X-Git-Url: https://ruderich.org/simon/gitweb/?p=ptyas%2Fptyas.git;a=blobdiff_plain;f=ptyas.c;h=dc5f3de85e5ba2646652d2440c1504f8c5a956a4;hp=d87ae34738e2f8321f6df618b81737db894d4365;hb=a340b52624733c23fe40d61d181916e4bd778945;hpb=0178c35881746d366a225b932f519f992035f24c

diff --git a/ptyas.c b/ptyas.c
index d87ae34..dc5f3de 100644
--- a/ptyas.c
+++ b/ptyas.c
@@ -2,20 +2,20 @@
  * Run the login shell or command as the given user in a new pty to prevent
  * terminal injection attacks.
  *
- * Copyright (C) 2016-2018  Simon Ruderich
+ * Copyright (C) 2016-2019  Simon Ruderich
  *
  * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
+ * it under the terms of the GNU Affero General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
+ * GNU Affero General Public License for more details.
  *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 #define _GNU_SOURCE
@@ -121,7 +121,7 @@ static void drop_privileges_or_die(uid_t uid, gid_t gid) {
         die("setgroups");
     }
     if (getgroups(0, NULL) != 0) {
-        die_fmt("failed to drop all supplementary groups");
+        die_fmt("failed to drop all supplementary groups\n");
     }
 
     /* Dropping groups may require privileges, do that first. */
@@ -145,12 +145,12 @@ static void drop_privileges_or_die(uid_t uid, gid_t gid) {
         }
         if (       uid != ruid || uid != euid || uid != suid
                 || gid != rgid || gid != egid || gid != sgid) {
-            die_fmt("failed to drop privileges");
+            die_fmt("failed to drop privileges\n");
         }
     }
     /* Just to be safe. */
     if (setuid(0) != -1) {
-        die_fmt("failed to drop privileges (setuid)");
+        die_fmt("failed to drop privileges (setuid)\n");
     }
 }
 
@@ -286,6 +286,28 @@ static void sigchld_handler(int signal) {
     }
 }
 
+/*
+ * SIGWINCH handler to handle resizes of the outer terminal.
+ *
+ * Errors are ignored without message because printing in signal handlers is
+ * problematic (no FILE * usable due to locks) and there's not much we can do
+ * at this point.
+ */
+static int sigwinch_ctty = -1;
+static int sigwinch_slave = -1;
+
+static void sigwinch_handler(int signal) {
+    (void)signal;
+
+    struct winsize size;
+    if (ioctl(sigwinch_ctty, TIOCGWINSZ, &size) == -1) {
+        return;
+    }
+    if (ioctl(sigwinch_slave, TIOCSWINSZ, &size) == -1) {
+        return;
+    }
+}
+
 
 int main(int argc, char **argv) {
     char *exec_argv_shell[] = { NULL, NULL }; /* filled below */
@@ -422,7 +444,18 @@ int main(int argc, char **argv) {
         }
         quit_with_matching_code(status);
     }
-    close_or_die(pty_slave);
+    /* Don't close pty_slave here as it's used in sigwinch_handler(). */
+
+    sigwinch_ctty = ctty;
+    sigwinch_slave = pty_slave;
+
+    struct sigaction action_sigwinch = {
+        .sa_handler = sigwinch_handler,
+    };
+    sigemptyset(&action_sigwinch.sa_mask);
+    if (sigaction(SIGWINCH, &action_sigwinch, NULL) != 0) {
+        die("sigaction SIGWINCH");
+    }
 
     pid_to_wait_for = pid;
     struct sigaction action_sigchld = {