Mercurial > dropbear
view curve25519.c @ 1861:2b3a8026a6ce
Add re-exec for server
This allows ASLR to re-randomize the address
space for every connection, preventing some
vulnerabilities from being exploitable by
repeated probing.
Overhead (memory and time) is yet to be confirmed.
At present this is only enabled on Linux. Other BSD platforms
with fexecve() would probably also work though have not been tested.
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Sun, 30 Jan 2022 10:14:56 +0800 |
parents | 41a0ff8d5a89 |
children |
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/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #include "dbrandom.h" #include "curve25519.h" #if DROPBEAR_CURVE25519 || DROPBEAR_ED25519 /* Modified TweetNaCl version 20140427, a self-contained public-domain C library. * https://tweetnacl.cr.yp.to/ */ #define FOR(i,n) for (i = 0;i < n;++i) #define sv static void typedef unsigned char u8; typedef unsigned long u32; typedef unsigned long long u64; typedef long long i64; typedef i64 gf[16]; #if DROPBEAR_CURVE25519 static const gf _121665 = {0xDB41,1}; #endif /* DROPBEAR_CURVE25519 */ #if DROPBEAR_ED25519 static const gf gf0, gf1 = {1}, D2 = {0xf159, 0x26b2, 0x9b94, 0xebd6, 0xb156, 0x8283, 0x149a, 0x00e0, 0xd130, 0xeef3, 0x80f2, 0x198e, 0xfce7, 0x56df, 0xd9dc, 0x2406}, X = {0xd51a, 0x8f25, 0x2d60, 0xc956, 0xa7b2, 0x9525, 0xc760, 0x692c, 0xdc5c, 0xfdd6, 0xe231, 0xc0a4, 0x53fe, 0xcd6e, 0x36d3, 0x2169}, Y = {0x6658, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666, 0x6666}; #if DROPBEAR_SIGNKEY_VERIFY static const gf D = {0x78a3, 0x1359, 0x4dca, 0x75eb, 0xd8ab, 0x4141, 0x0a4d, 0x0070, 0xe898, 0x7779, 0x4079, 0x8cc7, 0xfe73, 0x2b6f, 0x6cee, 0x5203}, I = {0xa0b0, 0x4a0e, 0x1b27, 0xc4ee, 0xe478, 0xad2f, 0x1806, 0x2f43, 0xd7a7, 0x3dfb, 0x0099, 0x2b4d, 0xdf0b, 0x4fc1, 0x2480, 0x2b83}; #endif /* DROPBEAR_SIGNKEY_VERIFY */ #endif /* DROPBEAR_ED25519 */ #if DROPBEAR_ED25519 #if DROPBEAR_SIGNKEY_VERIFY static int vn(const u8 *x,const u8 *y,u32 n) { u32 i,d = 0; FOR(i,n) d |= x[i]^y[i]; return (1 & ((d - 1) >> 8)) - 1; } static int crypto_verify_32(const u8 *x,const u8 *y) { return vn(x,y,32); } #endif /* DROPBEAR_SIGNKEY_VERIFY */ sv set25519(gf r, const gf a) { int i; FOR(i,16) r[i]=a[i]; } #endif /* DROPBEAR_ED25519 */ sv car25519(gf o) { int i; i64 c; FOR(i,16) { o[i]+=(1LL<<16); c=o[i]>>16; o[(i+1)*(i<15)]+=c-1+37*(c-1)*(i==15); o[i]-=c<<16; } } sv sel25519(gf p,gf q,int b) { i64 