Synopsis: buffer overrun in libkrb, untrusted environment variables in telnetd
NetBSD versions: 1.5
Thanks to: Jouko Pynnönen <jouko@solutions.fi>, Assar Westerlund <assar@netbsd.org>
Index: crypto/dist/krb4/lib/krb/extra.c
===================================================================
RCS file: /cvsroot/basesrc/crypto/dist/krb4/lib/krb/extra.c,v
retrieving revision 1.1.1.1
retrieving revision 1.1.1.1.2.1
diff -u -u -r1.1.1.1 -r1.1.1.1.2.1
--- crypto/dist/krb4/lib/krb/extra.c 2000/06/16 18:45:52 1.1.1.1
+++ crypto/dist/krb4/lib/krb/extra.c 2000/12/12 21:57:00 1.1.1.1.2.1
@@ -70,30 +70,6 @@
#ifndef WIN32
-struct obsolete {
- const char *from;
- const char *to;
-} obsolete [] = {
- { "KDC_TIMESYNC", "kdc_timesync" },
- { "KRB_REVERSE_DIRECTION", "reverse_lsb_test"},
- { "krb4_proxy", "krb4_proxy"},
- { NULL, NULL }
-};
-
-static void
-check_obsolete(void)
-{
- struct obsolete *r;
- for(r = obsolete; r->from; r++) {
- if(getenv(r->from)) {
- krb_warning("The environment variable `%s' is obsolete;\n"
- "set `%s' in your `krb.extra' file instead\n",
- r->from, r->to);
- define_variable(r->to, getenv(r->from));
- }
- }
-}
-
static int
read_extra_file(void)
{
@@ -103,7 +79,6 @@
if(_krb_extra_read)
return 0;
_krb_extra_read = 1;
- check_obsolete();
while(krb_get_krbextra(i++, file, sizeof(file)) == 0) {
FILE *f = fopen(file, "r");
if(f == NULL)
Index: crypto/dist/krb4/lib/krb/kdc_reply.c
===================================================================
RCS file: /cvsroot/basesrc/crypto/dist/krb4/lib/krb/kdc_reply.c,v
retrieving revision 1.1.1.1
retrieving revision 1.1.1.1.2.1
diff -u -u -r1.1.1.1 -r1.1.1.1.2.1
--- crypto/dist/krb4/lib/krb/kdc_reply.c 2000/06/16 18:45:53 1.1.1.1
+++ crypto/dist/krb4/lib/krb/kdc_reply.c 2000/12/12 21:56:37 1.1.1.1.2.1
@@ -121,6 +121,9 @@
p += krb_get_int(p, &exp_date, 4, little_endian);
p++; /* master key version number */
p += krb_get_int(p, &clen, 2, little_endian);
+ if (reply->length - (p - reply->dat) < clen)
+ return INTK_PROT;
+
cip->length = clen;
memcpy(cip->dat, p, clen);
p += clen;
Index: crypto/dist/krb4/lib/krb/tf_util.c
===================================================================
RCS file: /cvsroot/basesrc/crypto/dist/krb4/lib/krb/tf_util.c,v
retrieving revision 1.1.1.1
retrieving revision 1.1.1.1.2.1
diff -u -u -r1.1.1.1 -r1.1.1.1.2.1
--- crypto/dist/krb4/lib/krb/tf_util.c 2000/06/16 18:45:56 1.1.1.1
+++ crypto/dist/krb4/lib/krb/tf_util.c 2000/12/12 21:56:15 1.1.1.1.2.1
@@ -249,20 +249,6 @@
int
tf_create(char *tf_name)
{
- struct stat statbuf;
- char garbage[BUFSIZ];
-
- fd = open(tf_name, O_RDWR | O_BINARY, 0);
- if (fd >= 0) {
- if (fstat (fd, &statbuf) == 0) {
- int i;
-
- for (i = 0; i < statbuf.st_size; i += sizeof(garbage))
- write (fd, garbage, sizeof(garbage));
- }
- close (fd);
- }
-
if (unlink (tf_name) && errno != ENOENT)
return TKT_FIL_ACC;
Index: libexec/telnetd/sys_term.c
===================================================================
RCS file: /cvsroot/basesrc/libexec/telnetd/sys_term.c,v
retrieving revision 1.18
retrieving revision 1.18.4.2
diff -u -u -r1.18 -r1.18.4.2
--- libexec/telnetd/sys_term.c 1999/12/31 12:42:35 1.18
+++ libexec/telnetd/sys_term.c 2000/12/15 00:37:19 1.18.4.2
@@ -1881,22 +1881,50 @@
/*
* scrub_env()
*
- * Remove a few things from the environment that
- * don't need to be there.
+ * We only accept the environment variables listed below.
*/
+
void
scrub_env()
{
- register char **cpp, **cpp2;
+ static const char *reject[] = {
+ "TERMCAP=/",
+ NULL
+ };
+
+ static const char *accept[] = {
+ "XAUTH=", "XAUTHORITY=", "DISPLAY=",
+ "TERM=",
+ "EDITOR=",
+ "PAGER=",
+ "LOGNAME=",
+ "POSIXLY_CORRECT=",
+ "TERMCAP=",
+ "PRINTER=",
+ NULL
+ };
+
+ char **cpp, **cpp2;
+ const char **p;
for (cpp2 = cpp = environ; *cpp; cpp++) {
- if (strncmp(*cpp, "LD_", 3) &&
- strncmp(*cpp, "_RLD_", 5) &&
- strncmp(*cpp, "LIBPATH=", 8) &&
- strncmp(*cpp, "IFS=", 4))
+ int reject_it = 0;
+
+ for(p = reject; *p; p++)
+ if(strncmp(*cpp, *p, strlen(*p)) == 0) {
+ reject_it = 1;
+ break;
+ }
+ if (reject_it)
+ continue;
+
+ for(p = accept; *p; p++)
+ if(strncmp(*cpp, *p, strlen(*p)) == 0)
+ break;
+ if(*p != NULL)
*cpp2++ = *cpp;
}
- *cpp2 = 0;
+ *cpp2 = NULL;
}
/*