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upstream: Split per-connection sshd-session binary

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This splits the user authentication code from the sshd-session
binary into a separate sshd-auth binary. This will be executed by
sshd-session to complete the user authentication phase of the
protocol only.

Splitting this code into a separate binary ensures that the crucial
pre-authentication attack surface has an entirely disjoint address
space from the code used for the rest of the connection. It also
yields a small runtime memory saving as the authentication code will
be unloaded after thhe authentication phase completes.

Joint work with markus@ feedback deraadt@

Tested in snaps since last week

OpenBSD-Commit-ID: 9c3b2087ae08626ec31b4177b023db600e986d9c
This commit is contained in:
djm@openbsd.org 2024-10-14 01:57:50 +00:00 committed by Damien Miller
parent fe6c6330c1
commit 6072e4c938
No known key found for this signature in database
22 changed files with 1192 additions and 632 deletions
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27
Makefile.in
View File

@ -25,6 +25,7 @@ ASKPASS_PROGRAM=$(libexecdir)/ssh-askpass
SFTP_SERVER=$(libexecdir)/sftp-server
SSH_KEYSIGN=$(libexecdir)/ssh-keysign
SSHD_SESSION=$(libexecdir)/sshd-session
SSHD_AUTH=$(libexecdir)/sshd-auth
SSH_PKCS11_HELPER=$(libexecdir)/ssh-pkcs11-helper
SSH_SK_HELPER=$(libexecdir)/ssh-sk-helper
PRIVSEP_PATH=@PRIVSEP_PATH@
@ -71,7 +72,7 @@ MKDIR_P=@MKDIR_P@
.SUFFIXES: .lo
TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) sshd-session$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-keysign${EXEEXT} ssh-pkcs11-helper$(EXEEXT) ssh-agent$(EXEEXT) scp$(EXEEXT) sftp-server$(EXEEXT) sftp$(EXEEXT) ssh-sk-helper$(EXEEXT)
TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) sshd-session$(EXEEXT) sshd-auth$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-keysign${EXEEXT} ssh-pkcs11-helper$(EXEEXT) ssh-agent$(EXEEXT) scp$(EXEEXT) sftp-server$(EXEEXT) sftp$(EXEEXT) ssh-sk-helper$(EXEEXT)
XMSS_OBJS=\
ssh-xmss.o \
@ -137,9 +138,22 @@ SSHD_SESSION_OBJS=sshd-session.o auth-rhosts.o auth-passwd.o \
auth2-gss.o gss-serv.o gss-serv-krb5.o \
loginrec.o auth-pam.o auth-shadow.o auth-sia.o \
sftp-server.o sftp-common.o \
sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \
sandbox-seccomp-filter.o sandbox-capsicum.o sandbox-pledge.o \
sandbox-solaris.o uidswap.o $(SKOBJS)
uidswap.o $(SKOBJS)
SSHD_AUTH_OBJS=sshd-auth.o \
auth2-methods.o \
auth-rhosts.o auth-passwd.o sshpty.o sshlogin.o servconf.o \
serverloop.o auth.o auth2.o auth-options.o session.o auth2-chall.o \
groupaccess.o auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \
auth2-none.o auth2-passwd.o auth2-pubkey.o auth2-pubkeyfile.o \
auth2-gss.o gss-serv.o gss-serv-krb5.o \
monitor_wrap.o auth-krb5.o \
audit.o audit-bsm.o audit-linux.o platform.o \
loginrec.o auth-pam.o auth-shadow.o auth-sia.o \
sandbox-null.o sandbox-rlimit.o sandbox-darwin.o \
sandbox-seccomp-filter.o sandbox-capsicum.o sandbox-solaris.o \
sftp-server.o sftp-common.o \
uidswap.o $(SKOBJS)
SFTP_CLIENT_OBJS=sftp-common.o sftp-client.o sftp-glob.o
@ -220,6 +234,9 @@ sshd$(EXEEXT): libssh.a $(LIBCOMPAT) $(SSHDOBJS)
sshd-session$(EXEEXT): libssh.a $(LIBCOMPAT) $(SSHD_SESSION_OBJS)
$(LD) -o $@ $(SSHD_SESSION_OBJS) $(LDFLAGS) -lssh -lopenbsd-compat $(SSHDLIBS) $(LIBS) $(GSSLIBS) $(K5LIBS) $(CHANNELLIBS)
sshd-auth$(EXEEXT): libssh.a $(LIBCOMPAT) $(SSHD_AUTH_OBJS)
$(LD) -o $@ $(SSHD_AUTH_OBJS) $(LDFLAGS) -lssh -lopenbsd-compat $(SSHDLIBS) $(LIBS) $(GSSLIBS) $(K5LIBS) $(CHANNELLIBS)
scp$(EXEEXT): $(LIBCOMPAT) libssh.a $(SCP_OBJS)
$(LD) -o $@ $(SCP_OBJS) $(LDFLAGS) -lssh -lopenbsd-compat $(LIBS)
@ -411,6 +428,7 @@ install-files:
$(INSTALL) -m 0755 $(STRIP_OPT) ssh-keyscan$(EXEEXT) $(DESTDIR)$(bindir)/ssh-keyscan$(EXEEXT)
$(INSTALL) -m 0755 $(STRIP_OPT) sshd$(EXEEXT) $(DESTDIR)$(sbindir)/sshd$(EXEEXT)
$(INSTALL) -m 0755 $(STRIP_OPT) sshd-session$(EXEEXT) $(DESTDIR)$(SSHD_SESSION)$(EXEEXT)
$(INSTALL) -m 0755 $(STRIP_OPT) sshd-auth$(EXEEXT) $(DESTDIR)$(SSHD_AUTH)$(EXEEXT)
$(INSTALL) -m 4711 $(STRIP_OPT) ssh-keysign$(EXEEXT) $(DESTDIR)$(SSH_KEYSIGN)$(EXEEXT)
$(INSTALL) -m 0755 $(STRIP_OPT) ssh-pkcs11-helper$(EXEEXT) $(DESTDIR)$(SSH_PKCS11_HELPER)$(EXEEXT)
$(INSTALL) -m 0755 $(STRIP_OPT) ssh-sk-helper$(EXEEXT) $(DESTDIR)$(SSH_SK_HELPER)$(EXEEXT)
@ -754,6 +772,7 @@ interop-tests t-exec file-tests extra-tests: regress-prep regress-binaries $(TAR
TEST_SSH_SSH="$(BUILDDIR)/ssh" \
TEST_SSH_SSHD="$(BUILDDIR)/sshd" \
TEST_SSH_SSHD_SESSION="$(BUILDDIR)/sshd-session" \
TEST_SSH_SSHD_AUTH="$(BUILDDIR)/sshd-auth" \
TEST_SSH_SSHAGENT="$(BUILDDIR)/ssh-agent" \
TEST_SSH_SSHADD="$(BUILDDIR)/ssh-add" \
TEST_SSH_SSHKEYGEN="$(BUILDDIR)/ssh-keygen" \

4
log.c
View File

@ -460,9 +460,9 @@ sshlogv(const char *file, const char *func, int line, int showfunc,
if (nlog_verbose == 0 && level > log_level)
return;
snprintf(tag, sizeof(tag), "%.48s:%.48s():%d (pid=%ld)",
snprintf(tag, sizeof(tag), "%.48s:%.48s():%d (bin=%s, pid=%ld)",
(cp = strrchr(file, '/')) == NULL ? file : cp + 1, func, line,
(long)getpid());
argv0 == NULL ? "UNKNOWN" : argv0, (long)getpid());
for (i = 0; i < nlog_verbose; i++) {
if (match_pattern_list(tag, log_verbose[i], 0) == 1) {
forced = 1;

