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mbedtls: add GCM support #1764
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bfd3604
Add GCM support on mbedTLS.
AdrianMoranMontes 8b762ac
Fix style.
AdrianMoranMontes a73236d
drop redundant parenthesis
vszakats 5365298
Rebase fix-mbedtls-gcm branch with upstream master branch.
AdrianMoranMontes 7ca9ff5
Fix parameters naming.
AdrianMoranMontes dd764a4
Try to avoid different parameter names
AdrianMoranMontes 14bf697
mbedtls: use _libssh2_timingsafe_bcmp for GCM tag verification
AdrianMoranMontes e79e57f
mbedtls: replace typedef struct with named struct
AdrianMoranMontes 7aeabcb
mbedtls: fix LONGLINE in cipher_dtor
AdrianMoranMontes f5f5a04
use safe_free for GCM temporary buffer
AdrianMoranMontes bdb48a9
mbedtls: redefine _libssh2_cipher_ctx as pointer, remove UB casts
AdrianMoranMontes b8aea89
mbedtls: enable AES-GCM support
AdrianMoranMontes 99479d2
mbedtls: nullify context pointer in cipher_dtor to prevent double-free
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -109,45 +109,108 @@ _libssh2_mbedtls_cipher_init(_libssh2_cipher_ctx *h, | |
| unsigned char *secret, | ||
| int encrypt) | ||
| { | ||
| const mbedtls_cipher_info_t *cipher_info; | ||
| int ret, op; | ||
| struct _libssh2_mbedtls_cipher_ctx *cctx; | ||
| int ret; | ||
|
|
||
| if(!h) | ||
| return -1; | ||
|
|
||
| op = encrypt ? MBEDTLS_ENCRYPT : MBEDTLS_DECRYPT; | ||
|
|
||
| cipher_info = mbedtls_cipher_info_from_type(algo); | ||
| if(!cipher_info) | ||
| /* Allocate unified context structure */ | ||
| cctx = (struct _libssh2_mbedtls_cipher_ctx *) | ||
| mbedtls_calloc(1, sizeof(struct _libssh2_mbedtls_cipher_ctx)); | ||
| if(!cctx) | ||
| return -1; | ||
|
|
||
| mbedtls_cipher_init(h); | ||
| ret = mbedtls_cipher_setup(h, cipher_info); | ||
|
|
||
| /* libssh2 computes and adds SSH packet padding itself, so for CBC | ||
| * tell mbedTLS to expect no padding on the cipher layer. Only call | ||
| * set_padding_mode for CBC ciphers since other modes (CTR, stream) | ||
| * are not applicable and will cause an error. */ | ||
| if(!ret) { | ||
| if(algo == MBEDTLS_CIPHER_AES_128_CBC || | ||
| algo == MBEDTLS_CIPHER_AES_192_CBC || | ||
| algo == MBEDTLS_CIPHER_AES_256_CBC || | ||
| algo == MBEDTLS_CIPHER_DES_EDE3_CBC) { | ||
| ret = mbedtls_cipher_set_padding_mode(h, MBEDTLS_PADDING_NONE); | ||
| /* Store algorithm type and encryption flag */ | ||
| cctx->algo = algo; | ||
| cctx->encrypt = encrypt; | ||
|
|
||
| #if LIBSSH2_AES_GCM | ||
| /* Check if this is a GCM algorithm */ | ||
| if(algo == MBEDTLS_CIPHER_AES_128_GCM || | ||
| algo == MBEDTLS_CIPHER_AES_256_GCM) { | ||
| unsigned int keybits; | ||
|
|
||
| /* Store the initial IV (will be incremented per packet) */ | ||
| memcpy(cctx->ctx.gcm.iv, iv, 12); | ||
|
|
||
| /* Initialize GCM context */ | ||
| mbedtls_gcm_init(&cctx->ctx.gcm.gcm_ctx); | ||
|
|
||
| /* Set key length based on algorithm */ | ||
| if(algo == MBEDTLS_CIPHER_AES_128_GCM) | ||
| keybits = 128; | ||
| else /* MBEDTLS_CIPHER_AES_256_GCM */ | ||
| keybits = 256; | ||
|
|
||
| /* Setup GCM with AES cipher and key */ | ||
| ret = mbedtls_gcm_setkey(&cctx->ctx.gcm.gcm_ctx, | ||
| MBEDTLS_CIPHER_ID_AES, | ||
| secret, | ||
| keybits); | ||
|
|
||
| if(ret) { | ||
| mbedtls_gcm_free(&cctx->ctx.gcm.gcm_ctx); | ||
| mbedtls_free(cctx); | ||
| return -1; | ||
| } | ||
|
|
||
| /* Store the context pointer */ | ||
