1 files changed, 32 insertions, 21 deletions

diff --git a/src/firejail/main.c b/src/firejail/main.c
index 0f0086a6e..7a9521e42 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -861,19 +861,20 @@ static void run_cmd_and_exit(int i, int argc, char **argv) {
 }
 
 char *guess_shell(void) {
-        char *shell = NULL;
+        const char *shell;
+        char *retval;
         struct stat s;
 
-        shell = getenv("SHELL");
+        shell = env_get("SHELL");
         if (shell) {
                 invalid_filename(shell, 0); // no globbing
                 if (!is_dir(shell) && strstr(shell, "..") == NULL && stat(shell, &s) == 0 && access(shell, X_OK) == 0 &&
                     strcmp(shell, PATH_FIREJAIL) != 0)
-                        return shell;
+                        goto found;
         }
 
         // shells in order of preference
-        char *shells[] = {"/bin/bash", "/bin/csh", "/usr/bin/zsh", "/bin/sh", "/bin/ash", NULL };
+        static const char * const shells[] = {"/bin/bash", "/bin/csh", "/usr/bin/zsh", "/bin/sh", "/bin/ash", NULL };
 
         int i = 0;
         while (shells[i] != NULL) {
@@ -884,8 +885,11 @@ char *guess_shell(void) {
                 }
                 i++;
         }
-
-        return shell;
+ found:
+        retval = strdup(shell);
+        if (!retval)
+                errExit("strdup");
+        return retval;
 }
 
 // return argument index
@@ -926,9 +930,13 @@ static void run_builder(int argc, char **argv) {
         if (setresuid(-1, getuid(), getuid()) != 0)
                 errExit("setresuid");
 
+        assert(env_get("LD_PRELOAD") == NULL);
         assert(getenv("LD_PRELOAD") == NULL);
         umask(orig_umask);
 
+        // restore some environment variables
+        env_apply_whitelist_sbox();
+
         argv[0] = LIBDIR "/firejail/fbuilder";
         execvp(argv[0], argv);
 
@@ -994,6 +1002,16 @@ int main(int argc, char **argv, char **envp) {
                 exit(1);
         }
 
+        // Stash environment variables
+        for (i = 0, ptr = envp; ptr && *ptr && i < MAX_ENVS; i++, ptr++)
+                env_store(*ptr, SETENV_ALLOW_EMPTY);
+
+        // sanity check for environment variables
+        if (i >= MAX_ENVS) {
+                fprintf(stderr, "Error: too many environment variables, please use --rmenv\n");
+                exit(1);
+        }
+
         // sanity check for arguments
         for (i = 0; i < argc; i++) {
                 if (*argv[i] == 0) {
@@ -1005,29 +1023,19 @@ int main(int argc, char **argv, char **envp) {
                         exit(1);
                 }
                 // Also remove requested environment variables
-                // entirely to avoid tripping the length check below
                 if (strncmp(argv[i], "--rmenv=", 8) == 0)
-                        unsetenv(argv[i] + 8);
+                        env_store(argv[i] + 8, RMENV);
         }
 
-        // sanity check for environment variables
-        for (i = 0, ptr = envp; ptr && *ptr && i < MAX_ENVS; i++, ptr++) {
-                if (strlen(*ptr) >= MAX_ENV_LEN) {
-                        fprintf(stderr, "Error: too long environment variables, please use --rmenv\n");
-                        exit(1);
-                }
-        }
-        if (i >= MAX_ENVS) {
-                fprintf(stderr, "Error: too many environment variables, please use --rmenv\n");
-                exit(1);
-        }
+        // Reapply a minimal set of environment variables
+        env_apply_whitelist();
 
         // check if the user is allowed to use firejail
         init_cfg(argc, argv);
 
         // get starting timestamp, process --quiet
         timetrace_start();
-        char *env_quiet = getenv("FIREJAIL_QUIET");
+        const char *env_quiet = env_get("FIREJAIL_QUIET");
         if (check_arg(argc, argv, "--quiet", 1) || (env_quiet && strcmp(env_quiet, "yes") == 0))
                 arg_quiet = 1;
 
@@ -1037,7 +1045,7 @@ int main(int argc, char **argv, char **envp) {
 
         // build /run/firejail directory structure
         preproc_build_firejail_dir();
-        char *container_name = getenv("container");
+        const char *container_name = env_get("container");
         if (!container_name || strcmp(container_name, "firejail")) {
                 lockfd_directory = open(RUN_DIRECTORY_LOCK_FILE, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
                 if (lockfd_directory != -1) {
@@ -1170,6 +1178,9 @@ int main(int argc, char **argv, char **envp) {
 
                                                         drop_privs(1);
                                                         umask(orig_umask);
+
+                                                        // restore original environment variables
+                                                        env_apply_all();
                                                         int rv = system(argv[2]);
                                                         exit(rv);
                                                 }