107
monitor.c
View File

@ -105,7 +105,9 @@ static Gssctxt *gsscontext = NULL;
/* Imports */
extern ServerOptions options;
extern u_int utmp_len;
extern struct sshbuf *cfg;
extern struct sshbuf *loginmsg;
extern struct include_list includes;
extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
/* State exported from the child */
@ -126,6 +128,7 @@ int mm_answer_keyverify(struct ssh *, int, struct sshbuf *);
int mm_answer_pty(struct ssh *, int, struct sshbuf *);
int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *);
int mm_answer_term(struct ssh *, int, struct sshbuf *);
int mm_answer_state(struct ssh *, int, struct sshbuf *);
#ifdef USE_PAM
int mm_answer_pam_start(struct ssh *, int, struct sshbuf *);
@ -184,6 +187,7 @@ static int monitor_read(struct ssh *, struct monitor *, struct mon_table *,
static int monitor_read_log(struct monitor *);
struct mon_table mon_dispatch_proto20[] = {
{MONITOR_REQ_STATE, MON_ONCE, mm_answer_state},
#ifdef WITH_OPENSSL
{MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
#endif
@ -219,6 +223,7 @@ struct mon_table mon_dispatch_proto20[] = {
};
struct mon_table mon_dispatch_postauth20[] = {
{MONITOR_REQ_STATE, MON_ONCE, mm_answer_state},
#ifdef WITH_OPENSSL
{MONITOR_REQ_MODULI, 0, mm_answer_moduli},
#endif
@ -284,7 +289,8 @@ monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
authctxt->loginmsg = loginmsg;
mon_dispatch = mon_dispatch_proto20;
/* Permit requests for moduli and signatures */
/* Permit requests for state, moduli and signatures */
monitor_permit(mon_dispatch, MONITOR_REQ_STATE, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
@ -405,6 +411,7 @@ monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
mon_dispatch = mon_dispatch_postauth20;
/* Permit requests for moduli and signatures */
monitor_permit(mon_dispatch, MONITOR_REQ_STATE, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
@ -462,7 +469,8 @@ monitor_read_log(struct monitor *pmonitor)
/* Log it */
if (log_level_name(level) == NULL)
fatal_f("invalid log level %u (corrupted message?)", level);
sshlogdirect(level, forced, "%s [preauth]", msg);
sshlogdirect(level, forced, "%s [%s]", msg,
mon_dispatch == mon_dispatch_postauth20 ? "postauth" : "preauth");
sshbuf_free(logmsg);
free(msg);
@ -568,6 +576,82 @@ monitor_reset_key_state(void)
hostbased_chost = NULL;
}
int
mm_answer_state(struct ssh *ssh, int sock, struct sshbuf *m)
{
struct sshbuf *inc = NULL, *hostkeys = NULL;
struct sshbuf *opts = NULL, *confdata = NULL;
struct include_item *item = NULL;
int postauth;
int r;
sshbuf_reset(m);
debug_f("config len %zu", sshbuf_len(cfg));
if ((m = sshbuf_new()) == NULL ||
(inc = sshbuf_new()) == NULL ||
(opts = sshbuf_new()) == NULL ||
(confdata = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
/* XXX unneccessary? */
/* pack includes into a string */
TAILQ_FOREACH(item, &includes, entry) {
if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
(r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
(r = sshbuf_put_stringb(inc, item->contents)) != 0)
fatal_fr(r, "compose includes");
}
hostkeys = pack_hostkeys();
/*
* Protocol from monitor to unpriv privsep process:
* string configuration
* uint64 timing_secret XXX move delays to monitor and remove
* string host_keys[] {
* string public_key
* string certificate
* }
* string server_banner
* string client_banner
* string included_files[] {
* string selector
* string filename
* string contents
* }
* string configuration_data (postauth)
* string keystate (postauth)
* string authenticated_user (postauth)
* string session_info (postauth)
* string authopts (postauth)
*/
if ((r = sshbuf_put_stringb(m, cfg)) != 0 ||
(r = sshbuf_put_u64(m, options.timing_secret)) != 0 ||
(r = sshbuf_put_stringb(m, hostkeys)) != 0 ||
(r = sshbuf_put_stringb(m, ssh->kex->server_version)) != 0 ||
(r = sshbuf_put_stringb(m, ssh->kex->client_version)) != 0 ||
(r = sshbuf_put_stringb(m, inc)) != 0)
fatal_fr(r, "compose config");
postauth = (authctxt && authctxt->pw && authctxt->authenticated);
if (postauth) {
/* XXX shouldn't be reachable */
fatal_f("internal error: called in postauth");
}
sshbuf_free(inc);
sshbuf_free(opts);
sshbuf_free(confdata);
mm_request_send(sock, MONITOR_ANS_STATE, m);
debug3_f("done");
return (0);
}
#ifdef WITH_OPENSSL
int
mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m)
@ -613,24 +697,27 @@ int
mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
{
extern int auth_sock; /* XXX move to state struct? */
struct sshkey *key;
struct sshkey *pubkey, *key;
struct sshbuf *sigbuf = NULL;
u_char *p = NULL, *signature = NULL;
char *alg = NULL;
size_t datlen, siglen, alglen;
int r, is_proof = 0;
u_int keyid, compat;
size_t datlen, siglen;
int r, is_proof = 0, keyid;
u_int compat;
const char proof_req[] = "hostkeys-prove-00@openssh.com";
debug3_f("entering");
if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
if ((r = sshkey_froms(m, &pubkey)) != 0 ||
(r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
(r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 ||
(r = sshbuf_get_cstring(m, &alg, NULL)) != 0 ||
(r = sshbuf_get_u32(m, &compat)) != 0)
fatal_fr(r, "parse");
if (keyid > INT_MAX)
fatal_f("invalid key ID");
if ((keyid = get_hostkey_index(pubkey, 1, ssh)) == -1)
fatal_f("unknown hostkey");
debug_f("hostkey %s index %d", sshkey_ssh_name(pubkey), keyid);
sshkey_free(pubkey);
/*
* Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),

3
monitor.h
View File

@ -54,6 +54,7 @@ enum monitor_reqtype {
MONITOR_REQ_GSSUSEROK = 46, MONITOR_ANS_GSSUSEROK = 47,
MONITOR_REQ_GSSCHECKMIC = 48, MONITOR_ANS_GSSCHECKMIC = 49,
MONITOR_REQ_TERM = 50,
MONITOR_REQ_STATE = 51, MONITOR_ANS_STATE = 52,
MONITOR_REQ_PAM_START = 100,
MONITOR_REQ_PAM_ACCOUNT = 102, MONITOR_ANS_PAM_ACCOUNT = 103,
@ -96,4 +97,6 @@ void mm_get_keystate(struct ssh *, struct monitor *);
/* XXX: should be returned via a monitor call rather than config_fd */
void mm_encode_server_options(struct sshbuf *);
struct sshbuf *pack_hostkeys(void);
#endif /* _MONITOR_H_ */

81
monitor_wrap.c
View File

@ -111,16 +111,6 @@ mm_log_handler(LogLevel level, int forced, const char *msg, void *ctx)
sshbuf_free(log_msg);
}
int
mm_is_monitor(void)
{
/*
* m_pid is only set in the privileged part, and
* points to the unprivileged child.
*/
return (pmonitor && pmonitor->m_pid > 0);
}
static void
mm_reap(void)
{
@ -264,15 +254,13 @@ mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, const char *hostkey_alg,
const char *sk_provider, const char *sk_pin, u_int compat)
{
struct kex *kex = *pmonitor->m_pkex;
struct sshbuf *m;
u_int ndx = kex->host_key_index(key, 0, ssh);
int r;
debug3_f("entering");
if ((m = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
if ((r = sshbuf_put_u32(m, ndx)) != 0 ||
if ((r = sshkey_puts(key, m)) != 0 ||
(r = sshbuf_put_string(m, data, datalen)) != 0 ||
(r = sshbuf_put_cstring(m, hostkey_alg)) != 0 ||
(r = sshbuf_put_u32(m, compat)) != 0)
@ -285,6 +273,7 @@ mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
if ((r = sshbuf_get_string(m, sigp, lenp)) != 0)
fatal_fr(r, "parse");
sshbuf_free(m);
debug3_f("%s signature len=%zu", hostkey_alg, *lenp);
return (0);
}
@ -861,6 +850,72 @@ mm_terminate(void)
sshbuf_free(m);
}
/* Request state information */
void
mm_get_state(struct ssh *ssh, struct include_list *includes,
struct sshbuf *conf, struct sshbuf **confdatap,
uint64_t *timing_secretp,
struct sshbuf **hostkeysp, struct sshbuf **keystatep,
u_char **pw_namep,
struct sshbuf **authinfop, struct sshbuf **auth_optsp)
{
struct sshbuf *m, *inc;
u_char *cp;
size_t len;
int r;
struct include_item *item;
debug3_f("entering");
if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_STATE, m);
debug3_f("waiting for MONITOR_ANS_STATE");
mm_request_receive_expect(pmonitor->m_recvfd,
MONITOR_ANS_STATE, m);
if ((r = sshbuf_get_string(m, &cp, &len)) != 0 ||
(r = sshbuf_get_u64(m, timing_secretp)) != 0 ||
(r = sshbuf_froms(m, hostkeysp)) != 0 ||
(r = sshbuf_get_stringb(m, ssh->kex->server_version)) != 0 ||
(r = sshbuf_get_stringb(m, ssh->kex->client_version)) != 0 ||
(r = sshbuf_get_stringb(m, inc)) != 0)
fatal_fr(r, "parse config");
/* postauth */
if (confdatap) {
if ((r = sshbuf_froms(m, confdatap)) != 0 ||
(r = sshbuf_froms(m, keystatep)) != 0 ||
(r = sshbuf_get_string(m, pw_namep, NULL)) != 0 ||
(r = sshbuf_froms(m, authinfop)) != 0 ||
(r = sshbuf_froms(m, auth_optsp)) != 0)
fatal_fr(r, "parse config postauth");
}
if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
fatal_fr(r, "sshbuf_put");
while (sshbuf_len(inc) != 0) {
item = xcalloc(1, sizeof(*item));
if ((item->contents = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
(r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
(r = sshbuf_get_stringb(inc, item->contents)) != 0)
fatal_fr(r, "parse includes");
TAILQ_INSERT_TAIL(includes, item, entry);
}
free(cp);
sshbuf_free(m);
sshbuf_free(inc);
debug3_f("done");
}
static void
mm_chall_setup(char **name, char **infotxt, u_int *numprompts,
char ***prompts, u_int **echo_on)

