Add dbus filter options

The options --dbus-user.talk, --dbus-user.own, --dbus-system.talk, and
--dbus-system.own control which names can be accessed and owned on the user and
system buses.

1 files changed, 91 insertions, 2 deletions

diff --git a/src/firejail/dbus.c b/src/firejail/dbus.c
index 5cdd4b372..bf1ae9a1e 100644
--- a/src/firejail/dbus.c
+++ b/src/firejail/dbus.c
@@ -24,6 +24,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <string.h>
 
 #define DBUS_SOCKET_PATH_PREFIX "unix:path="
 #define DBUS_USER_SOCKET_FORMAT "/run/user/%d/bus"
@@ -33,12 +34,82 @@
 #define DBUS_SESSION_BUS_ADDRESS_ENV "DBUS_SESSION_BUS_ADDRESS"
 #define DBUS_USER_PROXY_SOCKET_FORMAT RUN_FIREJAIL_DBUS_DIR "/%d-user"
 #define DBUS_SYSTEM_PROXY_SOCKET_FORMAT RUN_FIREJAIL_DBUS_DIR "/%d-system"
+#define DBUS_MAX_NAME_LENGTH 255
 
 static pid_t dbus_proxy_pid = 0;
 static int dbus_proxy_status_fd = -1;
 static char *dbus_user_proxy_socket = NULL;
 static char *dbus_system_proxy_socket = NULL;
 
+int dbus_check_name(const char *name) {
+        unsigned long length = strlen(name);
+        if (length == 0 || length > DBUS_MAX_NAME_LENGTH)
+                return 0;
+        const char *p = name;
+        int segments = 1;
+        int in_segment = 0;
+        while (*p) {
+                int alpha = (*p >= 'a' && *p <= 'z') || (*p >= 'A' && *p <= 'Z');
+                int digit = *p >= '0' && *p <= '9';
+                if (in_segment) {
+                        if (*p == '.') {
+                                ++segments;
+                                in_segment = 0;
+                        } else if (!alpha && !digit && *p != '_' && *p != '-') {
+                                return 0;
+                        }
+                }
+                else {
+                        if (*p == '*') {
+                                return *(p + 1) == '\0';
+                        } else if (!alpha && *p != '_' && *p != '-') {
+                                return 0;
+                        }
+                        in_segment = 1;
+                }
+                ++p;
+        }
+        return in_segment && segments >= 2;
+}
+
+static void dbus_check_bus_profile(char const *prefix, DbusPolicy policy) {
+        size_t prefix_length = strlen(prefix);
+        ProfileEntry *it = cfg.profile;
+        while (it) {
+                char *data = it->data;
+                it = it->next;
+                if (strncmp(prefix, data, prefix_length) == 0) {
+                        switch (policy) {
+                        case DBUS_POLICY_ALLOW:
+                                // We should never get here, because profile parsing will fail earlier.
+                                fprintf(stderr,
+                                                "Error: %s filter rule configured, but the bus is not "
+                                                "set to filter.\n",
+                                                prefix);
+                                exit(1);
+                                break;
+                        case DBUS_POLICY_FILTER:
+                                // All good.
+                                break;
+                        case DBUS_POLICY_BLOCK:
+                                fwarning("%s filter rule configured, but the bus is blocked.\n", prefix);
+                                fwarning("Ignoring \"%s\" and any other %s filter rules.\n", data, prefix);
+                                break;
+                        default:
+                                fprintf(stderr, "Error: Unknown %s policy.\n", prefix);
+                                exit(1);
+                                break;
+                        }
+                        break;
+                }
+        }
+}
+
+void dbus_check_profile(void) {
+        dbus_check_bus_profile("dbus-user", arg_dbus_user);
+        dbus_check_bus_profile("dbus-system", arg_dbus_system);
+}
+
 static void write_arg(int fd, char const *format, ...) {
         va_list ap;
         va_start(ap, format);
@@ -55,6 +126,24 @@ static void write_arg(int fd, char const *format, ...) {
         free(arg);
 }
 
+static void write_profile(int fd, char const *prefix) {
+        size_t prefix_length = strlen(prefix);
+        ProfileEntry *it = cfg.profile;
+        while (it) {
+                char *data = it->data;
+                it = it->next;
+                if (strncmp(prefix, data, prefix_length) != 0)
+                        continue;
+                data += prefix_length;
+                int arg_length = 0;
+                while (data[arg_length] != '\0' && data[arg_length] != ' ')
+                        arg_length++;
+                if (data[arg_length] != ' ')
+                        continue;
+                write_arg(fd, "--%.*s=%s", arg_length, data, &data[arg_length + 1]);
+        }
+}
+
 void dbus_proxy_start(void) {
         int status_pipe[2];
         if (pipe(status_pipe) == -1)
@@ -96,7 +185,7 @@ void dbus_proxy_start(void) {
                                 errExit("asprintf");
                         write_arg(args_pipe[1], dbus_user_proxy_socket);
                         write_arg(args_pipe[1], "--filter");
-                        // TODO Write filter rules to pipe
+                        write_profile(args_pipe[1], "dbus-user.");
                 }
 
                 if (arg_dbus_system == DBUS_POLICY_FILTER) {
@@ -105,7 +194,7 @@ void dbus_proxy_start(void) {
                                 errExit("asprintf");
                         write_arg(args_pipe[1], dbus_system_proxy_socket);
                         write_arg(args_pipe[1], "--filter");
-                        // TODO Write filter rules to pipe
+                        write_profile(args_pipe[1], "dbus-system.");
                 }
 
                 if (close(args_pipe[1]) == -1)