diff options
| -rw-r--r-- | keyimport.c | 1979 |
1 files changed, 1004 insertions, 975 deletions
diff --git a/keyimport.c b/keyimport.c index 66a6df7..124fd92 100644 --- a/keyimport.c +++ b/keyimport.c @@ -47,65 +47,67 @@ static const unsigned char OID_SEC521R1_BLOB[] = {0x2b, 0x81, 0x04, 0x00, 0x23}; (cp)[0] = (unsigned char)((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])) + (((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])) static int openssh_encrypted(const char *filename); static sign_key *openssh_read(const char *filename, char *passphrase); static int openssh_write(const char *filename, sign_key *key, - char *passphrase); + char *passphrase); static int dropbear_write(const char*filename, sign_key * key); static sign_key *dropbear_read(const char* filename); +static int toint(unsigned u); + #if 0 static int sshcom_encrypted(const char *filename, char **comment); static struct ssh2_userkey *sshcom_read(const char *filename, char *passphrase); static int sshcom_write(const char *filename, struct ssh2_userkey *key, - char *passphrase); + char *passphrase); #endif int import_encrypted(const char* filename, int filetype) { if (filetype == KEYFILE_OPENSSH) { - return openssh_encrypted(filename); + return openssh_encrypted(filename); #if 0 } else if (filetype == KEYFILE_SSHCOM) { return sshcom_encrypted(filename, NULL); #endif - } - return 0; + } + return 0; } sign_key *import_read(const char *filename, char *passphrase, int filetype) { if (filetype == KEYFILE_OPENSSH) { - return openssh_read(filename, passphrase); + return openssh_read(filename, passphrase); } else if (filetype == KEYFILE_DROPBEAR) { return dropbear_read(filename); #if 0 } else if (filetype == KEYFILE_SSHCOM) { - return sshcom_read(filename, passphrase); + return sshcom_read(filename, passphrase); #endif } - return NULL; + return NULL; } int import_write(const char *filename, sign_key *key, char *passphrase, int filetype) { if (filetype == KEYFILE_OPENSSH) { - return openssh_write(filename, key, passphrase); + return openssh_write(filename, key, passphrase); } else if (filetype == KEYFILE_DROPBEAR) { return dropbear_write(filename, key); #if 0 } else if (filetype == KEYFILE_SSHCOM) { - return sshcom_write(filename, key, passphrase); + return sshcom_write(filename, key, passphrase); #endif } - return 0; + return 0; } static sign_key *dropbear_read(const char* filename) { @@ -183,11 +185,11 @@ out: * Helper routines. (The base64 ones are defined in sshpubk.c.) */ -#define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ - ((c) >= 'a' && (c) <= 'z') || \ - ((c) >= '0' && (c) <= '9') || \ - (c) == '+' || (c) == '/' || (c) == '=' \ - ) +#define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ + ((c) >= 'a' && (c) <= 'z') || \ + ((c) >= '0' && (c) <= '9') || \ + (c) == '+' || (c) == '/' || (c) == '=' \ + ) /* cpl has to be less than 100 */ static void base64_encode_fp(FILE * fp, unsigned char *data, @@ -220,57 +222,58 @@ static void base64_encode_fp(FILE * fp, unsigned char *data, */ /* ASN.1 tag classes. */ -#define ASN1_CLASS_UNIVERSAL (0 << 6) -#define ASN1_CLASS_APPLICATION (1 << 6) +#define ASN1_CLASS_UNIVERSAL (0 << 6) +#define ASN1_CLASS_APPLICATION (1 << 6) #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) -#define ASN1_CLASS_PRIVATE (3 << 6) -#define ASN1_CLASS_MASK (3 << 6) +#define ASN1_CLASS_PRIVATE (3 << 6) +#define ASN1_CLASS_MASK (3 << 6) /* Primitive versus constructed bit. */ -#define ASN1_CONSTRUCTED (1 << 5) +#define ASN1_CONSTRUCTED (1 << 5) static int ber_read_id_len(void *source, int sourcelen, - int *id, int *length, int *flags) + int *id, int *length, int *flags) { - unsigned char *p = (unsigned char *) source; - - if (sourcelen == 0) - return -1; + unsigned char *p = (unsigned char *) source; - *flags = (*p & 0xE0); - if ((*p & 0x1F) == 0x1F) { - *id = 0; - while (*p & 0x80) { - *id = (*id << 7) | (*p & 0x7F); - p++, sourcelen--; - if (sourcelen == 0) - return -1; - } - *id = (*id << 7) | (*p & 0x7F); - p++, sourcelen--; - } else { - *id = *p & 0x1F; - p++, sourcelen--; - } + if (sourcelen == 0) + return -1; - if (sourcelen == 0) + *flags = (*p & 0xE0); + if ((*p & 0x1F) == 0x1F) { + *id = 0; + while (*p & 0x80) { + p++, sourcelen--; + if (sourcelen == 0) return -1; - - if (*p & 0x80) { - int n = *p & 0x7F; - p++, sourcelen--; - if (sourcelen < n) - return -1; - *length = 0; - while (n--) - *length = (*length << 8) | (*p++); - sourcelen -= n; - } else { - *length = *p; - p++, sourcelen--; - } - - return p - (unsigned char *) source; + *id = (*id << 7) | (*p & 0x7F); + } + p++, sourcelen--; + } else { + *id = *p & 0x1F; + p++, sourcelen--; + } + + if (sourcelen == 0) + return -1; + + if (*p & 0x80) { + unsigned len; + int n = *p & 0x7F; + p++, sourcelen--; + if (sourcelen < n) + return -1; + len = 0; + while (n--) + len = (len << 8) | (*p++); + sourcelen -= n; + *length = toint(len); + } else { + *length = *p; + p++, sourcelen--; + } + + return p - (unsigned char *) source; } /* @@ -281,57 +284,57 @@ static int ber_read_id_len(void *source, int sourcelen, */ static int ber_write_id_len(void *dest, int id, int length, int flags) { - unsigned char *d = (unsigned char *)dest; - int len = 0; - - if (id <= 30) { - /* - * Identifier is one byte. - */ - len++; - if (d) *d++ = id | flags; - } else { - int n; - /* - * Identifier is multiple bytes: the first byte is 11111 - * plus the flags, and subsequent bytes encode the value of - * the identifier, 7 bits at a time, with the top bit of - * each byte 1 except the last one which is 0. - */ - len++; - if (d) *d++ = 0x1F | flags; - for (n = 1; (id >> (7*n)) > 0; n++) - continue; /* count the bytes */ - while (n--) { - len++; - if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); - } + unsigned char *d = (unsigned char *)dest; + int len = 0; + + if (id <= 30) { + /* + * Identifier is one byte. + */ + len++; + if (d) *d++ = id | flags; + } else { + int n; + /* + * Identifier is multiple bytes: the first byte is 11111 + * plus the flags, and subsequent bytes encode the value of + * the identifier, 7 bits at a time, with the top bit of + * each byte 1 except the last one which is 0. + */ + len++; + if (d) *d++ = 0x1F | flags; + for (n = 1; (id >> (7*n)) > 0; n++) + continue; /* count the bytes */ + while (n--) { + len++; + if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); } + } - if (length < 128) { - /* - * Length is one byte. - */ - len++; - if (d) *d++ = length; - } else { - int n; - /* - * Length is multiple bytes. The first is 0x80 plus the - * number of subsequent bytes, and the subsequent bytes - * encode the actual length. - */ - for (n = 1; (length >> (8*n)) > 0; n++) - continue; /* count the bytes */ - len++; - if (d) *d++ = 0x80 | n; - while (n--) { - len++; - if (d) *d++ = (length >> (8*n)) & 0xFF; - } + if (length < 128) { + /* + * Length is one byte. + */ + len++; + if (d) *d++ = length; + } else { + int n; + /* + * Length is multiple bytes. The first is 0x80 plus the + * number of subsequent bytes, and the subsequent bytes + * encode the actual length. + */ + for (n = 1; (length >> (8*n)) > 0; n++) + continue; /* count the bytes */ + len++; + if (d) *d++ = 0x80 | n; + while (n--) { + len++; + if (d) *d++ = (length >> (8*n)) & 0xFF; } + } - return len; + return len; } @@ -344,99 +347,99 @@ struct mpint_pos { void *start; int bytes; }; enum { OSSH_DSA, OSSH_RSA, OSSH_EC }; struct openssh_key { - int type; - int encrypted; - char iv[32]; - unsigned char *keyblob; + int type; + int encrypted; + char iv[32]; + unsigned char *keyblob; unsigned int keyblob_len, keyblob_size; }; static struct openssh_key *load_openssh_key(const char *filename) { - struct