version 1.91, 2002/05/13 02:37:39 |
version 1.92, 2002/05/25 18:51:07 |
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#include "includes.h" |
#include "includes.h" |
RCSID("$OpenBSD$"); |
RCSID("$OpenBSD$"); |
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#include <openssl/evp.h> |
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#include "ssh2.h" |
#include "ssh2.h" |
#include "xmalloc.h" |
#include "xmalloc.h" |
#include "rsa.h" |
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#include "sshpty.h" |
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#include "packet.h" |
#include "packet.h" |
#include "buffer.h" |
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#include "log.h" |
#include "log.h" |
#include "servconf.h" |
#include "servconf.h" |
#include "compat.h" |
#include "compat.h" |
#include "channels.h" |
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#include "bufaux.h" |
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#include "auth.h" |
#include "auth.h" |
#include "session.h" |
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#include "dispatch.h" |
#include "dispatch.h" |
#include "key.h" |
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#include "cipher.h" |
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#include "kex.h" |
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#include "pathnames.h" |
#include "pathnames.h" |
#include "uidswap.h" |
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#include "auth-options.h" |
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#include "hostfile.h" |
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#include "canohost.h" |
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#include "match.h" |
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#include "monitor_wrap.h" |
#include "monitor_wrap.h" |
#include "atomicio.h" |
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/* import */ |
/* import */ |
extern ServerOptions options; |
extern ServerOptions options; |
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int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); |
int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); |
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/* auth */ |
/* auth */ |
static void userauth_banner(void); |
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static int userauth_none(Authctxt *); |
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static int userauth_passwd(Authctxt *); |
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static int userauth_pubkey(Authctxt *); |
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static int userauth_hostbased(Authctxt *); |
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static int userauth_kbdint(Authctxt *); |
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Authmethod authmethods[] = { |
Authmethod authmethods[] = { |
{"none", |
{"none", |
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} |
} |
} |
} |
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char * |
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auth2_read_banner(void) |
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{ |
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struct stat st; |
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char *banner = NULL; |
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off_t len, n; |
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int fd; |
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if ((fd = open(options.banner, O_RDONLY)) == -1) |
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return (NULL); |
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if (fstat(fd, &st) == -1) { |
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close(fd); |
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return (NULL); |
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} |
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len = st.st_size; |
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banner = xmalloc(len + 1); |
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n = atomicio(read, fd, banner, len); |
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close(fd); |
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if (n != len) { |
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free(banner); |
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return (NULL); |
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} |
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banner[n] = '\0'; |
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return (banner); |
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} |
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static void |
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userauth_banner(void) |
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{ |
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char *banner = NULL; |
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if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) |
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return; |
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if ((banner = PRIVSEP(auth2_read_banner())) == NULL) |
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goto done; |
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packet_start(SSH2_MSG_USERAUTH_BANNER); |
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packet_put_cstring(banner); |
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packet_put_cstring(""); /* language, unused */ |
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packet_send(); |
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debug("userauth_banner: sent"); |
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done: |
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if (banner) |
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xfree(banner); |
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return; |
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} |
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static int |
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userauth_none(Authctxt *authctxt) |
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{ |
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/* disable method "none", only allowed one time */ |
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Authmethod *m = authmethod_lookup("none"); |
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if (m != NULL) |
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m->enabled = NULL; |
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packet_check_eom(); |
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userauth_banner(); |
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return (authctxt->valid ? PRIVSEP(auth_password(authctxt, "")) : 0); |
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} |
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static int |
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userauth_passwd(Authctxt *authctxt) |
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{ |
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char *password; |
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int authenticated = 0; |
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int change; |
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u_int len; |
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change = packet_get_char(); |
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if (change) |
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log("password change not supported"); |
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password = packet_get_string(&len); |
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packet_check_eom(); |
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if (authctxt->valid && |
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PRIVSEP(auth_password(authctxt, password)) == 1) |
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authenticated = 1; |
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memset(password, 0, len); |
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xfree(password); |
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return authenticated; |
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} |
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static int |
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userauth_kbdint(Authctxt *authctxt) |
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{ |
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int authenticated = 0; |
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char *lang, *devs; |
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lang = packet_get_string(NULL); |
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devs = packet_get_string(NULL); |
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packet_check_eom(); |
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debug("keyboard-interactive devs %s", devs); |
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if (options.challenge_response_authentication) |