| *h = cctx; | ||
| return 0; | ||
| } | ||
| #endif | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_setkey(h, | ||
| secret, | ||
| (int)mbedtls_cipher_info_get_key_bitlen(cipher_info), | ||
| op); | ||
| /* Non-GCM algorithms: use standard cipher API */ | ||
| { | ||
| const mbedtls_cipher_info_t *cipher_info; | ||
| int op; | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_set_iv(h, iv, | ||
| mbedtls_cipher_info_get_iv_size(cipher_info)); | ||
| op = encrypt ? MBEDTLS_ENCRYPT : MBEDTLS_DECRYPT; | ||
|
|
||
| return ret == 0 ? 0 : -1; | ||
| cipher_info = mbedtls_cipher_info_from_type(algo); | ||
| if(!cipher_info) { | ||
| mbedtls_free(cctx); | ||
| return -1; | ||
| } | ||
|
|
||
| mbedtls_cipher_init(&cctx->ctx.cipher_ctx); | ||
| ret = mbedtls_cipher_setup(&cctx->ctx.cipher_ctx, cipher_info); | ||
|
|
||
| /* libssh2 computes and adds SSH packet padding itself, so for CBC | ||
| * tell mbedTLS to expect no padding on the cipher layer. Only call | ||
| * set_padding_mode for CBC ciphers since other modes (CTR, stream) | ||
| * are not applicable and will cause an error. */ | ||
| if(!ret) { | ||
| if(algo == MBEDTLS_CIPHER_AES_128_CBC || | ||
| algo == MBEDTLS_CIPHER_AES_192_CBC || | ||
| algo == MBEDTLS_CIPHER_AES_256_CBC || | ||
| algo == MBEDTLS_CIPHER_DES_EDE3_CBC) { | ||
| ret = mbedtls_cipher_set_padding_mode(&cctx->ctx.cipher_ctx, | ||
| MBEDTLS_PADDING_NONE); | ||
| } | ||
| } | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_setkey(&cctx->ctx.cipher_ctx, | ||
| secret, | ||
| (int)mbedtls_cipher_info_get_key_bitlen(cipher_info), | ||
| op); | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_set_iv(&cctx->ctx.cipher_ctx, iv, | ||
| mbedtls_cipher_info_get_iv_size(cipher_info)); | ||
|
|
||
| if(ret) { | ||
| mbedtls_cipher_free(&cctx->ctx.cipher_ctx); | ||
| mbedtls_free(cctx); | ||
| return -1; | ||
| } | ||
|
|
||
| /* Store the context pointer */ | ||
| *h = cctx; | ||
| return 0; | ||
| } | ||
| } | ||
|
|
||
| int | ||
|
|
@@ -157,43 +220,160 @@ _libssh2_mbedtls_cipher_crypt(_libssh2_cipher_ctx *ctx, | |
| unsigned char *block, | ||
| size_t blocksize, int firstlast) | ||
| { | ||
| struct _libssh2_mbedtls_cipher_ctx *cctx; | ||
| int ret; | ||
| unsigned char *output; | ||
| size_t osize, olen, finish_olen; | ||
|
|
||
| (void)encrypt; | ||
| cctx = *ctx; | ||
| if(!cctx) | ||
| return -1; | ||
|
|
||
| (void)algo; | ||
| (void)firstlast; | ||
| (void)encrypt; | ||
|
|
||
| osize = blocksize + mbedtls_cipher_get_block_size(ctx); | ||
| #if LIBSSH2_AES_GCM | ||
| /* Check if this is a GCM algorithm based on stored algo type */ | ||
| if(cctx->algo == MBEDTLS_CIPHER_AES_128_GCM || | ||
| cctx->algo == MBEDTLS_CIPHER_AES_256_GCM) { | ||
| const int authlen = 16; /* GCM authentication tag length */ | ||
| const int aadlen = IS_FIRST(firstlast) ? 4 : 0; | ||
| const int authenticationtag = IS_LAST(firstlast) ? authlen : 0; | ||
| const int cryptlen = (int)blocksize - aadlen - authenticationtag; | ||
| unsigned char tag[16]; | ||
| unsigned char *buf = NULL; | ||
|
|
||
| /* Allocate temporary buffer for output */ | ||
| if(cryptlen > 0) { | ||
| buf = (unsigned char *)mbedtls_calloc(cryptlen, 1); | ||
| if(!buf) | ||
| return -1; | ||
| } | ||
|
Comment on lines
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+249
|
||
|
|
||
| output = (unsigned char *)mbedtls_calloc(osize, sizeof(char)); | ||
