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sanitise characters destined for xauth(1) (#1316529) 

Upstream:
9d47b8d3f5
This commit is contained in:
Jakub Jelen 2016-03-10 13:59:01 +01:00
parent 08f0c1b883
commit 47f126ca0a
2 changed files with 75 additions and 0 deletions
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72
openssh-6.9p1-xauth.patch Normal file
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@ -0,0 +1,72 @@
commit 9d47b8d3f50c3a6282896df8274147e3b9a38c56
Author: Damien Miller <djm@mindrot.org>
Date: Thu Mar 10 05:03:39 2016 +1100
sanitise characters destined for xauth(1)
reported by github.com/tintinweb
diff --git a/session.c b/session.c
index 7a02500..87fddfc 100644
--- a/session.c
+++ b/session.c
@@ -46,6 +46,7 @@
#include <arpa/inet.h>
+#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
@@ -274,6 +275,21 @@ do_authenticated(Authctxt *authctxt)
do_cleanup(authctxt);
}
+/* Check untrusted xauth strings for metacharacters */
+static int
+xauth_valid_string(const char *s)
+{
+ size_t i;
+
+ for (i = 0; s[i] != '\0'; i++) {
+ if (!isalnum((u_char)s[i]) &&
+ s[i] != '.' && s[i] != ':' && s[i] != '/' &&
+ s[i] != '-' && s[i] != '_')
+ return 0;
+ }
+ return 1;
+}
+
/*
* Prepares for an interactive session. This is called after the user has
* been successfully authenticated. During this message exchange, pseudo
@@ -347,7 +363,13 @@ do_authenticated1(Authctxt *authctxt)
s->screen = 0;
}
packet_check_eom();
- success = session_setup_x11fwd(s);
+ if (xauth_valid_string(s->auth_proto) &&
+ xauth_valid_string(s->auth_data))
+ success = session_setup_x11fwd(s);
+ else {
+ success = 0;
+ error("Invalid X11 forwarding data");
+ }
if (!success) {
free(s->auth_proto);
free(s->auth_data);
@@ -2178,7 +2200,13 @@ session_x11_req(Session *s)
s->screen = packet_get_int();
packet_check_eom();
- success = session_setup_x11fwd(s);
+ if (xauth_valid_string(s->auth_proto) &&
+ xauth_valid_string(s->auth_data))
+ success = session_setup_x11fwd(s);
+ else {
+ success = 0;
+ error("Invalid X11 forwarding data");
+ }
if (!success) {
free(s->auth_proto);
free(s->auth_data);

3
openssh.spec
View File

@ -240,6 +240,8 @@ Patch934: openssh-6.9p1-gssKexAlgorithms.patch
# CVE-2016-0777 OpenSSH: Client Information leak due to use of roaming connection feature
# Fix an out of-bound read access in the packet handling code
Patch935: openssh-6.9p1-security-7.1.patch
# Fix for security issue (openssh-7.2p2): sanitise characters destined for xauth(1)
Patch936: openssh-6.9p1-xauth.patch
License: BSD
@ -468,6 +470,7 @@ popd
%patch933 -p1 -b .fingerprint
%patch934 -p1 -b .gsskexalg
%patch935 -p1 -b .security71
%patch936 -p1 -b .xauth
%patch200 -p1 -b .audit
%patch700 -p1 -b .fips