version 1.75, 2018/03/03 03:06:02 |
version 1.76, 2018/03/03 03:15:51 |
|
|
/* $OpenBSD$ */ |
/* $OpenBSD$ */ |
/* |
/* |
* Author: Tatu Ylonen <ylo@cs.hut.fi> |
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
|
* All rights reserved |
|
* As far as I am concerned, the code I have written for this software |
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* can be used freely for any purpose. Any derived versions of this |
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* software must be clearly marked as such, and if the derived work is |
|
* incompatible with the protocol description in the RFC file, it must be |
|
* called by a name other than "ssh" or "Secure Shell". |
|
*/ |
|
/* |
|
* Copyright (c) 2018 Damien Miller <djm@mindrot.org> |
* Copyright (c) 2018 Damien Miller <djm@mindrot.org> |
* |
* |
* Permission to use, copy, modify, and distribute this software for any |
* Permission to use, copy, modify, and distribute this software for any |
|
|
#include <ctype.h> |
#include <ctype.h> |
#include <limits.h> |
#include <limits.h> |
|
|
#include "key.h" /* XXX for typedef */ |
|
#include "buffer.h" /* XXX for typedef */ |
|
#include "xmalloc.h" |
#include "xmalloc.h" |
#include "match.h" |
|
#include "ssherr.h" |
#include "ssherr.h" |
#include "ssh2.h" |
|
#include "log.h" |
#include "log.h" |
#include "canohost.h" |
|
#include "packet.h" |
|
#include "sshbuf.h" |
#include "sshbuf.h" |
#include "misc.h" |
#include "misc.h" |
#include "channels.h" |
|
#include "servconf.h" |
|
#include "sshkey.h" |
#include "sshkey.h" |
|
#include "match.h" |
|
#include "ssh2.h" |
#include "auth-options.h" |
#include "auth-options.h" |
#include "hostfile.h" |
|
#include "auth.h" |
|
|
|
/* Flags set authorized_keys flags */ |
|
int no_port_forwarding_flag = 0; |
|
int no_agent_forwarding_flag = 0; |
|
int no_x11_forwarding_flag = 0; |
|
int no_pty_flag = 0; |
|
int no_user_rc = 0; |
|
int key_is_cert_authority = 0; |
|
|
|
/* "command=" option. */ |
|
char *forced_command = NULL; |
|
|
|
/* "environment=" options. */ |
|
struct envstring *custom_environment = NULL; |
|
|
|
/* "tunnel=" option. */ |
|
int forced_tun_device = -1; |
|
|
|
/* "principals=" option. */ |
|
char *authorized_principals = NULL; |
|
|
|
extern ServerOptions options; |
|
|
|
/* XXX refactor to be stateless */ |
|
|
|
void |
|
auth_clear_options(void) |
|
{ |
|
struct ssh *ssh = active_state; /* XXX */ |
|
|
|
no_agent_forwarding_flag = 0; |
|
no_port_forwarding_flag = 0; |
|
no_pty_flag = 0; |
|
no_x11_forwarding_flag = 0; |
|
no_user_rc = 0; |
|
key_is_cert_authority = 0; |
|
while (custom_environment) { |
|
struct envstring *ce = custom_environment; |
|
custom_environment = ce->next; |
|
free(ce->s); |
|
free(ce); |
|
} |
|
free(forced_command); |
|
forced_command = NULL; |
|
free(authorized_principals); |
|
authorized_principals = NULL; |
|
forced_tun_device = -1; |
|
channel_clear_permitted_opens(ssh); |
|
} |
|
|
|
/* |
|
* Match flag 'opt' in *optsp, and if allow_negate is set then also match |
|
* 'no-opt'. Returns -1 if option not matched, 1 if option matches or 0 |
|
* if negated option matches. |
|
* If the option or negated option matches, then *optsp is updated to |
|
* point to the first character after the option and, if 'msg' is not NULL |
|
* then a message based on it added via auth_debug_add(). |
|
*/ |
|
static int |
|
match_flag(const char *opt, int allow_negate, char **optsp, const char *msg) |
|
{ |
|
size_t opt_len = strlen(opt); |
|
char *opts = *optsp; |
|
int negate = 0; |
|
|
|
if (allow_negate && strncasecmp(opts, "no-", 3) == 0) { |
|
opts += 3; |
|
negate = 1; |
|
} |
|
if (strncasecmp(opts, opt, opt_len) == 0) { |
|
*optsp = opts + opt_len; |
|
if (msg != NULL) { |
|
auth_debug_add("%s %s.", msg, |
|
negate ? "disabled" : "enabled"); |
|
} |
|
return negate ? 0 : 1; |
|
} |
|
return -1; |
|
} |
|
|
|
/* |
|
* return 1 if access is granted, 0 if not. |
