6381f3d4f
Denys Vlasenko
2021-04-26
Subject
tls: stop passing temporary buffer address in P256 code
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networking/tls_sp_c32.c+26 -35
| @@ -170,8 +170,8 @@ static sp_digit sp_256_cmp_10(const sp_digit* a, const sp_digit* b) | |
| int i; | |
| for (i = 9; i >= 0; i--) { | |
| r = a[i] - b[i]; | |
| - | if (r != 0) |
| - | break; |
| + | if (r != 0) |
| + | break; |
| } | |
| return r; | |
| } | |
| @@ -553,16 +553,15 @@ static void sp_256_mont_sqr_10(sp_digit* r, const sp_digit* a, const sp_digit* m | |
| * | |
| * r Inverse result. | |
| * a Number to invert. | |
| - | * td Temporary data. |
| */ | |
| /* Mod-2 for the P256 curve. */ | |
| static const uint32_t p256_mod_2[8] = { | |
| - | 0xfffffffd,0xffffffff,0xffffffff,0x00000000, |
| - | 0x00000000,0x00000000,0x00000001,0xffffffff, |
| + | 0xfffffffd,0xffffffff,0xffffffff,0x00000000, |
| + | 0x00000000,0x00000000,0x00000001,0xffffffff, |
| }; | |
| - | static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a, sp_digit* td) |
| + | static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a) |
| { | |
| - | sp_digit* t = td; |
| + | sp_digit t[2*10]; //can be just [10]? |
| int i; | |
| memcpy(t, a, sizeof(sp_digit) * 10); | |
| @@ -578,15 +577,14 @@ static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a, sp_digit* td) | |
| * | |
| * r Resulting affine co-ordinate point. | |
| * p Montgomery form projective co-ordinate point. | |
| - | * t Temporary ordinate data. |
| */ | |
| - | static void sp_256_map_10(sp_point* r, sp_point* p, sp_digit* t) |
| + | static void sp_256_map_10(sp_point* r, sp_point* p) |
| { | |
| - | sp_digit* t1 = t; |
| - | sp_digit* t2 = t + 2*10; |
| + | sp_digit t1[2*10]; |
| + | sp_digit t2[2*10]; |
| int32_t n; | |
| - | sp_256_mont_inv_10(t1, p->z, t + 2*10); |
| + | sp_256_mont_inv_10(t1, p->z); |
| sp_256_mont_sqr_10(t2, t1, p256_mod, p256_mp_mod); | |
| sp_256_mont_mul_10(t1, t2, t1, p256_mod, p256_mp_mod); | |
| @@ -617,21 +615,20 @@ static void sp_256_map_10(sp_point* r, sp_point* p, sp_digit* t) | |
| * | |
| * r Result of doubling point. | |
| * p Point to double. | |
| - | * t Temporary ordinate data. |
| */ | |
| - | static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p, sp_digit* t) |
| + | static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p) |
| { | |
| sp_point tp; | |
| - | sp_digit* t1 = t; |
| - | sp_digit* t2 = t + 2*10; |
| + | sp_digit t1[2*10]; |
| + | sp_digit t2[2*10]; |
| /* Put point to double into result */ | |
| if (r != p) | |
| *r = *p; /* struct copy */ | |
| if (r->infinity) { | |
| - | /* If infinity, don't double (work on dummy value) */ |
| - | r = &tp; |
| + | /* If infinity, don't double (work on dummy value) */ |
| + | r = &tp; |
| } | |
| /* T1 = Z * Z */ | |
| sp_256_mont_sqr_10(t1, r->z, p256_mod, p256_mp_mod); | |
| @@ -676,16 +673,14 @@ static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p, sp_digit* t) | |
| * r Result of addition. | |
| * p Frist point to add. | |
| * q Second point to add. | |
| - | * t Temporary ordinate data. |
| */ | |
| - | static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q, |
| - | sp_digit* t) |
| + | static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q) |
| { | |
| - | sp_digit* t1 = t; |
| - | sp_digit* t2 = t + 2*10; |
| - | sp_digit* t3 = t + 4*10; |
| - | sp_digit* t4 = t + 6*10; |
| - | sp_digit* t5 = t + 8*10; |
| + | sp_digit t1[2*10]; |
| + | sp_digit t2[2*10]; |
| + | sp_digit t3[2*10]; |
| + | sp_digit t4[2*10]; |
| + | sp_digit t5[2*10]; |
| /* Ensure only the first point is the same as the result. */ | |
| if (q == r) { | |
| @@ -701,7 +696,7 @@ static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q, | |
| && sp_256_cmp_equal_10(p->z, q->z) | |
| && (sp_256_cmp_equal_10(p->y, q->y) || sp_256_cmp_equal_10(p->y, t1)) | |
| ) { | |
| - | sp_256_proj_point_dbl_10(r, p, t); |
| + | sp_256_proj_point_dbl_10(r, p); |
| } | |
| else { | |
| sp_point tp; | |
| @@ -762,7 +757,6 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit* | |
| { | |
| enum { map = 1 }; /* we always convert result to affine coordinates */ | |
| sp_point t[3]; | |
| - | sp_digit tmp[2 * 10 * 5]; |
| sp_digit n; | |
| int i; | |
| int c, y; | |
| @@ -791,20 +785,17 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit* | |
| y = (n >> 25) & 1; | |
| n <<= 1; | |
| - | //FIXME: what's "tmp" and why do we pass it down? |
| - | //is it scratch space for "sensitive" data, to be memset(0) after we are done? |
| - | sp_256_proj_point_add_10(&t[y^1], &t[0], &t[1], tmp); |
| + | sp_256_proj_point_add_10(&t[y^1], &t[0], &t[1]); |
| memcpy(&t[2], &t[y], sizeof(sp_point)); | |
| - | sp_256_proj_point_dbl_10(&t[2], &t[2], tmp); |
| + | sp_256_proj_point_dbl_10(&t[2], &t[2]); |
| memcpy(&t[y], &t[2], sizeof(sp_point)); | |
| } | |
| if (map) | |
| - | sp_256_map_10(r, &t[0], tmp); |
| + | sp_256_map_10(r, &t[0]); |
| else | |
| memcpy(r, &t[0], sizeof(sp_point)); | |
| - | memset(tmp, 0, sizeof(tmp)); //paranoia |
| memset(t, 0, sizeof(t)); //paranoia | |
| } | |
| @@ -817,7 +808,7 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit* | |
| */ | |
| static void sp_256_ecc_mulmod_base_10(sp_point* r, sp_digit* k /*, int map*/) | |
| { | |
| - | sp_256_ecc_mulmod_10(r, &p256_base, k /*, map*/); |
| + | sp_256_ecc_mulmod_10(r, &p256_base, k /*, map*/); |
| } | |
| /* Multiply the point by the scalar and serialize the X ordinate. | |