windows: preserve service command-line arguments

Serialize service arguments with Windows quoting and backslash escaping
for both installation and parameter updates. Reject truncated executable
paths and command lines before accessing the Service Control Manager.

Keep the existing service-option prefix matching unchanged. Limit the
fix to command-line construction, without changing the command-line
parser, service function interfaces or SCInstance layout.

Ticket: 9241

src/win32-service.c

@@ -30,6 +30,102 @@
 #include "win32-service.h"
 #include "util-debug.h"
 
+/** Append a character, leaving room for the terminating NUL. */
+static bool SCServiceAppendChar(char *path, size_t size, size_t *len, char c)
+{
+    if (size == 0 || *len >= size - 1) {
+        return false;
+    }
+    path[(*len)++] = c;
+    path[*len] = '\0';
+    return true;
+}
+
+/**
+ * Quote an argument for the Windows C runtime. Backslashes are literal except
+ * before a double quote: emit 2n+1 backslashes before an embedded quote, and
+ * 2n before the closing quote. Always quote, including empty arguments.
+ */
+static bool SCServiceAppendArgument(char *path, size_t size, size_t *len, const char *arg)
+{
+    if (!SCServiceAppendChar(path, size, len, '"')) {
+        return false;
+    }
+    while (*arg != '\0') {
+        size_t backslashes = 0;
+        while (*arg == '\\') {
+            backslashes++;
+            arg++;
+        }
+        for (size_t i = 0; i < backslashes; i++) {
+            if (!SCServiceAppendChar(path, size, len, '\\')) {
+                return false;
+            }
+            if ((*arg == '"' || *arg == '\0') && !SCServiceAppendChar(path, size, len, '\\')) {
+                return false;
+            }
+        }
+        if (*arg == '\0') {
+            break;
+        }
+        if (*arg == '"' && !SCServiceAppendChar(path, size, len, '\\')) {
+            return false;
+        }
+        if (!SCServiceAppendChar(path, size, len, *arg++)) {
+            return false;
+        }
+    }
+    return SCServiceAppendChar(path, size, len, '"');
+}
+
+/** Build the service command line without accessing SCM. */
+static bool SCServiceBuildCommandLine(char *path, size_t size, const char *module, int argc,
+        const char *const *argv, const char *service_option)
+{
+    if (size == 0) {
+        return false;
+    }
+    path[0] = '\0';
+    size_t len = 0;
+    if (!SCServiceAppendArgument(path, size, &len, module)) {
+        return false;
+    }
+    for (int i = 1; i < argc; i++) {
+        /* Preserve the existing service-option prefix matching. */
+        if (strlen(argv[i]) <= strlen(service_option) &&
+                strncmp(service_option, argv[i], strlen(argv[i])) == 0) {
+            continue;
+        }
+        if (!SCServiceAppendChar(path, size, &len, ' ') ||
+                !SCServiceAppendArgument(path, size, &len, argv[i])) {
+            return false;
+        }
+    }
+    return true;
+}
+
+/** Resolve the executable and reject truncation before making any SCM calls. */
+static bool SCServiceGetCommandLine(
+        char *path, size_t size, int argc, char **argv, const char *service_option)
+{
+    char module[2048];
+    DWORD len = GetModuleFileName(NULL, module, sizeof(module));
+    if (len == 0) {
+        SCLogError("Can't get path to service binary: %d", (int)GetLastError());
+        return false;
+    }
+    if (len >= sizeof(module)) {
+        SCLogError("failed to construct service path string: binary path truncated");
+        return false;
+    }
+    if (!SCServiceBuildCommandLine(
+                path, size, module, argc, (const char *const *)argv, service_option)) {
+        SCLogError("failed to construct service path string: invalid or truncated command line");
+        return false;
+    }
+    return true;
+}
+
 static SERVICE_STATUS_HANDLE service_status_handle = 0;
 
 static int service_argc = 0;
@@ -214,35 +310,11 @@ int SCServiceInstall(int argc, char **argv)
     SC_HANDLE service = NULL;
     SC_HANDLE scm = NULL;
     int ret = -1;
-    int i = 0;
 
     do {
-        memset(path, 0, sizeof(path));
-
-        path[0] = '"';
-        if (GetModuleFileName(NULL, path + 1, sizeof(path) - 1) == 0) {
-            SCLogError("Can't get path to service binary: %d", (int)GetLastError());
+        if (!SCServiceGetCommandLine(path, sizeof(path), argc, argv, "--service-install")) {
             break;
         }
-        if (strlcat(path, "\"", sizeof(path)) >= sizeof(path)) {
-            SCLogError("failed to construct service path string: path truncated: %s", path);
-            break;
-        }
-
-        /* skip name of binary itself */
-        for (i = 1; i < argc; i++) {
-            if ((strlen(argv[i]) <= strlen("--service-install")) && (strncmp("--service-install", argv[i], strlen(argv[i])) == 0)) {
-                continue;
-            }
-            if (strlcat(path, " ", sizeof(path)) >= sizeof(path)) {
-                SCLogError("failed to construct service path string: path truncated: %s", path);
-                return -1;
-            }
-            if (strlcat(path, argv[i], sizeof(path)) >= sizeof(path)) {
-                SCLogError("failed to construct service path string: path truncated: %s", path);
-                return -1;
-            }
-        }
 
         if ((scm = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS)) == NULL) {
             SCLogError("Can't open SCM: %d", (int)GetLastError());
@@ -350,36 +422,12 @@ int SCServiceChangeParams(int argc, char **argv)
     SC_HANDLE service = NULL;
     SC_HANDLE scm = NULL;
     int ret = -1;
-    int i = 0;
 
     do {
-        memset(path, 0, sizeof(path));
-
-        path[0] = '"';
-        if (GetModuleFileName(NULL, path + 1, sizeof(path) - 1) == 0) {
-            SCLogError("Can't get path to service binary: %d", (int)GetLastError());
-            break;
-        }
-        if (strlcat(path, "\"", sizeof(path)) >= sizeof(path)) {
-            SCLogError("failed to construct service path string: path truncated: %s", path);
+        if (!SCServiceGetCommandLine(path, sizeof(path), argc, argv, "--service-change-params")) {
             break;
         }
 
-        /* skip name of binary itself */
-        for (i = 1; i < argc; i++) {
-            if ((strlen(argv[i]) <= strlen("--service-change-params")) && (strncmp("--service-change-params", argv[i], strlen(argv[i])) == 0)) {
-                continue;
-            }
-            if (strlcat(path, " ", sizeof(path)) >= sizeof(path)) {
-                SCLogError("failed to construct service path string: path truncated: %s", path);
-                return -1;
-            }
-            if (strlcat(path, argv[i], sizeof(path)) >= sizeof(path)) {
-                SCLogError("failed to construct service path string: path truncated: %s", path);
-                return -1;
-            }
-        }
-
         if ((scm = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS)) == NULL) {
             SCLogError("Can't open SCM: %d", (int)GetLastError());
             break;