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https://github.com/yuzu-emu/mbedtls.git
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Merge pull request #810 from paul-elliott-arm/cf_base64_work_2_16
Backport 2.16: Constant Flow Base64 Table Access
This commit is contained in:
Manuel Pégourié-Gonnard
GitHub
commit
c785394ba6
4
ChangeLog.d/make_base64_table_access_constant_flow.txt
Normal file
4
ChangeLog.d/make_base64_table_access_constant_flow.txt
Normal file
@ -0,0 +1,4 @@
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Security
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* Guard against strong local side channel attack against base64 tables by
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making access aceess to them use constant flow code.
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131
library/base64.c
131
library/base64.c
@ -96,6 +96,99 @@ static const unsigned char base64_dec_map[128] =
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#define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */
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/*
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* Constant flow conditional assignment to unsigned char
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*/
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static void mbedtls_base64_cond_assign_uchar( unsigned char * dest, const unsigned char * const src,
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unsigned char condition )
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{
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/* MSVC has a warning about unary minus on unsigned integer types,
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* but this is well-defined and precisely what we want to do here. */
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#if defined(_MSC_VER)
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#pragma warning( push )
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#pragma warning( disable : 4146 )
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#endif
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/* Generate bitmask from condition, mask will either be 0xFF or 0 */
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unsigned char mask = ( condition | -condition );
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mask >>= 7;
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mask = -mask;
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#if defined(_MSC_VER)
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#pragma warning( pop )
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#endif
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*dest = ( ( *src ) & mask ) | ( ( *dest ) & ~mask );
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}
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/*
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* Constant flow conditional assignment to uint_32
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*/
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static void mbedtls_base64_cond_assign_uint32( uint32_t * dest, const uint32_t src,
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uint32_t condition )
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{
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/* MSVC has a warning about unary minus on unsigned integer types,
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* but this is well-defined and precisely what we want to do here. */
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#if defined(_MSC_VER)
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#pragma warning( push )
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#pragma warning( disable : 4146 )
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#endif
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/* Generate bitmask from condition, mask will either be 0xFFFFFFFF or 0 */
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uint32_t mask = ( condition | -condition );
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mask >>= 31;
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mask = -mask;
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#if defined(_MSC_VER)
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#pragma warning( pop )
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#endif
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*dest = ( src & mask ) | ( ( *dest ) & ~mask );
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}
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/*
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* Constant flow check for equality
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*/
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static unsigned char mbedtls_base64_eq( size_t in_a, size_t in_b )
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{
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size_t difference = in_a ^ in_b;
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/* MSVC has a warning about unary minus on unsigned integer types,
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* but this is well-defined and precisely what we want to do here. */
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#if defined(_MSC_VER)
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#pragma warning( push )
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#pragma warning( disable : 4146 )
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#endif
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difference |= -difference;
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#if defined(_MSC_VER)
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#pragma warning( pop )
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#endif
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/* cope with the varying size of size_t per platform */
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difference >>= ( sizeof( difference ) * 8 - 1 );
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return (unsigned char) ( 1 ^ difference );
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}
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/*
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* Constant flow lookup into table.
