diff options
Diffstat (limited to 'arch/arm64/crypto/aes-modes.S')
| -rw-r--r-- | arch/arm64/crypto/aes-modes.S | 349 |
1 files changed, 246 insertions, 103 deletions
diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S index dc35eb0245c5..5abc834271f4 100644 --- a/arch/arm64/crypto/aes-modes.S +++ b/arch/arm64/crypto/aes-modes.S @@ -318,127 +318,211 @@ AES_FUNC_END(aes_cbc_cts_decrypt) .byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff .previous - /* - * aes_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds, - * int bytes, u8 ctr[]) + * This macro generates the code for CTR and XCTR mode. */ +.macro ctr_encrypt xctr + // Arguments + OUT .req x0 + IN .req x1 + KEY .req x2 + ROUNDS_W .req w3 + BYTES_W .req w4 + IV .req x5 + BYTE_CTR_W .req w6 // XCTR only + // Intermediate values + CTR_W .req w11 // XCTR only + CTR .req x11 // XCTR only + IV_PART .req x12 + BLOCKS .req x13 + BLOCKS_W .req w13 -AES_FUNC_START(aes_ctr_encrypt) stp x29, x30, [sp, #-16]! mov x29, sp - enc_prepare w3, x2, x12 - ld1 {vctr.16b}, [x5] + enc_prepare ROUNDS_W, KEY, IV_PART + ld1 {vctr.16b}, [IV] - umov x12, vctr.d[1] /* keep swabbed ctr in reg */ - rev x12, x12 - -.LctrloopNx: - add w7, w4, #15 - sub w4, w4, #MAX_STRIDE << 4 - lsr w7, w7, #4 + /* + * Keep 64 bits of the IV in a register. For CTR mode this lets us + * easily increment the IV. For XCTR mode this lets us efficiently XOR + * the 64-bit counter with the IV. + */ + .if \xctr + umov IV_PART, vctr.d[0] + lsr CTR_W, BYTE_CTR_W, #4 + .else + umov IV_PART, vctr.d[1] + rev IV_PART, IV_PART + .endif + +.LctrloopNx\xctr: + add BLOCKS_W, BYTES_W, #15 + sub BYTES_W, BYTES_W, #MAX_STRIDE << 4 + lsr BLOCKS_W, BLOCKS_W, #4 mov w8, #MAX_STRIDE - cmp w7, w8 - csel w7, w7, w8, lt - adds x12, x12, x7 + cmp BLOCKS_W, w8 + csel BLOCKS_W, BLOCKS_W, w8, lt + /* + * Set up the counter values in v0-v{MAX_STRIDE-1}. + * + * If we are encrypting less than MAX_STRIDE blocks, the tail block + * handling code expects the last keystream block to be in + * v{MAX_STRIDE-1}. For example: if encrypting two blocks with + * MAX_STRIDE=5, then v3 and v4 should have the next two counter blocks. + */ + .if \xctr + add CTR, CTR, BLOCKS + .else + adds IV_PART, IV_PART, BLOCKS + .endif mov v0.16b, vctr.16b mov v1.16b, vctr.16b mov v2.16b, vctr.16b mov v3.16b, vctr.16b ST5( mov v4.16b, vctr.16b ) - bcs 0f - - .subsection 1 - /* apply carry to outgoing counter */ -0: umov x8, vctr.d[0] - rev x8, x8 - add x8, x8, #1 - rev x8, x8 - ins vctr.d[0], x8 - - /* apply carry to N counter blocks for N := x12 */ - cbz x12, 2f - adr x16, 1f - sub x16, x16, x12, lsl #3 - br x16 - bti c - mov v0.d[0], vctr.d[0] - bti c - mov v1.d[0], vctr.d[0] - bti c - mov v2.d[0], vctr.d[0] - bti c - mov v3.d[0], vctr.d[0] -ST5( bti c ) -ST5( mov v4.d[0], vctr.d[0] ) -1: b 2f - .previous + .if \xctr + sub x6, CTR, #MAX_STRIDE - 1 + sub x7, CTR, #MAX_STRIDE - 2 + sub x8, CTR, #MAX_STRIDE - 3 + sub x9, CTR, #MAX_STRIDE - 4 +ST5( sub x10, CTR, #MAX_STRIDE - 5 ) + eor x6, x6, IV_PART + eor x7, x7, IV_PART + eor x8, x8, IV_PART + eor x9, x9, IV_PART +ST5( eor x10, x10, IV_PART ) + mov v0.d[0], x6 + mov v1.d[0], x7 + mov v2.d[0], x8 + mov v3.d[0], x9 +ST5( mov v4.d[0], x10 ) + .else + bcs 0f + .subsection 1 + /* + * This subsection handles carries. + * + * Conditional branching here is allowed with respect to time + * invariance since the branches are dependent on the IV instead + * of the plaintext or key. This code is rarely executed in + * practice anyway. + */ + + /* Apply carry to outgoing counter. */ +0: umov x8, vctr.d[0] + rev x8, x8 + add x8, x8, #1 + rev x8, x8 + ins vctr.d[0], x8 + + /* + * Apply carry to counter blocks if needed. + * + * Since the carry flag was set, we know 0 <= IV_PART < + * MAX_STRIDE. Using the value of IV_PART we can determine how + * many counter blocks need to be updated. + */ + cbz IV_PART, 2f + adr x16, 1f + sub x16, x16, IV_PART, lsl #3 + br x16 + bti c + mov v0.d[0], vctr.d[0] + bti c + mov v1.d[0], vctr.d[0] + bti c + mov v2.d[0], vctr.d[0] + bti c + mov v3.d[0], vctr.d[0] +ST5( bti c ) +ST5( mov v4.d[0], vctr.d[0] ) +1: b 2f + .previous + +2: rev x7, IV_PART + ins vctr.d[1], x7 + sub x7, IV_PART, #MAX_STRIDE - 1 + sub x8, IV_PART, #MAX_STRIDE - 2 + sub x9, IV_PART, #MAX_STRIDE - 3 + rev x7, x7 + rev x8, x8 + mov v1.d[1], x7 + rev x9, x9 +ST5( sub x10, IV_PART, #MAX_STRIDE - 4 ) + mov v2.d[1], x8 +ST5( rev x10, x10 ) + mov v3.d[1], x9 +ST5( mov v4.d[1], x10 ) + .endif -2: rev x7, x12 - ins vctr.d[1], x7 - sub x7, x12, #MAX_STRIDE - 1 - sub x8, x12, #MAX_STRIDE - 2 - sub x9, x12, #MAX_STRIDE - 3 - rev x7, x7 - rev x8, x8 - mov v1.d[1], x7 - rev x9, x9 -ST5( sub x10, x12, #MAX_STRIDE - 4 ) - mov v2.d[1], x8 -ST5( rev x10, x10 ) - mov v3.d[1], x9 -ST5( mov v4.d[1], x10 ) - tbnz w4, #31, .Lctrtail - ld1 {v5.16b-v7.16b}, [x1], #48 + /* + * If there are at least MAX_STRIDE blocks left, XOR the data with + * keystream and store. Otherwise jump to tail handling. + */ + tbnz BYTES_W, #31, .Lctrtail\xctr + ld1 {v5.16b-v7.16b}, [IN], #48 ST4( bl aes_encrypt_block4x ) ST5( bl aes_encrypt_block5x ) eor v0.16b, v5.16b, v0.16b -ST4( ld1 {v5.16b}, [x1], #16 ) +ST4( ld1 {v5.16b}, [IN], #16 ) eor v1.16b, v6.16b, v1.16b -ST5( ld1 {v5.16b-v6.16b}, [x1], #32 ) +ST5( ld1 {v5.16b-v6.16b}, [IN], #32 ) eor v2.16b, v7.16b, v2.16b eor v3.16b, v5.16b, v3.16b ST5( eor v4.16b, v6.16b, v4.16b ) - st1 {v0.16b-v3.16b}, [x0], #64 -ST5( st1 {v4.16b}, [x0], #16 ) - cbz w4, .Lctrout - b .LctrloopNx - -.Lctrout: - st1 {vctr.16b}, [x5] /* return next CTR value */ + st1 {v0.16b-v3.16b}, [OUT], #64 +ST5( st1 {v4.16b}, [OUT], #16 ) + cbz BYTES_W, .Lctrout\xctr + b .LctrloopNx\xctr + +.Lctrout\xctr: + .if !\xctr + st1 {vctr.16b}, [IV] /* return next CTR value */ + .endif ldp x29, x30, [sp], #16 ret -.Lctrtail: - /* XOR up to MAX_STRIDE * 16 - 1 bytes of in/output with v0 ... v3/v4 */ +.Lctrtail\xctr: + /* + * Handle up to MAX_STRIDE * 16 - 1 bytes of plaintext + * + * This code expects the last keystream block to be in v{MAX_STRIDE-1}. + * For example: if encrypting two blocks with MAX_STRIDE=5, then v3 and + * v4 should have the next two counter blocks. + * + * This allows us to store the ciphertext by writing to overlapping + * regions of memory. Any invalid ciphertext blocks get overwritten by + * correctly computed blocks. This approach greatly simplifies the + * logic for storing the ciphertext. + */ mov x16, #16 - ands x6, x4, #0xf - csel x13, x6, x16, ne + ands w7, BYTES_W, #0xf + csel x13, x7, x16, ne -ST5( cmp w4, #64 - (MAX_STRIDE << 4) ) +ST5( cmp BYTES_W, #64 - (MAX_STRIDE << 4)) ST5( csel x14, x16, xzr, gt ) - cmp w4, #48 - (MAX_STRIDE << 4) + cmp BYTES_W, #48 - (MAX_STRIDE << 4) csel x15, x16, xzr, gt - cmp w4, #32 - (MAX_STRIDE << 4) + cmp BYTES_W, #32 - (MAX_STRIDE << 4) csel x16, x16, xzr, gt - cmp w4, #16 - (MAX_STRIDE << 4) + cmp BYTES_W, #16 - (MAX_STRIDE << 4) - adr_l x12, .Lcts_permute_table - add x12, x12, x13 - ble .Lctrtail1x + adr_l x9, .Lcts_permute_table + add x9, x9, x13 + ble .Lctrtail1x\xctr -ST5( ld1 {v5.16b}, [x1], x14 ) - ld1 {v6.16b}, [x1], x15 - ld1 {v7.16b}, [x1], x16 +ST5( ld1 {v5.16b}, [IN], x14 ) + ld1 {v6.16b}, [IN], x15 + ld1 {v7.16b}, [IN], x16 ST4( bl aes_encrypt_block4x ) ST5( bl aes_encrypt_block5x ) - ld1 {v8.16b}, [x1], x13 - ld1 {v9.16b}, [x1] - ld1 {v10.16b}, [x12] + ld1 {v8.16b}, [IN], x13 + ld1 {v9.16b}, [IN] + ld1 {v10.16b}, [x9] ST4( eor v6.16b, v6.16b, v0.16b ) ST4( eor v7.16b, v7.16b, v1.16b ) @@ -453,32 +537,91 @@ ST5( eor v7.16b, v7.16b, v2.16b ) ST5( eor v8.16b, v8.16b, v3.16b ) ST5( eor v9.16b, v9.16b, v4.16b ) -ST5( st1 {v5.16b}, [x0], x14 ) - st1 {v6.16b}, [x0], x15 - st1 {v7.16b}, [x0], x16 - add x13, x13, x0 +ST5( st1 {v5.16b}, [OUT], x14 ) + st1 {v6.16b}, [OUT], x15 + st1 {v7.16b}, [OUT], x16 + add x13, x13, OUT st1 {v9.16b}, [x13] // overlapping stores - st1 {v8.16b}, [x0] - b .Lctrout - -.Lctrtail1x: - sub x7, x6, #16 - csel x6, x6, x7, eq - add x1, x1, x6 - add x0, x0, x6 - ld1 {v5.16b}, [x1] - ld1 {v6.16b}, [x0] + st1 {v8.16b}, [OUT] + b .Lctrout\xctr + +.Lctrtail1x\xctr: + /* + * Handle <= 16 bytes of plaintext + * + * This code always reads and writes 16 bytes. To avoid out of bounds + * accesses, XCTR and CTR modes must use a temporary buffer when + * encrypting/decrypting less than 16 bytes. + * + * This code is unusual in that it loads the input and stores the output + * relative to the end of the buffers rather than relative to the start. + * This causes unusual behaviour when encrypting/decrypting less than 16 + * bytes; the end of the data is expected to be at the end of the + * temporary buffer rather than the start of the data being at the start + * of the temporary buffer. + */ + sub x8, x7, #16 + csel x7, x7, x8, eq + add IN, IN, x7 + add OUT, OUT, x7 + ld1 {v5.16b}, [IN] + ld1 {v6.16b}, [OUT] ST5( mov v3.16b, v4.16b ) - encrypt_block v3, w3, x2, x8, w7 - ld1 {v10.16b-v11.16b}, [x12] + encrypt_block v3, ROUNDS_W, KEY, x8, w7 + ld1 {v10.16b-v11.16b}, [x9] tbl v3.16b, {v3.16b}, v10.16b sshr v11.16b, v11.16b, #7 eor v5.16b, v5.16b, v3.16b bif v5.16b, v6.16b, v11.16b - st1 {v5.16b}, [x0] - b .Lctrout + st1 {v5.16b}, [OUT] + b .Lctrout\xctr + + // Arguments + .unreq OUT + .unreq IN + .unreq KEY + .unreq ROUNDS_W + .unreq BYTES_W + .unreq IV + .unreq BYTE_CTR_W // XCTR only + // Intermediate values + .unreq CTR_W // XCTR only + .unreq CTR // XCTR only + .unreq IV_PART + .unreq BLOCKS + .unreq BLOCKS_W +.endm + + /* + * aes_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds, + * int bytes, u8 ctr[]) + * + * The input and output buffers must always be at least 16 bytes even if + * encrypting/decrypting less than 16 bytes. Otherwise out of bounds + * accesses will occur. The data to be encrypted/decrypted is expected + * to be at the end of this 16-byte temporary buffer rather than the + * start. + */ + +AES_FUNC_START(aes_ctr_encrypt) + ctr_encrypt 0 AES_FUNC_END(aes_ctr_encrypt) + /* + * aes_xctr_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds, + * int bytes, u8 const iv[], int byte_ctr) + * + * The input and output buffers must always be at least 16 bytes even if + * encrypting/decrypting less than 16 bytes. Otherwise out of bounds + * accesses will occur. The data to be encrypted/decrypted is expected + * to be at the end of this 16-byte temporary buffer rather than the + * start. + */ + +AES_FUNC_START(aes_xctr_encrypt) + ctr_encrypt 1 +AES_FUNC_END(aes_xctr_encrypt) + /* * aes_xts_encrypt(u8 out[], u8 const in[], u8 const rk1[], int rounds, |