| if(output) { | ||
| ret = mbedtls_cipher_reset(ctx); | ||
| /* First block: start GCM operation */ | ||
| if(IS_FIRST(firstlast)) { | ||
| ret = mbedtls_gcm_starts(&cctx->ctx.gcm.gcm_ctx, | ||
| cctx->encrypt ? MBEDTLS_GCM_ENCRYPT : | ||
| MBEDTLS_GCM_DECRYPT, | ||
| cctx->ctx.gcm.iv, 12); | ||
| if(ret) { | ||
| _libssh2_mbedtls_safe_free(buf, cryptlen); | ||
| return -1; | ||
| } | ||
|
|
||
| /* Process AAD (Additional Authenticated Data) */ | ||
| if(aadlen) { | ||
| ret = mbedtls_gcm_update_ad(&cctx->ctx.gcm.gcm_ctx, | ||
| block, aadlen); | ||
| if(ret) { | ||
| _libssh2_mbedtls_safe_free(buf, cryptlen); | ||
| return -1; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_update(ctx, block, blocksize, output, &olen); | ||
| /* Process payload */ | ||
| if(cryptlen > 0) { | ||
| size_t olen = 0; | ||
| ret = mbedtls_gcm_update(&cctx->ctx.gcm.gcm_ctx, | ||
| block + aadlen, cryptlen, | ||
| buf, cryptlen, &olen); | ||
| if(ret) { | ||
| _libssh2_mbedtls_safe_free(buf, cryptlen); | ||
| return -1; | ||
| } | ||
| memcpy(block + aadlen, buf, olen); | ||
| _libssh2_mbedtls_safe_free(buf, cryptlen); | ||
| } | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_finish(ctx, output + olen, &finish_olen); | ||
| /* Last block: finalize and handle authentication tag */ | ||
| if(IS_LAST(firstlast)) { | ||
| size_t olen_finish = 0; | ||
| unsigned char finish_buf[16]; | ||
| int i; | ||
|
|
||
| if(!ret) { | ||
| olen += finish_olen; | ||
| memcpy(block, output, olen); | ||
| ret = mbedtls_gcm_finish(&cctx->ctx.gcm.gcm_ctx, | ||
| finish_buf, sizeof(finish_buf), | ||
| &olen_finish, tag, authlen); | ||
| if(ret) | ||
| return -1; | ||
|
|
||
| if(cctx->encrypt) { | ||
| memcpy(block + blocksize - authlen, tag, authlen); | ||
| } | ||
| else { | ||
| if(_libssh2_timingsafe_bcmp(tag, block + blocksize - authlen, | ||
| authlen) != 0) | ||
| return MBEDTLS_ERR_GCM_AUTH_FAILED; | ||
| } | ||
|
|
||
| /* Increment IV for next packet */ | ||
| for(i = 11; i >= 4; i--) { | ||
| if(++cctx->ctx.gcm.iv[i]) | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| _libssh2_mbedtls_safe_free(output, osize); | ||
| return 0; | ||
| } | ||
| else | ||
| ret = -1; | ||
| #endif | ||
|
|
||
| return ret == 0 ? 0 : -1; | ||
| /* Non-GCM algorithms: use standard cipher API */ | ||
| { | ||
| unsigned char *output; | ||
| size_t osize, olen, finish_olen; | ||
|
|
||
| (void)firstlast; | ||
|
|
||
| osize = blocksize + | ||
| mbedtls_cipher_get_block_size(&cctx->ctx.cipher_ctx); | ||
|
|
||
| output = (unsigned char *)mbedtls_calloc(osize, sizeof(char)); | ||
| if(output) { | ||
| ret = mbedtls_cipher_reset(&cctx->ctx.cipher_ctx); | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_update(&cctx->ctx.cipher_ctx, block, | ||
| blocksize, output, &olen); | ||
|
|
||
| if(!ret) | ||
| ret = mbedtls_cipher_finish(&cctx->ctx.cipher_ctx, | ||
| output + olen, &finish_olen); | ||
|
|
||
| if(!ret) { | ||
| olen += finish_olen; | ||
| memcpy(block, output, olen); | ||
| } | ||
|
|
||
| _libssh2_mbedtls_safe_free(output, osize); | ||
| } | ||
| else | ||
| ret = -1; | ||
|
|
||
| return ret == 0 ? 0 : -1; | ||
| } | ||
| } | ||
|
|
||
| void | ||
| _libssh2_mbedtls_cipher_dtor(_libssh2_cipher_ctx *ctx) | ||
| { | ||
| mbedtls_cipher_free(ctx); | ||
| struct _libssh2_mbedtls_cipher_ctx *cctx = *ctx; | ||
|
|
||
| if(!cctx) | ||
| return; | ||
|
|
||
| #if LIBSSH2_AES_GCM | ||