|
* side effect: sets key option flags |
|
* XXX remove side effects; fill structure instead. |
|
*/ |
|
int |
|
auth_parse_options(struct passwd *pw, char *opts, const char *file, |
|
u_long linenum) |
|
{ |
|
struct ssh *ssh = active_state; /* XXX */ |
|
const char *cp; |
|
int i, r; |
|
|
|
/* reset options */ |
|
auth_clear_options(); |
|
|
|
if (!opts) |
|
return 1; |
|
|
|
while (*opts && *opts != ' ' && *opts != '\t') { |
|
if ((r = match_flag("cert-authority", 0, &opts, NULL)) != -1) { |
|
key_is_cert_authority = r; |
|
goto next_option; |
|
} |
|
if ((r = match_flag("restrict", 0, &opts, NULL)) != -1) { |
|
auth_debug_add("Key is restricted."); |
|
no_port_forwarding_flag = 1; |
|
no_agent_forwarding_flag = 1; |
|
no_x11_forwarding_flag = 1; |
|
no_pty_flag = 1; |
|
no_user_rc = 1; |
|
goto next_option; |
|
} |
|
if ((r = match_flag("port-forwarding", 1, &opts, |
|
"Port forwarding")) != -1) { |
|
no_port_forwarding_flag = r != 1; |
|
goto next_option; |
|
} |
|
if ((r = match_flag("agent-forwarding", 1, &opts, |
|
"Agent forwarding")) != -1) { |
|
no_agent_forwarding_flag = r != 1; |
|
goto next_option; |
|
} |
|
if ((r = match_flag("x11-forwarding", 1, &opts, |
|
"X11 forwarding")) != -1) { |
|
no_x11_forwarding_flag = r != 1; |
|
goto next_option; |
|
} |
|
if ((r = match_flag("pty", 1, &opts, |
|
"PTY allocation")) != -1) { |
|
no_pty_flag = r != 1; |
|
goto next_option; |
|
} |
|
if ((r = match_flag("user-rc", 1, &opts, |
|
"User rc execution")) != -1) { |
|
no_user_rc = r != 1; |
|
goto next_option; |
|
} |
|
cp = "command=\""; |
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) { |
|
opts += strlen(cp); |
|
free(forced_command); |
|
forced_command = xmalloc(strlen(opts) + 1); |
|
i = 0; |
|
while (*opts) { |
|
if (*opts == '"') |
|
break; |
|
if (*opts == '\\' && opts[1] == '"') { |
|
opts += 2; |
|
forced_command[i++] = '"'; |
|
continue; |
|
} |
|
forced_command[i++] = *opts++; |
|
} |
|
if (!*opts) { |
|
debug("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
free(forced_command); |
|
forced_command = NULL; |
|
goto bad_option; |
|
} |
|
forced_command[i] = '\0'; |
|
auth_debug_add("Forced command."); |
|
opts++; |
|
goto next_option; |
|
} |
|
cp = "principals=\""; |
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) { |
|
opts += strlen(cp); |
|
free(authorized_principals); |
|
authorized_principals = xmalloc(strlen(opts) + 1); |
|
i = 0; |
|
while (*opts) { |
|
if (*opts == '"') |
|
break; |
|
if (*opts == '\\' && opts[1] == '"') { |
|
opts += 2; |
|
authorized_principals[i++] = '"'; |
|
continue; |
|
} |
|
authorized_principals[i++] = *opts++; |
|
} |
|
if (!*opts) { |
|
debug("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
free(authorized_principals); |
|
authorized_principals = NULL; |
|
goto bad_option; |
|
} |
|
authorized_principals[i] = '\0'; |
|
auth_debug_add("principals: %.900s", |
|
authorized_principals); |
|
opts++; |
|
goto next_option; |
|
} |
|
cp = "environment=\""; |
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) { |
|
char *s; |
|
struct envstring *new_envstring; |
|
|
|
opts += strlen(cp); |
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s = xmalloc(strlen(opts) + 1); |
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i = 0; |
|
while (*opts) { |
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if (*opts == '"') |
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break; |
|
if (*opts == '\\' && opts[1] == '"') { |
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opts += 2; |
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s[i++] = '"'; |
|
continue; |
|
} |
|
s[i++] = *opts++; |
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} |
|
if (!*opts) { |
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debug("%.100s, line %lu: missing end quote", |
|
file, linenum); |
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auth_debug_add("%.100s, line %lu: missing end quote", |