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authenticated = auth2_challenge(authctxt, devs); |
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xfree(devs); |
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xfree(lang); |
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return authenticated; |
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} |
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static int |
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userauth_pubkey(Authctxt *authctxt) |
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{ |
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Buffer b; |
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Key *key = NULL; |
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char *pkalg; |
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u_char *pkblob, *sig; |
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u_int alen, blen, slen; |
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int have_sig, pktype; |
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int authenticated = 0; |
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if (!authctxt->valid) { |
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debug2("userauth_pubkey: disabled because of invalid user"); |
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return 0; |
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} |
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have_sig = packet_get_char(); |
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if (datafellows & SSH_BUG_PKAUTH) { |
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debug2("userauth_pubkey: SSH_BUG_PKAUTH"); |
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/* no explicit pkalg given */ |
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pkblob = packet_get_string(&blen); |
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buffer_init(&b); |
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buffer_append(&b, pkblob, blen); |
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/* so we have to extract the pkalg from the pkblob */ |
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pkalg = buffer_get_string(&b, &alen); |
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buffer_free(&b); |
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} else { |
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pkalg = packet_get_string(&alen); |
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pkblob = packet_get_string(&blen); |
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} |
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pktype = key_type_from_name(pkalg); |
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if (pktype == KEY_UNSPEC) { |
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/* this is perfectly legal */ |
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log("userauth_pubkey: unsupported public key algorithm: %s", |
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pkalg); |
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goto done; |
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} |
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key = key_from_blob(pkblob, blen); |
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if (key == NULL) { |
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error("userauth_pubkey: cannot decode key: %s", pkalg); |
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goto done; |
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} |
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if (key->type != pktype) { |
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error("userauth_pubkey: type mismatch for decoded key " |
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"(received %d, expected %d)", key->type, pktype); |
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goto done; |
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} |
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if (have_sig) { |
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sig = packet_get_string(&slen); |
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packet_check_eom(); |
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buffer_init(&b); |
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if (datafellows & SSH_OLD_SESSIONID) { |
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buffer_append(&b, session_id2, session_id2_len); |
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} else { |
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buffer_put_string(&b, session_id2, session_id2_len); |
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} |
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/* reconstruct packet */ |
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buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
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buffer_put_cstring(&b, authctxt->user); |
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buffer_put_cstring(&b, |
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datafellows & SSH_BUG_PKSERVICE ? |
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"ssh-userauth" : |
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authctxt->service); |
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if (datafellows & SSH_BUG_PKAUTH) { |
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buffer_put_char(&b, have_sig); |
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} else { |
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buffer_put_cstring(&b, "publickey"); |
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buffer_put_char(&b, have_sig); |
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buffer_put_cstring(&b, pkalg); |
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} |
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buffer_put_string(&b, pkblob, blen); |
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#ifdef DEBUG_PK |
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buffer_dump(&b); |
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#endif |
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/* test for correct signature */ |
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authenticated = 0; |
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if (PRIVSEP(user_key_allowed(authctxt->pw, key)) && |
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PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), |
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buffer_len(&b))) == 1) |
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authenticated = 1; |
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buffer_clear(&b); |
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xfree(sig); |
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} else { |
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debug("test whether pkalg/pkblob are acceptable"); |
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packet_check_eom(); |
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/* XXX fake reply and always send PK_OK ? */ |
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/* |
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* XXX this allows testing whether a user is allowed |
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* to login: if you happen to have a valid pubkey this |
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* message is sent. the message is NEVER sent at all |
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* if a user is not allowed to login. is this an |
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* issue? -markus |
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*/ |
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if (PRIVSEP(user_key_allowed(authctxt->pw, key))) { |
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packet_start(SSH2_MSG_USERAUTH_PK_OK); |
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packet_put_string(pkalg, alen); |
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packet_put_string(pkblob, blen); |
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packet_send(); |
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packet_write_wait(); |
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authctxt->postponed = 1; |
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} |
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} |
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if (authenticated != 1) |
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auth_clear_options(); |
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done: |
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debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); |
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if (key != NULL) |
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key_free(key); |
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xfree(pkalg); |
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xfree(pkblob); |
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return authenticated; |
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} |