openssh_key *ret; + struct openssh_key *ret; FILE *fp = NULL; - char buffer[256]; + char buffer[256]; char *errmsg = NULL, *p = NULL; - int headers_done; + int headers_done; unsigned long len, outlen; ret = (struct openssh_key*)m_malloc(sizeof(struct openssh_key)); - ret->keyblob = NULL; - ret->keyblob_len = ret->keyblob_size = 0; - ret->encrypted = 0; - memset(ret->iv, 0, sizeof(ret->iv)); + ret->keyblob = NULL; + ret->keyblob_len = ret->keyblob_size = 0; + ret->encrypted = 0; + memset(ret->iv, 0, sizeof(ret->iv)); if (strlen(filename) == 1 && filename[0] == '-') { fp = stdin; } else { fp = fopen(filename, "r"); } - if (!fp) { - errmsg = "Unable to open key file"; - goto error; - } - if (!fgets(buffer, sizeof(buffer), fp) || - 0 != strncmp(buffer, "-----BEGIN ", 11) || - 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { - errmsg = "File does not begin with OpenSSH key header"; - goto error; - } - if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) - ret->type = OSSH_RSA; - else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) - ret->type = OSSH_DSA; + if (!fp) { + errmsg = "Unable to open key file"; + goto error; + } + if (!fgets(buffer, sizeof(buffer), fp) || + 0 != strncmp(buffer, "-----BEGIN ", 11) || + 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { + errmsg = "File does not begin with OpenSSH key header"; + goto error; + } + if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) + ret->type = OSSH_RSA; + else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) + ret->type = OSSH_DSA; else if (!strcmp(buffer, "-----BEGIN EC PRIVATE KEY-----\n")) ret->type = OSSH_EC; - else { - errmsg = "Unrecognised key type"; + else { + errmsg = "Unrecognised key type"; + goto error; + } + + headers_done = 0; + while (1) { + if (!fgets(buffer, sizeof(buffer), fp)) { + errmsg = "Unexpected end of file"; + goto error; + } + if (0 == strncmp(buffer, "-----END ", 9) && + 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) + break; /* done */ + if ((p = strchr(buffer, ':')) != NULL) { + if (headers_done) { + errmsg = "Header found in body of key data"; goto error; - } - - headers_done = 0; - while (1) { - if (!fgets(buffer, sizeof(buffer), fp)) { - errmsg = "Unexpected end of file"; - goto error; + } + *p++ = '\0'; + while (*p && isspace((unsigned char)*p)) p++; + if (!strcmp(buffer, "Proc-Type")) { + if (p[0] != '4' || p[1] != ',') { + errmsg = "Proc-Type is not 4 (only 4 is supported)"; + goto error; } - if (0 == strncmp(buffer, "-----END ", 9) && - 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) - break; /* done */ - if ((p = strchr(buffer, ':')) != NULL) { - if (headers_done) { - errmsg = "Header found in body of key data"; - goto error; - } - *p++ = '\0'; - while (*p && isspace((unsigned char)*p)) p++; - if (!strcmp(buffer, "Proc-Type")) { - if (p[0] != '4' || p[1] != ',') { - errmsg = "Proc-Type is not 4 (only 4 is supported)"; - goto error; - } - p += 2; - if (!strcmp(p, "ENCRYPTED\n")) - ret->encrypted = 1; - } else if (!strcmp(buffer, "DEK-Info")) { - int i, j; - - if (strncmp(p, "DES-EDE3-CBC,", 13)) { - errmsg = "Ciphers other than DES-EDE3-CBC not supported"; - goto error; - } - p += 13; - for (i = 0; i < 8; i++) { - if (1 != sscanf(p, "%2x", &j)) - break; - ret->iv[i] = j; - p += 2; - } - if (i < 8) { - errmsg = "Expected 16-digit iv in DEK-Info"; - goto error; - } - } - } else { - headers_done = 1; + p += 2; + if (!strcmp(p, "ENCRYPTED\n")) + ret->encrypted = 1; + } else if (!strcmp(buffer, "DEK-Info")) { + int i, j; + + if (strncmp(p, "DES-EDE3-CBC,", 13)) { + errmsg = "Ciphers other than DES-EDE3-CBC not supported"; + goto error; + } + p += 13; + for (i = 0; i < 8; i++) { + if (1 != sscanf(p, "%2x", &j)) + break; + ret->iv[i] = j; + p += 2; + } + if (i < 8) { + errmsg = "Expected 16-digit iv in DEK-Info"; + goto error; + } + } + } else { + headers_done = 1; len = strlen(buffer); outlen = len*4/3; if (ret->keyblob_len + outlen > ret->keyblob_size) { @@ -448,65 +451,65 @@ static struct openssh_key *load_openssh_key(const char *filename) if (base64_decode((const unsigned char *)buffer, len, ret->keyblob + ret->keyblob_len, &outlen) != CRYPT_OK){ errmsg = "Error decoding base64"; - goto error; - } + goto error; + } ret->keyblob_len += outlen; - } + } } - if (ret->keyblob_len == 0 || !ret->keyblob) { - errmsg = "Key body not present"; - goto error; - } + if (ret->keyblob_len == 0 || !ret->keyblob) { + errmsg = "Key body not present"; + goto error; + } - if (ret->encrypted && ret->keyblob_len % 8 != 0) { - errmsg = "Encrypted key blob is not a multiple of cipher block size"; - goto error; - } + if (ret->encrypted && ret->keyblob_len % 8 != 0) { + errmsg = "Encrypted key blob is not a multiple of cipher block size"; + goto error; + } m_burn(buffer, sizeof(buffer)); - return ret; + return ret; - error: + error: m_burn(buffer, sizeof(buffer)); - if (ret) { - if (ret->keyblob) { + if (ret) { + if (ret->keyblob) { m_burn(ret->keyblob, ret->keyblob_size); m_free(ret->keyblob); - } + } m_free(ret); } if (fp) { fclose(fp); - } + } if (errmsg) { fprintf(stderr, "Error: %s\n", errmsg); } - return NULL; + return NULL; } static int openssh_encrypted(const char *filename) { - struct openssh_key *key = load_openssh_key(filename); - int ret; + struct openssh_key *key = load_openssh_key(filename); + int ret; - if (!key) - return 0; - ret = key->encrypted; + if (!key) + return 0; + ret = key->encrypted; m_burn(key->keyblob, key->keyblob_size); m_free(key->keyblob); m_free(key); - return ret; + return ret; } static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) { struct openssh_key *key; - unsigned char *p; - int ret, id, len, flags; + unsigned char *p; + int ret, id, len, flags; int i, num_integers = 0; sign_key *retval = NULL; - char *errmsg; + char *errmsg; unsigned char *modptr = NULL; int modlen = -9999; enum signkey_type type; @@ -518,86 +521,87 @@ static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) key = load_openssh_key(filename); - if (!key) - return NULL; + if (!key) + return NULL; - if (key->encrypted) { + if (key->encrypted) { errmsg = "encrypted keys not supported currently"; goto error; #if 0 /* matt TODO */ - /* - * Derive encryption key from passphrase and iv/salt: - * - * - let block A equal MD5(passphrase || iv) - * - let block B equal MD5(A || passphrase || iv) - * - block C would be MD5(B || passphrase || iv) and so on - * - encryption key is the first N bytes of A || B - */ - struct MD5Context md5c; - unsigned char keybuf[32]; - - MD5Init(&md5c); - MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); - MD5Update(&md5c, (unsigned char *)key->iv, 8); - MD5Final(keybuf, &md5c); - - MD5Init(&md5c); - MD5Update(&md5c, keybuf, 16); - MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); - MD5Update(&md5c, (unsigned char *)key->iv, 8); - MD5Final(keybuf+16, &md5c); - - /* - * Now decrypt the key blob. - */ - des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv, - key->keyblob, key->keyblob_len); - - memset(&md5c, 0, sizeof(md5c)); - memset(keybuf, 0, sizeof(keybuf)); -#endif - } + /* + * Derive encryption key from passphrase and iv/salt: + * + * - let block A equal MD5(passphrase || iv) + * - let block B equal MD5(A || passphrase || iv) + * - block C would be MD5(B || passphrase || iv) and so on + * - encryption key is the first N bytes of A || B + */ + struct MD5Context md5c; + unsigned char keybuf[32]; + + MD5Init(&md5c); + MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); + MD5Update(&md5c, (unsigned char *)key->iv, 8); + MD5Final(keybuf, &md5c); + + MD5Init(&md5c); + MD5Update(&md5c, keybuf, 16); + MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); + MD5Update(&md5c, (unsigned