diff options
Diffstat (limited to 'src/openvpn/crypto_mbedtls.c')
| -rw-r--r-- | src/openvpn/crypto_mbedtls.c | 173 |
1 files changed, 129 insertions, 44 deletions
diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c index 748043e..fbb1f12 100644 --- a/src/openvpn/crypto_mbedtls.c +++ b/src/openvpn/crypto_mbedtls.c @@ -34,21 +34,24 @@ #include "syshead.h" -#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS) +#if defined(ENABLE_CRYPTO_MBEDTLS) #include "errlevel.h" #include "basic.h" #include "buffer.h" +#include "crypto.h" #include "integer.h" #include "crypto_backend.h" #include "otime.h" #include "misc.h" +#include <mbedtls/base64.h> #include <mbedtls/des.h> #include <mbedtls/error.h> #include <mbedtls/md5.h> #include <mbedtls/cipher.h> #include <mbedtls/havege.h> +#include <mbedtls/pem.h> #include <mbedtls/entropy.h> @@ -138,26 +141,6 @@ const cipher_name_pair cipher_name_translation_table[] = { const size_t cipher_name_translation_table_count = sizeof(cipher_name_translation_table) / sizeof(*cipher_name_translation_table); -static void -print_cipher(const cipher_kt_t *info) -{ - if (info && (cipher_kt_mode_cbc(info) -#ifdef HAVE_AEAD_CIPHER_MODES - || cipher_kt_mode_aead(info) -#endif - )) - { - const char *ssl_only = cipher_kt_mode_cbc(info) ? - "" : ", TLS client/server mode only"; - const char *var_key_size = info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN ? - " by default" : ""; - - printf("%s (%d bit key%s, %d bit block%s)\n", - cipher_kt_name(info), cipher_kt_key_size(info) * 8, var_key_size, - cipher_kt_block_size(info) * 8, ssl_only); - } -} - void show_available_ciphers(void) { @@ -166,14 +149,16 @@ show_available_ciphers(void) #ifndef ENABLE_SMALL printf("The following ciphers and cipher modes are available for use\n" "with " PACKAGE_NAME ". Each cipher shown below may be used as a\n" - "parameter to the --cipher option. Using a CBC or GCM mode is\n" - "recommended. In static key mode only CBC mode is allowed.\n\n"); + "parameter to the --data-ciphers (or --cipher) option. Using a\n" + "GCM or CBC mode is recommended. In static key mode only CBC\n" + "mode is allowed.\n\n"); #endif while (*ciphers != 0) { const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers); - if (info && cipher_kt_block_size(info) >= 128/8) + if (info && !cipher_kt_insecure(info) + && (cipher_kt_mode_aead(info) || cipher_kt_mode_cbc(info))) { print_cipher(info); } @@ -186,7 +171,8 @@ show_available_ciphers(void) while (*ciphers != 0) { const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers); - if (info && cipher_kt_block_size(info) < 128/8) + if (info && cipher_kt_insecure(info) + && (cipher_kt_mode_aead(info) || cipher_kt_mode_cbc(info))) { print_cipher(info); } @@ -229,6 +215,84 @@ show_available_engines(void) "available\n"); } +bool +crypto_pem_encode(const char *name, struct buffer *dst, + const struct buffer *src, struct gc_arena *gc) +{ + /* 1000 chars is the PEM line length limit (+1 for tailing NUL) */ + char header[1000+1] = { 0 }; + char footer[1000+1] = { 0 }; + + if (!openvpn_snprintf(header, sizeof(header), "-----BEGIN %s-----\n", name)) + { + return false; + } + if (!openvpn_snprintf(footer, sizeof(footer), "-----END %s-----\n", name)) + { + return false; + } + + size_t out_len = 0; + if (MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL != + mbedtls_pem_write_buffer(header, footer, BPTR(src), BLEN(src), + NULL, 0, &out_len)) + { + return false; + } + + /* We set the size buf to out_len-1 to NOT include the 0 byte that + * mbedtls_pem_write_buffer in its length calculation */ + *dst = alloc_buf_gc(out_len, gc); + if (!mbed_ok(mbedtls_pem_write_buffer(header, footer, BPTR(src), BLEN(src), + BPTR(dst), BCAP(dst), &out_len)) + || !buf_inc_len(dst, out_len-1)) + { + CLEAR(*dst); + return false; + } + + return true; +} + +bool +crypto_pem_decode(const char *name, struct buffer *dst, + const struct buffer *src) +{ + /* 1000 chars is the PEM line length limit (+1 for tailing NUL) */ + char header[1000+1] = { 0 }; + char footer[1000+1] = { 0 }; + + if (!openvpn_snprintf(header, sizeof(header), "-----BEGIN %s-----", name)) + { + return false; + } + if (!openvpn_snprintf(footer, sizeof(footer), "-----END %s-----", name)) + { + return false; + } + + /* mbed TLS requires the src to be null-terminated */ + /* allocate a new buffer to avoid modifying the src buffer */ + struct gc_arena gc = gc_new(); + struct buffer input = alloc_buf_gc(BLEN(src) + 1, &gc); + buf_copy(&input, src); + buf_null_terminate(&input); + + size_t use_len = 0; + mbedtls_pem_context ctx = { 0 }; + bool ret = mbed_ok(mbedtls_pem_read_buffer(&ctx, header, footer, BPTR(&input), + NULL, 0, &use_len)); + if (ret && !buf_write(dst, ctx.buf, ctx.buflen)) + { + ret = false; + msg(M_WARN, "PEM decode error: destination buffer too small"); + } + + mbedtls_pem_free(&ctx); + gc_free(&gc); + return ret; +} + /* * * Random number functions, used in cases where we want @@ -402,6 +466,7 @@ cipher_kt_get(const char *ciphername) ASSERT(ciphername); + ciphername = translate_cipher_name_from_openvpn(ciphername); cipher = mbedtls_cipher_info_from_string(ciphername); if (NULL == cipher) @@ -466,15 +531,23 @@ cipher_kt_block_size(const mbedtls_cipher_info_t *cipher_kt) int cipher_kt_tag_size(const mbedtls_cipher_info_t *cipher_kt) { -#ifdef HAVE_AEAD_CIPHER_MODES if (cipher_kt && cipher_kt_mode_aead(cipher_kt)) { return OPENVPN_AEAD_TAG_LENGTH; } -#endif return 0; } +bool +cipher_kt_insecure(const mbedtls_cipher_info_t *cipher_kt) +{ + return !(cipher_kt_block_size(cipher_kt) >= 128 / 8 +#ifdef MBEDTLS_CHACHAPOLY_C + || cipher_kt->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 +#endif + ); +} + int cipher_kt_mode(const mbedtls_cipher_info_t *cipher_kt) { @@ -498,7 +571,11 @@ cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher) bool cipher_kt_mode_aead(const cipher_kt_t *cipher) { - return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_GCM; + return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_GCM +#ifdef MBEDTLS_CHACHAPOLY_C + || cipher_kt_mode(cipher) == MBEDTLS_MODE_CHACHAPOLY +#endif + ); } @@ -554,7 +631,6 @@ cipher_ctx_iv_length(const mbedtls_cipher_context_t *ctx) int cipher_ctx_get_tag(cipher_ctx_t *ctx, uint8_t *tag, int tag_len) { -#ifdef HAVE_AEAD_CIPHER_MODES if (tag_len > SIZE_MAX) { return 0; @@ -566,9 +642,6 @@ cipher_ctx_get_tag(cipher_ctx_t *ctx, uint8_t *tag, int tag_len) } return 1; -#else /* ifdef HAVE_AEAD_CIPHER_MODES */ - ASSERT(0); -#endif /* HAVE_AEAD_CIPHER_MODES */ } int @@ -592,7 +665,7 @@ cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx) } int -cipher_ctx_reset(mbedtls_cipher_context_t *ctx, uint8_t *iv_buf) +cipher_ctx_reset(mbedtls_cipher_context_t *ctx, const uint8_t *iv_buf) { if (!mbed_ok(mbedtls_cipher_reset(ctx))) { @@ -610,7 +683,6 @@ cipher_ctx_reset(mbedtls_cipher_context_t *ctx, uint8_t *iv_buf) int cipher_ctx_update_ad(cipher_ctx_t *ctx, const uint8_t *src, int src_len) { -#ifdef HAVE_AEAD_CIPHER_MODES if (src_len > SIZE_MAX) { return 0; @@ -622,9 +694,6 @@ cipher_ctx_update_ad(cipher_ctx_t *ctx, const uint8_t *src, int src_len) } return 1; -#else /* ifdef HAVE_AEAD_CIPHER_MODES */ - ASSERT(0); -#endif /* HAVE_AEAD_CIPHER_MODES */ } int @@ -663,7 +732,6 @@ int cipher_ctx_final_check_tag(mbedtls_cipher_context_t *ctx, uint8_t *dst, int *dst_len, uint8_t *tag, size_t tag_len) { -#ifdef HAVE_AEAD_CIPHER_MODES size_t olen = 0; if (MBEDTLS_DECRYPT != ctx->operation) @@ -695,9 +763,6 @@ cipher_ctx_final_check_tag(mbedtls_cipher_context_t *ctx, uint8_t *dst, } return 1; -#else /* ifdef HAVE_AEAD_CIPHER_MODES */ - ASSERT(0); -#endif /* HAVE_AEAD_CIPHER_MODES */ } void @@ -751,7 +816,7 @@ md_kt_name(const mbedtls_md_info_t *kt) return mbedtls_md_get_name(kt); } -int +unsigned char md_kt_size(const mbedtls_md_info_t *kt) { if (NULL == kt) @@ -781,7 +846,8 @@ md_ctx_new(void) return ctx; } -void md_ctx_free(mbedtls_md_context_t *ctx) +void +md_ctx_free(mbedtls_md_context_t *ctx) { free(ctx); } @@ -899,4 +965,23 @@ hmac_ctx_final(mbedtls_md_context_t *ctx, uint8_t *dst) ASSERT(0 == mbedtls_md_hmac_finish(ctx, dst)); } -#endif /* ENABLE_CRYPTO && ENABLE_CRYPTO_MBEDTLS */ +int +memcmp_constant_time(const void *a, const void *b, size_t size) +{ + /* mbed TLS has a no const time memcmp function that it exposes + * via its APIs like OpenSSL does with CRYPTO_memcmp + * Adapt the function that mbedtls itself uses in + * mbedtls_safer_memcmp as it considers that to be safe */ + volatile const unsigned char *A = (volatile const unsigned char *) a; + volatile const unsigned char *B = (volatile const unsigned char *) b; + volatile unsigned char diff = 0; + + for (size_t i = 0; i < size; i++) + { + unsigned char x = A[i], y = B[i]; + diff |= x ^ y; + } + + return diff; +} +#endif /* ENABLE_CRYPTO_MBEDTLS */ |