6
monitor_wrap.h
View File

@ -90,6 +90,12 @@ void mm_session_pty_cleanup2(struct Session *);
void mm_send_keystate(struct ssh *, struct monitor*);
/* state */
struct include_list;
void mm_get_state(struct ssh *, struct include_list *, struct sshbuf *,
struct sshbuf **, uint64_t *, struct sshbuf **, struct sshbuf **,
u_char **, struct sshbuf **, struct sshbuf **);
/* bsdauth */
int mm_bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **);
int mm_bsdauth_respond(void *, u_int, char **);

3
pathnames.h
View File

@ -51,6 +51,9 @@
#ifndef _PATH_SSHD_SESSION
#define _PATH_SSHD_SESSION "/usr/libexec/sshd-session"
#endif
#ifndef _PATH_SSHD_AUTH
#define _PATH_SSHD_AUTH "/usr/libexec/sshd-auth"
#endif
/*
* The process id of the daemon listening for connections is saved here to

26
sandbox-capsicum.c
View File

@ -45,8 +45,8 @@
*/
struct ssh_sandbox {
struct monitor *monitor;
pid_t child_pid;
int m_recvfd;
int m_log_sendfd;
};
struct ssh_sandbox *
@ -54,15 +54,10 @@ 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;
box->m_recvfd = monitor->m_recvfd;
box->m_log_sendfd = monitor->m_log_sendfd;
return box;
}
@ -112,17 +107,4 @@ ssh_sandbox_child(struct ssh_sandbox *box)
}
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 */

17
sandbox-darwin.c
View File

@ -37,7 +37,7 @@
/* Darwin/OS X sandbox */
struct ssh_sandbox {
pid_t child_pid;
int junk;
};
struct ssh_sandbox *
@ -51,8 +51,6 @@ ssh_sandbox_init(struct monitor *monitor)
*/
debug3("%s: preparing Darwin sandbox", __func__);
box = xcalloc(1, sizeof(*box));
box->child_pid = 0;
return box;
}
@ -83,17 +81,4 @@ ssh_sandbox_child(struct ssh_sandbox *box)
__func__, strerror(errno));
}
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_DARWIN */

12
sandbox-null.c
View File

@ -57,16 +57,4 @@ ssh_sandbox_child(struct ssh_sandbox *box)
/* Nothing to do here */
}
void
ssh_sandbox_parent_finish(struct ssh_sandbox *box)
{
free(box);
}
void
ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
{
/* Nothing to do here */
}
#endif /* SANDBOX_NULL */

77
sandbox-pledge.c
View File

@ -1,77 +0,0 @@
/* $OpenBSD: sandbox-pledge.c,v 1.2 2020/10/18 11:32:01 djm Exp $ */
/*
* Copyright (c) 2015 Theo de Raadt <deraadt@openbsd.org>
*
* 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_PLEDGE
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pwd.h>
#include "log.h"
#include "ssh-sandbox.h"
#include "xmalloc.h"
struct ssh_sandbox {
pid_t child_pid;
};
struct ssh_sandbox *
ssh_sandbox_init(struct monitor *m)
{
struct ssh_sandbox *box;
debug3_f("preparing pledge sandbox");
box = xcalloc(1, sizeof(*box));
box->child_pid = 0;
return box;
}
void
ssh_sandbox_child(struct ssh_sandbox *box)
{
if (pledge("stdio", NULL) == -1)
fatal_f("pledge()");
}
void
ssh_sandbox_parent_finish(struct ssh_sandbox *box)
{
free(box);
debug3_f("finished");
}
void
ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
{
box->child_pid = child_pid;
/* Nothing to do here */
}
#endif /* SANDBOX_PLEDGE */

17
sandbox-rlimit.c
View File

@ -37,7 +37,7 @@
/* Minimal sandbox that sets zero nfiles, nprocs and filesize rlimits */
struct ssh_sandbox {
pid_t child_pid;
int junk;
};
struct ssh_sandbox *
@ -51,8 +51,6 @@ ssh_sandbox_init(struct monitor *monitor)
*/
debug3_f("preparing rlimit sandbox");
box = xcalloc(1, sizeof(*box));
box->child_pid = 0;
return box;
}
@ -80,17 +78,4 @@ ssh_sandbox_child(struct ssh_sandbox *box)
#endif
}
void
ssh_sandbox_parent_finish(struct ssh_sandbox *box)
{
free(box);
debug3_f("finished");
}
void
ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
{
box->child_pid = child_pid;
}
#endif /* SANDBOX_RLIMIT */

17
sandbox-seccomp-filter.c
View File

@ -430,7 +430,7 @@ static const struct sock_fprog preauth_program = {
};
struct ssh_sandbox {
pid_t child_pid;
int junk;
};
struct ssh_sandbox *
@ -444,8 +444,6 @@ ssh_sandbox_init(struct monitor *monitor)
*/
debug3("%s: preparing seccomp filter sandbox", __func__);
box = xcalloc(1, sizeof(*box));
box->child_pid = 0;
return box;
}
@ -527,17 +525,4 @@ ssh_sandbox_child(struct ssh_sandbox *box)
"PR_SET_NO_NEW_PRIVS failed", __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_SECCOMP_FILTER */

14
sandbox-solaris.c
View File

@ -97,18 +97,4 @@ ssh_sandbox_child(struct ssh_sandbox *box)
fatal("setppriv: %s", strerror(errno));
}
void
ssh_sandbox_parent_finish(struct ssh_sandbox *box)
{
priv_freeset(box->pset);
box->pset = NULL;
free(box);
}
void
ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
{
/* Nothing to do here */
}
#endif /* SANDBOX_SOLARIS */