char *)key->iv, 8); + MD5Final(keybuf+16, &md5c); /* - * Now we have a decrypted key blob, which contains an ASN.1 - * encoded private key. We must now untangle the ASN.1. - * - * We expect the whole key blob to be formatted as a SEQUENCE - * (0x30 followed by a length code indicating that the rest of - * the blob is part of the sequence). Within that SEQUENCE we - * expect to see a bunch of INTEGERs. What those integers mean - * depends on the key type: - * - * - For RSA, we expect the integers to be 0, n, e, d, p, q, - * dmp1, dmq1, iqmp in that order. (The last three are d mod - * (p-1), d mod (q-1), inverse of q mod p respectively.) - * - * - For DSA, we expect them to be 0, p, q, g, y, x in that - * order. + * Now decrypt the key blob. */ - - p = key->keyblob; + des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv, + key->keyblob, key->keyblob_len); - /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ - ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); - p += ret; - if (ret < 0 || id != 16) { + memset(&md5c, 0, sizeof(md5c)); + memset(keybuf, 0, sizeof(keybuf)); +#endif + } + + /* + * Now we have a decrypted key blob, which contains an ASN.1 + * encoded private key. We must now untangle the ASN.1. + * + * We expect the whole key blob to be formatted as a SEQUENCE + * (0x30 followed by a length code indicating that the rest of + * the blob is part of the sequence). Within that SEQUENCE we + * expect to see a bunch of INTEGERs. What those integers mean + * depends on the key type: + * + * - For RSA, we expect the integers to be 0, n, e, d, p, q, + * dmp1, dmq1, iqmp in that order. (The last three are d mod + * (p-1), d mod (q-1), inverse of q mod p respectively.) + * + * - For DSA, we expect them to be 0, p, q, g, y, x in that + * order. + */ + + p = key->keyblob; + + /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ + ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); + p += ret; + if (ret < 0 || id != 16 || len < 0 || + key->keyblob+key->keyblob_len-p < len) { errmsg = "ASN.1 decoding failure - wrong password?"; - goto error; - } - - /* Expect a load of INTEGERs. */ - if (key->type == OSSH_RSA) - num_integers = 9; - else if (key->type == OSSH_DSA) - num_integers = 6; + goto error; + } + + /* Expect a load of INTEGERs. */ + if (key->type == OSSH_RSA) + num_integers = 9; + else if (key->type == OSSH_DSA) + num_integers = 6; else if (key->type == OSSH_EC) num_integers = 1; - /* - * Space to create key blob in. - */ + /* + * Space to create key blob in. + */ blobbuf = buf_new(3000); #ifdef DROPBEAR_DSS @@ -613,17 +617,17 @@ static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) } #endif - for (i = 0; i < num_integers; i++) { - ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, - &id, &len, &flags); - p += ret; - if (ret < 0 || id != 2 || - key->keyblob+key->keyblob_len-p < len) { - errmsg = "ASN.1 decoding failure"; - goto error; - } + for (i = 0; i < num_integers; i++) { + ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, + &id, &len, &flags); + p += ret; + if (ret < 0 || id != 2 || len < 0 || + key->keyblob+key->keyblob_len-p < len) { + errmsg = "ASN.1 decoding failure"; + goto error; + } - if (i == 0) { + if (i == 0) { /* First integer is a version indicator */ int expected = -1; switch (key->type) { @@ -636,36 +640,36 @@ static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) break; } if (len != 1 || p[0] != expected) { - errmsg = "Version number mismatch"; - goto error; - } - } else if (key->type == OSSH_RSA) { - /* + errmsg = "Version number mismatch"; + goto error; + } + } else if (key->type == OSSH_RSA) { + /* * OpenSSH key order is n, e, d, p, q, dmp1, dmq1, iqmp * but we want e, n, d, p, q - */ - if (i == 1) { - /* Save the details for after we deal with number 2. */ + */ + if (i == 1) { + /* Save the details for after we deal with number 2. */ modptr = p; - modlen = len; + modlen = len; } else if (i >= 2 && i <= 5) { buf_putstring(blobbuf, (const char*)p, len); - if (i == 2) { + if (i == 2) { buf_putstring(blobbuf, (const char*)modptr, modlen); - } - } - } else if (key->type == OSSH_DSA) { - /* + } + } + } else if (key->type == OSSH_DSA) { + /* * OpenSSH key order is p, q, g, y, x, * we want the same. - */ + */ buf_putstring(blobbuf, (const char*)p, len); - } - - /* Skip past the number. */ - p += len; } + /* Skip past the number. */ + p += len; + } + #ifdef DROPBEAR_ECDSA if (key->type == OSSH_EC) { unsigned char* private_key_bytes = NULL; @@ -780,12 +784,12 @@ static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) } #endif /* DROPBEAR_ECDSA */ - /* - * Now put together the actual key. Simplest way to do this is - * to assemble our own key blobs and feed them to the createkey - * functions; this is a bit faffy but it does mean we get all - * the sanity checks for free. - */ + /* + * Now put together the actual key. Simplest way to do this is + * to assemble our own key blobs and feed them to the createkey + * functions; this is a bit faffy but it does mean we get all + * the sanity checks for free. + */ if (key->type == OSSH_RSA || key->type == OSSH_DSA) { buf_setpos(blobbuf, 0); type = DROPBEAR_SIGNKEY_ANY; @@ -794,18 +798,18 @@ static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) errmsg = "unable to create key structure"; sign_key_free(retkey); retkey = NULL; - goto error; - } + goto error; + } } - errmsg = NULL; /* no error */ - retval = retkey; + errmsg = NULL; /* no error */ + retval = retkey; - error: + error: if (blobbuf) { buf_burn(blobbuf); buf_free(blobbuf); - } + } m_burn(key->keyblob, key->keyblob_size); m_free(key->keyblob); m_burn(key, sizeof(*key)); @@ -813,22 +817,22 @@ static sign_key *openssh_read(const char *filename, char * UNUSED(passphrase)) if (errmsg) { fprintf(stderr, "Error: %s\n", errmsg); } - return retval; + return retval; } static int openssh_write(const char *filename, sign_key *key, - char *passphrase) + char *passphrase) { buffer * keyblob = NULL; buffer * extrablob = NULL; /* used for calculated values to write */ unsigned char *outblob = NULL; int outlen = -9999; - struct mpint_pos numbers[9]; + struct mpint_pos numbers[9]; int nnumbers = -1, pos = 0, len = 0, seqlen, i; char *header = NULL, *footer = NULL; - char zero[1]; - int ret = 0; - FILE *fp; + char zero[1]; + int ret = 0; + FILE *fp; #ifdef DROPBEAR_RSA mp_int dmp1, dmq1, iqmp, tmpval; /* for rsa */ @@ -843,9 +847,9 @@ static int openssh_write(const char *filename, sign_key *key, #endif 0) { - /* - * Fetch the key blobs. - */ + /* + * Fetch the key blobs. + */ keyblob = buf_new(3000); buf_put_priv_key(keyblob, key, key->type); @@ -853,10 +857,10 @@ static int openssh_write(const char *filename, sign_key *key, /* skip the "ssh-rsa" or "ssh-dss" header */ buf_incrpos(keyblob, buf_getint(keyblob)); - /* - * Find the sequence of integers to be encoded into the OpenSSH - * key blob, and also decide on the header line. - */ + /* + * Find the sequence of integers to be encoded into the OpenSSH + * key blob, and also decide on the header line. + */ numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; #ifdef DROPBEAR_RSA @@ -871,17 +875,17 @@ static int openssh_write(const char *filename, sign_key *key, numbers[2].bytes = buf_getint(keyblob); numbers[2].start = buf_getptr(keyblob, numbers[2].bytes); buf_incrpos(keyblob, numbers[2].bytes); - + /* n */ numbers[1].bytes = buf_getint(keyblob); numbers[1].start = buf_getptr(keyblob, numbers[1].bytes); buf_incrpos(keyblob, numbers[1].bytes); - + /* d */ numbers[3].bytes = buf_getint(keyblob); numbers[3].start = buf_getptr(keyblob, numbers[3].bytes); buf_incrpos(keyblob, numbers[3].bytes); - + /* p */ numbers[4].bytes = buf_getint(keyblob); numbers[4].start = buf_getptr(keyblob, numbers[4].bytes); @@ -949,9 +953,9 @@ static int openssh_write(const char *filename, sign_key *key, numbers[8].start = buf_getptr(extrablob, numbers[8].bytes); buf_incrpos(extrablob, numbers[8].bytes); - nnumbers = 9; - header = "-----BEGIN RSA PRIVATE KEY-----\n"; - footer = "-----END RSA PRIVATE KEY-----\n"; + nnumbers = 9; + header = "-----BEGIN RSA PRIVATE KEY-----\n"; + footer = "-----END RSA PRIVATE KEY-----\n"; } #endif /* DROPBEAR_RSA */ @@ -983,45 +987,45 @@ static int openssh_write(const char *filename, sign_key *key, numbers[5].start = buf_getptr(keyblob, numbers[5].bytes); buf_incrpos(keyblob, numbers[5].bytes); - nnumbers = 6; - header = "-----BEGIN DSA PRIVATE KEY-----\n"; - footer = "-----END DSA PRIVATE KEY-----\n"; - } + nnumbers = 6; + header = "-----BEGIN DSA PRIVATE KEY-----\n"; + footer = "-----END DSA PRIVATE KEY-----\n"; + } #endif /* DROPBEAR_DSS */ - /* - * Now count up the total size of the ASN.1 encoded integers, - * so as to determine the length of the containing SEQUENCE. - */ - len = 0; - for (i = 0; i < nnumbers; i++) { - len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); - len += numbers[i].bytes; - } - seqlen = len; - /* Now add on the SEQUENCE header. */ - len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); - /* Round up to the cipher block size, ensuring we have at least one - * byte of padding (see below). */ - outlen = len; - if (passphrase) - outlen = (outlen+8) &~ 7; - - /* - * Now we know how big outblob needs to be. Allocate it. - */ + /* + * Now count up the total size of the ASN.1 encoded integers, + * so as to determine the length of the containing SEQUENCE. + */ + len = 0; + for (i = 0; i < nnumbers; i++) { + len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); + len += numbers[i].bytes; + } + seqlen = len; + /* Now add on the SEQUENCE header. */ + len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); + /* Round up to the cipher block size, ensuring we have at least one + * byte of padding (see below). */ + outlen = len; + if (passphrase) + outlen = (outlen+8) &~ 7; + + /* + * Now we know how big outblob needs to be. Allocate it. + */ outblob = (unsigned char*)m_malloc(outlen); - /* - * And write the data into it. - */ - pos = 0; - pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); - for (i = 0; i < nnumbers; i++) { - pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); - memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); - pos += numbers[i].bytes; - } + /* + * And write the data into it. + */ + pos = 0; + pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); + for (i = 0; i < nnumbers; i++) { + pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); + memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); + pos += numbers[i].bytes; + } } /* end RSA and DSS handling */ #ifdef DROPBEAR_ECDSA @@ -1116,40 +1120,40 @@ static int openssh_write(const char *filename, sign_key *key, } #endif - /* - * Padding on OpenSSH keys is deterministic. The number of - * padding bytes is always more than zero, and always at most - * the cipher block length. The value of each padding byte is - * equal to the number of padding bytes. So a plaintext that's - * an exact multiple of the block size will be padded with 08 - * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a - * plaintext one byte less than a multiple of the block size - * will be padded with just 01. - * - * This enables the OpenSSL key decryption function to strip - * off the padding algorithmically and return the unpadded - * plaintext to the next layer: it looks at the final byte, and - * then expects to find that many bytes at the end of the data - * with the same value. Those are all removed and the rest is - * returned. - */ + /* + * Padding on OpenSSH keys is deterministic. The number of + * padding bytes is always more than zero, and always at most + * the cipher block length. The value of each padding byte is + * equal to the number of padding bytes. So a plaintext that's + * an exact multiple of the block size will be padded with 08 + * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a + * plaintext one byte less than a multiple of the block size + * will be padded with just 01. + * + * This enables the OpenSSL key decryption function to strip + * off the padding algorithmically and return the unpadded + * plaintext to the next layer: it looks at the final byte, and + * then expects to find that many bytes at the end of the data + * with the same value. Those are all removed and the rest is + * returned. + */ dropbear_assert(pos == len); - while (pos < outlen) { - outblob[pos++] = outlen - len; - } - - /* - * Encrypt the key. - */ - if (passphrase) { + while (pos < outlen) { + outblob[pos++] = outlen - len; + } + + /* + * Encrypt the key. + */ + if (passphrase) { fprintf(stderr, "Encrypted keys aren't supported currently\n"); goto error; - } + } - /* - * And save it. We'll use Unix line endings just in case it's - * subsequently transferred in binary mode. - */ + /* + * And save it. We'll use Unix line endings just in case it's + * subsequently transferred in binary mode. + */ if (strlen(filename) == 1 && filename[0] == '-') { fp = stdout; } else { @@ -1157,28 +1161,28 @@ static int openssh_write(const char *filename, sign_key *key, } if (!fp) { fprintf(stderr, "Failed opening output file\n"); - goto error; + goto error; } - fputs(header, fp); + fputs(header, fp); base64_encode_fp(fp, outblob, outlen, 64); - fputs(footer, fp); - fclose(fp); - ret = 1; + fputs(footer, fp); + fclose(fp); + ret = 1; - error: - if (outblob) { - memset(outblob, 0, outlen); + error: + if (outblob) { + memset(outblob, 0, outlen); m_free(outblob); - } + } if (keyblob) { buf_burn(keyblob); buf_free(keyblob); - } + } if (extrablob) { buf_burn(extrablob); buf_free(extrablob); - } - return ret; + } + return ret; } #if 0 @@ -1196,10 +1200,10 @@ static int openssh_write(const char *filename, sign_key *key, * * So. The blob contains: * - * - uint32 0x3f6ff9eb (magic number) - * - uint32 size (total blob size) - * - string key-type (see below) - * - string cipher-type (tells you if key is encrypted) + * - uint32 0x3f6ff9eb (magic number) + * - uint32 size (total blob size) + * - string key-type (see below) + * - string cipher-type (tells you if key is encrypted) * - string encrypted-blob * * (The first size field includes the size field itself and the @@ -1255,654 +1259,679 @@ static int openssh_write(const char *filename, sign_key *key, * - first 16 bytes are MD5(passphrase) * - next 16 bytes are MD5(passphrase || first 16 bytes) * - if there were more, they'd be MD5(passphrase || first 32), - * and so on. + * and so on. */ #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb struct sshcom_key { - char comment[256]; /* allowing any length is overkill */ - unsigned char *keyblob; - int keyblob_len, keyblob_size; + char comment[256]; /* allowing any length is overkill */ + unsigned char *keyblob; + int keyblob_len, keyblob_size; }; static struct sshcom_key *load_sshcom_key(const char *filename) { - struct sshcom_key *ret; - FILE *fp; - char buffer[256]; - int len; - char *errmsg, *p; - int headers_done; - char base64_bit[4]; - int base64_chars = 0; - - ret = snew(struct sshcom_key); - ret->comment[0] = '\0'; - ret->keyblob = NULL; - ret->keyblob_len = ret->keyblob_size = 0; + struct sshcom_key *ret; + FILE *fp; + char buffer[256]; + int len; + char *errmsg, *p; + int headers_done; + char base64_bit[4]; + int base64_chars = 0; + + ret = snew(struct sshcom_key); + ret->comment[0] = '\0'; + ret->keyblob = NULL; + ret->keyblob_len = ret->keyblob_size = 0; fp = fopen(filename, "r"); - if (!fp) { - errmsg = "Unable to open key file"; - goto error; - } - if (!fgets(buffer, sizeof(buffer), fp) || - 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { - errmsg = "File does not begin with ssh.com key header"; + if (!fp) { + errmsg = "Unable to open key file"; + goto error; + } + if (!fgets(buffer, sizeof(buffer), fp) || + 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { + errmsg = "File does not begin with ssh.com key header"; + goto error; + } + + headers_done = 0; + while (1) { + if (!fgets(buffer, sizeof(buffer), fp)) { + errmsg = "Unexpected end of file"; + goto error; + } + if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) + break; /* done */ + if ((p = strchr(buffer, ':')) != NULL) { + if (headers_done) { + errmsg = "Header found in body of key data"; goto error; - } - - headers_done = 0; - while (1) { - if (!fgets(buffer, sizeof(buffer), fp)) { - errmsg = "Unexpected end of file"; - goto error; - } - if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) - break; /* done */ - if ((p = strchr(buffer, ':')) != NULL) { - if (headers_done) { - errmsg = "Header found in body of key data"; - goto error; - } - *p++ = '\0'; - while (*p && isspace((unsigned char)*p)) p++; - /* - * Header lines can end in a trailing backslash for - * continuation. - */ - while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) || - p[len-1] != '\n' || p[len-2] == '\\') { - if (len > (int)((p-buffer) + sizeof(buffer)-2)) { - errmsg = "Header line too long to deal with"; - goto error; - } - if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { - errmsg = "Unexpected end of file"; - goto error; - } - } - p[strcspn(p, "\n")] = '\0'; - if (!strcmp(buffer, "Comment")) { - /* Strip quotes in comment if present. */ - if (p[0] == '"' && p[strlen(p)-1] == '"') { - p++; - p[strlen(p)-1] = '\0'; - } - strncpy(ret->comment, p, sizeof(ret->comment)); - ret->comment[sizeof(ret->comment)-1] = '\0'; - } - } else { - headers_done = 1; + } + *p++ = '\0'; + while (*p && isspace((unsigned char)*p)) p++; + /* + * Header lines can end in a trailing backslash for + * continuation. + */ + while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) || + p[len-1] != '\n' || p[len-2] == '\\') { + if (len > (int)((p-buffer) + sizeof(buffer)-2)) { + errmsg = "Header line too long to deal with"; + goto error; + } + if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { + errmsg = "Unexpected end of file"; + goto error; + } + } + p[strcspn(p, "\n")] = '\0'; + if (!strcmp(buffer, "Comment")) { + /* Strip quotes in comment if present. */ + if (p[0] == '"' && p[strlen(p)-1] == '"') { + p++; + p[strlen(p)-1] = '\0'; + } + strncpy(ret->comment, p, sizeof(ret->comment)); + ret->comment[sizeof(ret->comment)-1] = '\0'; + } + } else { + headers_done = 1; - p = buffer; - while (isbase64(*p)) { - base64_bit[base64_chars++] = *p; - if (base64_chars == 4) { - unsigned char out[3]; + p = buffer; + while (isbase64(*p)) { + base64_bit[base64_chars++] = *p; + if (base64_chars == 4) { + unsigned char out[3]; - base64_chars = 0; + base64_chars = 0; - len = base64_decode_atom(base64_bit, out); + len = base64_decode_atom(base64_bit, out); - if (len <= 0) { - errmsg = "Invalid base64 encoding"; - goto error; - } + if (len <= 0) { + errmsg = "Invalid base64 encoding"; + goto error; + } - if (ret->keyblob_len + len > ret->keyblob_size) { - ret->keyblob_size = ret->keyblob_len + len + 256; - ret->keyblob = sresize(ret->keyblob, ret->keyblob_size, - unsigned char); - } + if (ret->keyblob_len + len > ret->keyblob_size) { + ret->keyblob_size = ret->keyblob_len + len + 256; + ret->keyblob = sresize(ret->keyblob, ret->keyblob_size, + unsigned char); + } - memcpy(ret->keyblob + ret->keyblob_len, out, len); - ret->keyblob_len += len; - } + memcpy(ret->keyblob + ret->keyblob_len, out, len); + ret->keyblob_len += len; + } - p++; - } - } + p++; + } } + } - if (ret->keyblob_len == 0 || !ret->keyblob) { - errmsg = "Key body not present"; - goto error; - } + if (ret->keyblob_len == 0 || !ret->keyblob) { + errmsg = "Key body not present"; + goto error; + } - return ret; + return ret; - error: - if (ret) { - if (ret->keyblob) { - memset(ret->keyblob, 0, ret->keyblob_size); + error: + if (ret) { + if (ret->keyblob) { + memset(ret->keyblob, 0, ret->keyblob_size); m_free(ret->keyblob); - } - memset(&ret, 0, sizeof(ret)); + } + memset(ret, 0, sizeof(*ret)); m_free(ret); - } - return NULL; + } + return NULL; } int sshcom_encrypted(const char *filename, char **comment) { - struct sshcom_key *key = load_sshcom_key(filename); - int pos, len, answer; - - *comment = NULL; - if (!key) - return 0; - - /* - * Check magic number. - */ - if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) - return 0; /* key is invalid */ - - /* - * Find the cipher-type string. - */ - answer = 0; - pos = 8; - if (key->keyblob_len < pos+4) - goto done; /* key is far too short */ - pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ - if (key->keyblob_len < pos+4) - goto done; /* key is far too short */ - len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ - if (key->keyblob_len < pos+4+len) - goto done; /* cipher type string is incomplete */ - if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) - answer = 1; - - done: - *comment = dupstr(key->comment); - memset(key->keyblob, 0, key->keyblob_size); + struct sshcom_key *key = load_sshcom_key(filename); + int pos, len, answer; + + *comment = NULL; + if (!key) + return 0; + + /* + * Check magic number. + */ + if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) + return 0; /* key is invalid */ + + /* + * Find the cipher-type string. + */ + answer = 0; + pos = 8; + if (key->keyblob_len < pos+4) + goto done; /* key is far too short */ + len = toint(GET_32BIT(key->keyblob + pos)); + if (len < 0 || len > key->keyblob_len - pos - 4) + goto done; /* key is far too short */ + pos += 4 + len; /* skip key type */ + len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */ + if (len < 0 || len > key->keyblob_len - pos - 4) + goto done; /* cipher type string is incomplete */ + if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) + answer = 1; + + done: + *comment = dupstr(key->comment); + memset(key->keyblob, 0, key->keyblob_size); m_free(key->keyblob); - memset(&key, 0, sizeof(key)); + memset(key, 0, sizeof(*key)); m_free(key); - return answer; + return answer; } static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) { - int bits; - int bytes; - unsigned char *d = (unsigned char *) data; + unsigned bits, bytes; + unsigned char *d = (unsigned char *) data; - if (len < 4) - goto error; - bits = GET_32BIT(d); + if (len < 4) + goto error; + bits = GET_32BIT(d); - bytes = (bits + 7) / 8; - if (len < 4+bytes) - goto error; + bytes = (bits + 7) / 8; + if (len < 4+bytes) + goto error; - ret->start = d + 4; - ret->bytes = bytes; - return bytes+4; + ret->start = d + 4; + ret->bytes = bytes; + return bytes+4; - error: - ret->start = NULL; - ret->bytes = -1; - return len; /* ensure further calls fail as well */ + error: + ret->start = NULL; + ret->bytes = -1; + return len; /* ensure further calls fail as well */ } static int sshcom_put_mpint(void *target, void *data, int len) { - unsigned char *d = (unsigned char *)target; - unsigned char *i = (unsigned char *)data; - int bits = len * 8 - 1; - - while (bits > 0) { - if (*i & (1 << (bits & 7))) - break; - if (!(bits-- & 7)) - i++, len--; - } - - PUT_32BIT(d, bits+1); - memcpy(d+4, i, len); - return len+4; + unsigned char *d = (unsigned char *)target; + unsigned char *i = (unsigned char *)data; + int bits = len * 8 - 1; + + while (bits > 0) { + if (*i & (1 << (bits & 7))) + break; + if (!