- (djm) [Makefile.in configure.ac sandbox-capsicum.c sandbox-darwin.c]

   [sandbox-null.c sandbox-rlimit.c sandbox-seccomp-filter.c]
   [sandbox-systrace.c ssh-sandbox.h sshd.c] Support preauth sandboxing
   using the Capsicum API introduced in FreeBSD 10. Patch by Dag-Erling
   Smorgrav, updated by Loganaden Velvindron @ AfriNIC; ok dtucker@

1 files changed, 118 insertions, 0 deletions

diff --git a/sandbox-capsicum.c b/sandbox-capsicum.c
new file mode 100644
index 000000000..5853a13ef
--- /dev/null
+++ b/sandbox-capsicum.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2011 Dag-Erling Smorgrav
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "includes.h"
+
+#ifdef SANDBOX_CAPSICUM
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/capability.h>
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "monitor.h"
+#include "ssh-sandbox.h"
+#include "xmalloc.h"
+
+/*
+ * Capsicum sandbox that sets zero nfiles, nprocs and filesize rlimits,
+ * limits rights on stdout, stdin, stderr, monitor and switches to
+ * capability mode.
+ */
+
+struct ssh_sandbox {
+        struct monitor *monitor;
+        pid_t child_pid;
+};
+
+struct ssh_sandbox *
+ssh_sandbox_init(struct monitor *monitor)
+{
+        struct ssh_sandbox *box;
+
+        /*
+         * Strictly, we don't need to maintain any state here but we need
+         * to return non-NULL to satisfy the API.
+         */
+        debug3("%s: preparing capsicum sandbox", __func__);
+        box = xcalloc(1, sizeof(*box));
+        box->monitor = monitor;
+        box->child_pid = 0;
+
+        return box;
+}
+
+void
+ssh_sandbox_child(struct ssh_sandbox *box)
+{
+        struct rlimit rl_zero;
+        cap_rights_t rights;
+
+        rl_zero.rlim_cur = rl_zero.rlim_max = 0;
+
+        if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1)
+                fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s",
+                        __func__, strerror(errno));
+        if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1)
+                fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s",
+                        __func__, strerror(errno));
+        if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1)
+                fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s",
+                        __func__, strerror(errno));
+
+        cap_rights_init(&rights);
+
+        if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS)
+                fatal("can't limit stdin: %m");
+        if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS)
+                fatal("can't limit stdin: %m");
+        if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS)
+                fatal("can't limit stdin: %m");
+
+        cap_rights_init(&rights, CAP_READ, CAP_WRITE);
+        if (cap_rights_limit(box->monitor->m_recvfd, &rights) == -1)
+                fatal("%s: failed to limit the network socket", __func__);
+        cap_rights_init(&rights, CAP_WRITE);
+        if (cap_rights_limit(box->monitor->m_log_sendfd, &rights) == -1)
+                fatal("%s: failed to limit the logging socket", __func__);
+        if (cap_enter() != 0 && errno != ENOSYS)
+                fatal("%s: failed to enter capability mode", __func__);
+
+}
+
+void
+ssh_sandbox_parent_finish(struct ssh_sandbox *box)
+{
+        free(box);
+        debug3("%s: finished", __func__);
+}
+
+void
+ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
+{
+        box->child_pid = child_pid;
+}
+
+#endif /* SANDBOX_CAPSICUM */