218
sandbox-systrace.c
View File

@ -1,218 +0,0 @@
/* $OpenBSD: sandbox-systrace.c,v 1.18 2015/10/02 01:39:26 deraadt Exp $ */
/*
* Copyright (c) 2011 Damien Miller <djm@mindrot.org>
*
* 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_SYSTRACE
#include <sys/types.h>
#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>
#include <string.h>
#include <unistd.h>
#include "atomicio.h"
#include "log.h"
#include "ssh-sandbox.h"
#include "xmalloc.h"
struct sandbox_policy {
int syscall;
int action;
};
/* Permitted syscalls in preauth. Unlisted syscalls get SYSTR_POLICY_KILL */
static const struct sandbox_policy preauth_policy[] = {
{ SYS_exit, SYSTR_POLICY_PERMIT },
#ifdef SYS_kbind
{ SYS_kbind, SYSTR_POLICY_PERMIT },
#endif
{ SYS_getpid, SYSTR_POLICY_PERMIT },
{ SYS_getpgid, SYSTR_POLICY_PERMIT },
{ SYS_clock_gettime, SYSTR_POLICY_PERMIT },
{ SYS_gettimeofday, SYSTR_POLICY_PERMIT },
{ SYS_nanosleep, SYSTR_POLICY_PERMIT },
{ SYS_sigprocmask, SYSTR_POLICY_PERMIT },
#ifdef SYS_getentropy
/* OpenBSD 5.6 and newer use getentropy(2) to seed arc4random(3). */
{ SYS_getentropy, SYSTR_POLICY_PERMIT },
#else
/* Previous releases used sysctl(3)'s kern.arnd variable. */
{ SYS___sysctl, SYSTR_POLICY_PERMIT },
#endif
#ifdef SYS_sendsyslog
{ SYS_sendsyslog, SYSTR_POLICY_PERMIT },
#endif
{ SYS_madvise, SYSTR_POLICY_PERMIT },
{ SYS_mmap, SYSTR_POLICY_PERMIT },
{ SYS_mprotect, SYSTR_POLICY_PERMIT },
{ SYS_mquery, SYSTR_POLICY_PERMIT },
{ SYS_munmap, SYSTR_POLICY_PERMIT },
{ SYS_poll, SYSTR_POLICY_PERMIT },
{ SYS_select, SYSTR_POLICY_PERMIT },
{ SYS_read, SYSTR_POLICY_PERMIT },
{ SYS_write, SYSTR_POLICY_PERMIT },
{ SYS_shutdown, SYSTR_POLICY_PERMIT },
{ SYS_close, SYSTR_POLICY_PERMIT },
{ SYS_open, SYSTR_POLICY_NEVER },
{ -1, -1 }
};
struct ssh_sandbox {
int systrace_fd;
pid_t child_pid;
void (*osigchld)(int);
};
struct ssh_sandbox *
ssh_sandbox_init(struct monitor *monitor)
{
struct ssh_sandbox *box;
debug3("%s: preparing systrace sandbox", __func__);
box = xcalloc(1, sizeof(*box));
box->systrace_fd = -1;
box->child_pid = 0;
box->osigchld = ssh_signal(SIGCHLD, SIG_IGN);
return box;
}
void
ssh_sandbox_child(struct ssh_sandbox *box)
{
debug3("%s: ready", __func__);
ssh_signal(SIGCHLD, box->osigchld);
if (kill(getpid(), SIGSTOP) != 0)
fatal("%s: kill(%d, SIGSTOP)", __func__, getpid());
debug3("%s: started", __func__);
}
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, 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);
ssh_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;
/* Set up systracing of child */
if ((dev_systrace = open("/dev/systrace", O_RDONLY)) == -1)
fatal("%s: open(\"/dev/systrace\"): %s", __func__,
strerror(errno));
if (ioctl(dev_systrace, STRIOCCLONE, &box->systrace_fd) == -1)
fatal("%s: ioctl(STRIOCCLONE, %d): %s", __func__,
dev_systrace, strerror(errno));
close(dev_systrace);
debug3("%s: systrace attach, fd=%d", __func__, box->systrace_fd);
if (ioctl(box->systrace_fd, STRIOCATTACH, &child_pid) == -1)
fatal("%s: ioctl(%d, STRIOCATTACH, %d): %s", __func__,
box->systrace_fd, child_pid, strerror(errno));
/* Allocate and assign policy */
memset(&policy, 0, sizeof(policy));
policy.strp_op = SYSTR_POLICY_NEW;
policy.strp_maxents = SYS_MAXSYSCALL;
if (ioctl(box->systrace_fd, STRIOCPOLICY, &policy) == -1)
fatal("%s: ioctl(%d, STRIOCPOLICY (new)): %s", __func__,
box->systrace_fd, strerror(errno));
policy.strp_op = SYSTR_POLICY_ASSIGN;
policy.strp_pid = box->child_pid;
if (ioctl(box->systrace_fd, STRIOCPOLICY, &policy) == -1)
fatal("%s: ioctl(%d, STRIOCPOLICY (assign)): %s",
__func__, box->systrace_fd, strerror(errno));
/* Set per-syscall policy */
for (i = 0; i < SYS_MAXSYSCALL; i++) {
found = 0;
for (j = 0; allowed_syscalls[j].syscall != -1; j++) {
if (allowed_syscalls[j].syscall == i) {
found = 1;
break;
}
}
policy.strp_op = SYSTR_POLICY_MODIFY;
policy.strp_code = i;
policy.strp_policy = found ?
allowed_syscalls[j].action : SYSTR_POLICY_KILL;
if (found)
debug3("%s: policy: enable syscall %d", __func__, i);
if (ioctl(box->systrace_fd, STRIOCPOLICY, &policy) == -1)
fatal("%s: ioctl(%d, STRIOCPOLICY (modify)): %s",
__func__, box->systrace_fd, strerror(errno));
}
/* Signal the child to start running */
debug3("%s: start child %ld", __func__, (long)child_pid);
if (kill(box->child_pid, SIGCONT) != 0)
fatal("%s: kill(%d, SIGCONT)", __func__, box->child_pid);
}
void
ssh_sandbox_parent_finish(struct ssh_sandbox *box)
{
/* Closing this before the child exits will terminate it */
close(box->systrace_fd);
free(box);
debug3("%s: finished", __func__);
}
void
ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
{
ssh_sandbox_parent(box, child_pid, preauth_policy);
}
#endif /* SANDBOX_SYSTRACE */

11
servconf.c
View File

@ -214,6 +214,7 @@ initialize_server_options(ServerOptions *options)
options->num_channel_timeouts = 0;
options->unused_connection_timeout = -1;
options->sshd_session_path = NULL;
options->sshd_auth_path = NULL;
options->refuse_connection = -1;
}
@ -493,6 +494,8 @@ fill_default_server_options(ServerOptions *options)
options->unused_connection_timeout = 0;
if (options->sshd_session_path == NULL)
options->sshd_session_path = xstrdup(_PATH_SSHD_SESSION);
if (options->sshd_auth_path == NULL)
options->sshd_auth_path = xstrdup(_PATH_SSHD_AUTH);
if (options->refuse_connection == -1)
options->refuse_connection = 0;
@ -577,7 +580,7 @@ typedef enum {
sAllowStreamLocalForwarding, sFingerprintHash, sDisableForwarding,
sExposeAuthInfo, sRDomain, sPubkeyAuthOptions, sSecurityKeyProvider,
sRequiredRSASize, sChannelTimeout, sUnusedConnectionTimeout,
sSshdSessionPath, sRefuseConnection,
sSshdSessionPath, sSshdAuthPath, sRefuseConnection,
sDeprecated, sIgnore, sUnsupported
} ServerOpCodes;
@ -745,6 +748,7 @@ static struct {
{ "channeltimeout", sChannelTimeout, SSHCFG_ALL },
{ "unusedconnectiontimeout", sUnusedConnectionTimeout, SSHCFG_ALL },
{ "sshdsessionpath", sSshdSessionPath, SSHCFG_GLOBAL },
{ "sshdauthpath", sSshdAuthPath, SSHCFG_GLOBAL },
{ "refuseconnection", sRefuseConnection, SSHCFG_ALL },
{ NULL, sBadOption, 0 }
};
@ -2703,6 +2707,10 @@ process_server_config_line_depth(ServerOptions *options, char *line,
charptr = &options->sshd_session_path;
goto parse_filename;
case sSshdAuthPath:
charptr = &options->sshd_auth_path;
goto parse_filename;
case sRefuseConnection:
intptr = &options->refuse_connection;
multistate_ptr = multistate_flag;
@ -3288,6 +3296,7 @@ dump_config(ServerOptions *o)
dump_cfg_string(sRDomain, o->routing_domain);
#endif
dump_cfg_string(sSshdSessionPath, o->sshd_session_path);
dump_cfg_string(sSshdAuthPath, o->sshd_auth_path);
dump_cfg_string(sPerSourcePenaltyExemptList, o->per_source_penalty_exempt);
/* string arguments requiring a lookup */

1
servconf.h
View File

@ -249,6 +249,7 @@ typedef struct {
int unused_connection_timeout;
char *sshd_session_path;
char *sshd_auth_path;
int refuse_connection;
} ServerOptions;

7
session.c
View File

@ -1510,8 +1510,7 @@ do_child(struct ssh *ssh, Session *s, const char *command)
sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
/* remove hostkey from the child's memory */
destroy_sensitive_data();
/* remove keys from memory */
ssh_packet_clear_keys(ssh);
/* Force a password change */
@ -2145,10 +2144,6 @@ session_signal_req(struct ssh *ssh, Session *s)
signame, s->forced ? "forced-command" : "subsystem");
goto out;
}
if (mm_is_monitor()) {
error_f("session signalling requires privilege separation");
goto out;
}
debug_f("signal %s, killpg(%ld, %d)", signame, (long)s->pid, sig);
temporarily_use_uid(s->pw);

2
ssh-sandbox.h
View File

@ -20,5 +20,3 @@ struct ssh_sandbox;
struct ssh_sandbox *ssh_sandbox_init(struct monitor *);
void ssh_sandbox_child(struct ssh_sandbox *);
void ssh_sandbox_parent_finish(struct ssh_sandbox *);
void ssh_sandbox_parent_preauth(struct ssh_sandbox *, pid_t);