(bits-- & 7)) + i++, len--; + } + + PUT_32BIT(d, bits+1); + memcpy(d+4, i, len); + return len+4; } sign_key *sshcom_read(const char *filename, char *passphrase) { - struct sshcom_key *key = load_sshcom_key(filename); - char *errmsg; - int pos, len; - const char prefix_rsa[] = "if-modn{sign{rsa"; - const char prefix_dsa[] = "dl-modp{sign{dsa"; - enum { RSA, DSA } type; - int encrypted; - char *ciphertext; - int cipherlen; - struct ssh2_userkey *ret = NULL, *retkey; - const struct ssh_signkey *alg; - unsigned char *blob = NULL; - int blobsize, publen, privlen; - - if (!key) - return NULL; - - /* - * Check magic number. - */ - if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { - errmsg = "Key does not begin with magic number"; - goto error; - } - + struct sshcom_key *key = load_sshcom_key(filename); + char *errmsg; + int pos, len; + const char prefix_rsa[] = "if-modn{sign{rsa"; + const char prefix_dsa[] = "dl-modp{sign{dsa"; + enum { RSA, DSA } type; + int encrypted; + char *ciphertext; + int cipherlen; + struct ssh2_userkey *ret = NULL, *retkey; + const struct ssh_signkey *alg; + unsigned char *blob = NULL; + int blobsize = 0, publen, privlen; + + if (!key) + return NULL; + + /* + * Check magic number. + */ + if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { + errmsg = "Key does not begin with magic number"; + goto error; + } + + /* + * Determine the key type. + */ + pos = 8; + if (key->keyblob_len < pos+4 || + (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { + errmsg = "Key blob does not contain a key type string"; + goto error; + } + if (len > sizeof(prefix_rsa) - 1 && + !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { + type = RSA; + } else if (len > sizeof(prefix_dsa) - 1 && + !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { + type = DSA; + } else { + errmsg = "Key is of unknown type"; + goto error; + } + pos += 4+len; + + /* + * Determine the cipher type. + */ + if (key->keyblob_len < pos+4 || + (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { + errmsg = "Key blob does not contain a cipher type string"; + goto error; + } + if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) + encrypted = 0; + else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) + encrypted = 1; + else { + errmsg = "Key encryption is of unknown type"; + goto error; + } + pos += 4+len; + + /* + * Get hold of the encrypted part of the key. + */ + if (key->keyblob_len < pos+4 || + (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { + errmsg = "Key blob does not contain actual key data"; + goto error; + } + ciphertext = (char *)key->keyblob + pos + 4; + cipherlen = len; + if (cipherlen == 0) { + errmsg = "Length of key data is zero"; + goto error; + } + + /* + * Decrypt it if necessary. + */ + if (encrypted) { /* - * Determine the key type. - */ - pos = 8; - if (key->keyblob_len < pos+4 || - (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { - errmsg = "Key blob does not contain a key type string"; - goto error; - } - if (len > sizeof(prefix_rsa) - 1 && - !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { - type = RSA; - } else if (len > sizeof(prefix_dsa) - 1 && - !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { - type = DSA; - } else { - errmsg = "Key is of unknown type"; - goto error; - } - pos += 4+len; - - /* - * Determine the cipher type. - */ - if (key->keyblob_len < pos+4 || - (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { - errmsg = "Key blob does not contain a cipher type string"; - goto error; - } - if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) - encrypted = 0; - else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) - encrypted = 1; - else { - errmsg = "Key encryption is of unknown type"; - goto error; - } - pos += 4+len; - - /* - * Get hold of the encrypted part of the key. + * Derive encryption key from passphrase and iv/salt: + * + * - let block A equal MD5(passphrase) + * - let block B equal MD5(passphrase || A) + * - block C would be MD5(passphrase || A || B) and so on + * - encryption key is the first N bytes of A || B */ - if (key->keyblob_len < pos+4 || - (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { - errmsg = "Key blob does not contain actual key data"; - goto error; - } - ciphertext = (char *)key->keyblob + pos + 4; - cipherlen = len; - if (cipherlen == 0) { - errmsg = "Length of key data is zero"; - goto error; - } + struct MD5Context md5c; + unsigned char keybuf[32], iv[8]; - /* - * Decrypt it if necessary. - */ - if (encrypted) { - /* - * Derive encryption key from passphrase and iv/salt: - * - * - let block A equal MD5(passphrase) - * - let block B equal MD5(passphrase || A) - * - block C would be MD5(passphrase || A || B) and so on - * - encryption key is the first N bytes of A || B - */ - struct MD5Context md5c; - unsigned char keybuf[32], iv[8]; - - if (cipherlen % 8 != 0) { - errmsg = "Encrypted part of key is not a multiple of cipher block" - " size"; - goto error; - } + if (cipherlen % 8 != 0) { + errmsg = "Encrypted part of key is not a multiple of cipher block" + " size"; + goto error; + } - MD5Init(&md5c); - MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); - MD5Final(keybuf, &md5c); - - MD5Init(&md5c); - MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); - MD5Update(&md5c, keybuf, 16); - MD5Final(keybuf+16, &md5c); - - /* - * Now decrypt the key blob. - */ - memset(iv, 0, sizeof(iv)); - des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, - cipherlen); - - memset(&md5c, 0, sizeof(md5c)); - memset(keybuf, 0, sizeof(keybuf)); - - /* - * Hereafter we return WRONG_PASSPHRASE for any parsing - * error. (But only if we've just tried to decrypt it! - * Returning WRONG_PASSPHRASE for an unencrypted key is - * automatic doom.) - */ - if (encrypted) - ret = SSH2_WRONG_PASSPHRASE; - } + MD5Init(&md5c); + MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); + MD5Final(keybuf, &md5c); - /* - * Strip away the containing string to get to the real meat. - */ - len = GET_32BIT(ciphertext); - if (len > cipherlen-4) { - errmsg = "containing string was ill-formed"; - goto error; - } - ciphertext += 4; - cipherlen = len; + MD5Init(&md5c); + MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); + MD5Update(&md5c, keybuf, 16); + MD5Final(keybuf+16, &md5c); /* - * Now we break down into RSA versus DSA. In either case we'll - * construct public and private blobs in our own format, and - * end up feeding them to alg->createkey(). + * Now decrypt the key blob. */ - blobsize = cipherlen + 256; - blob = snewn(blobsize, unsigned char); - privlen = 0; - if (type == RSA) { - struct mpint_pos n, e, d, u, p, q; - int pos = 0; - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); - if (!q.start) { - errmsg = "key data did not contain six integers"; - goto error; - } - - alg = &ssh_rsa; - pos = 0; - pos += put_string(blob+pos, "ssh-rsa", 7); - pos += put_mp(blob+pos, e.start, e.bytes); - pos += put_mp(blob+pos, n.start, n.bytes); - publen = pos; - pos += put_string(blob+pos, d.start, d.bytes); - pos += put_mp(blob+pos, q.start, q.bytes); - pos += put_mp(blob+pos, p.start, p.bytes); - pos += put_mp(blob+pos, u.start, u.bytes); - privlen = pos - publen; - } else if (type == DSA) { - struct mpint_pos p, q, g, x, y; - int pos = 4; - if (GET_32BIT(ciphertext) != 0) { - errmsg = "predefined DSA parameters not supported"; - goto error; - } - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); - pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); - if (!x.start) { - errmsg = "key data did not contain five integers"; - goto error; - } - - alg = &ssh_dss; - pos = 0; - pos += put_string(blob+pos, "ssh-dss", 