X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/3d88e64dfcf5dc0fd361ce0c504c67a9196ce44c..f7aa4b367eaf2c1e928f97263bcf4da74680aff3:/sshpubk.c diff --git a/sshpubk.c b/sshpubk.c index d0594b77..ac9e0fa7 100644 --- a/sshpubk.c +++ b/sshpubk.c @@ -1,7 +1,7 @@ /* * Generic SSH public-key handling operations. In particular, * reading of SSH public-key files, and also the generic `sign' - * operation for ssh2 (which checks the type of the key and + * operation for SSH-2 (which checks the type of the key and * dispatches to the appropriate key-type specific function). */ @@ -13,18 +13,6 @@ #include "ssh.h" #include "misc.h" -#define PUT_32BIT(cp, value) do { \ - (cp)[3] = (value); \ - (cp)[2] = (value) >> 8; \ - (cp)[1] = (value) >> 16; \ - (cp)[0] = (value) >> 24; } while (0) - -#define GET_32BIT(cp) \ - (((unsigned long)(unsigned char)(cp)[0] << 24) | \ - ((unsigned long)(unsigned char)(cp)[1] << 16) | \ - ((unsigned long)(unsigned char)(cp)[2] << 8) | \ - ((unsigned long)(unsigned char)(cp)[3])) - #define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n" #define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\ @@ -34,7 +22,8 @@ (x)=='/' ? 63 : 0 ) static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, - char **commentptr, char *passphrase) + char **commentptr, char *passphrase, + const char **error) { unsigned char buf[16384]; unsigned char keybuf[16]; @@ -44,13 +33,18 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, struct MD5Context md5c; char *comment; + *error = NULL; + /* Slurp the whole file (minus the header) into a buffer. */ len = fread(buf, 1, sizeof(buf), fp); fclose(fp); - if (len < 0 || len == sizeof(buf)) + if (len < 0 || len == sizeof(buf)) { + *error = "error reading file"; goto end; /* file too big or not read */ + } i = 0; + *error = "file format error"; /* * A zero byte. (The signature includes a terminating NUL.) @@ -72,20 +66,16 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, || buf[i + 3] != 0) goto end; /* reserved field nonzero, panic! */ i += 4; - /* Now the serious stuff. An ordinary SSH 1 public key. */ - i += makekey(buf + i, key, NULL, 1); - if (len - i < 0) + /* Now the serious stuff. An ordinary SSH-1 public key. */ + j = makekey(buf + i, len, key, NULL, 1); + if (j < 0) goto end; /* overran */ - - if (pub_only) { - ret = 1; - goto end; - } + i += j; /* Next, the comment field. */ - j = GET_32BIT(buf + i); + j = toint(GET_32BIT(buf + i)); i += 4; - if (len - i < j) + if (j < 0 || len - i < j) goto end; comment = snewn(j + 1, char); if (comment) { @@ -94,11 +84,21 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, } i += j; if (commentptr) - *commentptr = comment; + *commentptr = dupstr(comment); if (key) key->comment = comment; + else + sfree(comment); + + if (pub_only) { + ret = 1; + goto end; + } + if (!key) { - return ciphertype != 0; + ret = ciphertype != 0; + *error = NULL; + goto end; } /* @@ -109,7 +109,7 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); MD5Final(keybuf, &md5c); des3_decrypt_pubkey(keybuf, buf + i, (len - i + 7) & ~7); - memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ + smemclr(keybuf, sizeof(keybuf)); /* burn the evidence */ } /* @@ -119,6 +119,7 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, if (len - i < 4) goto end; if (buf[i] != buf[i + 2] || buf[i + 1] != buf[i + 3]) { + *error = "wrong passphrase"; ret = -1; goto end; } @@ -129,52 +130,69 @@ static int loadrsakey_main(FILE * fp, struct RSAKey *key, int pub_only, * decryption exponent, and then the three auxiliary values * (iqmp, q, p). */ - i += makeprivate(buf + i, key); - if (len - i < 0) - goto end; - i += ssh1_read_bignum(buf + i, &key->iqmp); - if (len - i < 0) - goto end; - i += ssh1_read_bignum(buf + i, &key->q); - if (len - i < 0) - goto end; - i += ssh1_read_bignum(buf + i, &key->p); - if (len - i < 0) - goto end; + j = makeprivate(buf + i, len - i, key); + if (j < 0) goto end; + i += j; + j = ssh1_read_bignum(buf + i, len - i, &key->iqmp); + if (j < 0) goto end; + i += j; + j = ssh1_read_bignum(buf + i, len - i, &key->q); + if (j < 0) goto end; + i += j; + j = ssh1_read_bignum(buf + i, len - i, &key->p); + if (j < 0) goto end; + i += j; if (!rsa_verify(key)) { + *error = "rsa_verify failed"; freersakey(key); ret = 0; } else ret = 1; end: - memset(buf, 0, sizeof(buf)); /* burn the evidence */ + smemclr(buf, sizeof(buf)); /* burn the evidence */ return ret; } -int loadrsakey(const Filename *filename, struct RSAKey *key, char *passphrase) +int loadrsakey(const Filename *filename, struct RSAKey *key, char *passphrase, + const char **errorstr) { FILE *fp; char buf[64]; + int ret = 0; + const char *error = NULL; - fp = f_open(*filename, "rb"); - if (!fp) - return 0; /* doesn't even exist */ + fp = f_open(filename, "rb", FALSE); + if (!fp) { + error = "can't open file"; + goto end; + } /* * Read the first line of the file and see if it's a v1 private * key file. */ if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) { - return loadrsakey_main(fp, key, FALSE, NULL, passphrase); + /* + * This routine will take care of calling fclose() for us. + */ + ret = loadrsakey_main(fp, key, FALSE, NULL, passphrase, &error); + fp = NULL; + goto end; } /* * Otherwise, we have nothing. Return empty-handed. */ - fclose(fp); - return 0; + error = "not an SSH-1 RSA file"; + + end: + if (fp) + fclose(fp); + if ((ret != 1) && errorstr) + *errorstr = error; + return ret; } /* @@ -186,7 +204,7 @@ int rsakey_encrypted(const Filename *filename, char **comment) FILE *fp; char buf[64]; - fp = f_open(*filename, "rb"); + fp = f_open(filename, "rb", FALSE); if (!fp) return 0; /* doesn't even exist */ @@ -195,7 +213,11 @@ int rsakey_encrypted(const Filename *filename, char **comment) * key file. */ if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) { - return loadrsakey_main(fp, NULL, FALSE, comment, NULL); + const char *dummy; + /* + * This routine will take care of calling fclose() for us. + */ + return loadrsakey_main(fp, NULL, FALSE, comment, NULL, &dummy); } fclose(fp); return 0; /* wasn't the right kind of file */ @@ -206,21 +228,25 @@ int rsakey_encrypted(const Filename *filename, char **comment) * an RSA key, as given in the agent protocol (modulus bits, * exponent, modulus). */ -int rsakey_pubblob(const Filename *filename, void **blob, int *bloblen) +int rsakey_pubblob(const Filename *filename, void **blob, int *bloblen, + char **commentptr, const char **errorstr) { FILE *fp; char buf[64]; struct RSAKey key; int ret; + const char *error = NULL; /* Default return if we fail. */ *blob = NULL; *bloblen = 0; ret = 0; - fp = f_open(*filename, "rb"); - if (!fp) - return 0; /* doesn't even exist */ + fp = f_open(filename, "rb", FALSE); + if (!fp) { + error = "can't open file"; + goto end; + } /* * Read the first line of the file and see if it's a v1 private @@ -228,13 +254,21 @@ int rsakey_pubblob(const Filename *filename, void **blob, int *bloblen) */ if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) { memset(&key, 0, sizeof(key)); - if (loadrsakey_main(fp, &key, TRUE, NULL, NULL)) { + if (loadrsakey_main(fp, &key, TRUE, commentptr, NULL, &error)) { *blob = rsa_public_blob(&key, bloblen); freersakey(&key); ret = 1; } + fp = NULL; /* loadrsakey_main unconditionally closes fp */ + } else { + error = "not an SSH-1 RSA file"; } - fclose(fp); + + end: + if (fp) + fclose(fp); + if ((ret != 1) && errorstr) + *errorstr = error; return ret; } @@ -265,7 +299,7 @@ int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase) p += 4; /* - * An ordinary SSH 1 public key consists of: a uint32 + * An ordinary SSH-1 public key consists of: a uint32 * containing the bit count, then two bignums containing the * modulus and exponent respectively. */ @@ -325,27 +359,28 @@ int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase) MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); MD5Final(keybuf, &md5c); des3_encrypt_pubkey(keybuf, estart, p - estart); - memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ + smemclr(keybuf, sizeof(keybuf)); /* burn the evidence */ } /* * Done. Write the result to the file. */ - fp = f_open(*filename, "wb"); + fp = f_open(filename, "wb", TRUE); if (fp) { int ret = (fwrite(buf, 1, p - buf, fp) == (size_t) (p - buf)); - ret = ret && (fclose(fp) == 0); + if (fclose(fp)) + ret = 0; return ret; } else return 0; } /* ---------------------------------------------------------------------- - * SSH2 private key load/store functions. + * SSH-2 private key load/store functions. */ /* - * PuTTY's own format for SSH2 keys is as follows: + * PuTTY's own format for SSH-2 keys is as follows: * * The file is text. Lines are terminated by CRLF, although CR-only * and LF-only are tolerated on input. @@ -361,7 +396,7 @@ int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase) * * Next there is a line saying "Public-Lines: " plus a number N. * The following N lines contain a base64 encoding of the public - * part of the key. This is encoded as the standard SSH2 public key + * part of the key. This is encoded as the standard SSH-2 public key * blob (with no initial length): so for RSA, for example, it will * read * @@ -401,8 +436,7 @@ int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase) * data "putty-private-key-file-mac-key" * data passphrase * - * Encrypted keys should have a MAC, whereas unencrypted ones must - * have a hash. + * (An empty passphrase is used for unencrypted keys.) * * If the key is encrypted, the encryption key is derived from the * passphrase by means of a succession of SHA-1 hashes. Each hash @@ -419,10 +453,9 @@ int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase) * with "PuTTY-User-Key-File-1" (version number differs). In this * format the Private-MAC: field only covers the private-plaintext * field and nothing else (and without the 4-byte string length on - * the front too). Moreover, for RSA keys the Private-MAC: field - * can be replaced with a Private-Hash: field which is a plain - * SHA-1 hash instead of an HMAC. This is not allowable in DSA - * keys. (Yes, the old format was a mess. Guess why it changed :-) + * the front too). Moreover, the Private-MAC: field can be replaced + * with a Private-Hash: field which is a plain SHA-1 hash instead of + * an HMAC (this was generated for unencrypted keys). */ static int read_header(FILE * fp, char *header) @@ -430,7 +463,7 @@ static int read_header(FILE * fp, char *header) int len = 39; int c; - while (len > 0) { + while (1) { c = fgetc(fp); if (c == '\n' || c == '\r' || c == EOF) return 0; /* failure */ @@ -463,17 +496,15 @@ static char *read_body(FILE * fp) while (1) { c = fgetc(fp); - if (c == '\r' || c == '\n') { - c = fgetc(fp); - if (c != '\r' && c != '\n' && c != EOF) - ungetc(c, fp); + if (c == '\r' || c == '\n' || c == EOF) { + if (c != EOF) { + c = fgetc(fp); + if (c != '\r' && c != '\n') + ungetc(c, fp); + } return text; } - if (c == EOF) { - sfree(text); - return NULL; - } - if (len + 1 > size) { + if (len + 1 >= size) { size += 128; text = sresize(text, size, char); } @@ -574,8 +605,18 @@ struct ssh2_userkey ssh2_wrong_passphrase = { NULL, NULL, NULL }; +const struct ssh_signkey *find_pubkey_alg(const char *name) +{ + if (!strcmp(name, "ssh-rsa")) + return &ssh_rsa; + else if (!strcmp(name, "ssh-dss")) + return &ssh_dss; + else + return NULL; +} + struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, - char *passphrase) + char *passphrase, const char **errorstr) { FILE *fp; char header[40], *b, *encryption, *comment, *mac; @@ -586,14 +627,17 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, int public_blob_len, private_blob_len; int i, is_mac, old_fmt; int passlen = passphrase ? strlen(passphrase) : 0; + const char *error = NULL; ret = NULL; /* return NULL for most errors */ encryption = comment = mac = NULL; public_blob = private_blob = NULL; - fp = f_open(*filename, "rb"); - if (!fp) + fp = f_open(filename, "rb", FALSE); + if (!fp) { + error = "can't open file"; goto error; + } /* Read the first header line which contains the key type. */ if (!read_header(fp, header)) @@ -604,16 +648,21 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, /* this is an old key file; warn and then continue */ old_keyfile_warning(); old_fmt = 1; - } else + } else if (0 == strncmp(header, "PuTTY-User-Key-File-", 20)) { + /* this is a key file FROM THE FUTURE; refuse it, but with a + * more specific error message than the generic one below */ + error = "PuTTY key format too new"; goto error; + } else { + error = "not a PuTTY SSH-2 private key"; + goto error; + } + error = "file format error"; if ((b = read_body(fp)) == NULL) goto error; /* Select key algorithm structure. */ - if (!strcmp(b, "ssh-rsa")) - alg = &ssh_rsa; - else if (!strcmp(b, "ssh-dss")) - alg = &ssh_dss; - else { + alg = find_pubkey_alg(b); + if (!alg) { sfree(b); goto error; } @@ -631,7 +680,6 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, cipher = 0; cipherblk = 1; } else { - sfree(encryption); goto error; } @@ -668,8 +716,7 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, if ((mac = read_body(fp)) == NULL) goto error; is_mac = 1; - } else if (0 == strcmp(header, "Private-Hash") && - alg == &ssh_rsa && old_fmt) { + } else if (0 == strcmp(header, "Private-Hash") && old_fmt) { if ((mac = read_body(fp)) == NULL) goto error; is_mac = 0; @@ -746,20 +793,20 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, SHA_Init(&s); SHA_Bytes(&s, header, sizeof(header)-1); - if (passphrase) + if (cipher && passphrase) SHA_Bytes(&s, passphrase, passlen); SHA_Final(&s, mackey); hmac_sha1_simple(mackey, 20, macdata, maclen, binary); - memset(mackey, 0, sizeof(mackey)); - memset(&s, 0, sizeof(s)); + smemclr(mackey, sizeof(mackey)); + smemclr(&s, sizeof(s)); } else { SHA_Simple(macdata, maclen, binary); } if (free_macdata) { - memset(macdata, 0, maclen); + smemclr(macdata, maclen); sfree(macdata); } @@ -769,7 +816,13 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, if (strcmp(mac, realmac)) { /* An incorrect MAC is an unconditional Error if the key is * unencrypted. Otherwise, it means Wrong Passphrase. */ - ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL; + if (cipher) { + error = "wrong passphrase"; + ret = SSH2_WRONG_PASSPHRASE; + } else { + error = "MAC failed"; + ret = NULL; + } goto error; } } @@ -787,10 +840,14 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, sfree(ret->comment); sfree(ret); ret = NULL; + error = "createkey failed"; + goto error; } sfree(public_blob); sfree(private_blob); sfree(encryption); + if (errorstr) + *errorstr = NULL; return ret; /* @@ -809,11 +866,14 @@ struct ssh2_userkey *ssh2_load_userkey(const Filename *filename, sfree(public_blob); if (private_blob) sfree(private_blob); + if (errorstr) + *errorstr = error; return ret; } -char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm, - int *pub_blob_len) +unsigned char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm, + int *pub_blob_len, char **commentptr, + const char **errorstr) { FILE *fp; char header[40], *b; @@ -821,26 +881,33 @@ char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm, unsigned char *public_blob; int public_blob_len; int i; + const char *error = NULL; + char *comment; public_blob = NULL; - fp = f_open(*filename, "rb"); - if (!fp) + fp = f_open(filename, "rb", FALSE); + if (!fp) { + error = "can't open file"; goto error; + } /* Read the first header line which contains the key type. */ if (!read_header(fp, header) || (0 != strcmp(header, "PuTTY-User-Key-File-2") && - 0 != strcmp(header, "PuTTY-User-Key-File-1"))) + 0 != strcmp(header, "PuTTY-User-Key-File-1"))) { + if (0 == strncmp(header, "PuTTY-User-Key-File-", 20)) + error = "PuTTY key format too new"; + else + error = "not a PuTTY SSH-2 private key"; goto error; + } + error = "file format error"; if ((b = read_body(fp)) == NULL) goto error; - /* Select key algorithm structure. Currently only ssh-rsa. */ - if (!strcmp(b, "ssh-rsa")) - alg = &ssh_rsa; - else if (!strcmp(b, "ssh-dss")) - alg = &ssh_dss; - else { + /* Select key algorithm structure. */ + alg = find_pubkey_alg(b); + if (!alg) { sfree(b); goto error; } @@ -856,9 +923,13 @@ char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm, /* Read the Comment header line. */ if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) goto error; - if ((b = read_body(fp)) == NULL) + if ((comment = read_body(fp)) == NULL) goto error; - sfree(b); /* we don't care */ + + if (commentptr) + *commentptr = comment; + else + sfree(comment); /* Read the Public-Lines header line and the public blob. */ if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines")) @@ -875,7 +946,7 @@ char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm, *pub_blob_len = public_blob_len; if (algorithm) *algorithm = alg->name; - return (char *)public_blob; + return public_blob; /* * Error processing. @@ -885,6 +956,8 @@ char *ssh2_userkey_loadpub(const Filename *filename, char **algorithm, fclose(fp); if (public_blob) sfree(public_blob); + if (errorstr) + *errorstr = error; return NULL; } @@ -897,7 +970,7 @@ int ssh2_userkey_encrypted(const Filename *filename, char **commentptr) if (commentptr) *commentptr = NULL; - fp = f_open(*filename, "rb"); + fp = f_open(filename, "rb", FALSE); if (!fp) return 0; if (!read_header(fp, header) @@ -935,6 +1008,8 @@ int ssh2_userkey_encrypted(const Filename *filename, char **commentptr) if (commentptr) *commentptr = comment; + else + sfree(comment); fclose(fp); if (!strcmp(b, "aes256-cbc")) @@ -1051,10 +1126,10 @@ int ssh2_save_userkey(const Filename *filename, struct ssh2_userkey *key, SHA_Bytes(&s, passphrase, strlen(passphrase)); SHA_Final(&s, mackey); hmac_sha1_simple(mackey, 20, macdata, maclen, priv_mac); - memset(macdata, 0, maclen); + smemclr(macdata, maclen); sfree(macdata); - memset(mackey, 0, sizeof(mackey)); - memset(&s, 0, sizeof(s)); + smemclr(mackey, sizeof(mackey)); + smemclr(&s, sizeof(s)); } if (passphrase) { @@ -1074,11 +1149,11 @@ int ssh2_save_userkey(const Filename *filename, struct ssh2_userkey *key, aes256_encrypt_pubkey(key, priv_blob_encrypted, priv_encrypted_len); - memset(key, 0, sizeof(key)); - memset(&s, 0, sizeof(s)); + smemclr(key, sizeof(key)); + smemclr(&s, sizeof(s)); } - fp = f_open(*filename, "w"); + fp = f_open(filename, "w", TRUE); if (!fp) return 0; fprintf(fp, "PuTTY-User-Key-File-2: %s\n", key->alg->name); @@ -1095,7 +1170,7 @@ int ssh2_save_userkey(const Filename *filename, struct ssh2_userkey *key, fclose(fp); sfree(pub_blob); - memset(priv_blob, 0, priv_blob_len); + smemclr(priv_blob, priv_blob_len); sfree(priv_blob); sfree(priv_blob_encrypted); return 1; @@ -1114,7 +1189,7 @@ int key_type(const Filename *filename) const char openssh_sig[] = "-----BEGIN "; int i; - fp = f_open(*filename, "r"); + fp = f_open(filename, "r", FALSE); if (!fp) return SSH_KEYTYPE_UNOPENABLE; i = fread(buf, 1, sizeof(buf), fp); @@ -1143,10 +1218,10 @@ char *key_type_to_str(int type) switch (type) { case SSH_KEYTYPE_UNOPENABLE: return "unable to open file"; break; case SSH_KEYTYPE_UNKNOWN: return "not a private key"; break; - case SSH_KEYTYPE_SSH1: return "SSH1 private key"; break; - case SSH_KEYTYPE_SSH2: return "PuTTY SSH2 private key"; break; - case SSH_KEYTYPE_OPENSSH: return "OpenSSH SSH2 private key"; break; - case SSH_KEYTYPE_SSHCOM: return "ssh.com SSH2 private key"; break; + case SSH_KEYTYPE_SSH1: return "SSH-1 private key"; break; + case SSH_KEYTYPE_SSH2: return "PuTTY SSH-2 private key"; break; + case SSH_KEYTYPE_OPENSSH: return "OpenSSH SSH-2 private key"; break; + case SSH_KEYTYPE_SSHCOM: return "ssh.com SSH-2 private key"; break; default: return "INTERNAL ERROR"; break; } }