fix: resolve critical IPC security vulnerabilities

- Validate IP/CIDR values from IPC before passing to Linux firewall
- Replace shell interpolation with direct execve in firewall update functions
- Block dangerous OpenVPN/WireGuard arguments in sanitizeArguments()
- Add programId bounds check in IpcServerProcess::setProgram()
- Add SO_PEERCRED peer authentication for IPC connections on Linux

client/platforms/linux/daemon/linuxfirewall.cpp

@@ -448,16 +448,33 @@ void LinuxFirewall::updateDNSServers(const QStringList& servers)
     static QStringList existingServers {};
 
     existingServers = servers;
-    execute(QStringLiteral("iptables -F %1.320.allowDNS").arg(kAnchorName));
-    for (const QString& rule : getDNSRules(servers))
-        execute(QStringLiteral("iptables -A %1.320.allowDNS %2").arg(kAnchorName, rule));
+    const QString chain = QStringLiteral("%1.320.allowDNS").arg(kAnchorName);
+    executeIptables(QStringLiteral("iptables"), {QStringLiteral("-F"), chain});
+    const QStringList ifaces = {
+        QStringLiteral("amn0+"), QStringLiteral("tun0+"), QStringLiteral("tun2+")
+    };
+    for (const QString& server : servers) {
+        for (const QString& iface : ifaces) {
+            executeIptables(QStringLiteral("iptables"),
+                {QStringLiteral("-A"), chain, QStringLiteral("-o"), iface,
+                 QStringLiteral("-d"), server, QStringLiteral("-p"), QStringLiteral("udp"),
+                 QStringLiteral("--dport"), QStringLiteral("53"), QStringLiteral("-j"), QStringLiteral("ACCEPT")});
+            executeIptables(QStringLiteral("iptables"),
+                {QStringLiteral("-A"), chain, QStringLiteral("-o"), iface,
+                 QStringLiteral("-d"), server, QStringLiteral("-p"), QStringLiteral("tcp"),
+                 QStringLiteral("--dport"), QStringLiteral("53"), QStringLiteral("-j"), QStringLiteral("ACCEPT")});
+        }
+    }
 }
 
 void LinuxFirewall::updateAllowNets(const QStringList& servers)
 {
-    execute(QStringLiteral("iptables -F %1.110.allowNets").arg(kAnchorName));
-    for (const QString& rule : getAllowRule(servers))
-        execute(QStringLiteral("iptables -A %1.110.allowNets %2").arg(kAnchorName, rule));
+    const QString chain = QStringLiteral("%1.110.allowNets").arg(kAnchorName);
+    executeIptables(QStringLiteral("iptables"), {QStringLiteral("-F"), chain});
+    for (const QString& server : servers)
+        executeIptables(QStringLiteral("iptables"),
+            {QStringLiteral("-A"), chain, QStringLiteral("-d"), server,
+             QStringLiteral("-j"), QStringLiteral("ACCEPT")});
 }
 
 void LinuxFirewall::updateBlockNets(const QStringList& servers)
@@ -465,9 +482,12 @@ void LinuxFirewall::updateBlockNets(const QStringList& servers)
     static QStringList existingServers {};
 
     existingServers = servers;
-    execute(QStringLiteral("iptables -F %1.120.blockNets").arg(kAnchorName));
-    for (const QString& rule : getBlockRule(servers))
-        execute(QStringLiteral("iptables -A %1.120.blockNets %2").arg(kAnchorName, rule));
+    const QString chain = QStringLiteral("%1.120.blockNets").arg(kAnchorName);
+    executeIptables(QStringLiteral("iptables"), {QStringLiteral("-F"), chain});
+    for (const QString& server : servers)
+        executeIptables(QStringLiteral("iptables"),
+            {QStringLiteral("-A"), chain, QStringLiteral("-d"), server,
+             QStringLiteral("-j"), QStringLiteral("REJECT")});
 }
 
 int waitForExitCode(QProcess& process)
@@ -500,6 +520,24 @@ int LinuxFirewall::execute(const QString &command, bool ignoreErrors)
     return exitCode;
 }
 