7); - pos += put_mp(blob+pos, p.start, p.bytes); - pos += put_mp(blob+pos, q.start, q.bytes); - pos += put_mp(blob+pos, g.start, g.bytes); - pos += put_mp(blob+pos, y.start, y.bytes); - publen = pos; - pos += put_mp(blob+pos, x.start, x.bytes); - privlen = pos - publen; - } + memset(iv, 0, sizeof(iv)); + des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, + cipherlen); + + memset(&md5c, 0, sizeof(md5c)); + memset(keybuf, 0, sizeof(keybuf)); + + /* + * Hereafter we return WRONG_PASSPHRASE for any parsing + * error. (But only if we've just tried to decrypt it! + * Returning WRONG_PASSPHRASE for an unencrypted key is + * automatic doom.) + */ + if (encrypted) + ret = SSH2_WRONG_PASSPHRASE; + } + + /* + * Strip away the containing string to get to the real meat. + */ + len = toint(GET_32BIT(ciphertext)); + if (len < 0 || len > cipherlen-4) { + errmsg = "containing string was ill-formed"; + goto error; + } + ciphertext += 4; + cipherlen = len; + + /* + * Now we break down into RSA versus DSA. In either case we'll + * construct public and private blobs in our own format, and + * end up feeding them to alg->createkey(). + */ + blobsize = cipherlen + 256; + blob = snewn(blobsize, unsigned char); + privlen = 0; + if (type == RSA) { + struct mpint_pos n, e, d, u, p, q; + int pos = 0; + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); + if (!q.start) { + errmsg = "key data did not contain six integers"; + goto error; + } + + alg = &ssh_rsa; + pos = 0; + pos += put_string(blob+pos, "ssh-rsa", 7); + pos += put_mp(blob+pos, e.start, e.bytes); + pos += put_mp(blob+pos, n.start, n.bytes); + publen = pos; + pos += put_string(blob+pos, d.start, d.bytes); + pos += put_mp(blob+pos, q.start, q.bytes); + pos += put_mp(blob+pos, p.start, p.bytes); + pos += put_mp(blob+pos, u.start, u.bytes); + privlen = pos - publen; + } else if (type == DSA) { + struct mpint_pos p, q, g, x, y; + int pos = 4; + if (GET_32BIT(ciphertext) != 0) { + errmsg = "predefined DSA parameters not supported"; + goto error; + } + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); + pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); + if (!x.start) { + errmsg = "key data did not contain five integers"; + goto error; + } + + alg = &ssh_dss; + pos = 0; + pos += put_string(blob+pos, "ssh-dss", 7); + pos += put_mp(blob+pos, p.start, p.bytes); + pos += put_mp(blob+pos, q.start, q.bytes); + pos += put_mp(blob+pos, g.start, g.bytes); + pos += put_mp(blob+pos, y.start, y.bytes); + publen = pos; + pos += put_mp(blob+pos, x.start, x.bytes); + privlen = pos - publen; + } else + return NULL; dropbear_assert(privlen > 0); /* should have bombed by now if not */ - retkey = snew(struct ssh2_userkey); - retkey->alg = alg; - retkey->data = alg->createkey(blob, publen, blob+publen, privlen); - if (!retkey->data) { + retkey = snew(struct ssh2_userkey); + retkey->alg = alg; + retkey->data = alg->createkey(blob, publen, blob+publen, privlen); + if (!retkey->data) { m_free(retkey); - errmsg = "unable to create key data structure"; - goto error; - } - retkey->comment = dupstr(key->comment); + errmsg = "unable to create key data structure"; + goto error; + } + retkey->comment = dupstr(key->comment); - errmsg = NULL; /* no error */ - ret = retkey; + errmsg = NULL; /* no error */ + ret = retkey; - error: - if (blob) { - memset(blob, 0, blobsize); + error: + if (blob) { + memset(blob, 0, blobsize); m_free(blob); - } - memset(key->keyblob, 0, key->keyblob_size); + } + memset(key->keyblob, 0, key->keyblob_size); m_free(key->keyblob); - memset(&key, 0, sizeof(key)); + memset(key, 0, sizeof(*key)); m_free(key); - return ret; + return ret; } int sshcom_write(const char *filename, sign_key *key, - char *passphrase) + char *passphrase) { - unsigned char *pubblob, *privblob; - int publen, privlen; - unsigned char *outblob; - int outlen; - struct mpint_pos numbers[6]; - int nnumbers, initial_zero, pos, lenpos, i; - char *type; - char *ciphertext; - int cipherlen; - int ret = 0; - FILE *fp; - - /* - * Fetch the key blobs. - */ - pubblob = key->alg->public_blob(key->data, &publen); - privblob = key->alg->private_blob(key->data, &privlen); - outblob = NULL; - - /* - * Find the sequence of integers to be encoded into the OpenSSH - * key blob, and also decide on the header line. - */ - if (key->alg == &ssh_rsa) { - int pos; - struct mpint_pos n, e, d, p, q, iqmp; - - pos = 4 + GET_32BIT(pubblob); - pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); - pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); - pos = 0; - pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); - pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); - pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); - pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); + unsigned char *pubblob, *privblob; + int publen, privlen; + unsigned char *outblob; + int outlen; + struct mpint_pos numbers[6]; + int nnumbers, initial_zero, pos, lenpos, i; + char *type; + char *ciphertext; + int cipherlen; + int ret = 0; + FILE *fp; + + /* + * Fetch the key blobs. + */ + pubblob = key->alg->public_blob(key->data, &publen); + privblob = key->alg->private_blob(key->data, &privlen); + outblob = NULL; + + /* + * Find the sequence of integers to be encoded into the OpenSSH + * key blob, and also decide on the header line. + */ + if (key->alg == &ssh_rsa) { + int pos; + struct mpint_pos n, e, d, p, q, iqmp; + + pos = 4 + GET_32BIT(pubblob); + pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); + pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); + pos = 0; + pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); + pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); + pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); + pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); dropbear_assert(e.start && iqmp.start); /* can't go wrong */ - numbers[0] = e; - numbers[1] = d; - numbers[2] = n; - numbers[3] = iqmp; - numbers[4] = q; - numbers[5] = p; - - nnumbers = 6; - initial_zero = 0; - type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; - } else if (key->alg == &ssh_dss) { - int pos; - struct mpint_pos p, q, g, y, x; - - pos = 4 + GET_32BIT(pubblob); - pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); - pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); - pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); - pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); - pos = 0; - pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); + numbers[0] = e; + numbers[1] = d; + numbers[2] = n; + numbers[3] = iqmp; + numbers[4] = q; + numbers[5] = p; + + nnumbers = 6; + initial_zero = 0; + type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; + } else if (key->alg == &ssh_dss) { + int pos; + struct mpint_pos p, q, g, y, x; + + pos = 4 + GET_32BIT(pubblob); + pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); + pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); + pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); + pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); + pos = 0; + pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); dropbear_assert(y.start && x.start); /* can't go wrong */ - numbers[0] = p; - numbers[1] = g; - numbers[2] = q; - numbers[3] = y; - numbers[4] = x; + numbers[0] = p; + numbers[1] = g; + numbers[2] = q; + numbers[3] = y; + numbers[4] = x; - nnumbers = 5; - initial_zero = 1; - type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; - } else { + nnumbers = 5; + initial_zero = 1; + type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; + } else { dropbear_assert(0); /* zoinks! */ - } - - /* - * Total size of key blob will be somewhere under 