version 1.5, 2000/04/26 20:56:29 |
version 1.6, 2000/04/26 21:28:31 |
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#include "includes.h" |
#include "includes.h" |
RCSID("$OpenBSD$"); |
RCSID("$OpenBSD$"); |
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#include <openssl/dsa.h> |
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#include <openssl/rsa.h> |
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#include <openssl/evp.h> |
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#include "xmalloc.h" |
#include "xmalloc.h" |
#include "rsa.h" |
#include "rsa.h" |
#include "ssh.h" |
#include "ssh.h" |
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#include "compat.h" |
#include "compat.h" |
#include "channels.h" |
#include "channels.h" |
#include "match.h" |
#include "match.h" |
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#include "bufaux.h" |
#include "bufaux.h" |
#include "ssh2.h" |
#include "ssh2.h" |
#include "auth.h" |
#include "auth.h" |
#include "session.h" |
#include "session.h" |
#include "dispatch.h" |
#include "dispatch.h" |
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#include "key.h" |
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#include "kex.h" |
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#include "dsa.h" |
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#include "uidswap.h" |
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#include "channels.h" |
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/* import */ |
/* import */ |
extern ServerOptions options; |
extern ServerOptions options; |
|
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} |
} |
/* We found no reason not to let this user try to log on... */ |
/* We found no reason not to let this user try to log on... */ |
return 1; |
return 1; |
} |
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/* import */ |
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extern ServerOptions options; |
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extern char *forced_command; |
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/* |
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* convert ssh auth msg type into description |
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*/ |
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char * |
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get_authname(int type) |
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{ |
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static char buf[1024]; |
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switch (type) { |
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case SSH_CMSG_AUTH_PASSWORD: |
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return "password"; |
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case SSH_CMSG_AUTH_RSA: |
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return "rsa"; |
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case SSH_CMSG_AUTH_RHOSTS_RSA: |
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return "rhosts-rsa"; |
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case SSH_CMSG_AUTH_RHOSTS: |
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return "rhosts"; |
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#ifdef KRB4 |
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case SSH_CMSG_AUTH_KERBEROS: |
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return "kerberos"; |
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#endif |
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#ifdef SKEY |
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case SSH_CMSG_AUTH_TIS_RESPONSE: |
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return "s/key"; |
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#endif |
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} |
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snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); |
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return buf; |
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} |
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#define AUTH_FAIL_MAX 6 |
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#define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2) |
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#define AUTH_FAIL_MSG "Too many authentication failures for %.100s" |
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/* |
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* The user does not exist or access is denied, |
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* but fake indication that authentication is needed. |
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*/ |
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void |
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do_fake_authloop1(char *user) |
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{ |
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int attempt = 0; |
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log("Faking authloop for illegal user %.200s from %.200s port %d", |
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user, |
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get_remote_ipaddr(), |
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get_remote_port()); |
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/* Indicate that authentication is needed. */ |
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packet_start(SSH_SMSG_FAILURE); |
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packet_send(); |
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packet_write_wait(); |
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/* |
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* Keep reading packets, and always respond with a failure. This is |
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* to avoid disclosing whether such a user really exists. |
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*/ |
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for (attempt = 1;; attempt++) { |
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/* Read a packet. This will not return if the client disconnects. */ |
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int plen; |
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int type = packet_read(&plen); |
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#ifdef SKEY |
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unsigned int dlen; |
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char *password, *skeyinfo; |
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password = NULL; |
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/* Try to send a fake s/key challenge. */ |
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if (options.skey_authentication == 1 && |
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(skeyinfo = skey_fake_keyinfo(user)) != NULL) { |
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if (type == SSH_CMSG_AUTH_TIS) { |