t,i,c=~(b-1); FOR(i,16) { t= c&(p[i]^q[i]); p[i]^=t; q[i]^=t; } } sv pack25519(u8 *o,const gf n) { int i,j,b; gf m,t; FOR(i,16) t[i]=n[i]; car25519(t); car25519(t); car25519(t); FOR(j,2) { m[0]=t[0]-0xffed; for(i=1;i<15;i++) { m[i]=t[i]-0xffff-((m[i-1]>>16)&1); m[i-1]&=0xffff; } m[15]=t[15]-0x7fff-((m[14]>>16)&1); b=(m[15]>>16)&1; m[14]&=0xffff; sel25519(t,m,1-b); } FOR(i,16) { o[2*i]=t[i]&0xff; o[2*i+1]=t[i]>>8; } } #if DROPBEAR_ED25519 #if DROPBEAR_SIGNKEY_VERIFY static int neq25519(const gf a, const gf b) { u8 c[32],d[32]; pack25519(c,a); pack25519(d,b); return crypto_verify_32(c,d); } #endif /* DROPBEAR_SIGNKEY_VERIFY */ static u8 par25519(const gf a) { u8 d[32]; pack25519(d,a); return d[0]&1; } #endif /* DROPBEAR_ED25519 */ sv unpack25519(gf o, const u8 *n) { int i; FOR(i,16) o[i]=n[2*i]+((i64)n[2*i+1]<<8); o[15]&=0x7fff; } sv A(gf o,const gf a,const gf b) { int i; FOR(i,16) o[i]=a[i]+b[i]; } sv Z(gf o,const gf a,const gf b) { int i; FOR(i,16) o[i]=a[i]-b[i]; } sv M(gf o,const gf a,const gf b) { i64 i,j,t[31]; FOR(i,31) t[i]=0; FOR(i,16) FOR(j,16) t[i+j]+=a[i]*b[j]; FOR(i,15) t[i]+=38*t[i+16]; FOR(i,16) o[i]=t[i]; car25519(o); car25519(o); } sv S(gf o,const gf a) { M(o,a,a); } sv inv25519(gf o,const gf i) { gf c; int a; FOR(a,16) c[a]=i[a]; for(a=253;a>=0;a--) { S(c,c); if(a!=2&&a!=4) M(c,c,i); } FOR(a,16) o[a]=c[a]; } #if DROPBEAR_ED25519 && DROPBEAR_SIGNKEY_VERIFY sv pow2523(gf o,const gf i) { gf c; int a; FOR(a,16) c[a]=i[a]; for(a=250;a>=0;a--) { S(c,c); if(a!=1) M(c,c,i); } FOR(a,16) o[a]=c[a]; } #endif /* DROPBEAR_ED25519 && DROPBEAR_SIGNKEY_VERIFY */ #if DROPBEAR_CURVE25519 void dropbear_curve25519_scalarmult(u8 *q,const u8 *n,const u8 *p) { u8 z[32]; i64 x[80],r,i; gf a,b,c,d,e,f; FOR(i,31) z[i]=n[i]; z[31]=(n[31]&127)|64; z[0]&=248; unpack25519(x,p); FOR(i,16) { b[i]=x[i]; d[i]=a[i]=c[i]=0; } a[0]=d[0]=1; for(i=254;i>=0;--i) { r=(z[i>>3]>>(i&7))&1; sel25519(a,b,r); sel25519(c,d,r); A(e,a,c); Z(a,a,c); A(c,b,d); Z(b,b,d); S(d,e); S(f,a); M(a,c,a); M(c,b,e); A(e,a,c); Z(a,a,c); S(b,a); Z(c,d,f); M(a,c,_121665); A(a,a,d); M(c,c,a); M(a,d,f); M(d,b,x); S(b,e); sel25519(a,b,r); sel25519(c,d,r); } FOR(i,16) { x[i+16]=a[i]; x[i+32]=c[i]; x[i+48]=b[i]; x[i+64]=d[i]; } inv25519(x+32,x+32); M(x+16,x+16,x+32); pack25519(q,x+16); } #endif /* DROPBEAR_CURVE25519 */ #if DROPBEAR_ED25519 static int crypto_hash(u8 *out,const u8 *m,u64 n) { hash_state hs; sha512_init(&hs); sha512_process(&hs, m, n); return sha512_done(&hs, out); } sv