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static int |
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userauth_hostbased(Authctxt *authctxt) |
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{ |
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Buffer b; |
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Key *key = NULL; |
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char *pkalg, *cuser, *chost, *service; |
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u_char *pkblob, *sig; |
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u_int alen, blen, slen; |
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int pktype; |
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int authenticated = 0; |
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if (!authctxt->valid) { |
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debug2("userauth_hostbased: disabled because of invalid user"); |
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return 0; |
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} |
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pkalg = packet_get_string(&alen); |
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pkblob = packet_get_string(&blen); |
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chost = packet_get_string(NULL); |
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cuser = packet_get_string(NULL); |
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sig = packet_get_string(&slen); |
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debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", |
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cuser, chost, pkalg, slen); |
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#ifdef DEBUG_PK |
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debug("signature:"); |
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buffer_init(&b); |
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buffer_append(&b, sig, slen); |
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buffer_dump(&b); |
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buffer_free(&b); |
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#endif |
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pktype = key_type_from_name(pkalg); |
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if (pktype == KEY_UNSPEC) { |
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/* this is perfectly legal */ |
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log("userauth_hostbased: unsupported " |
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"public key algorithm: %s", pkalg); |
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goto done; |
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} |
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key = key_from_blob(pkblob, blen); |
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if (key == NULL) { |
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error("userauth_hostbased: cannot decode key: %s", pkalg); |
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goto done; |
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} |
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if (key->type != pktype) { |
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error("userauth_hostbased: type mismatch for decoded key " |
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"(received %d, expected %d)", key->type, pktype); |
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goto done; |
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} |
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service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : |
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authctxt->service; |
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buffer_init(&b); |
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buffer_put_string(&b, session_id2, session_id2_len); |
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/* reconstruct packet */ |
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buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
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buffer_put_cstring(&b, authctxt->user); |
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buffer_put_cstring(&b, service); |
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buffer_put_cstring(&b, "hostbased"); |
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buffer_put_string(&b, pkalg, alen); |
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buffer_put_string(&b, pkblob, blen); |
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buffer_put_cstring(&b, chost); |
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buffer_put_cstring(&b, cuser); |
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#ifdef DEBUG_PK |
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buffer_dump(&b); |
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#endif |
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/* test for allowed key and correct signature */ |
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authenticated = 0; |
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if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) && |
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PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), |
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buffer_len(&b))) == 1) |
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authenticated = 1; |
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buffer_clear(&b); |
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done: |
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debug2("userauth_hostbased: authenticated %d", authenticated); |
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if (key != NULL) |
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key_free(key); |
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xfree(pkalg); |
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xfree(pkblob); |
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xfree(cuser); |
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xfree(chost); |
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xfree(sig); |
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return authenticated; |
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} |
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/* get current user */ |
/* get current user */ |
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struct passwd* |
struct passwd* |
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return method; |
return method; |
debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); |
debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); |
return NULL; |
return NULL; |
} |
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/* return 1 if user allows given key */ |
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static int |
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user_key_allowed2(struct passwd *pw, Key *key, char *file) |
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{ |
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char line[8192]; |
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int found_key = 0; |
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FILE *f; |
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u_long linenum = 0; |
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struct stat st; |
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Key *found; |
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char *fp; |
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if (pw == NULL) |
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return 0; |
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/* Temporarily use the user's uid. */ |
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temporarily_use_uid(pw); |
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debug("trying public key file %s", file); |
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/* Fail quietly if file does not exist */ |
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if (stat(file, &st) < 0) { |
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/* Restore the privileged uid. */ |
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restore_uid(); |
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return 0; |
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} |
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/* Open the file containing the authorized keys. */ |
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f = fopen(file, "r"); |
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if (!f) { |
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/* Restore the privileged uid. */ |
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restore_uid(); |
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return 0; |
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} |
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if (options.strict_modes && |
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secure_filename(f, file, pw, line, sizeof(line)) != 0) { |
