diff options
| -rw-r--r-- | unix/xserver/hw/vnc/Xvnc.man | 15 | ||||
| -rw-r--r-- | unix/xserver/hw/vnc/vncExt.c | 15 | ||||
| -rw-r--r-- | unix/xserver/hw/vnc/vncExtInit.cc | 45 | ||||
| -rw-r--r-- | unix/xserver/hw/vnc/vncExtInit.h | 2 |
4 files changed, 69 insertions, 8 deletions
diff --git a/unix/xserver/hw/vnc/Xvnc.man b/unix/xserver/hw/vnc/Xvnc.man index 4a833157..a4d9f8d3 100644 --- a/unix/xserver/hw/vnc/Xvnc.man +++ b/unix/xserver/hw/vnc/Xvnc.man @@ -300,6 +300,21 @@ Key affected by NumLock often require a fake Shift to be inserted in order for the correct symbol to be generated. Turning on this option avoids these extra fake Shift events but may result in a slightly different symbol (e.g. a Return instead of a keypad Enter). +. +.TP +.B \-AllowOverride +Comma separated list of parameters that can be modified using VNC extension. +Parameters can be modified for example using \fBvncconfig\fP(1) program from +inside a running session. + +Allowing override of parameters such as \fBPAMService\fP or \fBPasswordFile\fP +can negatively impact security if Xvnc runs under different user than the +programs allowed to override the parameters. + +When \fBNoClipboard\fP parameter is set, allowing override of \fBSendCutText\fP +and \fBAcceptCutText\fP has no effect. + +Default is \fBdesktop,AcceptPointerEvents,SendCutText,AcceptCutText\fP. .SH USAGE WITH INETD By configuring the \fBinetd\fP(1) service appropriately, Xvnc can be launched diff --git a/unix/xserver/hw/vnc/vncExt.c b/unix/xserver/hw/vnc/vncExt.c index 43794dad..b27115f6 100644 --- a/unix/xserver/hw/vnc/vncExt.c +++ b/unix/xserver/hw/vnc/vncExt.c @@ -182,17 +182,16 @@ static int ProcVncExtSetParam(ClientPtr client) rep.sequenceNumber = client->sequence; /* - * Allow to change only certain parameters. - * Changing other parameters (for example PAM service name) - * could have negative security impact. + * Prevent change of clipboard related parameters if clipboard is disabled. */ - if (strncasecmp(param, "desktop", 7) != 0 && - strncasecmp(param, "AcceptPointerEvents", 19) != 0 && - (vncNoClipboard || strncasecmp(param, "SendCutText", 11) != 0) && - (vncNoClipboard || strncasecmp(param, "AcceptCutText", 13) != 0)) + if (vncNoClipboard && + (strncasecmp(param, "SendCutText", 11) == 0 || + strncasecmp(param, "AcceptCutText", 13) == 0)) + goto deny; + + if (!vncOverrideParam(param)) goto deny; - vncSetParamSimple(param); rep.success = 1; // Send DesktopName update if desktop name has been changed diff --git a/unix/xserver/hw/vnc/vncExtInit.cc b/unix/xserver/hw/vnc/vncExtInit.cc index 863cd36b..1d374938 100644 --- a/unix/xserver/hw/vnc/vncExtInit.cc +++ b/unix/xserver/hw/vnc/vncExtInit.cc @@ -20,6 +20,9 @@ #include <stdio.h> #include <errno.h> +#include <set> +#include <string> + #include <rfb/Configuration.h> #include <rfb/Logger_stdio.h> #include <rfb/LogWriter.h> @@ -52,6 +55,15 @@ int vncFbstride[MAXSCREENS]; int vncInetdSock = -1; +struct CaseInsensitiveCompare { + bool operator() (const std::string &a, const std::string &b) const { + return strcasecmp(a.c_str(), b.c_str()) < 0; + } +}; + +typedef std::set<std::string, CaseInsensitiveCompare> ParamSet; +static ParamSet allowOverrideSet; + rfb::StringParameter httpDir("httpd", "Directory containing files to serve via HTTP", ""); @@ -69,6 +81,9 @@ rfb::StringParameter interface("interface", rfb::BoolParameter avoidShiftNumLock("AvoidShiftNumLock", "Avoid fake Shift presses for keys affected by NumLock.", true); +rfb::StringParameter allowOverride("AllowOverride", + "Comma separated list of parameters that can be modified using VNC extension.", + "desktop,AcceptPointerEvents,SendCutText,AcceptCutText"); static PixelFormat vncGetPixelFormat(int scrIdx) { @@ -99,6 +114,19 @@ static PixelFormat vncGetPixelFormat(int scrIdx) redShift, greenShift, blueShift); } +static void parseOverrideList(const char *text, ParamSet &out) +{ + for (const char* iter = text; ; ++iter) { + if (*iter == ',' || *iter == '\0') { + out.insert(std::string(text, iter)); + text = iter + 1; + + if (*iter == '\0') + break; + } + } +} + void vncExtensionInit(void) { int ret; @@ -128,6 +156,10 @@ void vncExtensionInit(void) try { if (!initialised) { rfb::initStdIOLoggers(); + + parseOverrideList(allowOverride, allowOverrideSet); + allowOverride.setImmutable(); + initialised = true; } @@ -379,3 +411,16 @@ void vncRefreshScreenLayout(int scrIdx) { desktop[scrIdx]->refreshScreenLayout(); } + +int vncOverrideParam(const char *nameAndValue) +{ + const char* equalSign = strchr(nameAndValue, '='); + if (!equalSign) + return 0; + + std::string key(nameAndValue, equalSign); + if (allowOverrideSet.find(key) == allowOverrideSet.end()) + return 0; + + return rfb::Configuration::setParam(nameAndValue); +} diff --git a/unix/xserver/hw/vnc/vncExtInit.h b/unix/xserver/hw/vnc/vncExtInit.h index 6430ac05..be6487c8 100644 --- a/unix/xserver/hw/vnc/vncExtInit.h +++ b/unix/xserver/hw/vnc/vncExtInit.h @@ -90,6 +90,8 @@ void vncPreScreenResize(int scrIdx); void vncPostScreenResize(int scrIdx, int success, int width, int height); void vncRefreshScreenLayout(int scrIdx); +int vncOverrideParam(const char *nameAndValue); + #ifdef __cplusplus } #endif |