@@ -1062,13 +1062,10 @@ get_args(char *cmnd)
 static void
 get_hostname(void)
 {
-    char *p, thost[HOST_NAME_MAX + 1];
+    char *p;
     debug_decl(get_hostname, SUDOERS_DEBUG_UTIL)
 
-    if (gethostname(thost, sizeof(thost)) != -1) {
-	thost[sizeof(thost) - 1] = '\0';
-	user_host = sudo_estrdup(thost);
-
+    if ((user_host = sudo_gethostname()) != NULL) {
 	if ((p = strchr(user_host, '.'))) {
 	    *p = '\0';
 	    user_shost = sudo_estrdup(user_host);

src/sudo.c

@@ -447,7 +447,7 @@ get_user_groups(struct user_details *ud)
 static char **
 get_user_info(struct user_details *ud)
 {
-    char *cp, **user_info, cwd[PATH_MAX], host[HOST_NAME_MAX + 1];
+    char *cp, **user_info, cwd[PATH_MAX];
     struct passwd *pw;
     int fd, i = 0;
     debug_decl(get_user_info, SUDO_DEBUG_UTIL)
@@ -515,14 +515,12 @@ get_user_info(struct user_details *ud)
 	sudo_efree(cp);
     }
 
-    if (gethostname(host, sizeof(host)) == 0)
-	host[sizeof(host) - 1] = '\0';
-    else
-	strlcpy(host, "localhost", sizeof(host));
-    user_info[++i] = sudo_new_key_val("host", host);
+    cp = sudo_gethostname();
+    user_info[++i] = sudo_new_key_val("host", cp ? cp : "localhost");
     if (user_info[i] == NULL)
 	sudo_fatal(NULL);
     ud->host = user_info[i] + sizeof("host=") - 1;
+    sudo_efree(cp);
 
     sudo_get_ttysize(&ud->ts_lines, &ud->ts_cols);
     sudo_easprintf(&user_info[++i], "lines=%d", ud->ts_lines);