]> andersk Git - openssh.git/blobdiff - auth-rsa.c
- markus@cvs.openbsd.org 2001/12/28 14:50:54
[openssh.git] / auth-rsa.c
index 522f01f84cb982d9267be7263ac088d68e573341..f7ae03cfdaf13009c5b28b2e5fc6d5dd92a86aa6 100644 (file)
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-rsa.c,v 1.31 2000/10/11 19:59:52 markus Exp $");
+RCSID("$OpenBSD: auth-rsa.c,v 1.50 2001/12/28 14:50:54 markus Exp $");
+
+#include <openssl/rsa.h>
+#include <openssl/md5.h>
 
 #include "rsa.h"
 #include "packet.h"
 #include "xmalloc.h"
-#include "ssh.h"
+#include "ssh1.h"
 #include "mpaux.h"
 #include "uidswap.h"
 #include "match.h"
-#include "servconf.h"
 #include "auth-options.h"
-
-#include <openssl/rsa.h>
-#include <openssl/md5.h>
-
+#include "pathnames.h"
+#include "log.h"
+#include "servconf.h"
+#include "auth.h"
+#include "hostfile.h"
 
 /* import */
 extern ServerOptions options;
@@ -37,7 +40,7 @@ extern ServerOptions options;
  * Session identifier that is used to bind key exchange and authentication
  * responses to a particular session.
  */
-extern unsigned char session_id[16];
+extern u_char session_id[16];
 
 /*
  * The .ssh/authorized_keys file contains public keys, one per line, in the
@@ -60,17 +63,20 @@ auth_rsa_challenge_dialog(RSA *pk)
 {
        BIGNUM *challenge, *encrypted_challenge;
        BN_CTX *ctx;
-       unsigned char buf[32], mdbuf[16], response[16];
+       u_char buf[32], mdbuf[16], response[16];
        MD5_CTX md;
-       unsigned int i;
-       int plen, len;
+       u_int i;
+       int len;
 
-       encrypted_challenge = BN_new();
-       challenge = BN_new();
+       if ((encrypted_challenge = BN_new()) == NULL)
+               fatal("auth_rsa_challenge_dialog: BN_new() failed");
+       if ((challenge = BN_new()) == NULL)
+               fatal("auth_rsa_challenge_dialog: BN_new() failed");
 
        /* Generate a random challenge. */
        BN_rand(challenge, 256, 0, 0);
-       ctx = BN_CTX_new();
+       if ((ctx = BN_CTX_new()) == NULL)
+               fatal("auth_rsa_challenge_dialog: BN_CTX_new() failed");
        BN_mod(challenge, challenge, pk->n, ctx);
        BN_CTX_free(ctx);
 
@@ -85,10 +91,10 @@ auth_rsa_challenge_dialog(RSA *pk)
        packet_write_wait();
 
        /* Wait for a response. */
-       packet_read_expect(&plen, SSH_CMSG_AUTH_RSA_RESPONSE);
-       packet_integrity_check(plen, 16, SSH_CMSG_AUTH_RSA_RESPONSE);
+       packet_read_expect(SSH_CMSG_AUTH_RSA_RESPONSE);
        for (i = 0; i < 16; i++)
                response[i] = packet_get_char();
+       packet_check_eom();
 
        /* The response is MD5 of decrypted challenge plus session id. */
        len = BN_num_bytes(challenge);
@@ -120,29 +126,31 @@ auth_rsa_challenge_dialog(RSA *pk)
 int
 auth_rsa(struct passwd *pw, BIGNUM *client_n)
 {
-       char line[8192], file[1024];
+       char line[8192], *file;
        int authenticated;
-       unsigned int bits;
+       u_int bits;
        FILE *f;
-       unsigned long linenum = 0;
+       u_long linenum = 0;
        struct stat st;
-       RSA *pk;
+       Key *key;
+       char *fp;
 
        /* no user given */
        if (pw == NULL)
                return 0;
 
        /* Temporarily use the user's uid. */
-       temporarily_use_uid(pw->pw_uid);
+       temporarily_use_uid(pw);
 
        /* The authorized keys. */
-       snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
-                SSH_USER_PERMITTED_KEYS);
+       file = authorized_keys_file(pw);
+       debug("trying public RSA key file %s", file);
 