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file, linenum); |
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free(s); |
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goto bad_option; |
|
} |
|
s[i] = '\0'; |
|
opts++; |
|
if (options.permit_user_env) { |
|
auth_debug_add("Adding to environment: " |
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"%.900s", s); |
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debug("Adding to environment: %.900s", s); |
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new_envstring = xcalloc(1, |
|
sizeof(*new_envstring)); |
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new_envstring->s = s; |
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new_envstring->next = custom_environment; |
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custom_environment = new_envstring; |
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s = NULL; |
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} |
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free(s); |
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goto next_option; |
|
} |
|
cp = "from=\""; |
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if (strncasecmp(opts, cp, strlen(cp)) == 0) { |
|
const char *remote_ip = ssh_remote_ipaddr(ssh); |
|
const char *remote_host = auth_get_canonical_hostname( |
|
ssh, options.use_dns); |
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char *patterns = xmalloc(strlen(opts) + 1); |
|
|
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opts += strlen(cp); |
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i = 0; |
|
while (*opts) { |
|
if (*opts == '"') |
|
break; |
|
if (*opts == '\\' && opts[1] == '"') { |
|
opts += 2; |
|
patterns[i++] = '"'; |
|
continue; |
|
} |
|
patterns[i++] = *opts++; |
|
} |
|
if (!*opts) { |
|
debug("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
free(patterns); |
|
goto bad_option; |
|
} |
|
patterns[i] = '\0'; |
|
opts++; |
|
switch (match_host_and_ip(remote_host, remote_ip, |
|
patterns)) { |
|
case 1: |
|
free(patterns); |
|
/* Host name matches. */ |
|
goto next_option; |
|
case -1: |
|
debug("%.100s, line %lu: invalid criteria", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: " |
|
"invalid criteria", file, linenum); |
|
/* FALLTHROUGH */ |
|
case 0: |
|
free(patterns); |
|
logit("Authentication tried for %.100s with " |
|
"correct key but not from a permitted " |
|
"host (host=%.200s, ip=%.200s).", |
|
pw->pw_name, remote_host, remote_ip); |
|
auth_debug_add("Your host '%.200s' is not " |
|
"permitted to use this key for login.", |
|
remote_host); |
|
break; |
|
} |
|
/* deny access */ |
|
return 0; |
|
} |
|
cp = "permitopen=\""; |
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) { |
|
char *host, *p; |
|
int port; |
|
char *patterns = xmalloc(strlen(opts) + 1); |
|
|
|
opts += strlen(cp); |
|
i = 0; |
|
while (*opts) { |
|
if (*opts == '"') |
|
break; |
|
if (*opts == '\\' && opts[1] == '"') { |
|
opts += 2; |
|
patterns[i++] = '"'; |
|
continue; |
|
} |
|
patterns[i++] = *opts++; |
|
} |
|
if (!*opts) { |
|
debug("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: missing " |
|
"end quote", file, linenum); |
|
free(patterns); |
|
goto bad_option; |
|
} |
|
patterns[i] = '\0'; |
|
opts++; |
|
p = patterns; |
|
/* XXX - add streamlocal support */ |
|
host = hpdelim(&p); |
|
if (host == NULL || strlen(host) >= NI_MAXHOST) { |
|
debug("%.100s, line %lu: Bad permitopen " |
|
"specification <%.100s>", file, linenum, |
|
patterns); |
|
auth_debug_add("%.100s, line %lu: " |
|
"Bad permitopen specification", file, |
|
linenum); |
|
free(patterns); |
|
goto bad_option; |
|
} |
|
host = cleanhostname(host); |
|
if (p == NULL || (port = permitopen_port(p)) < 0) { |
|
debug("%.100s, line %lu: Bad permitopen port " |
|
"<%.100s>", file, linenum, p ? p : ""); |
|
auth_debug_add("%.100s, line %lu: " |