| if(cctx->algo == MBEDTLS_CIPHER_AES_128_GCM || | ||
| cctx->algo == MBEDTLS_CIPHER_AES_256_GCM) { | ||
| mbedtls_gcm_free(&cctx->ctx.gcm.gcm_ctx); | ||
| mbedtls_free(cctx); | ||
| *ctx = NULL; | ||
| return; | ||
| } | ||
| #endif | ||
|
|
||
| /* Regular cipher context */ | ||
| mbedtls_cipher_free(&cctx->ctx.cipher_ctx); | ||
| mbedtls_free(cctx); | ||
| *ctx = NULL; | ||
| } | ||
|
|
||
| int | ||
|
|
||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -47,6 +47,7 @@ | |
| #include <mbedtls/rsa.h> | ||
| #include <mbedtls/bignum.h> | ||
| #include <mbedtls/cipher.h> | ||
| #include <mbedtls/gcm.h> | ||
| #ifdef MBEDTLS_ECDH_C | ||
| # include <mbedtls/ecdh.h> | ||
| #endif | ||
|
|
@@ -67,7 +68,7 @@ | |
|
|
||
| #define LIBSSH2_AES_CBC 1 | ||
| #define LIBSSH2_AES_CTR 1 | ||
| #define LIBSSH2_AES_GCM 0 | ||
| #define LIBSSH2_AES_GCM 1 | ||
| #ifdef MBEDTLS_CIPHER_BLOWFISH_CBC | ||
| # define LIBSSH2_BLOWFISH 1 | ||
| #else | ||
|
|
@@ -337,7 +338,26 @@ typedef enum { | |
| * mbedTLS backend: Cipher Context structure | ||
| */ | ||
|
|
||
| #define _libssh2_cipher_ctx mbedtls_cipher_context_t | ||
| /* | ||
| * Unified cipher context structure. | ||
| * Handles both regular ciphers and AEAD ciphers (GCM) | ||
| * using a union to optimize memory usage. | ||
| */ | ||
| struct _libssh2_mbedtls_cipher_ctx { | ||
| mbedtls_cipher_type_t algo; | ||
| int encrypt; | ||
| union { | ||
| mbedtls_cipher_context_t cipher_ctx; | ||
| #if LIBSSH2_AES_GCM | ||
| struct { | ||
| mbedtls_gcm_context gcm_ctx; | ||
| unsigned char iv[12]; | ||
| } gcm; | ||
| #endif | ||
| } ctx; | ||
| }; | ||
|
|
||
| #define _libssh2_cipher_ctx struct _libssh2_mbedtls_cipher_ctx * | ||
|
|
||
| #define _libssh2_cipher_type(algo) mbedtls_cipher_type_t algo | ||
|
|
||
|
|
@@ -354,15 +374,17 @@ typedef enum { | |
| #define _libssh2_cipher_arcfour MBEDTLS_CIPHER_ARC4_128 | ||
| #endif | ||
| #define _libssh2_cipher_3des MBEDTLS_CIPHER_DES_EDE3_CBC | ||
| #define _libssh2_cipher_aes128gcm MBEDTLS_CIPHER_AES_128_GCM | ||
| #define _libssh2_cipher_aes256gcm MBEDTLS_CIPHER_AES_256_GCM | ||
| #define _libssh2_cipher_chacha20 MBEDTLS_CIPHER_CHACHA20_POLY1305 | ||
|
|
||
| /*******************************************************************/ | ||
| /* | ||
| * mbedTLS backend: Cipher functions | ||
| */ | ||
|
|
||
| #define _libssh2_cipher_init(ctx, type, iv, secret, encrypt) \ | ||
| _libssh2_mbedtls_cipher_init(ctx, type, iv, secret, encrypt) | ||
| #define _libssh2_cipher_init(h, type, iv, secret, encrypt) \ | ||
| _libssh2_mbedtls_cipher_init(h, type, iv, secret, encrypt) | ||
|
Comment on lines
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|
||
| #define _libssh2_cipher_crypt(ctx, type, encrypt, block, blocklen, fl) \ | ||
| _libssh2_mbedtls_cipher_crypt(ctx, type, encrypt, block, blocklen, fl) | ||
| #define _libssh2_cipher_dtor(ctx) \ | ||
|
|
||
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_libssh2_mbedtls_cipher_init()storescctxvia*(void **)h = cctx;, but in the mbedTLS backend_libssh2_cipher_ctxis defined asmbedtls_cipher_context_t(a struct), not a pointer type. This is undefined behavior (strict aliasing/alignment) and makes the_libssh2_cipher_ctxABI inconsistent. Fix by redefining_libssh2_cipher_ctxfor mbedTLS to be a pointer type (and updating init/crypt/dtor accordingly) or by embedding the unified context directly in_libssh2_cipher_ctx.