Forbid control chars in names

2 files changed, 20 insertions, 7 deletions

diff --git a/src/firejail/main.c b/src/firejail/main.c
index 0e5363cb0..62035ff04 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -1575,7 +1575,7 @@ int main(int argc, char **argv, char **envp) {
                                 exit(1);
                         }
                         invalid_filename(arg_tracefile, 0); // no globbing
-                        if (strstr(arg_tracefile, "..")) {
+                        if (strstr(arg_tracefile, "..") || has_cntrl_chars(arg_tracefile)) {
                                 fprintf(stderr, "Error: invalid file name %s\n", arg_tracefile);
                                 exit(1);
                         }
@@ -2186,18 +2186,31 @@ int main(int argc, char **argv, char **envp) {
                                 fprintf(stderr, "Error: please provide a name for sandbox\n");
                                 return 1;
                         }
-                        if (invalid_name(cfg.name)) {
+                        if (invalid_name(cfg.name) || has_cntrl_chars(cfg.name)) {
                                 fprintf(stderr, "Error: invalid sandbox name\n");
                                 return 1;
                         }
                 }
                 else if (strncmp(argv[i], "--hostname=", 11) == 0) {
                         cfg.hostname = argv[i] + 11;
-                        if (strlen(cfg.hostname) == 0) {
-                                fprintf(stderr, "Error: please provide a hostname for sandbox\n");
+                        size_t len = strlen(cfg.hostname);
+                        if (len == 0 || len > 253) {
+                                fprintf(stderr, "Error: please provide a valid hostname for sandbox, with maximum length of 253 ASCII characters\n");
                                 return 1;
                         }
-                        if (invalid_name(cfg.hostname)) {
+                        int invalid = invalid_name(cfg.hostname);
+                        char* hostname = cfg.hostname;
+                        while (*hostname && !invalid) {
+                                invalid = invalid || !(
+                                                (*hostname >= 'a' && *hostname <= 'z') ||
+                                                (*hostname >= 'A' && *hostname <= 'Z') ||
+                                                (*hostname >= '0' && *hostname <= '9') ||
+                                                (*hostname == '-' || *hostname == '.'));
+                                hostname++;
+                        }
+                        invalid = invalid || cfg.hostname[0] == '-'; // must not start with -
+                        invalid = invalid || cfg.hostname[len - 1] == '-'; // must not end with -
+                        if (invalid) {
                                 fprintf(stderr, "Error: invalid hostname\n");
                                 return 1;
                         }
diff --git a/src/firejail/output.c b/src/firejail/output.c
index 57679901f..687aaba9c 100644
--- a/src/firejail/output.c
+++ b/src/firejail/output.c
@@ -66,8 +66,8 @@ void check_output(int argc, char **argv) {
         }
 
         // do not accept directories, links, and files with ".."
-        if (strstr(outfile, "..") || is_link(outfile) || is_dir(outfile)) {
-                fprintf(stderr, "Error: invalid output file. Links, directories and files with \"..\" are not allowed.\n");
+        if (strstr(outfile, "..") || is_link(outfile) || is_dir(outfile) || has_cntrl_chars(outfile)) {
+                fprintf(stderr, "Error: invalid output file. Links, directories, files with \"..\" and control characters in filenames are not allowed.\n");
                 exit(1);
         }