From: Todd C. Miller <Todd.Miller@courtesan.com>
Date: Thu, 12 Jan 2012 19:54:18 +0000 (-0500)
Subject: Handle different Unix domain socket (actually socketpair) semantics
X-Git-Tag: SUDO_1_7_9~37
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b3fa13bc56f9cf8c9742c2b6cf7241c7ca98521b;p=sudo

Handle different Unix domain socket (actually socketpair) semantics
in BSD vs. Linux. In BSD if one end of the socketpair goes away
select() returns the fd as readable and the read will fail with
ECONNRESET. This doesn't appear to happen on Linux so if we notice
that the monitor process has died when I/O logging is enabled,
behave like the command has exited. This means we log the wait
status of the monitor, not the command, but there is nothing else
we can do at that point. This should only be an issue if SIGKILL
is sent to the monitor process.

--HG--
branch : 1.7
---

diff --git a/exec.c b/exec.c
index 401b71848..8235829cf 100644
--- a/exec.c
+++ b/exec.c
@@ -372,17 +372,23 @@ sudo_execve(path, argv, envp, uid, cstat, dowait, bgmode)
 	if (FD_ISSET(sv[0], fdsr)) {
 	    /* read child status */
 	    n = recv(sv[0], cstat, sizeof(*cstat), 0);
-	    if (n == -1) {
-		if (errno == EINTR)
-		    continue;
+	    if (n != sizeof(*cstat)) {
+		if (n == -1) {
+		    if (errno == EINTR)
+			continue;
 #ifdef _PATH_SUDO_IO_LOGDIR
-		/*
-		 * If not logging I/O we will receive ECONNRESET when
-		 * the command is executed.  It is safe to ignore this.
-		 */
-		if (log_io && errno != EAGAIN) {
-		    cstat->type = CMD_ERRNO;
-		    cstat->val = errno;
+		    /*
+		     * If not logging I/O we will receive ECONNRESET when
+		     * the command is executed.  It is safe to ignore this.
+		     */
+		    if (log_io && errno != EAGAIN) {
+			cstat->type = CMD_ERRNO;
+			cstat->val = errno;
+			break;
+		    }
+		} else {
+		    /* Short read or EOF. */
+		    /* XXX - should set cstat */
 		    break;
 		}
 #endif
@@ -490,9 +496,23 @@ handle_signals(fd, child, cstat)
 #endif
 	    } while (pid == -1 && errno == EINTR);
 	    if (pid == child) {
-		/* If not logging I/O and child has exited we are done. */
 #ifdef _PATH_SUDO_IO_LOGDIR
-		if (!log_io)
+		if (log_io) {
+		    /*
+		     * On BSD we get ECONNRESET on sv[0] if monitor dies
+		     * and select() will return with sv[0] readable.
+		     * On Linux that doesn't appear to happen so we
+		     * treat the monitor dying as a fatal error.
+		     * Note that the wait status we return is that of
+		     * the monitor and not the command; unfortunately
+		     * that is the best that we can do here.
+		     */
+		    if (!WIFSTOPPED(status)) {
+			cstat->type = CMD_WSTATUS;
+			cstat->val = status;
+			return 0;
+		    }
+		} else
 #endif
 		{
 		    if (WIFSTOPPED(status)) {
@@ -522,7 +542,6 @@ handle_signals(fd, child, cstat)
 			return 0;
 		    }
 		}
-		/* Else we get ECONNRESET on sv[0] if child dies. */
 	    }
 	} else {
 #ifdef _PATH_SUDO_IO_LOGDIR
@@ -570,6 +589,7 @@ forward_signals(sock)
 		    tq_remove(&sigfwd_list, sigfwd);
 		    efree(sigfwd);
 		}
+		/* XXX - child (monitor) is dead, we should exit too? */
 	    }
 	    break;
 	}