X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=crypt.c;h=f064fb3a535d9df3306818d7e9c27ca85193bd50;hp=99804470783c04e3758e8800f87f083c4e54f623;hb=4990334538fe7f18964a6027b22d47c7640c3ec0;hpb=e4db7671a91a7552c642acc979f0eb278f8d467f diff --git a/crypt.c b/crypt.c index 99804470..f064fb3a 100644 --- a/crypt.c +++ b/crypt.c @@ -7,35 +7,27 @@ /** \file crypt.c Openssl-based encryption/decryption routines. */ #include -#include +#include #include #include #include #include #include #include +#include +#include #include "para.h" #include "error.h" #include "string.h" #include "crypt.h" #include "fd.h" +#include "crypt_backend.h" struct asymmetric_key { RSA *rsa; }; -/** - * Fill a buffer with random content. - * - * \param buf The buffer to fill. - * \param num The size of \a buf in bytes. - * - * This function puts \a num cryptographically strong pseudo-random bytes into - * buf. If libssl can not guarantee an unpredictable byte sequence (for example - * because the PRNG has not been seeded with enough randomness) the function - * logs an error message and calls exit(). - */ void get_random_bytes_or_die(unsigned char *buf, int num) { unsigned long err; @@ -48,13 +40,10 @@ void get_random_bytes_or_die(unsigned char *buf, int num) exit(EXIT_FAILURE); } -/** - * Seed pseudo random number generators. - * - * This function reads 64 bytes from /dev/urandom and adds them to the SSL - * PRNG. It also seeds the PRNG used by random() with a random seed obtained - * from SSL. If /dev/random could not be read, an error message is logged and - * the function calls exit(). +/* + * Read 64 bytes from /dev/urandom and adds them to the SSL PRNG. Seed the PRNG + * used by random() with a random seed obtained from SSL. If /dev/random is not + * readable the function calls exit(). * * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3), * random(3), \ref para_random(). @@ -71,19 +60,6 @@ void init_random_seed_or_die(void) srandom(seed); } -static int check_key_file(const char *file, int private) -{ - struct stat st; - - if (stat(file, &st) != 0) - return -ERRNO_TO_PARA_ERROR(errno); - if (private != LOAD_PRIVATE_KEY) - return 0; - if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) - return -E_KEY_PERM; - return 1; -} - static EVP_PKEY *load_key(const char *file, int private) { BIO *key; @@ -107,44 +83,135 @@ static EVP_PKEY *load_key(const char *file, int private) return pkey; } -/** - * Read an asymmetric key from a file. - * - * \param key_file The file containing the key. - * \param private if non-zero, read the private key, otherwise the public key. - * \param result The key structure is returned here. - * - * \return The size of the key on success, negative on errors. - * - * \sa openssl(1), rsa(1). - */ -int get_asymmetric_key(const char *key_file, int private, - struct asymmetric_key **result) +static int get_openssl_key(const char *key_file, RSA **rsa, int private) { - struct asymmetric_key *key; - RSA *rsa; - EVP_PKEY *pkey = load_key(key_file, private); + EVP_PKEY *key = load_key(key_file, private); - if (!pkey) + if (!key) return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY : -E_PUBLIC_KEY; - rsa = EVP_PKEY_get1_RSA(pkey); - EVP_PKEY_free(pkey); - if (!rsa) + *rsa = EVP_PKEY_get1_RSA(key); + EVP_PKEY_free(key); + if (!