From: Simon McVittie <smcv@debian.org>
Date: Sat, 18 Feb 2012 20:33:51 +0000
Subject: CVE-2006-2082 - do not allow download of arbitrary files from a
 server

Any file readable by the server user could be read, via ../ sequences.

Original patches by Thilo Schulz, ioquake3 r777 (which fixed the
vulnerability) and r781 (which fixed a regression in r777 where
uninitialized variables led to some allowed downloads being rejected too).

Origin: backport
Bug-Debian: http://bugs.debian.org/660831
Bug-CVE: http://security-tracker.debian.org/tracker/CVE-2006-2082
---
 src/server/sv_client.c |   51 ++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/src/server/sv_client.c b/src/server/sv_client.c
index 0272fab..53f5998 100644
--- src/server/sv_client.c
+++ src/server/sv_client.c
@@ -618,24 +618,57 @@ void SV_WriteDownloadToClient( client_t *cl , msg_t *msg )
 	int curindex;
 	int rate;
 	int blockspersnap;
-	int idPack, missionPack;
+	int idPack = 0, missionPack = 0, unreferenced = 1;
 	char errorMessage[1024];
+	char pakbuf[MAX_QPATH], *pakptr;
+	int numRefPaks;
 
 	if (!*cl->downloadName)
 		return;	// Nothing being downloaded
 
 	if (!cl->download) {
-		// We open the file here
+		// Chop off filename extension.
+		Com_sprintf(pakbuf, sizeof(pakbuf), "%s", cl->downloadName);
+		pakptr = Q_strrchr(pakbuf, '.');
 
-		Com_Printf( "clientDownload: %d : begining \"%s\"\n", cl - svs.clients, cl->downloadName );
+		if (pakptr)
+		{
+			*pakptr = '\0';
 
-		missionPack = FS_idPak(cl->downloadName, "missionpack");
-		idPack = missionPack || FS_idPak(cl->downloadName, "baseq3");
+			// Check for pk3 filename extension
+			if(!Q_stricmp(pakptr + 1, "pk3"))
+			{
+				const char *referencedPaks = FS_ReferencedPakNames();
+
+				// Check whether the file appears in the list of referenced
+				// paks to prevent downloading of arbitrary files
+				Cmd_TokenizeStringIgnoreQuotes(referencedPaks);
+				numRefPaks = Cmd_Argc();
+
+				for(curindex = 0; curindex < numRefPaks; curindex++)
+				{
+					if(!FS_FilenameCompare(Cmd_Argv(curindex), pakbuf))
+					{
+						unreferenced = 0;
+						// now that we know the file is referenced, check whether it's legal to download it.
+						missionPack = FS_idPak(pakbuf, "missionpack");
+						idPack = missionPack || FS_idPak(pakbuf, BASEGAME);
+						break;
+					}
+				}
+			}
+		}
 
-		if ( !sv_allowDownload->integer || idPack ||
+		// We open the file here
+		if ( !sv_allowDownload->integer || idPack || unreferenced ||
 			( cl->downloadSize = FS_SV_FOpenFileRead( cl->downloadName, &cl->download ) ) <= 0 ) {
 			// cannot auto-download file
-			if (idPack) {
+			if(unreferenced)
+			{
+				Com_Printf("clientDownload: %d : \"%s\" is not referenced and cannot be downloaded.\n", cl - svs.clients, cl->downloadName);
+				Com_sprintf(errorMessage, sizeof(errorMessage), "File \"%s\" is not referenced and cannot be downloaded.", cl->downloadName);
+			}
+			else if (idPack) {
 				Com_Printf("clientDownload: %d : \"%s\" cannot download id pk3 files\n", cl - svs.clients, cl->downloadName);
 				if (missionPack) {
 					Com_sprintf(errorMessage, sizeof(errorMessage), "Cannot autodownload Team Arena file \"%s\"\n"
@@ -670,7 +703,9 @@ void SV_WriteDownloadToClient( client_t *cl , msg_t *msg )
 			*cl->downloadName = 0;
 			return;
 		}
- 
+
+		Com_Printf( "clientDownload: %d : beginning \"%s\"\n", cl - svs.clients, cl->downloadName );
+		
 		// Init
 		cl->downloadCurrentBlock = cl->downloadClientBlock = cl->downloadXmitBlock = 0;
 		cl->downloadCount = 0;