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packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
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packet_put_string(skeyinfo, strlen(skeyinfo)); |
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packet_send(); |
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packet_write_wait(); |
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continue; |
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} else if (type == SSH_CMSG_AUTH_PASSWORD && |
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options.password_authentication && |
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(password = packet_get_string(&dlen)) != NULL && |
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dlen == 5 && |
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strncasecmp(password, "s/key", 5) == 0 ) { |
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packet_send_debug(skeyinfo); |
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} |
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} |
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if (password != NULL) |
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xfree(password); |
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#endif |
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if (attempt > AUTH_FAIL_MAX) |
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packet_disconnect(AUTH_FAIL_MSG, user); |
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/* |
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* Send failure. This should be indistinguishable from a |
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* failed authentication. |
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*/ |
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packet_start(SSH_SMSG_FAILURE); |
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packet_send(); |
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packet_write_wait(); |
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} |
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/* NOTREACHED */ |
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abort(); |
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} |
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/* |
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* read packets and try to authenticate local user *pw. |
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* return if authentication is successfull |
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*/ |
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void |
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do_authloop(struct passwd * pw) |
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{ |
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int attempt = 0; |
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unsigned int bits; |
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RSA *client_host_key; |
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BIGNUM *n; |
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char *client_user, *password; |
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char user[1024]; |
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unsigned int dlen; |
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int plen, nlen, elen; |
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unsigned int ulen; |
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int type = 0; |
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void (*authlog) (const char *fmt,...) = verbose; |
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/* Indicate that authentication is needed. */ |
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packet_start(SSH_SMSG_FAILURE); |
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packet_send(); |
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packet_write_wait(); |
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for (attempt = 1;; attempt++) { |
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int authenticated = 0; |
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strlcpy(user, "", sizeof user); |
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/* Get a packet from the client. */ |
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type = packet_read(&plen); |
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/* Process the packet. */ |
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switch (type) { |
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#ifdef AFS |
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case SSH_CMSG_HAVE_KERBEROS_TGT: |
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if (!options.kerberos_tgt_passing) { |
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/* packet_get_all(); */ |
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verbose("Kerberos tgt passing disabled."); |
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break; |
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} else { |
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/* Accept Kerberos tgt. */ |
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char *tgt = packet_get_string(&dlen); |
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packet_integrity_check(plen, 4 + dlen, type); |
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if (!auth_kerberos_tgt(pw, tgt)) |
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verbose("Kerberos tgt REFUSED for %s", pw->pw_name); |
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xfree(tgt); |
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} |
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continue; |
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case SSH_CMSG_HAVE_AFS_TOKEN: |
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if (!options.afs_token_passing || !k_hasafs()) { |
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/* packet_get_all(); */ |
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verbose("AFS token passing disabled."); |
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break; |
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} else { |
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/* Accept AFS token. */ |
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char *token_string = packet_get_string(&dlen); |
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packet_integrity_check(plen, 4 + dlen, type); |
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if (!auth_afs_token(pw, token_string)) |
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verbose("AFS token REFUSED for %s", pw->pw_name); |
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xfree(token_string); |
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} |
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continue; |
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#endif /* AFS */ |
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#ifdef KRB4 |