+int LinuxFirewall::executeIptables(const QString &program, const QStringList &args, bool ignoreErrors)
+{
+    QProcess p;
+    p.start(program, args, QProcess::ReadOnly);
+    p.closeWriteChannel();
+
+    int exitCode = waitForExitCode(p);
+    auto out = p.readAllStandardOutput().trimmed();
+    auto err = p.readAllStandardError().trimmed();
+    if ((exitCode != 0 || !err.isEmpty()) && !ignoreErrors)
+        logger.warning() << "(" << exitCode << ") $ " << program << args.join(QLatin1Char(' '));
+    if (!out.isEmpty())
+        logger.info() << out;
+    if (!err.isEmpty())
+        logger.warning() << err;
+    return exitCode;
+}
+
 void LinuxFirewall::setupTrafficSplitting()
 {
     auto cGroupDir = "/sys/fs/cgroup/net_cls/" BRAND_CODE "vpnexclusions/";

client/platforms/linux/daemon/linuxfirewall.h

@@ -85,6 +85,7 @@ private:
     static void setupTrafficSplitting();
     static void teardownTrafficSplitting();
     static int execute(const QString& command, bool ignoreErrors = false);
+    static int executeIptables(const QString& program, const QStringList& args, bool ignoreErrors = false);
 private:
     // Chain names
     static QString kOutputChain, kRootChain, kPostRoutingChain, kPreRoutingChain;

ipc/ipc.h

@@ -3,6 +3,8 @@
 
 #include <QObject>
 #include <QString>
+#include <QRegularExpression>
+#include <QSet>
 
 #include "../client/utilities.h"
 
@@ -15,7 +17,8 @@ enum PermittedProcess {
     OpenVPN,
     Wireguard,
     Tun2Socks,
-    CertUtil
+    CertUtil,
+    _Count
 };
 
 inline QString permittedProcessPath(PermittedProcess pid)
@@ -57,16 +60,56 @@ inline QStringList sanitizeArguments(PermittedProcess proc, const QStringList &a
     QList<Validator> positionalArgs;
 
     switch (proc) {
+    case OpenVPN: {
+        static const QSet<QString> blocked = {
+            QStringLiteral("--script-security"),
+            QStringLiteral("--up"),
+            QStringLiteral("--down"),
+            QStringLiteral("--route-up"),
+            QStringLiteral("--ipchange"),
+            QStringLiteral("--tls-verify"),
+            QStringLiteral("--plugin"),
+            QStringLiteral("--auth-user-pass-verify"),
+            QStringLiteral("--learn-address"),
+            QStringLiteral("--client-connect"),
+            QStringLiteral("--client-disconnect"),
+            QStringLiteral("--management"),
+            QStringLiteral("--management-external-key")
+        };
+        QStringList out;
+        for (int i = 0; i < args.size(); ++i) {
+            if (blocked.contains(args[i])) {
+                qWarning() << "IPC: blocked OpenVPN argument:" << args[i];
+                ++i; // skip following value
+                continue;
+            }
+            out << args[i];
+        }
+        return out;
+    }
+    case Wireguard: {
+        static const QRegularExpression hookRe(
+            QStringLiteral(R"((?i)(PostUp|PreUp|PostDown|PreDown)\s*=)"));
+        QStringList out;
+        for (const QString& a : args) {
+            if (hookRe.match(a).hasMatch()) {
+                qWarning() << "IPC: blocked WireGuard hook argument:" << a;
+                continue;
+            }
+            out << a;
+        }
+        return out;
+    }
     case Tun2Socks:
         namedArgs["-device"] = [](const QString& v) { return v.startsWith("tun://"); };
         namedArgs["-proxy"] = [](const QString& v) { return v.startsWith("socks5://"); };
         break;
-    default:
-        //FIXME
+    case CertUtil:
         return args;
+    default:
+        return {};
     }
 
-
     QStringList sanitized;
 
     for (int i = 0, pos = 0; i < args.size(); i++) {

ipc/ipcserver.cpp

@@ -22,6 +22,27 @@
     #include "tapcontroller_win.h"
 #endif
 
+#ifdef Q_OS_LINUX
+#include <sys/socket.h>
+#include <sys/types.h>
+
+extern uid_t g_allowedUid;
+extern bool g_allowedUidSet;
+
+static bool checkPrivPeerCredentials(QLocalSocket *socket) {
+    struct ucred cred{};
+    socklen_t len = sizeof(cred);
+    if (getsockopt(socket->socketDescriptor(), SOL_SOCKET, SO_PEERCRED, &cred, &len) != 0) {
+        qWarning() << "IpcServer: SO_PEERCRED failed, rejecting privileged process connection";
+        return false;
+    }
+    if (cred.uid == 0) return true;
+    if (g_allowedUidSet && cred.uid == g_allowedUid) return true;
+    qWarning() << "IpcServer: rejected privileged process connection from unauthorized UID" << cred.uid;
+    return false;
+}
+#endif
+
 