|
"Bad permitopen port", file, linenum); |
|
free(patterns); |
|
goto bad_option; |
|
} |
|
if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) |
|
channel_add_permitted_opens(ssh, host, port); |
|
free(patterns); |
|
goto next_option; |
|
} |
|
cp = "tunnel=\""; |
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) { |
|
char *tun = NULL; |
|
opts += strlen(cp); |
|
tun = xmalloc(strlen(opts) + 1); |
|
i = 0; |
|
while (*opts) { |
|
if (*opts == '"') |
|
break; |
|
tun[i++] = *opts++; |
|
} |
|
if (!*opts) { |
|
debug("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: missing end quote", |
|
file, linenum); |
|
free(tun); |
|
forced_tun_device = -1; |
|
goto bad_option; |
|
} |
|
tun[i] = '\0'; |
|
forced_tun_device = a2tun(tun, NULL); |
|
free(tun); |
|
if (forced_tun_device == SSH_TUNID_ERR) { |
|
debug("%.100s, line %lu: invalid tun device", |
|
file, linenum); |
|
auth_debug_add("%.100s, line %lu: invalid tun device", |
|
file, linenum); |
|
forced_tun_device = -1; |
|
goto bad_option; |
|
} |
|
auth_debug_add("Forced tun device: %d", forced_tun_device); |
|
opts++; |
|
goto next_option; |
|
} |
|
next_option: |
|
/* |
|
* Skip the comma, and move to the next option |
|
* (or break out if there are no more). |
|
*/ |
|
if (!*opts) |
|
fatal("Bugs in auth-options.c option processing."); |
|
if (*opts == ' ' || *opts == '\t') |
|
break; /* End of options. */ |
|
if (*opts != ',') |
|
goto bad_option; |
|
opts++; |
|
/* Process the next option. */ |
|
} |
|
|
|
/* grant access */ |
|
return 1; |
|
|
|
bad_option: |
|
logit("Bad options in %.100s file, line %lu: %.50s", |
|
file, linenum, opts); |
|
auth_debug_add("Bad options in %.100s file, line %lu: %.50s", |
|
file, linenum, opts); |
|
|
|
/* deny access */ |
|
return 0; |
|
} |
|
|
|
#define OPTIONS_CRITICAL 1 |
|
#define OPTIONS_EXTENSIONS 2 |
|
static int |
|
parse_option_list(struct sshbuf *oblob, struct passwd *pw, |
|
u_int which, int crit, |
|
int *cert_no_port_forwarding_flag, |
|
int *cert_no_agent_forwarding_flag, |
|
int *cert_no_x11_forwarding_flag, |
|
int *cert_no_pty_flag, |
|
int *cert_no_user_rc, |
|
char **cert_forced_command, |
|
int *cert_source_address_done) |
|
{ |
|
struct ssh *ssh = active_state; /* XXX */ |
|
char *command, *allowed; |
|
const char *remote_ip; |
|
char *name = NULL; |
|
struct sshbuf *c = NULL, *data = NULL; |
|
int r, ret = -1, result, found; |
|
|
|
if ((c = sshbuf_fromb(oblob)) == NULL) { |
|
error("%s: sshbuf_fromb failed", __func__); |
|
goto out; |
|
} |
|
|
|
while (sshbuf_len(c) > 0) { |
|
sshbuf_free(data); |
|
data = NULL; |
|
if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 || |
|
(r = sshbuf_froms(c, &data)) != 0) { |
|
error("Unable to parse certificate options: %s", |
|
ssh_err(r)); |
|
goto out; |
|
} |
|
debug3("found certificate option \"%.100s\" len %zu", |
|
name, sshbuf_len(data)); |
|
found = 0; |
|
if ((which & OPTIONS_EXTENSIONS) != 0) { |
|
if (strcmp(name, "permit-X11-forwarding") == 0) { |
|
*cert_no_x11_forwarding_flag = 0; |
|
found = 1; |
|
} else if (strcmp(name, |
|
"permit-agent-forwarding") == 0) { |
|
*cert_no_agent_forwarding_flag = 0; |
|
found = 1; |
|
} else if (strcmp(name, |
|
"permit-port-forwarding") == 0) { |
|
*cert_no_port_forwarding_flag = 0; |
|
found = 1; |
|
} else if (strcmp(name, "permit-pty") == 0) { |
|
*cert_no_pty_flag = 0; |
|
found = 1; |
|
} else if (strcmp(name, "permit-user-rc") == 0) { |
|
*cert_no_user_rc = 0; |
|
found = 1; |
|
} |
|
} |
|
if (!found && (which & OPTIONS_CRITICAL) != 0) { |
|
if (strcmp(name, "force-command") == 0) { |
|
if ((r = sshbuf_get_cstring(data, &command, |
|
NULL)) != 0) { |
|
error("Unable to parse \"%s\" " |
|
"section: %s", name, ssh_err(r)); |
|
goto out; |
|
} |
|
if (*cert_forced_command != NULL) { |
|
error("Certificate has multiple " |
|
"force-command options"); |
|
free(command); |
|
goto out; |
|
} |
|
*cert_forced_command = command; |