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case SSH_CMSG_AUTH_KERBEROS: |
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if (!options.kerberos_authentication) { |
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/* packet_get_all(); */ |
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verbose("Kerberos authentication disabled."); |
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break; |
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} else { |
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/* Try Kerberos v4 authentication. */ |
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KTEXT_ST auth; |
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char *tkt_user = NULL; |
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char *kdata = packet_get_string((unsigned int *) &auth.length); |
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packet_integrity_check(plen, 4 + auth.length, type); |
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if (auth.length < MAX_KTXT_LEN) |
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memcpy(auth.dat, kdata, auth.length); |
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xfree(kdata); |
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authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); |
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if (authenticated) { |
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snprintf(user, sizeof user, " tktuser %s", tkt_user); |
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xfree(tkt_user); |
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} |
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} |
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break; |
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#endif /* KRB4 */ |
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case SSH_CMSG_AUTH_RHOSTS: |
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if (!options.rhosts_authentication) { |
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verbose("Rhosts authentication disabled."); |
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break; |
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} |
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/* |
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* Get client user name. Note that we just have to |
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* trust the client; this is one reason why rhosts |
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* authentication is insecure. (Another is |
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* IP-spoofing on a local network.) |
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*/ |
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client_user = packet_get_string(&ulen); |
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packet_integrity_check(plen, 4 + ulen, type); |
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/* Try to authenticate using /etc/hosts.equiv and |
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.rhosts. */ |
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authenticated = auth_rhosts(pw, client_user); |
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|
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snprintf(user, sizeof user, " ruser %s", client_user); |
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xfree(client_user); |
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break; |
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case SSH_CMSG_AUTH_RHOSTS_RSA: |
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if (!options.rhosts_rsa_authentication) { |
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verbose("Rhosts with RSA authentication disabled."); |
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break; |
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} |
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/* |
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* Get client user name. Note that we just have to |
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* trust the client; root on the client machine can |
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* claim to be any user. |
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*/ |
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client_user = packet_get_string(&ulen); |
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/* Get the client host key. */ |
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client_host_key = RSA_new(); |
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if (client_host_key == NULL) |
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fatal("RSA_new failed"); |
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client_host_key->e = BN_new(); |
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client_host_key->n = BN_new(); |
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if (client_host_key->e == NULL || client_host_key->n == NULL) |
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fatal("BN_new failed"); |
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bits = packet_get_int(); |
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packet_get_bignum(client_host_key->e, &elen); |
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packet_get_bignum(client_host_key->n, &nlen); |
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if (bits != BN_num_bits(client_host_key->n)) |
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error("Warning: keysize mismatch for client_host_key: " |
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"actual %d, announced %d", BN_num_bits(client_host_key->n), bits); |
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packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); |
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authenticated = auth_rhosts_rsa(pw, client_user, client_host_key); |
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RSA_free(client_host_key); |
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snprintf(user, sizeof user, " ruser %s", client_user); |
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xfree(client_user); |
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break; |
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case SSH_CMSG_AUTH_RSA: |
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if (!options.rsa_authentication) { |
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verbose("RSA authentication disabled."); |
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break; |
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} |
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/* RSA authentication requested. */ |
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n = BN_new(); |
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packet_get_bignum(n, &nlen); |
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packet_integrity_check(plen, nlen, type); |
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authenticated = auth_rsa(pw, n); |
