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- markus@cvs.openbsd.org 2012/06/30 14:35:09 

[sandbox-systrace.c sshd.c]
     fix a during the load of the sandbox policies (child can still make
     the read-syscall and wait forever for systrace-answers) by replacing
     the read/write synchronisation with SIGSTOP/SIGCONT;
     report and help hshoexer@; ok djm@, dtucker@
This commit is contained in:
Darren Tucker 2012-07-02 18:54:31 +10:00
parent ecbf14aa53
commit 3b4b2d3021
3 changed files with 35 additions and 30 deletions
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6
ChangeLog
View File

@ -4,6 +4,12 @@
[ssh_config.5 sshd_config.5]
match the documented MAC order of preference to the actual one;
ok dtucker@
- markus@cvs.openbsd.org 2012/06/30 14:35:09
[sandbox-systrace.c sshd.c]
fix a during the load of the sandbox policies (child can still make
the read-syscall and wait forever for systrace-answers) by replacing
the read/write synchronisation with SIGSTOP/SIGCONT;
report and help hshoexer@; ok djm@, dtucker@
20120629
- OpenBSD CVS Sync

55
sandbox-systrace.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sandbox-systrace.c,v 1.5 2012/06/26 11:02:30 dtucker Exp $ */
/* $OpenBSD: sandbox-systrace.c,v 1.6 2012/06/30 14:35:09 markus Exp $ */
/*
* Copyright (c) 2011 Damien Miller <djm@mindrot.org>
*
@ -24,12 +24,14 @@
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <dev/systrace.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
@ -69,26 +71,21 @@ static const struct sandbox_policy preauth_policy[] = {
};
struct ssh_sandbox {
int child_sock;
int parent_sock;
int systrace_fd;
pid_t child_pid;
void (*osigchld)(int);
};
struct ssh_sandbox *
ssh_sandbox_init(void)
{
struct ssh_sandbox *box;
int s[2];
debug3("%s: preparing systrace sandbox", __func__);
box = xcalloc(1, sizeof(*box));
if (socketpair(AF_UNIX, SOCK_STREAM, 0, s) == -1)
fatal("%s: socketpair: %s", __func__, strerror(errno));
box->child_sock = s[0];
box->parent_sock = s[1];
box->systrace_fd = -1;
box->child_pid = 0;
box->osigchld = signal(SIGCHLD, SIG_IGN);
return box;
}
@ -96,35 +93,38 @@ ssh_sandbox_init(void)
void
ssh_sandbox_child(struct ssh_sandbox *box)
{
char whatever = 0;
close(box->parent_sock);
/* Signal parent that we are ready */
debug3("%s: ready", __func__);
if (atomicio(vwrite, box->child_sock, &whatever, 1) != 1)
fatal("%s: write: %s", __func__, strerror(errno));
/* Wait for parent to signal for us to go */
if (atomicio(read, box->child_sock, &whatever, 1) != 1)
fatal("%s: read: %s", __func__, strerror(errno));
signal(SIGCHLD, box->osigchld);
if (kill(getpid(), SIGSTOP) != 0)
fatal("%s: kill(%d, SIGSTOP)", __func__, getpid());
debug3("%s: started", __func__);
close(box->child_sock);
}
static void
ssh_sandbox_parent(struct ssh_sandbox *box, pid_t child_pid,
const struct sandbox_policy *allowed_syscalls)
{
int dev_systrace, i, j, found;
char whatever = 0;
int dev_systrace, i, j, found, status;
pid_t pid;
struct systrace_policy policy;
/* Wait for the child to send itself a SIGSTOP */
debug3("%s: wait for child %ld", __func__, (long)child_pid);
do {
pid = waitpid(child_pid, &status, WUNTRACED);
} while (pid == -1 && errno == EINTR);
signal(SIGCHLD, box->osigchld);
if (!WIFSTOPPED(status)) {
if (WIFSIGNALED(status))
fatal("%s: child terminated with signal %d",
__func__, WTERMSIG(status));
if (WIFEXITED(status))
fatal("%s: child exited with status %d",
__func__, WEXITSTATUS(status));
fatal("%s: child not stopped", __func__);
}
debug3("%s: child %ld stopped", __func__, (long)child_pid);
box->child_pid = child_pid;
close(box->child_sock);
/* Wait for child to signal that it is ready */
if (atomicio(read, box->parent_sock, &whatever, 1) != 1)
fatal("%s: read: %s", __func__, strerror(errno));
debug3("%s: child %ld ready", __func__, (long)child_pid);
/* Set up systracing of child */
if ((dev_systrace = open("/dev/systrace", O_RDONLY)) == -1)
@ -175,9 +175,8 @@ ssh_sandbox_parent(struct ssh_sandbox *box, pid_t child_pid,
/* Signal the child to start running */
debug3("%s: start child %ld", __func__, (long)child_pid);
if (atomicio(vwrite, box->parent_sock, &whatever, 1) != 1)
fatal("%s: write: %s", __func__, strerror(errno));
close(box->parent_sock);
if (kill(box->child_pid, SIGCONT) != 0)
fatal("%s: kill(%d, SIGCONT)", __func__, box->child_pid);
}
void

4
sshd.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sshd.c,v 1.391 2012/05/13 01:42:32 dtucker Exp $ */
/* $OpenBSD: sshd.c,v 1.392 2012/06/30 14:35:09 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -643,9 +643,9 @@ privsep_preauth(Authctxt *authctxt)
} else if (pid != 0) {
debug2("Network child is on pid %ld", (long)pid);
pmonitor->m_pid = pid;
if (box != NULL)
ssh_sandbox_parent_preauth(box, pid);
pmonitor->m_pid = pid;
monitor_child_preauth(authctxt, pmonitor);
/* Sync memory */