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fclose(f); |
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log("Authentication refused: %s", line); |
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restore_uid(); |
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return 0; |
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} |
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found_key = 0; |
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found = key_new(key->type); |
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while (fgets(line, sizeof(line), f)) { |
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char *cp, *options = NULL; |
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linenum++; |
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/* Skip leading whitespace, empty and comment lines. */ |
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for (cp = line; *cp == ' ' || *cp == '\t'; cp++) |
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; |
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if (!*cp || *cp == '\n' || *cp == '#') |
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continue; |
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if (key_read(found, &cp) != 1) { |
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/* no key? check if there are options for this key */ |
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int quoted = 0; |
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debug2("user_key_allowed: check options: '%s'", cp); |
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options = cp; |
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for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { |
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if (*cp == '\\' && cp[1] == '"') |
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cp++; /* Skip both */ |
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else if (*cp == '"') |
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quoted = !quoted; |
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} |
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/* Skip remaining whitespace. */ |
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for (; *cp == ' ' || *cp == '\t'; cp++) |
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; |
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if (key_read(found, &cp) != 1) { |
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debug2("user_key_allowed: advance: '%s'", cp); |
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/* still no key? advance to next line*/ |
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continue; |
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} |
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} |
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if (key_equal(found, key) && |
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auth_parse_options(pw, options, file, linenum) == 1) { |
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found_key = 1; |
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debug("matching key found: file %s, line %lu", |
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file, linenum); |
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fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); |
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verbose("Found matching %s key: %s", |
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key_type(found), fp); |
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xfree(fp); |
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break; |
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} |
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} |
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restore_uid(); |
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fclose(f); |
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key_free(found); |
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if (!found_key) |
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debug2("key not found"); |
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return found_key; |
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} |
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/* check whether given key is in .ssh/authorized_keys* */ |
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int |
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user_key_allowed(struct passwd *pw, Key *key) |
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{ |
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int success; |
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char *file; |
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file = authorized_keys_file(pw); |
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success = user_key_allowed2(pw, key, file); |
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xfree(file); |
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if (success) |
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return success; |
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/* try suffix "2" for backward compat, too */ |
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file = authorized_keys_file2(pw); |
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success = user_key_allowed2(pw, key, file); |
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xfree(file); |
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return success; |
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} |
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/* return 1 if given hostkey is allowed */ |
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int |
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hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, |
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Key *key) |
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{ |
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const char *resolvedname, *ipaddr, *lookup; |
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HostStatus host_status; |
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int len; |
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resolvedname = get_canonical_hostname(options.verify_reverse_mapping); |
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ipaddr = get_remote_ipaddr(); |
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debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", |
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chost, resolvedname, ipaddr); |
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if (options.hostbased_uses_name_from_packet_only) { |
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if (auth_rhosts2(pw, cuser, chost, chost) == 0) |
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return 0; |
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lookup = chost; |
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} else { |
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if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { |
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debug2("stripping trailing dot from chost %s", chost); |
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chost[len - 1] = '\0'; |
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} |
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if (strcasecmp(resolvedname, chost) != 0) |
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log("userauth_hostbased mismatch: " |
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"client sends %s, but we resolve %s to %s", |
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chost, ipaddr, resolvedname); |
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if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) |
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return 0; |
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lookup = resolvedname; |
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} |
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debug2("userauth_hostbased: access allowed by auth_rhosts2"); |
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host_status = check_key_in_hostfiles(pw, key, lookup, |
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_PATH_SSH_SYSTEM_HOSTFILE, |
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options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); |
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/* backward compat if no key has been found. */ |
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if (host_status == HOST_NEW) |
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host_status = check_key_in_hostfiles(pw, key, lookup, |
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_PATH_SSH_SYSTEM_HOSTFILE2, |
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options.ignore_user_known_hosts ? NULL : |
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_PATH_SSH_USER_HOSTFILE2); |
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return (host_status == HOST_OK); |
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} |
} |