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BN_clear_free(n); |
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break; |
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case SSH_CMSG_AUTH_PASSWORD: |
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if (!options.password_authentication) { |
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verbose("Password authentication disabled."); |
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break; |
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} |
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/* |
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* Read user password. It is in plain text, but was |
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* transmitted over the encrypted channel so it is |
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* not visible to an outside observer. |
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*/ |
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password = packet_get_string(&dlen); |
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packet_integrity_check(plen, 4 + dlen, type); |
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|
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/* Try authentication with the password. */ |
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authenticated = auth_password(pw, password); |
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|
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memset(password, 0, strlen(password)); |
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xfree(password); |
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break; |
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#ifdef SKEY |
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case SSH_CMSG_AUTH_TIS: |
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debug("rcvd SSH_CMSG_AUTH_TIS"); |
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if (options.skey_authentication == 1) { |
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char *skeyinfo = skey_keyinfo(pw->pw_name); |
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if (skeyinfo == NULL) { |
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debug("generating fake skeyinfo for %.100s.", pw->pw_name); |
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skeyinfo = skey_fake_keyinfo(pw->pw_name); |
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} |
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if (skeyinfo != NULL) { |
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/* we send our s/key- in tis-challenge messages */ |
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debug("sending challenge '%s'", skeyinfo); |
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packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
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packet_put_string(skeyinfo, strlen(skeyinfo)); |
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packet_send(); |
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packet_write_wait(); |
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continue; |
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} |
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} |
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break; |
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case SSH_CMSG_AUTH_TIS_RESPONSE: |
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debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); |
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if (options.skey_authentication == 1) { |
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char *response = packet_get_string(&dlen); |
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debug("skey response == '%s'", response); |
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packet_integrity_check(plen, 4 + dlen, type); |
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authenticated = (skey_haskey(pw->pw_name) == 0 && |
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skey_passcheck(pw->pw_name, response) != -1); |
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xfree(response); |
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} |
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break; |
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#else |
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case SSH_CMSG_AUTH_TIS: |
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/* TIS Authentication is unsupported */ |
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log("TIS authentication unsupported."); |
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break; |
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#endif |
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default: |
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/* |
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* Any unknown messages will be ignored (and failure |
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* returned) during authentication. |
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*/ |
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log("Unknown message during authentication: type %d", type); |
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break; |
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} |
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|
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/* |
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* Check if the user is logging in as root and root logins |
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* are disallowed. |
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* Note that root login is allowed for forced commands. |
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*/ |
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if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) { |
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if (forced_command) { |
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log("Root login accepted for forced command."); |
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} else { |
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authenticated = 0; |
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log("ROOT LOGIN REFUSED FROM %.200s", |
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get_canonical_hostname()); |
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} |
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} |
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|
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/* Raise logging level */ |
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if (authenticated || |
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attempt == AUTH_FAIL_LOG || |
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type == SSH_CMSG_AUTH_PASSWORD) |
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authlog = log; |