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*/
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static unsigned char mbedtls_base64_table_lookup( const unsigned char * const table,
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const size_t table_size, const size_t table_index )
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{
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size_t i;
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unsigned char result = 0;
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for( i = 0; i < table_size; ++i )
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{
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mbedtls_base64_cond_assign_uchar( &result, &table[i], mbedtls_base64_eq( i, table_index ) );
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}
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return result;
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}
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/*
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* Encode a buffer into base64 format
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*/
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@ -136,10 +229,17 @@ int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
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C2 = *src++;
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C3 = *src++;
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*p++ = base64_enc_map[(C1 >> 2) & 0x3F];
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*p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
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*p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F];
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*p++ = base64_enc_map[C3 & 0x3F];
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( C1 >> 2 ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( ( C2 & 15 ) << 2 ) + ( C3 >> 6 ) ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( C3 & 0x3F ) );
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}
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if( i < slen )
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@ -147,11 +247,15 @@ int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
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C1 = *src++;
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C2 = ( ( i + 1 ) < slen ) ? *src++ : 0;
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*p++ = base64_enc_map[(C1 >> 2) & 0x3F];
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*p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( C1 >> 2 ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ) );
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if( ( i + 1 ) < slen )
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*p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F];
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( C2 & 15 ) << 2 ) & 0x3F ) );
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else *p++ = '=';
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*p++ = '=';
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@ -172,6 +276,7 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
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size_t i, n;
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uint32_t j, x;
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unsigned char *p;
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unsigned char dec_map_lookup;
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/* First pass: check for validity and get output length */
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for( i = n = j = 0; i < slen; i++ )
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@ -202,10 +307,12 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
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if( src[i] == '=' && ++j > 2 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( src[i] > 127 || base64_dec_map[src[i]] == 127 )
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dec_map_lookup = mbedtls_base64_table_lookup( base64_dec_map, sizeof( base64_dec_map ), src[i] );
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if( src[i] > 127 || dec_map_lookup == 127 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( base64_dec_map[src[i]] < 64 && j != 0 )
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if( dec_map_lookup < 64 && j != 0 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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n++;
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@ -235,8 +342,10 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
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if( *src == '\r' || *src == '\n' || *src == ' ' )
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continue;
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j -= ( base64_dec_map[*src] == 64 );
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x = ( x << 6 ) | ( base64_dec_map[*src] & 0x3F );
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dec_map_lookup = mbedtls_base64_table_lookup( base64_dec_map, sizeof( base64_dec_map ), *src );
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mbedtls_base64_cond_assign_uint32( &j, j - 1, mbedtls_base64_eq( dec_map_lookup, 64 ) );
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x = ( x << 6 ) | ( dec_map_lookup & 0x3F );
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if( ++n == 4 )
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{
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@ -151,6 +151,20 @@ base64_encode_hex:"0102030405060708":"AQIDBAUGBwg=":13:0
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Base64 encode hex #4
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base64_encode_hex:"01020304050607":"AQIDBAUGBw==":13:0
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# Rotate the bytes around so that they end up at each offset modulo 3 in
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# successive test cases.
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Base64 encode hex all valid input bytes #0
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base64_encode_hex:"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff":"AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w==":345:0
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Base64 encode hex all valid input bytes #1