512 plus - * combined length of integers. We'll calculate the more - * precise size as we construct the blob. - */ - outlen = 512; - for (i = 0; i < nnumbers; i++) - outlen += 4 + numbers[i].bytes; - outblob = snewn(outlen, unsigned char); - - /* - * Create the unencrypted key blob. - */ - pos = 0; - PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; - pos += 4; /* length field, fill in later */ - pos += put_string(outblob+pos, type, strlen(type)); - { - char *ciphertype = passphrase ? "3des-cbc" : "none"; - pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); - } - lenpos = pos; /* remember this position */ - pos += 4; /* encrypted-blob size */ - pos += 4; /* encrypted-payload size */ - if (initial_zero) { - PUT_32BIT(outblob+pos, 0); - pos += 4; - } - for (i = 0; i < nnumbers; i++) - pos += sshcom_put_mpint(outblob+pos, - numbers[i].start, numbers[i].bytes); - /* Now wrap up the encrypted payload. */ - PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); - /* Pad encrypted blob to a multiple of cipher block size. */ - if (passphrase) { - int padding = -(pos - (lenpos+4)) & 7; - while (padding--) - outblob[pos++] = random_byte(); - } - ciphertext = (char *)outblob+lenpos+4; - cipherlen = pos - (lenpos+4); + } + + /* + * Total size of key blob will be somewhere under 512 plus + * combined length of integers. We'll calculate the more + * precise size as we construct the blob. + */ + outlen = 512; + for (i = 0; i < nnumbers; i++) + outlen += 4 + numbers[i].bytes; + outblob = snewn(outlen, unsigned char); + + /* + * Create the unencrypted key blob. + */ + pos = 0; + PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; + pos += 4; /* length field, fill in later */ + pos += put_string(outblob+pos, type, strlen(type)); + { + char *ciphertype = passphrase ? "3des-cbc" : "none"; + pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); + } + lenpos = pos; /* remember this position */ + pos += 4; /* encrypted-blob size */ + pos += 4; /* encrypted-payload size */ + if (initial_zero) { + PUT_32BIT(outblob+pos, 0); + pos += 4; + } + for (i = 0; i < nnumbers; i++) + pos += sshcom_put_mpint(outblob+pos, + numbers[i].start, numbers[i].bytes); + /* Now wrap up the encrypted payload. */ + PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); + /* Pad encrypted blob to a multiple of cipher block size. */ + if (passphrase) { + int padding = -(pos - (lenpos+4)) & 7; + while (padding--) + outblob[pos++] = random_byte(); + } + ciphertext = (char *)outblob+lenpos+4; + cipherlen = pos - (lenpos+4); dropbear_assert(!passphrase || cipherlen % 8 == 0); - /* Wrap up the encrypted blob string. */ - PUT_32BIT(outblob+lenpos, cipherlen); - /* And finally fill in the total length field. */ - PUT_32BIT(outblob+4, pos); + /* Wrap up the encrypted blob string. */ + PUT_32BIT(outblob+lenpos, cipherlen); + /* And finally fill in the total length field. */ + PUT_32BIT(outblob+4, pos); dropbear_assert(pos < outlen); + /* + * Encrypt the key. + */ + if (passphrase) { /* - * Encrypt the key. + * Derive encryption key from passphrase and iv/salt: + * + * - let block A equal MD5(passphrase) + * - let block B equal MD5(passphrase || A) + * - block C would be MD5(passphrase || A || B) and so on + * - encryption key is the first N bytes of A || B */ - if (passphrase) { - /* - * Derive encryption key from passphrase and iv/salt: - * - * - let block A equal MD5(passphrase) - * - let block B equal MD5(passphrase || A) - * - block C would be MD5(passphrase || A || B) and so on - * - encryption key is the first N bytes of A || B - */ - struct MD5Context md5c; - unsigned char keybuf[32], iv[8]; - - MD5Init(&md5c); - MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); - MD5Final(keybuf, &md5c); - - MD5Init(&md5c); - MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); - MD5Update(&md5c, keybuf, 16); - MD5Final(keybuf+16, &md5c); - - /* - * Now decrypt the key blob. - */ - memset(iv, 0, sizeof(iv)); - des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, - cipherlen); - - memset(&md5c, 0, sizeof(md5c)); - memset(keybuf, 0, sizeof(keybuf)); - } + struct MD5Context md5c; + unsigned char keybuf[32], iv[8]; + + MD5Init(&md5c); + MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); + MD5Final(keybuf, &md5c); + + MD5Init(&md5c); + MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); + MD5Update(&md5c, keybuf, 16); + MD5Final(keybuf+16, &md5c); /* - * And save it. We'll use Unix line endings just in case it's - * subsequently transferred in binary mode. + * Now decrypt the key blob. */ + memset(iv, 0, sizeof(iv)); + des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, + cipherlen); + + memset(&md5c, 0, sizeof(md5c)); + memset(keybuf, 0, sizeof(keybuf)); + } + + /* + * And save it. We'll use Unix line endings just in case it's + * subsequently transferred in binary mode. + */ fp = fopen(filename, "wb"); /* ensure Unix line endings */ - if (!fp) - goto error; - fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); - fprintf(fp, "Comment: \""); - /* - * Comment header is broken with backslash-newline if it goes - * over 70 chars. Although it's surrounded by quotes, it - * _doesn't_ escape backslashes or quotes within the string. - * Don't ask me, I didn't design it. - */ - { - int slen = 60; /* starts at 60 due to "Comment: " */ - char *c = key->comment; - while ((int)strlen(c) > slen) { - fprintf(fp, "%.*s\\\n", slen, c); - c += slen; - slen = 70; /* allow 70 chars on subsequent lines */ - } - fprintf(fp, "%s\"\n", c); - } + if (!fp) + goto error; + fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); + fprintf(fp, "Comment: \""); + /* + * Comment header is broken with backslash-newline if it goes + * over 70 chars. Although it's surrounded by quotes, it + * _doesn't_ escape backslashes or quotes within the string. + * Don't ask me, I didn't design it. + */ + { + int slen = 60; /* starts at 60 due to "Comment: " */ + char *c = key->comment; + while ((int)strlen(c) > slen) { + fprintf(fp, "%.*s\\\n", slen, c); + c += slen; + slen = 70; /* allow 70 chars on subsequent lines */ + } + fprintf(fp, "%s\"\n", c); + } base64_encode_fp(fp, outblob, pos, 70); - fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); - fclose(fp); - ret = 1; + fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); + fclose(fp); + ret = 1; - error: - if (outblob) { - memset(outblob, 0, outlen); + error: + if (outblob) { + memset(outblob, 0, outlen); m_free(outblob); - } - if (privblob) { - memset(privblob, 0, privlen); + } + if (privblob) { + memset(privblob, 0, privlen); m_free(privblob); - } - if (pubblob) { - memset(pubblob, 0, publen); + } + if (pubblob) { + memset(pubblob, 0, publen); m_free(pubblob); - } - return ret; + } + return ret; } #endif /* ssh.com stuff disabled */ + +/* From PuTTY misc.c */ +static int toint(unsigned u) +{ + /* + * Convert an unsigned to an int, without running into the + * undefined behaviour which happens by the strict C standard if + * the value overflows. You'd hope that sensible compilers would + * do the sensible thing in response to a cast, but actually I + * don't trust modern compilers not to do silly things like + * assuming that _obviously_ you wouldn't have caused an overflow + * and so they can elide an 'if (i < 0)' test immediately after + * the cast. + * + * Sensible compilers ought of course to optimise this entire + * function into 'just return the input value'! + */ + if (u <= (unsigned)INT_MAX) + return (int)u; + else if (u >= (unsigned)INT_MIN) /* wrap in cast _to_ unsigned is OK */ + return INT_MIN + (int)(u - (unsigned)INT_MIN); + else + return INT_MIN; /* fallback; should never occur on binary machines */ +} |