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authlog("%s %s for %.200s from %.200s port %d%s", |
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authenticated ? "Accepted" : "Failed", |
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get_authname(type), |
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pw->pw_uid == 0 ? "ROOT" : pw->pw_name, |
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get_remote_ipaddr(), |
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get_remote_port(), |
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user); |
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if (authenticated) |
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return; |
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|
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if (attempt > AUTH_FAIL_MAX) |
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packet_disconnect(AUTH_FAIL_MSG, pw->pw_name); |
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|
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/* Send a message indicating that the authentication attempt failed. */ |
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packet_start(SSH_SMSG_FAILURE); |
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packet_send(); |
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packet_write_wait(); |
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} |
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} |
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|
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/* |
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* Performs authentication of an incoming connection. Session key has already |
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* been exchanged and encryption is enabled. |
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*/ |
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void |
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do_authentication() |
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{ |
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struct passwd *pw, pwcopy; |
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int plen; |
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unsigned int ulen; |
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char *user; |
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|
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/* Get the name of the user that we wish to log in as. */ |
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packet_read_expect(&plen, SSH_CMSG_USER); |
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|
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/* Get the user name. */ |
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user = packet_get_string(&ulen); |
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packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); |
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|
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setproctitle("%s", user); |
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#ifdef AFS |
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/* If machine has AFS, set process authentication group. */ |
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if (k_hasafs()) { |
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k_setpag(); |
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k_unlog(); |
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} |
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#endif /* AFS */ |
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|
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/* Verify that the user is a valid user. */ |
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pw = getpwnam(user); |
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if (!pw || !allowed_user(pw)) |
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do_fake_authloop1(user); |
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xfree(user); |
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|
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/* Take a copy of the returned structure. */ |
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memset(&pwcopy, 0, sizeof(pwcopy)); |
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pwcopy.pw_name = xstrdup(pw->pw_name); |
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pwcopy.pw_passwd = xstrdup(pw->pw_passwd); |
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pwcopy.pw_uid = pw->pw_uid; |
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pwcopy.pw_gid = pw->pw_gid; |
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pwcopy.pw_dir = xstrdup(pw->pw_dir); |
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pwcopy.pw_shell = xstrdup(pw->pw_shell); |
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pw = &pwcopy; |
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|
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/* |
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* If we are not running as root, the user must have the same uid as |
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* the server. |
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*/ |
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if (getuid() != 0 && pw->pw_uid != getuid()) |
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packet_disconnect("Cannot change user when server not running as root."); |
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|
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debug("Attempting authentication for %.100s.", pw->pw_name); |
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|
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/* If the user has no password, accept authentication immediately. */ |
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if (options.password_authentication && |
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#ifdef KRB4 |
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(!options.kerberos_authentication || options.kerberos_or_local_passwd) && |
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#endif /* KRB4 */ |
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auth_password(pw, "")) { |
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/* Authentication with empty password succeeded. */ |
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log("Login for user %s from %.100s, accepted without authentication.", |
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pw->pw_name, get_remote_ipaddr()); |
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} else { |
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/* Loop until the user has been authenticated or the |
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connection is closed, do_authloop() returns only if |
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authentication is successfull */ |
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do_authloop(pw); |