861
sshd-auth.c Normal file
View File

@ -0,0 +1,861 @@
/* $OpenBSD$ */
/*
* SSH2 implementation:
* Privilege Separation:
*
* Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
* Copyright (c) 2002 Niels Provos. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/time.h>
#include "openbsd-compat/sys-tree.h"
#include "openbsd-compat/sys-queue.h"
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <paths.h>
#include <pwd.h>
#include <grp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <limits.h>
#ifdef WITH_OPENSSL
#include <openssl/bn.h>
#include <openssl/evp.h>
#endif
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "sshpty.h"
#include "packet.h"
#include "log.h"
#include "sshbuf.h"
#include "misc.h"
#include "match.h"
#include "servconf.h"
#include "uidswap.h"
#include "compat.h"
#include "cipher.h"
#include "digest.h"
#include "sshkey.h"
#include "kex.h"
#include "authfile.h"
#include "pathnames.h"
#include "atomicio.h"
#include "canohost.h"
#include "hostfile.h"
#include "auth.h"
#include "authfd.h"
#include "msg.h"
#include "dispatch.h"
#include "channels.h"
#include "session.h"
#include "monitor.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "auth-options.h"
#include "version.h"
#include "ssherr.h"
#include "sk-api.h"
#include "srclimit.h"
#include "ssh-sandbox.h"
#include "dh.h"
/* Privsep fds */
#define PRIVSEP_MONITOR_FD (STDERR_FILENO + 1)
#define PRIVSEP_LOG_FD (STDERR_FILENO + 2)
#define PRIVSEP_MIN_FREE_FD (STDERR_FILENO + 3)
extern char *__progname;
/* Server configuration options. */
ServerOptions options;
/* Name of the server configuration file. */
char *config_file_name = _PATH_SERVER_CONFIG_FILE;
/*
* Debug mode flag. This can be set on the command line. If debug
* mode is enabled, extra debugging output will be sent to the system
* log, the daemon will not go to background, and will exit after processing
* the first connection.
*/
int debug_flag = 0;
/* Flag indicating that the daemon is being started from inetd. */
static int inetd_flag = 0;
/* Saved arguments to main(). */
static char **saved_argv;
/* Daemon's agent connection */
int auth_sock = -1;
static int have_agent = 0;
u_int num_hostkeys;
struct sshkey **host_pubkeys; /* all public host keys */
struct sshkey **host_certificates; /* all public host certificates */
/* record remote hostname or ip */
u_int utmp_len = HOST_NAME_MAX+1;
/* variables used for privilege separation */
struct monitor *pmonitor = NULL;
int privsep_is_preauth = 1;
static int privsep_chroot = 1;
/* global connection state and authentication contexts */
Authctxt *the_authctxt = NULL;
struct ssh *the_active_state;
/* global key/cert auth options. XXX move to permanent ssh->authctxt? */
struct sshauthopt *auth_opts = NULL;
/* sshd_config buffer */
struct sshbuf *cfg;
/* Included files from the configuration file */
struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
/* message to be displayed after login */
struct sshbuf *loginmsg;
/* Prototypes for various functions defined later in this file. */
static void do_ssh2_kex(struct ssh *);
/* Unprivileged user */
struct passwd *privsep_pw = NULL;
/* XXX stub */
int
mm_is_monitor(void)
{
return 0;
}
static void
privsep_child_demote(void)
{
gid_t gidset[1];
#ifndef HAVE_PLEDGE
struct ssh_sandbox *box = NULL;
if ((box = ssh_sandbox_init(pmonitor)) == NULL)
fatal_f("ssh_sandbox_init failed");
#endif
/* Demote the child */
if (privsep_chroot) {
/* Change our root directory */
if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
strerror(errno));
if (chdir("/") == -1)
fatal("chdir(\"/\"): %s", strerror(errno));
/*
* Drop our privileges
* NB. Can't use setusercontext() after chroot.
*/
debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
(u_int)privsep_pw->pw_gid);
gidset[0] = privsep_pw->pw_gid;
if (setgroups(1, gidset) == -1)
fatal("setgroups: %.100s", strerror(errno));
permanently_set_uid(privsep_pw);
}
/* sandbox ourselves */
#ifdef HAVE_PLEDGE
if (pledge("stdio", NULL) == -1)
fatal_f("pledge()");
#else
ssh_sandbox_child(box);
#endif
}
static void
append_hostkey_type(struct sshbuf *b, const char *s)
{
int r;
if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
debug3_f("%s key not permitted by HostkeyAlgorithms", s);
return;
}
if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
fatal_fr(r, "sshbuf_putf");
}
static char *
list_hostkey_types(void)
{
struct sshbuf *b;
struct sshkey *key;
char *ret;
u_int i;
if ((b = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
for (i = 0; i < options.num_host_key_files; i++) {
key = host_pubkeys[i];
if (key == NULL)
continue;
switch (key->type) {
case KEY_RSA:
/* for RSA we also support SHA2 signatures */
append_hostkey_type(b, "rsa-sha2-512");
append_hostkey_type(b, "rsa-sha2-256");
/* FALLTHROUGH */
case KEY_DSA:
case KEY_ECDSA:
case KEY_ED25519:
case KEY_ECDSA_SK:
case KEY_ED25519_SK:
case KEY_XMSS:
append_hostkey_type(b, sshkey_ssh_name(key));
break;
}
/* If the private key has a cert peer, then list that too */
key = host_certificates[i];
if (key == NULL)
continue;
switch (key->type) {
case KEY_RSA_CERT:
/* for RSA we also support SHA2 signatures */
append_hostkey_type(b,
"rsa-sha2-512-cert-v01@openssh.com");
append_hostkey_type(b,
"rsa-sha2-256-cert-v01@openssh.com");
/* FALLTHROUGH */
case KEY_DSA_CERT:
case KEY_ECDSA_CERT:
case KEY_ED25519_CERT:
case KEY_ECDSA_SK_CERT:
case KEY_ED25519_SK_CERT:
case KEY_XMSS_CERT:
append_hostkey_type(b, sshkey_ssh_name(key));
break;
}
}
if ((ret = sshbuf_dup_string(b)) == NULL)
fatal_f("sshbuf_dup_string failed");
sshbuf_free(b);
debug_f("%s", ret);
return ret;
}
struct sshkey *
get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
{
u_int i;
struct sshkey *key;
for (i = 0; i < options.num_host_key_files; i++) {
switch (type) {
case KEY_RSA_CERT:
case KEY_DSA_CERT:
case KEY_ECDSA_CERT:
case KEY_ED25519_CERT:
case KEY_ECDSA_SK_CERT:
case KEY_ED25519_SK_CERT:
case KEY_XMSS_CERT:
key = host_certificates[i];
break;
default:
key = host_pubkeys[i];
break;
}
if (key == NULL || key->type != type)
continue;
switch (type) {
case KEY_ECDSA:
case KEY_ECDSA_SK:
case KEY_ECDSA_CERT:
case KEY_ECDSA_SK_CERT:
if (key->ecdsa_nid != nid)
continue;
/* FALLTHROUGH */
default:
return key;
}
}
return NULL;
}
/* XXX remove */
struct sshkey *
get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
{
return NULL;
}
/* XXX remove */
struct sshkey *
get_hostkey_by_index(int ind)
{
return NULL;
}
struct sshkey *
get_hostkey_public_by_index(int ind, struct ssh *ssh)
{
if (ind < 0 || (u_int)ind >= options.num_host_key_files)
return (NULL);
return host_pubkeys[ind];
}
int
get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
{
u_int i;
for (i = 0; i < options.num_host_key_files; i++) {
if (sshkey_is_cert(key)) {
if (key == host_certificates[i] ||
(compare && host_certificates[i] &&
sshkey_equal(key, host_certificates[i])))
return (i);
} else {
if (key == host_pubkeys[i] ||
(compare && host_pubkeys[i] &&
sshkey_equal(key, host_pubkeys[i])))
return (i);
}
}
return (-1);
}
static void
usage(void)
{
fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION);
fprintf(stderr,
"usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n"
" [-E log_file] [-f config_file] [-g login_grace_time]\n"
" [-h host_key_file] [-o option] [-p port] [-u len]\n"
);
exit(1);
}
static void
parse_hostkeys(struct sshbuf *hostkeys)
{
int r;
u_int num_keys = 0;
struct sshkey *k;
const u_char *cp;
size_t len;
while (sshbuf_len(hostkeys) != 0) {
if (num_keys > 2048)
fatal_f("too many hostkeys");
host_pubkeys = xrecallocarray(host_pubkeys,
num_keys, num_keys + 1, sizeof(*host_pubkeys));
host_certificates = xrecallocarray(host_certificates,
num_keys, num_keys + 1, sizeof(*host_certificates));
/* public key */
k = NULL;
if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
fatal_fr(r, "extract pubkey");
if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
fatal_fr(r, "parse pubkey");
host_pubkeys[num_keys] = k;
if (k)
debug2_f("key %u: %s", num_keys, sshkey_ssh_name(k));
/* certificate */
k = NULL;
if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
fatal_fr(r, "extract pubkey");
if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
fatal_fr(r, "parse pubkey");
host_certificates[num_keys] = k;
if (k)
debug2_f("cert %u: %s", num_keys, sshkey_ssh_name(k));
num_keys++;
}
num_hostkeys = num_keys;
}
static void
recv_privsep_state(struct ssh *ssh, struct sshbuf *conf,
uint64_t *timing_secretp)
{
struct sshbuf *hostkeys;
debug3_f("begin");
mm_get_state(ssh, &includes, conf, NULL, timing_secretp,
&hostkeys, NULL, NULL, NULL, NULL);
parse_hostkeys(hostkeys);
sshbuf_free(hostkeys);
debug3_f("done");
}
/*
* Main program for the daemon.
*/
int
main(int ac, char **av)
{
struct ssh *ssh = NULL;
extern char *optarg;
extern int optind;
int r, opt, have_key = 0;
int sock_in = -1, sock_out = -1, rexeced_flag = 0;
char *line, *logfile = NULL;
u_int i;
mode_t new_umask;
Authctxt *authctxt;
struct connection_info *connection_info = NULL;
sigset_t sigmask;
uint64_t timing_secret = 0;
closefrom(PRIVSEP_MIN_FREE_FD);
sigemptyset(&sigmask);
sigprocmask(SIG_SETMASK, &sigmask, NULL);
/* Save argv. */
saved_argv = av;
/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
sanitise_stdfd();
/* Initialize configuration options to their default values. */
initialize_server_options(&options);
/* Parse command-line arguments. */
while ((opt = getopt(ac, av,
"C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) {
switch (opt) {
case '4':
options.address_family = AF_INET;
break;
case '6':