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base64_encode_hex:"0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff00":"AQIDBAUGBwgJCgsMDQ4PEBESExQVFhcYGRobHB0eHyAhIiMkJSYnKCkqKywtLi8wMTIzNDU2Nzg5Ojs8PT4/QEFCQ0RFRkdISUpLTE1OT1BRUlNUVVZXWFlaW1xdXl9gYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXp7fH1+f4CBgoOEhYaHiImKi4yNjo+QkZKTlJWWl5iZmpucnZ6foKGio6SlpqeoqaqrrK2ur7CxsrO0tba3uLm6u7y9vr/AwcLDxMXGx8jJysvMzc7P0NHS09TV1tfY2drb3N3e3+Dh4uPk5ebn6Onq6+zt7u/w8fLz9PX29/j5+vv8/f7/AA==":345:0
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Base64 encode hex all valid input bytes #2
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base64_encode_hex:"02030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff0001":"AgMEBQYHCAkKCwwNDg8QERITFBUWFxgZGhscHR4fICEiIyQlJicoKSorLC0uLzAxMjM0NTY3ODk6Ozw9Pj9AQUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVpbXF1eX2BhYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ent8fX5/gIGCg4SFhoeIiYqLjI2Oj5CRkpOUlZaXmJmam5ydnp+goaKjpKWmp6ipqqusra6vsLGys7S1tre4ubq7vL2+v8DBwsPExcbHyMnKy8zNzs/Q0dLT1NXW19jZ2tvc3d7f4OHi4+Tl5ufo6err7O3u7/Dx8vP09fb3+Pn6+/z9/v8AAQ==":345:0
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Base64 encode all valid output characters at all offsets
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base64_encode_hex:"00108310518720928b30d38f41149351559761969b71d79f8218a39259a7a29aabb2dbafc31cb3d35db7e39ebbf3dfbff800420c41461c824a2cc34e3d04524d45565d865a6dc75e7e08628e49669e8a6aaecb6ebf0c72cf4d76df8e7aefcf7effe00108310518720928b30d38f41149351559761969b71d79f8218a39259a7a29aabb2dbafc31cb3d35db7e39ebbf3dfbff800420c41461c824a2cc34e3d04524d45565d865a6dc75e7e08628e49669e8a6aaecb6ebf0c72cf4d76df8e7aefcf7efd0":"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/+ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/+ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/+ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/Q":261:0
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Base64 decode hex #1
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base64_decode_hex:"AQIDBAUGBwgJ":"010203040506070809":9:0
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@ -166,6 +180,9 @@ base64_decode_hex:"AQIDBAUGBw==":"01020304050607":7:0
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Base64 decode hex #5 (buffer too small)
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base64_decode_hex:"AQIDBAUGBw==":"01020304050607":6:MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL
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Base64 decode all valid input characters at all offsets
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base64_decode_hex:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/+ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/+ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/+ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/Q":"00108310518720928b30d38f41149351559761969b71d79f8218a39259a7a29aabb2dbafc31cb3d35db7e39ebbf3dfbff800420c41461c824a2cc34e3d04524d45565d865a6dc75e7e08628e49669e8a6aaecb6ebf0c72cf4d76df8e7aefcf7effe00108310518720928b30d38f41149351559761969b71d79f8218a39259a7a29aabb2dbafc31cb3d35db7e39ebbf3dfbff800420c41461c824a2cc34e3d04524d45565d865a6dc75e7e08628e49669e8a6aaecb6ebf0c72cf4d76df8e7aefcf7efd0":195:0
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Base64 Selftest
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depends_on:MBEDTLS_SELF_TEST
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base64_selftest:
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@ -13,13 +13,22 @@ void mbedtls_base64_encode( char * src_string, char * dst_string,
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{
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unsigned char src_str[1000];
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unsigned char dst_str[1000];
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size_t len;
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size_t len, src_len;
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memset(src_str, 0x00, 1000);
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memset(dst_str, 0x00, 1000);
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strncpy( (char *) src_str, src_string, sizeof(src_str) - 1 );
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TEST_ASSERT( mbedtls_base64_encode( dst_str, dst_buf_size, &len, src_str, strlen( (char *) src_str ) ) == result );
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src_len = strlen( (char *) src_str );
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TEST_CF_SECRET( src_str, sizeof( src_str ) );
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TEST_ASSERT( mbedtls_base64_encode( dst_str, dst_buf_size, &len, src_str, src_len) == result );
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TEST_CF_PUBLIC( src_str, sizeof( src_str ) );
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/* dest_str will have had tainted data copied to it, prevent the TEST_ASSERT below from triggering
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CF failures by unmarking it. */
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TEST_CF_PUBLIC( dst_str, len );
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if( result == 0 )
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{
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TEST_ASSERT( strcmp( (char *) dst_str, dst_string ) == 0 );
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@ -57,7 +66,14 @@ void base64_encode_hex( data_t * src, char * dst, int dst_buf_size,
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res = zero_alloc( dst_buf_size );
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TEST_CF_SECRET( src->x, src->len );
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TEST_ASSERT( mbedtls_base64_encode( res, dst_buf_size, &len, src->x, src->len ) == result );
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TEST_CF_PUBLIC( src->x, src->len );
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/* res will have had tainted data copied to it, prevent the TEST_ASSERT below from triggering
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CF failures by unmarking it. */
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TEST_CF_PUBLIC( res, len );
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if( result == 0 )
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{
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TEST_ASSERT( len == strlen( dst ) );
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