*rsa) return -E_RSA; - key = para_malloc(sizeof(*key)); - key->rsa = rsa; - *result = key; - return RSA_size(rsa); + return RSA_size(*rsa); } -/** - * Deallocate an asymmetric key structure. - * - * \param key Pointer to the key structure to free. - * - * This must be called for any key obtained by get_asymmetric_key(). +/* + * The public key loading functions below were inspired by corresponding code + * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen , Espoo, + * Finland. However, not much of the original code remains. */ + +static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result) +{ + const unsigned char *p = buf, *end = buf + len; + uint32_t bnsize; + BIGNUM *bn; + + if (p + 4 < p) + return -E_BIGNUM; + if (p + 4 > end) + return -E_BIGNUM; + bnsize = read_ssh_u32(p); + PARA_DEBUG_LOG("bnsize: %u\n", bnsize); + p += 4; + if (p + bnsize < p) + return -E_BIGNUM; + if (p + bnsize > end) + return -E_BIGNUM; + if (bnsize > 8192) + return -E_BIGNUM; + bn = BN_bin2bn(p, bnsize, NULL); + if (!bn) + return -E_BIGNUM; + *result = bn; + return bnsize + 4; +} + +static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result) +{ + int ret; + RSA *rsa; + const unsigned char *p = blob, *end = blob + blen; + + rsa = RSA_new(); + if (!rsa) + return -E_BIGNUM; + ret = read_bignum(p, end - p, &rsa->e); + if (ret < 0) + goto fail; + p += ret; + ret = read_bignum(p, end - p, &rsa->n); + if (ret < 0) + goto fail; + *result = rsa; + return 1; +fail: + if (rsa) + RSA_free(rsa); + return ret; +} + +int get_asymmetric_key(const char *key_file, int private, + struct asymmetric_key **result) +{ + struct asymmetric_key *key = NULL; + void *map = NULL; + unsigned char *blob = NULL; + size_t map_size, blob_size, decoded_size; + int ret, ret2; + char *cp; + + key = para_malloc(sizeof(*key)); + if (private) { + ret = get_openssl_key(key_file, &key->rsa, LOAD_PRIVATE_KEY); + goto out; + } + ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL); + if (ret < 0) + goto out; + ret = is_ssh_rsa_key(map, map_size); + if (!ret) { + ret = para_munmap(map, map_size); + map = NULL; + if (ret < 0) + goto out; + ret = get_openssl_key(key_file, &key->rsa, LOAD_PUBLIC_KEY); + goto out; + } + cp = map + ret; + PARA_INFO_LOG("decoding public rsa-ssh key %s\n", key_file); + ret = -ERRNO_TO_PARA_ERROR(EOVERFLOW); + if (map_size > INT_MAX / 4) + goto out; + blob_size = 2 * map_size; + blob = para_malloc(blob_size); + ret = uudecode(cp, blob, blob_size); + if (ret < 0) + goto out; + decoded_size = ret; + ret = check_ssh_key_header(blob, decoded_size); + if (ret < 0) + goto out; + ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa); + if (ret < 0) + goto out; + ret = RSA_size(key->rsa); +out: + ret2 = para_munmap(map, map_size); + if (ret >= 0 && ret2 < 0) + ret = ret2; + if (ret < 0) { + free(key); + result = NULL; + PARA_ERROR_LOG("key %s: %s\n", key_file, para_strerror(-ret)); + } else + *result = key; + free(blob); + return ret; +} + void free_asymmetric_key(struct asymmetric_key *key) { if (!key) @@ -153,20 +220,6 @@ void free_asymmetric_key(struct asymmetric_key *key) free(key); } -/** - * Decrypt a buffer using a private key. - * - * \param key_file Full path of the key. - * \param outbuf The output buffer. - * \param inbuf The encrypted input buffer. - * \param inlen The length of \a inbuf in bytes. - * - * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes. - * - * \return The size of the recovered plaintext on success, negative on errors. - * - * \sa RSA_private_decrypt(3) - **/ int priv_decrypt(const char *key_file, unsigned char *outbuf, unsigned char *inbuf, int inlen) { @@ -195,18 +248,6 @@ out: return ret; } -/** - * Encrypt a buffer using an RSA key - * - * \param pub: The public key. - * \param inbuf The input buffer. - * \param len The length of \a inbuf. - * \param outbuf The output buffer. - * - * \return The size of the encrypted data on success, negative on errors. - * - * \sa RSA_public_encrypt(3) - */ int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf, unsigned len, unsigned char *outbuf) { @@ -219,19 +260,10 @@ int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf, return ret < 0? -E_ENCRYPT : ret; } -#define RC4_ALIGN 8 struct stream_cipher { RC4_KEY key; }; -/** - * Allocate and initialize a stream cipher structure. - * - * \param data The key. - * \param len The size of the key. - * - * \return A new stream cipher structure. - */ struct stream_cipher *sc_new(const unsigned char *data, int len) { struct stream_cipher *sc = para_malloc(sizeof(*sc)); @@ -239,28 +271,19 @@ struct stream_cipher *sc_new(const unsigned char *data, int len) return sc; } -/** - * Deallocate a stream cipher structure. - * - * \param sc A stream cipher previously obtained by sc_new(). - */ void sc_free(struct stream_cipher *sc) { free(sc); } /** - * Encrypt and send a buffer. - * - * \param scc The context. - * \param buf The buffer to send. - * \param len The size of \a buf in bytes. - * - * \return The return value of the underyling call to write_all(). - * - * \sa \ref write_all(), RC4(3). + * The RC4() implementation of openssl apparently reads and writes data in + * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple + * of this. */ -int sc_send_bin_buffer(struct stream_cipher_context *scc, const char *buf, +#define RC4_ALIGN 8 + +int sc_send_bin_buffer(struct stream_cipher_context *scc, char *buf, size_t len) { int ret; @@ -280,51 +303,6 @@ int sc_send_bin_buffer(struct stream_cipher_context *scc, const char *buf, return ret; } -/** - * Encrypt and send a \p NULL-terminated buffer. - * - * \param scc The context. - * \param buf The buffer to send. - * - * \return The return value of the underyling call to sc_send_bin_buffer(). - */ -int sc_send_buffer(struct stream_cipher_context *scc, const char *buf) -{ - return sc_send_bin_buffer(scc, buf, strlen(buf)); -} - -/** - * Format, encrypt and send a buffer. - * - * \param scc The context. - * \param fmt A format string. - * - * \return The return value of the underyling call to sc_send_buffer(). - */ -__printf_2_3 int sc_send_va_buffer(struct stream_cipher_context *scc, - const char *fmt, ...) -{ - char *msg; - int ret; - - PARA_VSPRINTF(fmt, msg); - ret = sc_send_buffer(scc, msg); - free(msg); - return ret; -} - -/** - * Receive a buffer and decrypt it. - * - * \param scc The context. - * \param buf The buffer to write the decrypted data to. - * \param size The size of \a buf. - * - * \return The number of bytes received on success, negative on errors, zero if - * the peer has performed an orderly shutdown. - * - * \sa recv(2), RC4(3). - */ int sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf, size_t size) { @@ -339,28 +317,10 @@ int sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf, return ret; } -/** - * Receive a buffer, decrypt it and write terminating NULL byte. - * - * \param scc The context. - * \param buf The buffer to write the decrypted data to. - * \param size The size of \a buf. - * - * Read at most \a size - 1 bytes from file descriptor given by \a scc, decrypt - * the received data and write a NULL byte at the end of the decrypted data. - * - * \return The return value of the underlying call to \ref - * sc_recv_bin_buffer(). - */ -int sc_recv_buffer(struct stream_cipher_context *scc, char *buf, size_t size) +void hash_function(const char *data, unsigned long len, unsigned char *hash) { - int n; - - assert(size); - n = sc_recv_bin_buffer(scc, buf, size - 1); - if (n >= 0) - buf[n] = '\0'; - else - *buf = '\0'; - return n; + SHA_CTX c; + SHA1_Init(&c); + SHA1_Update(&c, data, len); + SHA1_Final(hash, &c); }