options.address_family = AF_INET6;
break;
case 'f':
config_file_name = optarg;
break;
case 'c':
servconf_add_hostcert("[command-line]", 0,
&options, optarg);
break;
case 'd':
if (debug_flag == 0) {
debug_flag = 1;
options.log_level = SYSLOG_LEVEL_DEBUG1;
} else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
options.log_level++;
break;
case 'D':
/* ignore */
break;
case 'E':
logfile = optarg;
/* FALLTHROUGH */
case 'e':
/* ignore */
break;
case 'i':
inetd_flag = 1;
break;
case 'r':
/* ignore */
break;
case 'R':
rexeced_flag = 1;
break;
case 'Q':
/* ignored */
break;
case 'q':
options.log_level = SYSLOG_LEVEL_QUIET;
break;
case 'b':
/* protocol 1, ignored */
break;
case 'p':
options.ports_from_cmdline = 1;
if (options.num_ports >= MAX_PORTS) {
fprintf(stderr, "too many ports.\n");
exit(1);
}
options.ports[options.num_ports++] = a2port(optarg);
if (options.ports[options.num_ports-1] <= 0) {
fprintf(stderr, "Bad port number.\n");
exit(1);
}
break;
case 'g':
if ((options.login_grace_time = convtime(optarg)) == -1) {
fprintf(stderr, "Invalid login grace time.\n");
exit(1);
}
break;
case 'k':
/* protocol 1, ignored */
break;
case 'h':
servconf_add_hostkey("[command-line]", 0,
&options, optarg, 1);
break;
case 't':
case 'T':
case 'G':
fatal("test/dump modes not supported");
break;
case 'C':
connection_info = server_get_connection_info(ssh, 0, 0);
if (parse_server_match_testspec(connection_info,
optarg) == -1)
exit(1);
break;
case 'u':
utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
if (utmp_len > HOST_NAME_MAX+1) {
fprintf(stderr, "Invalid utmp length.\n");
exit(1);
}
break;
case 'o':
line = xstrdup(optarg);
if (process_server_config_line(&options, line,
"command-line", 0, NULL, NULL, &includes) != 0)
exit(1);
free(line);
break;
case 'V':
fprintf(stderr, "%s, %s\n",
SSH_VERSION, SSH_OPENSSL_VERSION);
exit(0);
default:
usage();
break;
}
}
if (!rexeced_flag)
fatal("sshd-auth should not be executed directly");
#ifdef WITH_OPENSSL
OpenSSL_add_all_algorithms();
#endif
/* If requested, redirect the logs to the specified logfile. */
if (logfile != NULL) {
char *cp, pid_s[32];
snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid());
cp = percent_expand(logfile,
"p", pid_s,
"P", "sshd-auth",
(char *)NULL);
log_redirect_stderr_to(cp);
free(cp);
}
log_init(__progname,
options.log_level == SYSLOG_LEVEL_NOT_SET ?
SYSLOG_LEVEL_INFO : options.log_level,
options.log_facility == SYSLOG_FACILITY_NOT_SET ?
SYSLOG_FACILITY_AUTH : options.log_facility, 1);
/* XXX can't use monitor_init(); it makes fds */
pmonitor = xcalloc(1, sizeof(*pmonitor));
pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
pmonitor->m_recvfd = PRIVSEP_MONITOR_FD;
pmonitor->m_log_sendfd = PRIVSEP_LOG_FD;
set_log_handler(mm_log_handler, pmonitor);
/* Check that there are no remaining arguments. */
if (optind < ac) {
fprintf(stderr, "Extra argument %s.\n", av[optind]);
exit(1);
}
debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
/* Connection passed by stdin/out */
if (inetd_flag) {
/*
* NB. must be different fd numbers for the !socket case,
* as packet_connection_is_on_socket() depends on this.
*/
sock_in = dup(STDIN_FILENO);
sock_out = dup(STDOUT_FILENO);
} else {
/* rexec case; accept()ed socket in ancestor listener */
sock_in = sock_out = dup(STDIN_FILENO);
}
if (stdfd_devnull(1, 1, 0) == -1)
error("stdfd_devnull failed");
debug("network sockets: %d, %d", sock_in, sock_out);
/*
* Register our connection. This turns encryption off because we do
* not have a key.
*/
if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL)
fatal("Unable to create connection");
the_active_state = ssh;
ssh_packet_set_server(ssh);
pmonitor->m_pkex = &ssh->kex;
/* Fetch our configuration */
if ((cfg = sshbuf_new()) == NULL)
fatal("sshbuf_new config buf failed");
setproctitle("%s", "[session-auth early]");
recv_privsep_state(ssh, cfg, &timing_secret);
parse_server_config(&options, "rexec", cfg, &includes, NULL, 1);
/* Fill in default values for those options not explicitly set. */
fill_default_server_options(&options);
options.timing_secret = timing_secret; /* XXX eliminate from unpriv */
/* Store privilege separation user for later use if required. */
privsep_chroot = (getuid() == 0 || geteuid() == 0);
if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
if (privsep_chroot || options.kerberos_authentication)
fatal("Privilege separation user %s does not exist",
SSH_PRIVSEP_USER);
} else {
privsep_pw = pwcopy(privsep_pw);
freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
privsep_pw->pw_passwd = xstrdup("*");
}
endpwent();
#ifdef WITH_OPENSSL
if (options.moduli_file != NULL)
dh_set_moduli_file(options.moduli_file);
#endif
if (options.host_key_agent) {
if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
setenv(SSH_AUTHSOCKET_ENV_NAME,
options.host_key_agent, 1);
if ((r = ssh_get_authentication_socket(NULL)) == 0)
have_agent = 1;
else
error_r(r, "Could not connect to agent \"%s\"",
options.host_key_agent);
}
if (options.num_host_key_files != num_hostkeys) {
fatal("internal error: hostkeys confused (config %u recvd %u)",
options.num_host_key_files, num_hostkeys);
}
for (i = 0; i < options.num_host_key_files; i++) {
if (host_pubkeys[i] != NULL) {
have_key = 1;
break;
}
}
if (!have_key)
fatal("internal error: recieved no hostkeys");
/* Ensure that umask disallows at least group and world write */
new_umask = umask(0077) | 0022;
(void) umask(new_umask);
/* Initialize the log (it is reinitialized below in case we forked). */
log_init(__progname, options.log_level, options.log_facility, 1);
set_log_handler(mm_log_handler, pmonitor);
for (i = 0; i < options.num_log_verbose; i++)
log_verbose_add(options.log_verbose[i]);
/*
* Chdir to the root directory so that the current disk can be
* unmounted if desired.
*/
if (chdir("/") == -1)
error("chdir(\"/\"): %s", strerror(errno));
/* This is the child authenticating a new connection. */
setproctitle("%s", "[session-auth]");
/* Executed child processes don't need these. */
fcntl(sock_out, F_SETFD, FD_CLOEXEC);
fcntl(sock_in, F_SETFD, FD_CLOEXEC);
ssh_signal(SIGPIPE, SIG_IGN);
ssh_signal(SIGALRM, SIG_DFL);
ssh_signal(SIGHUP, SIG_DFL);
ssh_signal(SIGTERM, SIG_DFL);
ssh_signal(SIGQUIT, SIG_DFL);
ssh_signal(SIGCHLD, SIG_DFL);
/* Prepare the channels layer */
channel_init_channels(ssh);
channel_set_af(ssh, options.address_family);
server_process_channel_timeouts(ssh);
server_process_permitopen(ssh);
ssh_packet_set_nonblocking(ssh);
/* allocate authentication context */
authctxt = xcalloc(1, sizeof(*authctxt));
ssh->authctxt = authctxt;
/* XXX global for cleanup, access from other modules */
the_authctxt = authctxt;
/* Set default key authentication options */
if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
fatal("allocation failed");
/* prepare buffer to collect messages to display to user after login */
if ((loginmsg = sshbuf_new()) == NULL)
fatal("sshbuf_new loginmsg failed");
auth_debug_reset();
/* Enable challenge-response authentication for privilege separation */
privsep_challenge_enable();
#ifdef GSSAPI
/* Cache supported mechanism OIDs for later use */
ssh_gssapi_prepare_supported_oids();
#endif
privsep_child_demote();
/* perform the key exchange */
/* authenticate user and start session */
do_ssh2_kex(ssh);
do_authentication2(ssh);
/*
* The unprivileged child now transfers the current keystate and exits.
*/
mm_send_keystate(ssh, pmonitor);
ssh_packet_clear_keys(ssh);
exit(0);
}
int
sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
struct sshkey *pubkey, u_char **signature, size_t *slenp,
const u_char *data, size_t dlen, const char *alg)
{
if (privkey) {
if (mm_sshkey_sign(ssh, privkey, signature, slenp,
data, dlen, alg, options.sk_provider, NULL,
ssh->compat) < 0)
fatal_f("privkey sign failed");
} else {
if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
data, dlen, alg, options.sk_provider, NULL,
ssh->compat) < 0)
fatal_f("pubkey sign failed");
}
return 0;
}
/* SSH2 key exchange */
static void
do_ssh2_kex(struct ssh *ssh)
{
char *hkalgs = NULL, *myproposal[PROPOSAL_MAX];
const char *compression = NULL;
struct kex *kex;
int r;
if (options.rekey_limit || options.rekey_interval)
ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
options.rekey_interval);
if (options.compression == COMP_NONE)
compression = "none";
hkalgs = list_hostkey_types();
kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms,
options.ciphers, options.macs, compression, hkalgs);
free(hkalgs);
/* start key exchange */
if ((r = kex_setup(ssh, myproposal)) != 0)
fatal_r(r, "kex_setup");
kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
kex = ssh->kex;
#ifdef WITH_OPENSSL
kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
# ifdef OPENSSL_HAS_ECC
kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
# endif /* OPENSSL_HAS_ECC */
#endif /* WITH_OPENSSL */
kex->kex[KEX_C25519_SHA256] = kex_gen_server;
kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server;
kex->load_host_public_key=&get_hostkey_public_by_type;
kex->load_host_private_key=&get_hostkey_private_by_type;
kex->host_key_index=&get_hostkey_index;
kex->sign = sshd_hostkey_sign;
ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done);
kex_proposal_free_entries(myproposal);
#ifdef DEBUG_KEXDH
/* send 1st encrypted/maced/compressed message */
if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
(r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal_fr(r, "send test");
#endif
debug("KEX done");
}
/* server specific fatal cleanup */
void
cleanup_exit(int i)
{
_exit(i);
}