 IpcServer::IpcServer(QObject *parent) : IpcInterfaceSource(parent)
 {
@@ -48,8 +69,16 @@ int IpcServer::createPrivilegedProcess()
     // Make sure any connections are handed to QtRO
     QObject::connect(pd.localServer.data(), &QLocalServer::newConnection, this, [pd]() {
         qDebug() << "IpcServer new connection";
+        QLocalSocket *conn = pd.localServer->nextPendingConnection();
+#ifdef Q_OS_LINUX
+        if (!checkPrivPeerCredentials(conn)) {
+            conn->close();
+            conn->deleteLater();
+            return;
+        }
+#endif
         if (pd.serverNode) {
-            pd.serverNode->addHostSideConnection(pd.localServer->nextPendingConnection());
+            pd.serverNode->addHostSideConnection(conn);
             pd.serverNode->enableRemoting(pd.ipcProcess.data());
         }
     });

ipc/ipcserverprocess.cpp

@@ -77,6 +77,11 @@ void IpcServerProcess::setProcessChannelMode(QProcess::ProcessChannelMode mode)
 
 void IpcServerProcess::setProgram(int programId)
 {
+    if (programId <= static_cast<int>(amnezia::PermittedProcess::Invalid) ||
+        programId >= static_cast<int>(amnezia::PermittedProcess::_Count)) {
+        qWarning() << "IPC: invalid programId" << programId << ", ignoring";
+        return;
+    }
     m_program = static_cast<amnezia::PermittedProcess>(programId);
     m_process->setProgram(amnezia::permittedProcessPath(m_program));
     m_process->setArguments({});

service/server/killswitch.cpp

@@ -3,11 +3,43 @@
 
 #include <QApplication>
 #include <QHostAddress>
+#include <QRegularExpression>
 
 #include "../client/protocols/protocols_defs.h"
 #include "qjsonarray.h"
 #include "version.h"
 
+#ifdef Q_OS_LINUX
+static bool isValidIpOrCidr(const QString &value) {
+    static const QRegularExpression re(
+        QStringLiteral(R"(^(\d{1,3}\.){3}\d{1,3}(/\d{1,2})?$)"));
+    if (!re.match(value).hasMatch()) return false;
+    const QStringList ipParts = value.split(QLatin1Char('/'))[0].split(QLatin1Char('.'));
+    for (const QString &part : ipParts) {
+        bool ok;
+        int octet = part.toInt(&ok);
+        if (!ok || octet < 0 || octet > 255) return false;
+    }
+    if (value.contains(QLatin1Char('/'))) {
+        bool ok;
+        int prefix = value.split(QLatin1Char('/'))[1].toInt(&ok);
+        if (!ok || prefix < 0 || prefix > 32) return false;
+    }
+    return true;
+}
+
+static QStringList filterIpList(const QStringList &values) {
+    QStringList safe;
+    for (const QString &v : values) {
+        if (isValidIpOrCidr(v))
+            safe << v;
+        else
+            qWarning() << "IPC: rejected invalid IP/CIDR value:" << v;
+    }
+    return safe;
+}
+#endif
+
 #ifdef Q_OS_WIN
     #include "../client/platforms/windows/daemon/windowsfirewall.h"
     #include "../client/platforms/windows/daemon/windowsdaemon.h"
@@ -159,7 +191,11 @@ bool KillSwitch::disableAllTraffic() {
 
 bool KillSwitch::resetAllowedRange(const QStringList &ranges) {
 
+#ifdef Q_OS_LINUX
+    m_allowedRanges = filterIpList(ranges);
+#else
     m_allowedRanges = ranges;
+#endif
 
 #ifdef Q_OS_LINUX
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("110.allowNets"), true);
@@ -182,7 +218,12 @@ bool KillSwitch::resetAllowedRange(const QStringList &ranges) {
 }
 
