From 9d55ae892f82a792fffccf6ec902d3f452807bb2 Mon Sep 17 00:00:00 2001
From: "Todd C. Miller" <Todd.Miller@sudo.ws>
Date: Wed, 22 Mar 2023 12:44:41 -0600
Subject: [PATCH] exec_pty: always copy the terminal settings from /dev/tty the
 pty. Previously, we only did this when running in the foreground but this can
 cause problems when running a program that reads the terminal settings or
 window size in the background.  If sudo is running in the background, the
 terminal settings will be updated if it transitions to the foreground
 process. Based on a suggestion from From Duncan Overbruck.

---
 src/exec_pty.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/src/exec_pty.c b/src/exec_pty.c
index 4ca44b814..b4af177b3 100644
--- a/src/exec_pty.c
+++ b/src/exec_pty.c
@@ -161,7 +161,7 @@ check_foreground(struct exec_closure *ec)
 	if ((ret = tcgetpgrp(io_fds[SFD_USERTTY])) != -1) {
 	    foreground = ret == ec->ppgrp;
 	    if (foreground && !tty_initialized) {
-		/* Lazily initialize the pty if needed. */
+		/* Re-initialize the pty if needed. */
 		if (sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER]))
 		    tty_initialized = true;
 	    }
@@ -1233,20 +1233,23 @@ exec_pty(struct command_details *details, struct command_status *cstat)
 	}
     }
 
+    /*
+     * Copy terminal settings from user tty -> pty.  If sudo is a
+     * background process, we'll re-init the pty when foregrounded.
+     */
+    if (!sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER])) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+	    "%s: unable to copy terminal settings to pty", __func__);
+	foreground = false;
+    }
+
+    /* Start in raw mode unless part of a pipeline or backgrounded. */
     if (foreground) {
-	/* Copy terminal attrs from user tty -> pty. */
-	if (!sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER])) {
-            sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
-                "%s: unable to copy terminal settings to pty", __func__);
-	    foreground = false;
-	} else {
-	    /* Start in raw mode unless part of a pipeline or backgrounded. */
-	    if (!pipeline && !ISSET(details->flags, CD_EXEC_BG)) {
-		if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
-		    ttymode = TERM_RAW;
-	    }
-	    tty_initialized = true;
+	if (!pipeline && !ISSET(details->flags, CD_EXEC_BG)) {
+	    if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
+		ttymode = TERM_RAW;
 	}
+	tty_initialized = true;
     }
 
     /*
@@ -1412,6 +1415,9 @@ sync_ttysize(struct exec_closure *ec)
 
     if (ioctl(io_fds[SFD_USERTTY], TIOCGWINSZ, &wsize) == 0) {
 	if (wsize.ws_row != ec->rows || wsize.ws_col != ec->cols) {
+	    sudo_debug_printf(SUDO_DEBUG_INFO, "%s: %hd x %hd -> %hd x %hd",
+		__func__, ec->rows, ec->cols, wsize.ws_row, wsize.ws_col);
+
 	    /* Log window change event. */
 	    log_winchange(ec, wsize.ws_row, wsize.ws_col);