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} |
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|
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/* The user has been authenticated and accepted. */ |
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packet_start(SSH_SMSG_SUCCESS); |
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packet_send(); |
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packet_write_wait(); |
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|
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/* Perform session preparation. */ |
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do_authenticated(pw); |
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} |
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|
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/* import */ |
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extern ServerOptions options; |
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extern unsigned char *session_id2; |
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extern int session_id2_len; |
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|
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/* protocol */ |
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|
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void input_service_request(int type, int plen); |
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void input_userauth_request(int type, int plen); |
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void protocol_error(int type, int plen); |
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|
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/* auth */ |
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int ssh2_auth_none(struct passwd *pw); |
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int ssh2_auth_password(struct passwd *pw); |
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int ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen); |
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|
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/* helper */ |
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struct passwd* auth_set_user(char *u, char *s); |
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int user_dsa_key_allowed(struct passwd *pw, Key *key); |
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|
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typedef struct Authctxt Authctxt; |
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struct Authctxt { |
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char *user; |
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char *service; |
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struct passwd pw; |
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int valid; |
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}; |
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static Authctxt *authctxt = NULL; |
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static int userauth_success = 0; |
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|
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/* set and get current user */ |
|
|
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struct passwd* |
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auth_get_user(void) |
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{ |
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return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL; |
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} |
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|
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struct passwd* |
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auth_set_user(char *u, char *s) |
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{ |
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struct passwd *pw, *copy; |
|
|
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if (authctxt == NULL) { |
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authctxt = xmalloc(sizeof(*authctxt)); |
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authctxt->valid = 0; |
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authctxt->user = xstrdup(u); |
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authctxt->service = xstrdup(s); |
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setproctitle("%s", u); |
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pw = getpwnam(u); |
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if (!pw || !allowed_user(pw)) { |
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log("auth_set_user: bad user %s", u); |
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return NULL; |
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} |
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copy = &authctxt->pw; |
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memset(copy, 0, sizeof(*copy)); |
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copy->pw_name = xstrdup(pw->pw_name); |
|
copy->pw_passwd = xstrdup(pw->pw_passwd); |
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copy->pw_uid = pw->pw_uid; |
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copy->pw_gid = pw->pw_gid; |
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copy->pw_dir = xstrdup(pw->pw_dir); |
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copy->pw_shell = xstrdup(pw->pw_shell); |
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authctxt->valid = 1; |
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} else { |
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if (strcmp(u, authctxt->user) != 0 || |
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strcmp(s, authctxt->service) != 0) { |
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log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)", |
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u, s, authctxt->user, authctxt->service); |
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return NULL; |
|
} |
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} |
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return auth_get_user(); |
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} |
|
|
|
/* |
|
* loop until userauth_success == TRUE |
|
*/ |
|
|
|
void |
|
do_authentication2() |
|
{ |
|
dispatch_init(&protocol_error); |
|
dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
|
dispatch_run(DISPATCH_BLOCK, &userauth_success); |
|
do_authenticated2(); |
|
} |
|
|
|
void |
|
protocol_error(int type, int plen) |
|
{ |
|
log("auth: protocol error: type %d plen %d", type, plen); |
|
packet_start(SSH2_MSG_UNIMPLEMENTED); |
|
packet_put_int(0); |
|
packet_send(); |
|
packet_write_wait(); |
|
} |
|
|
|
void |
|
input_service_request(int type, int plen) |
|
{ |
|
unsigned int len; |
|
int accept = 0; |
|
char *service = packet_get_string(&len); |
|
packet_done(); |
|
|
|
if (strcmp(service, "ssh-userauth") == 0) { |
|
if (!userauth_success) { |
|