306
sshd-session.c
View File

@ -102,7 +102,6 @@
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "ssh-sandbox.h"
#include "auth-options.h"
#include "version.h"
#include "ssherr.h"
@ -116,6 +115,11 @@
#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
/* Privsep fds */
#define PRIVSEP_MONITOR_FD (STDERR_FILENO + 1)
#define PRIVSEP_LOG_FD (STDERR_FILENO + 2)
#define PRIVSEP_MIN_FREE_FD (STDERR_FILENO + 3)
extern char *__progname;
/* Server configuration options. */
@ -193,7 +197,17 @@ struct sshbuf *loginmsg;
/* Prototypes for various functions defined later in this file. */
void destroy_sensitive_data(void);
void demote_sensitive_data(void);
static void do_ssh2_kex(struct ssh *);
/* XXX reduce to stub once postauth split */
int
mm_is_monitor(void)
{
/*
* m_pid is only set in the privileged part, and
* points to the unprivileged child.
*/
return (pmonitor && pmonitor->m_pid > 0);
}
/*
* Signal handler for the alarm after the login grace period has expired.
@ -283,41 +297,41 @@ reseed_prngs(void)
explicit_bzero(rnd, sizeof(rnd));
}
static void
privsep_preauth_child(void)
struct sshbuf *
pack_hostkeys(void)
{
gid_t gidset[1];
struct sshbuf *keybuf = NULL, *hostkeys = NULL;
int r;
u_int i;
/* Enable challenge-response authentication for privilege separation */
privsep_challenge_enable();
if ((hostkeys = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
#ifdef GSSAPI
/* Cache supported mechanism OIDs for later use */
ssh_gssapi_prepare_supported_oids();
#endif
reseed_prngs();
/* Demote the private keys to public keys. */
demote_sensitive_data();
/* Demote the child */
if (privsep_chroot) {
/* Change our root directory */
if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
strerror(errno));
if (chdir("/") == -1)
fatal("chdir(\"/\"): %s", strerror(errno));
/* Drop our privileges */
debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
(u_int)privsep_pw->pw_gid);
gidset[0] = privsep_pw->pw_gid;
if (setgroups(1, gidset) == -1)
fatal("setgroups: %.100s", strerror(errno));
permanently_set_uid(privsep_pw);
/* pack hostkeys into a string. Empty key slots get empty strings */
for (i = 0; i < options.num_host_key_files; i++) {
/* public key */
if (sensitive_data.host_pubkeys[i] != NULL) {
if ((r = sshkey_puts(sensitive_data.host_pubkeys[i],
hostkeys)) != 0)
fatal_fr(r, "compose hostkey public");
} else {
if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
fatal_fr(r, "compose hostkey empty public");
}
/* cert */
if (sensitive_data.host_certificates[i] != NULL) {
if ((r = sshkey_puts(
sensitive_data.host_certificates[i],
hostkeys)) != 0)
fatal_fr(r, "compose host cert");
} else {
if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
fatal_fr(r, "compose host cert empty");
}
}
sshbuf_free(keybuf);
return hostkeys;
}
static int
@ -325,18 +339,15 @@ privsep_preauth(struct ssh *ssh)
{
int status, r;
pid_t pid;
struct ssh_sandbox *box = NULL;
/* Set up unprivileged child process to deal with network data */
pmonitor = monitor_init();
/* Store a pointer to the kex for later rekeying */
pmonitor->m_pkex = &ssh->kex;
box = ssh_sandbox_init(pmonitor);
pid = fork();
if (pid == -1) {
if ((pid = fork()) == -1)
fatal("fork of unprivileged child failed");
} else if (pid != 0) {
else if (pid != 0) {
debug2("Network child is on pid %ld", (long)pid);
pmonitor->m_pid = pid;
@ -347,8 +358,6 @@ privsep_preauth(struct ssh *ssh)
have_agent = 0;
}
}
if (box != NULL)
ssh_sandbox_parent_preauth(box, pid);
monitor_child_preauth(ssh, pmonitor);
/* Wait for the child's exit status */
@ -367,23 +376,46 @@ privsep_preauth(struct ssh *ssh)
} else if (WIFSIGNALED(status))
fatal_f("preauth child terminated by signal %d",
WTERMSIG(status));
if (box != NULL)
ssh_sandbox_parent_finish(box);
return 1;
} else {
/* child */
close(pmonitor->m_sendfd);
close(pmonitor->m_log_recvfd);
/* Arrange for logging to be sent to the monitor */
set_log_handler(mm_log_handler, pmonitor);
/*
* Arrange unpriv-preauth child process fds:
* 0, 1 network socket
* 2 optional stderr
* 3 reserved
* 4 monitor message socket
* 5 monitor logging socket
*
* We know that the monitor sockets will have fds > 4 because
* of the reserved fds in main()
*/
privsep_preauth_child();
setproctitle("%s", "[net]");
if (box != NULL)
ssh_sandbox_child(box);
if (ssh_packet_get_connection_in(ssh) != STDIN_FILENO &&
dup2(ssh_packet_get_connection_in(ssh), STDIN_FILENO) == -1)
fatal("dup2 stdin failed: %s", strerror(errno));
if (ssh_packet_get_connection_out(ssh) != STDOUT_FILENO &&
dup2(ssh_packet_get_connection_out(ssh),
STDOUT_FILENO) == -1)
fatal("dup2 stdout failed: %s", strerror(errno));
/* leave stderr as-is */
log_redirect_stderr_to(NULL); /* dup can clobber log fd */
if (pmonitor->m_recvfd != PRIVSEP_MONITOR_FD &&
dup2(pmonitor->m_recvfd, PRIVSEP_MONITOR_FD) == -1)
fatal("dup2 monitor fd: %s", strerror(errno));
if (pmonitor->m_log_sendfd != PRIVSEP_LOG_FD &&
dup2(pmonitor->m_log_sendfd, PRIVSEP_LOG_FD) == -1)
fatal("dup2 log fd: %s", strerror(errno));
closefrom(PRIVSEP_MIN_FREE_FD);
return 0;
saved_argv[0] = options.sshd_auth_path;
execv(options.sshd_auth_path, saved_argv);
fatal_f("exec of %s failed: %s",
options.sshd_auth_path, strerror(errno));
}
}
@ -445,79 +477,6 @@ privsep_postauth(struct ssh *ssh, Authctxt *authctxt)
ssh_packet_set_authenticated(ssh);
}
static void
append_hostkey_type(struct sshbuf *b, const char *s)
{
int r;
if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
debug3_f("%s key not permitted by HostkeyAlgorithms", s);
return;
}
if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
fatal_fr(r, "sshbuf_putf");
}
static char *
list_hostkey_types(void)
{
struct sshbuf *b;
struct sshkey *key;
char *ret;
u_int i;
if ((b = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
for (i = 0; i < options.num_host_key_files; i++) {
