Attachment 2981 Details for Bug 2718 – sftp idle timeout

[patch] sftp idle timeout

0001-SFTP-idle-timeout.patch (text/plain), 4.03 KB, created by Tomas Kuthan on 2017-05-22 22:50:28 AEST

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Creator: Tomas Kuthan

Created: 2017-05-22 22:50:28 AEST

Size: 4.03 KB

patch

obsolete

>From 6c4758e3e97c040773fb6eee38118f85f7582c7e Mon Sep 17 00:00:00 2001
>From: Tomas Kuthan <tkuthan@gmail.com>
>Date: Fri, 19 May 2017 10:25:18 +0200
>Subject: [PATCH 1/2] SFTP idle timeout
>
>Implements new sftp-server option '-t idle_timeout'. When there is no
>user activity for idle_timeout seconds, sftp session is forcibly closed
>by the server. By default there is no time limit.
>---
> sftp-server.8 |  6 ++++++
> sftp-server.c | 35 +++++++++++++++++++++++++++++++++--
> 2 files changed, 39 insertions(+), 2 deletions(-)
>
>diff --git a/sftp-server.8 b/sftp-server.8
>index c117398..a3f22de 100644
>--- a/sftp-server.8
>+++ b/sftp-server.8
>@@ -37,6 +37,7 @@
> .Op Fl l Ar log_level
> .Op Fl P Ar blacklisted_requests
> .Op Fl p Ar whitelisted_requests
>+.Op Fl t Ar idle_timeout
> .Op Fl u Ar umask
> .Ek
> .Nm
>@@ -133,6 +134,11 @@ Places this instance of
> into a read-only mode.
> Attempts to open files for writing, as well as other operations that change
> the state of the filesystem, will be denied.
>+.It Fl t Ar idle_timeout
>+Sets idle timeout for sftp sessions. When there is no client request for
>+.Pa idle_timeout
>+seconds, the session is forcibly closed by the server.
>+The default value 0 means no time limit.
> .It Fl u Ar umask
> Sets an explicit
> .Xr umask 2
>diff --git a/sftp-server.c b/sftp-server.c
>index df0fb50..6d7e355 100644
>--- a/sftp-server.c
>+++ b/sftp-server.c
>@@ -39,6 +39,7 @@
> #include <time.h>
> #include <unistd.h>
> #include <stdarg.h>
>+#include <signal.h>
> 
> #include "xmalloc.h"
> #include "sshbuf.h"
>@@ -83,6 +84,9 @@ struct Stat {
> 	Attrib attrib;
> };
> 
>+/* sftp idle timeout */
>+static volatile sig_atomic_t g_timed_out = 0;
>+
> /* Packet handlers */
> static void process_open(u_int32_t id);
> static void process_close(u_int32_t id);
>@@ -1490,17 +1494,24 @@ sftp_server_usage(void)
> 	fprintf(stderr,
> 	    "usage: %s [-ehR] [-d start_directory] [-f log_facility] "
> 	    "[-l log_level]\n\t[-P blacklisted_requests] "
>-	    "[-p whitelisted_requests] [-u umask]\n"
>+	    "[-p whitelisted_requests] [-t idle_timeout] [-u umask]\n"
> 	    "       %s -Q protocol_feature\n",
> 	    __progname, __progname);
> 	exit(1);
> }
> 
>+static void
>+sftp_alarm_handler(int sig)
>+{
>+	g_timed_out = 1;
>+}
>+
> int
> sftp_server_main(int argc, char **argv, struct passwd *user_pw)
> {
> 	fd_set *rset, *wset;
> 	int i, r, in, out, max, ch, skipargs = 0, log_stderr = 0;
>+	int timeout = 0;
> 	ssize_t len, olen, set_size;
> 	SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
> 	char *cp, *homedir = NULL, buf[4*4096];
>@@ -1516,7 +1527,7 @@ sftp_server_main(int argc, char **argv, struct passwd *user_pw)
> 	pw = pwcopy(user_pw);
> 
> 	while (!skipargs && (ch = getopt(argc, argv,
>-	    "d:f:l:P:p:Q:u:cehR")) != -1) {
>+	    "d:f:l:P:p:Q:u:t:cehR")) != -1) {
> 		switch (ch) {
> 		case 'Q':
> 			if (strcasecmp(optarg, "requests") != 0) {
>@@ -1576,6 +1587,15 @@ sftp_server_main(int argc, char **argv, struct passwd *user_pw)
> 				fatal("Invalid umask \"%s\"", optarg);
> 			(void)umask((mode_t)mask);
> 			break;
>+		case 't':
>+			timeout = atoi(optarg);
>+			if (timeout <= 0) {
>+				/* -t0 is redundant, though technically valid */
>+				error("Invalid timeout: \"%s\". Ignored.",
>+				    optarg);
>+				timeout = 0;
>+			}
>+			break;
> 		case 'h':
> 		default:
> 			sftp_server_usage();
>@@ -1639,6 +1659,7 @@ sftp_server_main(int argc, char **argv, struct passwd *user_pw)
> 	}
> 
> 	set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
>+	signal(SIGALRM, sftp_alarm_handler);
> 	for (;;) {
> 		memset(rset, 0, set_size);
> 		memset(wset, 0, set_size);
>@@ -1660,13 +1681,23 @@ sftp_server_main(int argc, char **argv, struct passwd *user_pw)
> 		if (olen > 0)
> 			FD_SET(out, wset);
> 
>+		if (timeout > 0)
>+			alarm(timeout);
>+
> 		if (select(max+1, rset, wset, NULL, NULL) < 0) {
>+			if (g_timed_out){
>+				debug("SFTP idle timeout, closing session.");
>+				sftp_server_cleanup_exit(3);
>+			}
> 			if (errno == EINTR)
> 				continue;
> 			error("select: %s", strerror(errno));
> 			sftp_server_cleanup_exit(2);
> 		}
> 
>+		if (timeout > 0)
>+			alarm(0);
>+
> 		/* copy stdin to iqueue */
> 		if (FD_ISSET(in, rset)) {
> 			len = read(in, buf, sizeof buf);
>-- 
>2.7.4
>

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