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Fix MAX_UNAUTH_CLIENTS regression

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Since re-exec change in 2022.82 Dropbear count
treat authenticated sessions towards the unauthenticated
session limit. This is fixed by passing the childpipe FD
through to the re-execed process.
This commit is contained in:
Matt Johnston 2022-06-08 21:26:20 +08:00
parent f2318d831b
commit 544f28a051
3 changed files with 26 additions and 15 deletions
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5
runopts.h
View File

@ -79,8 +79,9 @@ typedef struct svr_runopts {
char *addresses[DROPBEAR_MAX_PORTS];
int inetdmode;
/* Hidden "-2" flag indicates it's re-executing itself */
int reexec_child;
/* Hidden "-2 childpipe_fd" flag indicates it's re-executing itself,
stores the childpipe preauth file descriptor. Set to -1 otherwise. */
int reexec_childpipe;
/* Flags indicating whether to use ipv4 and ipv6 */
/* not used yet

21
svr-main.c
View File

@ -71,7 +71,7 @@ int main(int argc, char ** argv)
#endif
#if DROPBEAR_DO_REEXEC
if (svr_opts.reexec_child) {
if (svr_opts.reexec_childpipe >= 0) {
#ifdef PR_SET_NAME
/* Fix the "Name:" in /proc/pid/status, otherwise it's
a FD number from fexecve.
@ -102,7 +102,7 @@ static void main_inetd() {
seedrandom();
if (!svr_opts.reexec_child) {
if (svr_opts.reexec_childpipe < 0) {
/* In case our inetd was lax in logging source addresses */
get_socket_address(0, NULL, NULL, &host, &port, 0);
dropbear_log(LOG_INFO, "Child connection from %s:%s", host, port);
@ -115,10 +115,8 @@ static void main_inetd() {
setsid();
}
/* Start service program
* -1 is a dummy childpipe, just something we can close() without
* mattering. */
svr_session(0, -1);
/* -1 for childpipe in the inetd case is discarded */
svr_session(0, svr_opts.reexec_childpipe);
/* notreached */
}
@ -347,9 +345,10 @@ static void main_noinetd(int argc, char ** argv, const char* multipath) {
if (execfd >= 0) {
#if DROPBEAR_DO_REEXEC
/* Add "-2" to the args and re-execute ourself. */
char **new_argv = m_malloc(sizeof(char*) * (argc+3));
int pos0 = 0, new_argc = argc+1;
/* Add "-2 childpipe[1]" to the args and re-execute ourself. */
char **new_argv = m_malloc(sizeof(char*) * (argc+4));
char buf[10];
int pos0 = 0, new_argc = argc+2;
/* We need to specially handle "dropbearmulti dropbear". */
if (multipath) {
@ -359,7 +358,9 @@ static void main_noinetd(int argc, char ** argv, const char* multipath) {
}
memcpy(&new_argv[pos0], argv, sizeof(char*) * argc);
new_argv[new_argc-1] = "-2";
new_argv[new_argc-2] = "-2";
snprintf(buf, sizeof(buf), "%d", childpipe[1]);
new_argv[new_argc-1] = buf;
new_argv[new_argc] = NULL;
if ((dup2(childsock, STDIN_FILENO) < 0)) {

15
svr-runopts.c
View File

@ -138,6 +138,7 @@ void svr_getopts(int argc, char ** argv) {
char* keepalive_arg = NULL;
char* idle_timeout_arg = NULL;
char* maxauthtries_arg = NULL;
char* reexec_fd_arg = NULL;
char* keyfile = NULL;
char c;
#if DROPBEAR_PLUGIN
@ -175,6 +176,7 @@ void svr_getopts(int argc, char ** argv) {
svr_opts.pubkey_plugin_options = NULL;
#endif
svr_opts.pass_on_env = 0;
svr_opts.reexec_childpipe = -1;
#ifndef DISABLE_ZLIB
opts.compress_mode = DROPBEAR_COMPRESS_DELAYED;
@ -250,12 +252,12 @@ void svr_getopts(int argc, char ** argv) {
#if DROPBEAR_DO_REEXEC && NON_INETD_MODE
/* For internal use by re-exec */
case '2':
svr_opts.reexec_child = 1;
next = &reexec_fd_arg;
break;
#endif
case 'p':
nextisport = 1;
break;
nextisport = 1;
break;
case 'P':
next = &svr_opts.pidfile;
break;
@ -426,6 +428,13 @@ void svr_getopts(int argc, char ** argv) {
dropbear_log(LOG_INFO, "Forced command set to '%s'", svr_opts.forced_command);
}
if (reexec_fd_arg) {
if (m_str_to_uint(reexec_fd_arg, &svr_opts.reexec_childpipe) == DROPBEAR_FAILURE
|| svr_opts.reexec_childpipe < 0) {
dropbear_exit("Bad -2");
}
}
#if INETD_MODE
if (svr_opts.inetdmode && (
opts.usingsyslog == 0