|
found = 1; |
|
} |
|
if (strcmp(name, "source-address") == 0) { |
|
if ((r = sshbuf_get_cstring(data, &allowed, |
|
NULL)) != 0) { |
|
error("Unable to parse \"%s\" " |
|
"section: %s", name, ssh_err(r)); |
|
goto out; |
|
} |
|
if ((*cert_source_address_done)++) { |
|
error("Certificate has multiple " |
|
"source-address options"); |
|
free(allowed); |
|
goto out; |
|
} |
|
remote_ip = ssh_remote_ipaddr(ssh); |
|
result = addr_match_cidr_list(remote_ip, |
|
allowed); |
|
free(allowed); |
|
switch (result) { |
|
case 1: |
|
/* accepted */ |
|
break; |
|
case 0: |
|
/* no match */ |
|
logit("Authentication tried for %.100s " |
|
"with valid certificate but not " |
|
"from a permitted host " |
|
"(ip=%.200s).", pw->pw_name, |
|
remote_ip); |
|
auth_debug_add("Your address '%.200s' " |
|
"is not permitted to use this " |
|
"certificate for login.", |
|
remote_ip); |
|
goto out; |
|
case -1: |
|
default: |
|
error("Certificate source-address " |
|
"contents invalid"); |
|
goto out; |
|
} |
|
found = 1; |
|
} |
|
} |
|
|
|
if (!found) { |
|
if (crit) { |
|
error("Certificate critical option \"%s\" " |
|
"is not supported", name); |
|
goto out; |
|
} else { |
|
logit("Certificate extension \"%s\" " |
|
"is not supported", name); |
|
} |
|
} else if (sshbuf_len(data) != 0) { |
|
error("Certificate option \"%s\" corrupt " |
|
"(extra data)", name); |
|
goto out; |
|
} |
|
free(name); |
|
name = NULL; |
|
} |
|
/* successfully parsed all options */ |
|
ret = 0; |
|
|
|
out: |
|
if (ret != 0 && |
|
cert_forced_command != NULL && |
|
*cert_forced_command != NULL) { |
|
free(*cert_forced_command); |
|
*cert_forced_command = NULL; |
|
} |
|
free(name); |
|
sshbuf_free(data); |
|
sshbuf_free(c); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Set options from critical certificate options. These supersede user key |
|
* options so this must be called after auth_parse_options(). |
|
*/ |
|
int |
|
auth_cert_options(struct sshkey *k, struct passwd *pw, const char **reason) |
|
{ |
|
int cert_no_port_forwarding_flag = 1; |
|
int cert_no_agent_forwarding_flag = 1; |
|
int cert_no_x11_forwarding_flag = 1; |
|
int cert_no_pty_flag = 1; |
|
int cert_no_user_rc = 1; |
|
char *cert_forced_command = NULL; |
|
int cert_source_address_done = 0; |
|
|
|
*reason = "invalid certificate options"; |
|
|
|
/* Separate options and extensions for v01 certs */ |
|
if (parse_option_list(k->cert->critical, pw, |
|
OPTIONS_CRITICAL, 1, NULL, NULL, NULL, NULL, NULL, |
|
&cert_forced_command, |
|
&cert_source_address_done) == -1) |
|
return -1; |
|
if (parse_option_list(k->cert->extensions, pw, |
|
OPTIONS_EXTENSIONS, 0, |
|
&cert_no_port_forwarding_flag, |
|
&cert_no_agent_forwarding_flag, |
|
&cert_no_x11_forwarding_flag, |
|
&cert_no_pty_flag, |
|
&cert_no_user_rc, |
|
NULL, NULL) == -1) |
|
return -1; |
|
|
|
no_port_forwarding_flag |= cert_no_port_forwarding_flag; |
|
no_agent_forwarding_flag |= cert_no_agent_forwarding_flag; |
|
no_x11_forwarding_flag |= cert_no_x11_forwarding_flag; |
|
no_pty_flag |= cert_no_pty_flag; |
|
no_user_rc |= cert_no_user_rc; |
|
/* |
|
* Only permit both CA and key option forced-command if they match. |
|
* Otherwise refuse the certificate. |
|
*/ |
|
if (cert_forced_command != NULL && forced_command != NULL) { |
|
if (strcmp(forced_command, cert_forced_command) == 0) { |
|
free(forced_command); |
|
forced_command = cert_forced_command; |
|
} else { |
|
*reason = "certificate and key options forced command " |
|
"do not match"; |
|
free(cert_forced_command); |
|
return -1; |
|
} |
|
} else if (cert_forced_command != NULL) |
|
forced_command = cert_forced_command; |
|
/* success */ |
|
*reason = NULL; |
|
return 0; |
|
} |
|
|
|
/* |
|
* authorized_keys options processing. |
|
*/ |
|
|
|
/* |
/* |
* Match flag 'opt' in *optsp, and if allow_negate is set then also match |
* Match flag 'opt' in *optsp, and if allow_negate is set then also match |