        /* Fail quietly if file does not exist */
        if (stat(file, &st) < 0) {
                /* Restore the privileged uid. */
                restore_uid();
+               xfree(file);
                return 0;
        }
        /* Open the file containing the authorized keys. */
@@ -152,50 +160,22 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
                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.");
+               xfree(file);
                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, "RSA 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, "RSA authentication refused for %.100s: "
-                                                "bad ownership or modes for '%s'.", pw->pw_name, line);
-                                       fail = 1;
-                                       break;
-                               }
-                       }
-               }
-               if (fail) {
-                       fclose(f);
-                       log("%s",buf);
-                       packet_send_debug("%s",buf);
-                       restore_uid();
-                       return 0;
-               }
+       if (options.strict_modes &&
+           secure_filename(f, file, pw, line, sizeof(line)) != 0) {
+               xfree(file);
+               fclose(f);
+               log("Authentication refused: %s", line);
+               packet_send_debug("Authentication refused: %s", line);
+               restore_uid();
+               return 0;
        }
        /* Flag indicating whether authentication has succeeded. */
        authenticated = 0;
 
-       pk = RSA_new();
-       pk->e = BN_new();
-       pk->n = BN_new();
+       key = key_new(KEY_RSA1);
 
        /*
         * Go though the accepted keys, looking for the current key.  If
@@ -233,33 +213,41 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
                        options = NULL;
 
                /* Parse the key from the line. */
-               if (!auth_rsa_read_key(&cp, &bits, pk->e, pk->n)) {
-                       debug("%.100s, line %lu: bad key syntax",
-                             SSH_USER_PERMITTED_KEYS, linenum);
-                       packet_send_debug("%.100s, line %lu: bad key syntax",
-                                         SSH_USER_PERMITTED_KEYS, linenum);
+               if (hostfile_read_key(&cp, &bits, key) == 0) {
+                       debug("%.100s, line %lu: non ssh1 key syntax",
+                           file, linenum);
                        continue;
                }
                /* cp now points to the comment part. */
 
                /* Check if the we have found the desired key (identified by its modulus). */
-               if (BN_cmp(pk->n, client_n) != 0)
+               if (BN_cmp(key->rsa->n, client_n) != 0)
                        continue;
 
                /* check the real bits  */
-               if (bits != BN_num_bits(pk->n))
-                       log("Warning: %s, line %ld: keysize mismatch: "
+               if (bits != BN_num_bits(key->rsa->n))
+                       log("Warning: %s, line %lu: keysize mismatch: "
                            "actual %d vs. announced %d.",
-                           file, linenum, BN_num_bits(pk->n), bits);
+                           file, linenum, BN_num_bits(key->rsa->n), bits);
 
                /* We have found the desired key. */
+               /*
+                * If our options do not allow this key to be used,
+                * do not send challenge.
+                */
+               if (!auth_parse_options(pw, options, file, linenum))
+                       continue;
 
                /* Perform the challenge-response dialog for this key. */
-               if (!auth_rsa_challenge_dialog(pk)) {
+               if (!auth_rsa_challenge_dialog(key->rsa)) {
                        /* Wrong response. */
                        verbose("Wrong response to RSA authentication challenge.");
                        packet_send_debug("Wrong response to RSA authentication challenge.");
-                       continue;
+                       /*
+                        * Break out of the loop. Otherwise we might send
+                        * another challenge and break the protocol.
+                        */
+                       break;
                }
                /*
                 * Correct response.  The client has been successfully
@@ -269,18 +257,24 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
                 * Break out of the loop if authentication was successful;
                 * otherwise continue searching.
                 */
-               authenticated = auth_parse_options(pw, options, linenum);
-               if (authenticated)
-                       break;
+               authenticated = 1;
+
+               fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+               verbose("Found matching %s key: %s",
+                   key_type(key), fp);
+               xfree(fp);
+
+               break;
        }
 
        /* Restore the privileged uid. */
        restore_uid();
 
        /* Close the file. */
+       xfree(file);
        fclose(f);
 
-       RSA_free(pk);
+       key_free(key);
 
        if (authenticated)
                packet_send_debug("RSA authentication accepted.");
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