accept = 1; |
|
/* now we can handle user-auth requests */ |
|
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); |
|
} |
|
} |
|
/* XXX all other service requests are denied */ |
|
|
|
if (accept) { |
|
packet_start(SSH2_MSG_SERVICE_ACCEPT); |
|
packet_put_cstring(service); |
|
packet_send(); |
|
packet_write_wait(); |
|
} else { |
|
debug("bad service request %s", service); |
|
packet_disconnect("bad service request %s", service); |
|
} |
|
xfree(service); |
|
} |
|
|
|
void |
|
input_userauth_request(int type, int plen) |
|
{ |
|
static int try = 0; |
|
unsigned int len, rlen; |
|
int authenticated = 0; |
|
char *raw, *user, *service, *method; |
|
struct passwd *pw; |
|
|
|
if (++try == AUTH_FAIL_MAX) |
|
packet_disconnect("too many failed userauth_requests"); |
|
|
|
raw = packet_get_raw(&rlen); |
|
if (plen != rlen) |
|
fatal("plen != rlen"); |
|
user = packet_get_string(&len); |
|
service = packet_get_string(&len); |
|
method = packet_get_string(&len); |
|
debug("userauth-request for user %s service %s method %s", user, service, method); |
|
|
|
/* XXX we only allow the ssh-connection service */ |
|
pw = auth_set_user(user, service); |
|
if (pw && strcmp(service, "ssh-connection")==0) { |
|
if (strcmp(method, "none") == 0) { |
|
authenticated = ssh2_auth_none(pw); |
|
} else if (strcmp(method, "password") == 0) { |
|
authenticated = ssh2_auth_password(pw); |
|
} else if (strcmp(method, "publickey") == 0) { |
|
authenticated = ssh2_auth_pubkey(pw, raw, rlen); |
|
} |
|
} |
|
/* XXX check if other auth methods are needed */ |
|
if (authenticated == 1) { |
|
log("userauth success for %s method %s", user, method); |
|
/* turn off userauth */ |
|
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error); |
|
packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
|
packet_send(); |
|
packet_write_wait(); |
|
/* now we can break out */ |
|
userauth_success = 1; |
|
} else if (authenticated == 0) { |
|
log("userauth failure for %s method %s", user, method); |
|
packet_start(SSH2_MSG_USERAUTH_FAILURE); |
|
packet_put_cstring("publickey,password"); /* XXX dynamic */ |
|
packet_put_char(0); /* XXX partial success, unused */ |
|
packet_send(); |
|
packet_write_wait(); |
|
} else { |
|
log("userauth postponed for %s method %s", user, method); |
|
} |
|
xfree(service); |
|
xfree(user); |
|
xfree(method); |
|
} |
|
|
|
int |
|
ssh2_auth_none(struct passwd *pw) |
|
{ |
|
packet_done(); |
|
return auth_password(pw, ""); |
|
} |
|
int |
|
ssh2_auth_password(struct passwd *pw) |
|
{ |
|
char *password; |
|
int authenticated = 0; |
|
int change; |
|
unsigned int len; |
|
change = packet_get_char(); |
|
if (change) |
|
log("password change not supported"); |
|
password = packet_get_string(&len); |
|
packet_done(); |
|
if (auth_password(pw, password)) |
|
authenticated = 1; |
|
memset(password, 0, len); |
|
xfree(password); |
|
return authenticated; |
|
} |
|
|
|
int |
|
ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen) |
|
{ |
|
Buffer b; |
|
Key *key; |
|
char *pkalg, *pkblob, *sig; |
|
unsigned int alen, blen, slen; |
|
int have_sig; |
|
int authenticated = 0; |
|
|
|
have_sig = packet_get_char(); |
|
pkalg = packet_get_string(&alen); |
|
if (strcmp(pkalg, KEX_DSS) != 0) { |
|
xfree(pkalg); |
|
log("bad pkalg %s", pkalg); /*XXX*/ |
|
return 0; |
|
} |
|
pkblob = packet_get_string(&blen); |
|
key = dsa_key_from_blob(pkblob, blen); |
|
|
|
if (have_sig && key != NULL) { |
|
sig = packet_get_string(&slen); |
|
packet_done(); |
|
buffer_init(&b); |
|
buffer_append(&b, session_id2, session_id2_len); |
|
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
|
if (slen + 4 > rlen) |
|
fatal("bad rlen/slen"); |
|
buffer_append(&b, raw, rlen - slen - 4); |
|
#ifdef DEBUG_DSS |
|
buffer_dump(&b); |
|
#endif |
|
/* test for correct signature */ |
|
if (user_dsa_key_allowed(pw, key) && |
|
dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) |
|
authenticated = 1; |
|
buffer_clear(&b); |
|
xfree(sig); |
|
} else if (!have_sig && key != NULL) { |
|
packet_done(); |
|
debug("test key..."); |
|
/* test whether pkalg/pkblob are acceptable */ |
|
/* XXX fake reply and always send PK_OK ? */ |
|
if (user_dsa_key_allowed(pw, key)) { |
|
packet_start(SSH2_MSG_USERAUTH_PK_OK); |
|
packet_put_string(pkalg, alen); |
|
packet_put_string(pkblob, blen); |
|
packet_send(); |
|
packet_write_wait(); |
|
authenticated = -1; |
|
} |
|
} |
|
xfree(pkalg); |
|
xfree(pkblob); |
|
return authenticated; |
|
} |
|
|
|
/* return 1 if user allows given key */ |
|
int |
|
user_dsa_key_allowed(struct passwd *pw, Key *key) |
|
{ |
|
char line[8192], file[1024]; |
|
int found_key = 0; |
|
unsigned int bits = -1; |
|
FILE *f; |
|
unsigned long linenum = 0; |
|
struct stat st; |
|
Key *found; |
|
|
|
/* Temporarily use the user's uid. */ |
|
temporarily_use_uid(pw->pw_uid); |
|
|
|
/* The authorized keys. */ |
|
snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, |
|
SSH_USER_PERMITTED_KEYS2); |
|
|
|
/* Fail quietly if file does not exist */ |
|
if (stat(file, &st) < 0) { |
|
/* Restore the privileged uid. */ |
|
restore_uid(); |
|
return 0; |
|
} |
|
/* Open the file containing the authorized keys. */ |
|
f = fopen(file, "r"); |
|
if (!f) { |
|
/* Restore the privileged uid. */ |
|
restore_uid(); |
|
packet_send_debug("Could not open %.900s for reading.", file); |
|
packet_send_debug("If your home is on an NFS volume, it may need to be world-readable."); |
|
return 0; |
|
} |
|
if (options.strict_modes) { |
|
int fail = 0; |
|
char buf[1024]; |
|
/* Check open file in order to avoid open/stat races */ |
|
if (fstat(fileno(f), &st) < 0 || |
|
(st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
|
(st.st_mode & 022) != 0) { |
|
snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: " |
|
"bad ownership or modes for '%s'.", pw->pw_name, file); |
|
fail = 1; |
|
} else { |
|
/* Check path to SSH_USER_PERMITTED_KEYS */ |
|
int i; |
|
static const char *check[] = { |
|
"", SSH_USER_DIR, NULL |
|
}; |
|
for (i = 0; check[i]; i++) { |
|
snprintf(line, sizeof line, "%.500s/%.100s", |
|
pw->pw_dir, check[i]); |
|
if (stat(line, &st) < 0 || |
|
(st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
|
(st.st_mode & 022) != 0) { |
|
snprintf(buf, sizeof buf, |
|
"DSA authentication refused for %.100s: " |
|
"bad ownership or modes for '%s'.", |
|
pw->pw_name, line); |
|
fail = 1; |
|
break; |
|
} |
|
} |
|
} |
|
if (fail) { |
|
log(buf); |
|
fclose(f); |
|
restore_uid(); |
|
return 0; |
|
} |
|
} |
|
found_key = 0; |
|
found = key_new(KEY_DSA); |
|
|
|
while (fgets(line, sizeof(line), f)) { |
|
char *cp; |
|
linenum++; |
|
/* Skip leading whitespace, empty and comment lines. */ |
|
for (cp = line; *cp == ' ' || *cp == '\t'; cp++) |
|
; |
|
if (!*cp || *cp == '\n' || *cp == '#') |
|
continue; |
|
bits = key_read(found, &cp); |
|
if (bits == 0) |
|
continue; |
|
if (key_equal(found, key)) { |
|
found_key = 1; |
|
debug("matching key found: file %s, line %ld", |
|
file, linenum); |
|
break; |
|
} |
|
} |
|
restore_uid(); |
|
fclose(f); |
|
key_free(found); |
|
return found_key; |
|
} |
} |