key = sensitive_data.host_keys[i];
if (key == NULL)
key = sensitive_data.host_pubkeys[i];
if (key == NULL)
continue;
switch (key->type) {
case KEY_RSA:
/* for RSA we also support SHA2 signatures */
append_hostkey_type(b, "rsa-sha2-512");
append_hostkey_type(b, "rsa-sha2-256");
/* FALLTHROUGH */
case KEY_DSA:
case KEY_ECDSA:
case KEY_ED25519:
case KEY_ECDSA_SK:
case KEY_ED25519_SK:
case KEY_XMSS:
append_hostkey_type(b, sshkey_ssh_name(key));
break;
}
/* If the private key has a cert peer, then list that too */
key = sensitive_data.host_certificates[i];
if (key == NULL)
continue;
switch (key->type) {
case KEY_RSA_CERT:
/* for RSA we also support SHA2 signatures */
append_hostkey_type(b,
"rsa-sha2-512-cert-v01@openssh.com");
append_hostkey_type(b,
"rsa-sha2-256-cert-v01@openssh.com");
/* FALLTHROUGH */
case KEY_DSA_CERT:
case KEY_ECDSA_CERT:
case KEY_ED25519_CERT:
case KEY_ECDSA_SK_CERT:
case KEY_ED25519_SK_CERT:
case KEY_XMSS_CERT:
append_hostkey_type(b, sshkey_ssh_name(key));
break;
}
}
if ((ret = sshbuf_dup_string(b)) == NULL)
fatal_f("sshbuf_dup_string failed");
sshbuf_free(b);
debug_f("%s", ret);
return ret;
}
static struct sshkey *
get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
{
@ -871,7 +830,7 @@ main(int ac, char **av)
struct ssh *ssh = NULL;
extern char *optarg;
extern int optind;
int r, opt, on = 1, remote_port;
int devnull, r, opt, on = 1, remote_port;
int sock_in = -1, sock_out = -1, rexeced_flag = 0, have_key = 0;
const char *remote_ip, *rdomain;
char *line, *laddr, *logfile = NULL;
@ -1035,6 +994,14 @@ main(int ac, char **av)
closefrom(REEXEC_MIN_FREE_FD);
/* Reserve fds we'll need later for reexec things */
if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1)
fatal("open %s: %s", _PATH_DEVNULL, strerror(errno));
while (devnull < PRIVSEP_MIN_FREE_FD) {
if ((devnull = dup(devnull)) == -1)
fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno));
}
seed_rng();
/* If requested, redirect the logs to the specified logfile. */
@ -1068,7 +1035,9 @@ main(int ac, char **av)
fatal("sshbuf_new config buf failed");
setproctitle("%s", "[rexeced]");
recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg, &timing_secret);
close(REEXEC_CONFIG_PASS_FD);
/* close the fd, but keep the slot reserved */
if (dup2(devnull, REEXEC_CONFIG_PASS_FD) == -1)
fatal("dup2 devnull->config fd: %s", strerror(errno));
parse_server_config(&options, "rexec", cfg, &includes, NULL, 1);
/* Fill in default values for those options not explicitly set. */
fill_default_server_options(&options);
@ -1087,9 +1056,13 @@ main(int ac, char **av)
}
endpwent();
if (!debug_flag) {
startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
close(REEXEC_STARTUP_PIPE_FD);
if (!debug_flag && !inetd_flag) {
if ((startup_pipe = dup(REEXEC_STARTUP_PIPE_FD)) == -1)
fatal("internal error: no startup pipe");
/* close the fd, but keep the slot reserved */
if (dup2(devnull, REEXEC_STARTUP_PIPE_FD) == -1)
fatal("dup2 devnull->startup fd: %s", strerror(errno));
/*
* Signal parent that this child is at a point where
* they can go away if they have a SIGHUP pending.
@ -1311,22 +1284,11 @@ main(int ac, char **av)
fatal("sshbuf_new loginmsg failed");
auth_debug_reset();
if (privsep_preauth(ssh) == 1)
goto authenticated;
if (privsep_preauth(ssh) != 1)
fatal("privsep_preauth failed");
/* perform the key exchange */
/* authenticate user and start session */
do_ssh2_kex(ssh);
do_authentication2(ssh);
/* Now user is authenticated */
/*
* The unprivileged child now transfers the current keystate and exits.
*/
mm_send_keystate(ssh, pmonitor);
ssh_packet_clear_keys(ssh);
exit(0);
authenticated:
/*
* Cancel the alarm we set to limit the time taken for
* authentication.
@ -1423,68 +1385,6 @@ sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
return 0;
}
/* SSH2 key exchange */
static void
do_ssh2_kex(struct ssh *ssh)
{
char *hkalgs = NULL, *myproposal[PROPOSAL_MAX];
const char *compression = NULL;
struct kex *kex;
int r;
if (options.rekey_limit || options.rekey_interval)
ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
options.rekey_interval);
if (options.compression == COMP_NONE)
compression = "none";
hkalgs = list_hostkey_types();
kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms,
options.ciphers, options.macs, compression, hkalgs);
free(hkalgs);
/* start key exchange */
if ((r = kex_setup(ssh, myproposal)) != 0)
fatal_r(r, "kex_setup");
kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
kex = ssh->kex;
#ifdef WITH_OPENSSL
kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
#ifdef OPENSSL_HAS_ECC
kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
#endif
#endif
kex->kex[KEX_C25519_SHA256] = kex_gen_server;
kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server;
kex->load_host_public_key=&get_hostkey_public_by_type;
kex->load_host_private_key=&get_hostkey_private_by_type;
kex->host_key_index=&get_hostkey_index;
kex->sign = sshd_hostkey_sign;
ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done);
kex_proposal_free_entries(myproposal);
#ifdef DEBUG_KEXDH
/* send 1st encrypted/maced/compressed message */
if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
(r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal_fr(r, "send test");
#endif
debug("KEX done");
}
/* server specific fatal cleanup */
void
cleanup_exit(int i)

7
sshd.c
View File

@ -1664,6 +1664,13 @@ main(int ac, char **av)
fatal("%s does not exist or is not executable", rexec_argv[0]);
debug3("using %s for re-exec", rexec_argv[0]);
/* Ensure that the privsep binary exists now too. */
if (stat(options.sshd_auth_path, &sb) != 0 ||
!(sb.st_mode & (S_IXOTH|S_IXUSR))) {
fatal("%s does not exist or is not executable",
options.sshd_auth_path);
}
listener_proctitle = prepare_proctitle(ac, av);
/* Ensure that umask disallows at least group and world write */