 bool KillSwitch::addAllowedRange(const QStringList &ranges) {
-    for (const QString &range : ranges) {
+#ifdef Q_OS_LINUX
+    const QStringList safeRanges = filterIpList(ranges);
+#else
+    const QStringList &safeRanges = ranges;
+#endif
+    for (const QString &range : safeRanges) {
         if (!range.isEmpty() && !m_allowedRanges.contains(range)) {
             m_allowedRanges.append(range);
         }
@@ -307,9 +348,9 @@ bool KillSwitch::enableKillSwitch(const QJsonObject &configStr, int vpnAdapterIn
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("000.allowLoopback"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("100.blockAll"), blockAll);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("110.allowNets"), allowNets);
-    LinuxFirewall::updateAllowNets(allownets);
+    LinuxFirewall::updateAllowNets(filterIpList(allownets));
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("120.blockNets"), blockAll);
-    LinuxFirewall::updateBlockNets(blocknets);
+    LinuxFirewall::updateBlockNets(filterIpList(blocknets));
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("200.allowVPN"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv6, QStringLiteral("250.blockIPv6"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("290.allowDHCP"), true);
@@ -317,23 +358,35 @@ bool KillSwitch::enableKillSwitch(const QJsonObject &configStr, int vpnAdapterIn
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("310.blockDNS"), true);
     QStringList dnsServers;
 
-    dnsServers.append(configStr.value(amnezia::config_key::dns1).toString());
+    const QString dns1 = configStr.value(amnezia::config_key::dns1).toString();
+    if (isValidIpOrCidr(dns1))
+        dnsServers.append(dns1);
+    else if (!dns1.isEmpty())
+        qWarning() << "IPC: rejected invalid dns1:" << dns1;
 
     // We don't use secondary DNS if primary DNS is AmneziaDNS
-    if (!configStr.value(amnezia::config_key::dns1).toString().contains(amnezia::protocols::dns::amneziaDnsIp)) {
-        dnsServers.append(configStr.value(amnezia::config_key::dns2).toString());
+    if (!dns1.contains(amnezia::protocols::dns::amneziaDnsIp)) {
+        const QString dns2 = configStr.value(amnezia::config_key::dns2).toString();
+        if (isValidIpOrCidr(dns2))
+            dnsServers.append(dns2);
+        else if (!dns2.isEmpty())
+            qWarning() << "IPC: rejected invalid dns2:" << dns2;
     }
 
     dnsServers.append("127.0.0.1");
     dnsServers.append("127.0.0.53");
-    
+
     for (auto dns : configStr.value(amnezia::config_key::allowedDnsServers).toArray()) {
         if (!dns.isString()) {
             break;
         }
-        dnsServers.append(dns.toString());
+        const QString dnsStr = dns.toString();
+        if (isValidIpOrCidr(dnsStr))
+            dnsServers.append(dnsStr);
+        else if (!dnsStr.isEmpty())
+            qWarning() << "IPC: rejected invalid allowedDnsServer:" << dnsStr;
     }
-    
+
     LinuxFirewall::updateDNSServers(dnsServers);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("320.allowDNS"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("400.allowPIA"), true);

service/server/localserver.cpp

@@ -17,6 +17,35 @@
     #include "tapcontroller_win.h"
 #endif
 
+#ifdef Q_OS_LINUX
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+uid_t g_allowedUid = static_cast<uid_t>(-1);
+bool g_allowedUidSet = false;
+
+static bool checkPeerCredentials(QLocalSocket *socket) {
+    struct ucred cred{};
+    socklen_t len = sizeof(cred);
+    if (getsockopt(socket->socketDescriptor(), SOL_SOCKET, SO_PEERCRED, &cred, &len) != 0) {
+        qWarning() << "LocalServer: SO_PEERCRED failed, rejecting connection";
+        return false;
+    }
+    if (cred.uid == 0) return true;
+    if (!g_allowedUidSet) {
+        g_allowedUid = cred.uid;
+        g_allowedUidSet = true;
+        qDebug() << "LocalServer: registered session UID" << g_allowedUid;
+    }
+    if (cred.uid != g_allowedUid) {
+        qWarning() << "LocalServer: rejected connection from unauthorized UID" << cred.uid;
+        return false;
+    }
+    return true;
+}
+#endif
+
 namespace {
 Logger logger("WgDaemonServer");
 }
@@ -35,7 +64,15 @@ LocalServer::LocalServer(QObject *parent) : QObject(parent),
 
     QObject::connect(m_server.data(), &QLocalServer::newConnection, this, [this]() {
         qDebug() << "LocalServer new connection";
-        m_serverNode.addHostSideConnection(m_server->nextPendingConnection());
+        QLocalSocket *conn = m_server->nextPendingConnection();
+#ifdef Q_OS_LINUX
+        if (!checkPeerCredentials(conn)) {
+            conn->close();
+            conn->deleteLater();
+            return;
+        }
+#endif
+        m_serverNode.addHostSideConnection(conn);
 
         if (!m_isRemotingEnabled) {
             m_isRemotingEnabled = true;