openssh: add backported security fix patches

Fixes a critical security bug allowing remote code execution as root:
<https://www.openssh.com/txt/release-9.8>

This may be CVE-2024-6387 (currently embargoed):
<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-6387>

Thanks to upstream and Sam James <[email protected]> for the backport:
<gentoo/gentoo@1633ef4>

pkgs/tools/networking/openssh/default.nix

@@ -12,7 +12,11 @@ in
       hash = "sha256-SQQm92bYKidj/KzY2D6j1weYdQx70q/y5X3FZg93P/0=";
     };
 
-    extraPatches = [ ./ssh-keysign-8.5.patch ];
+    extraPatches = [
+      ./ssh-keysign-8.5.patch
+      ./openssh-9.6_p1-CVE-2024-6387.patch
+      ./openssh-9.6_p1-chaff-logic.patch
+    ];
     extraMeta.maintainers = lib.teams.helsinki-systems.members;
   };
 

pkgs/tools/networking/openssh/openssh-9.6_p1-CVE-2024-6387.patch

@@ -0,0 +1,19 @@
+https://bugs.gentoo.org/935271
+Backport proposed by upstream at https://marc.info/?l=oss-security&m=171982317624594&w=2.
+--- a/log.c
++++ b/log.c
+@@ -451,12 +451,14 @@ void
+ sshsigdie(const char *file, const char *func, int line, int showfunc,
+     LogLevel level, const char *suffix, const char *fmt, ...)
+ {
++#ifdef SYSLOG_R_SAFE_IN_SIGHAND
+ 	va_list args;
+
+ 	va_start(args, fmt);
+ 	sshlogv(file, func, line, showfunc, SYSLOG_LEVEL_FATAL,
+ 	    suffix, fmt, args);
+ 	va_end(args);
++#endif
+ 	_exit(1);
+ }
+

pkgs/tools/networking/openssh/openssh-9.6_p1-chaff-logic.patch

@@ -0,0 +1,16 @@
+"Minor logic error in ObscureKeystrokeTiming"
+https://marc.info/?l=oss-security&m=171982317624594&w=2
+--- a/clientloop.c
++++ b/clientloop.c
+@@ -608,8 +608,9 @@ obfuscate_keystroke_timing(struct ssh *ssh, struct timespec *timeout,
+ 		if (timespeccmp(&now, &chaff_until, >=)) {
+ 			/* Stop if there have been no keystrokes for a while */
+ 			stop_reason = "chaff time expired";
+-		} else if (timespeccmp(&now, &next_interval, >=)) {
+-			/* Otherwise if we were due to send, then send chaff */
++		} else if (timespeccmp(&now, &next_interval, >=) &&
++		    !ssh_packet_have_data_to_write(ssh)) {
++			/* If due to send but have no data, then send chaff */
+ 			if (send_chaff(ssh))
+ 				nchaff++;
+ 		}