add(gf p[4],gf q[4]) { gf a,b,c,d,t,e,f,g,h; Z(a, p[1], p[0]); Z(t, q[1], q[0]); M(a, a, t); A(b, p[0], p[1]); A(t, q[0], q[1]); M(b, b, t); M(c, p[3], q[3]); M(c, c, D2); M(d, p[2], q[2]); A(d, d, d); Z(e, b, a); Z(f, d, c); A(g, d, c); A(h, b, a); M(p[0], e, f); M(p[1], h, g); M(p[2], g, f); M(p[3], e, h); } sv cswap(gf p[4],gf q[4],u8 b) { int i; FOR(i,4) sel25519(p[i],q[i],b); } sv pack(u8 *r,gf p[4]) { gf tx, ty, zi; inv25519(zi, p[2]); M(tx, p[0], zi); M(ty, p[1], zi); pack25519(r, ty); r[31] ^= par25519(tx) << 7; } sv scalarmult(gf p[4],gf q[4],const u8 *s) { int i; set25519(p[0],gf0); set25519(p[1],gf1); set25519(p[2],gf1); set25519(p[3],gf0); for (i = 255;i >= 0;--i) { u8 b = (s[i/8]>>(i&7))&1; cswap(p,q,b); add(q,p); add(p,p); cswap(p,q,b); } } sv scalarbase(gf p[4],const u8 *s) { gf q[4]; set25519(q[0],X); set25519(q[1],Y); set25519(q[2],gf1); M(q[3],X,Y); scalarmult(p,q,s); } void dropbear_ed25519_make_key(u8 *pk,u8 *sk) { u8 d[64]; gf p[4]; genrandom(sk, 32); crypto_hash(d, sk, 32); d[0] &= 248; d[31] &= 127; d[31] |= 64; scalarbase(p,d); pack(pk,p); } static const u64 L[32] = {0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x10}; sv modL(u8 *r,i64 x[64]) { i64 carry,i,j; for (i = 63;i >= 32;--i) { carry = 0; for (j = i - 32;j < i - 12;++j) { x[j] += carry - 16 * x[i] * L[j - (i - 32)]; carry = (x[j] + 128) >> 8; x[j] -= carry << 8; } x[j] += carry; x[i] = 0; } carry = 0; FOR(j,32) { x[j] += carry - (x[31] >> 4) * L[j]; carry = x[j] >> 8; x[j] &= 255; } FOR(j,32) x[j] -= carry * L[j]; FOR(i,32) { x[i+1] += x[i] >> 8; r[i] = x[i] & 255; } } sv reduce(u8 *r) { i64 x[64],i; FOR(i,64) x[i] = (u64) r[i]; FOR(i,64) r[i] = 0; modL(r,x); } void dropbear_ed25519_sign(const u8 *m,u32 mlen,u8 *s,u32 *slen,const u8 *sk, const u8 *pk) { hash_state hs; u8 d[64],h[64],r[64]; i64 x[64]; gf p[4]; u32 i,j; crypto_hash(d, sk, 32); d[0] &= 248; d[31] &= 127; d[31] |= 64; *slen = 64; sha512_init(&hs); sha512_process(&hs,d + 32,32); sha512_process(&hs,m,mlen); sha512_done(&hs,r); reduce(r); scalarbase(p,r); pack(s,p); sha512_init(&hs); sha512_process(&hs,s,32); sha512_process(&hs,pk,32); sha512_process(&hs,m,mlen); sha512_done(&hs,h); reduce(h); FOR(i,64) x[i] = 0; FOR(i,32) x[i] = (u64) r[i]; FOR(i,32) FOR(j,32) x[i+j] += h[i] * (u64) d[j]; modL(s + 32,x); } #if DROPBEAR_SIGNKEY_VERIFY static int unpackneg(gf r[4],const u8 p[32]) { gf t, chk, num, den, den2, den4, den6; set25519(r[2],gf1); unpack25519(r[1],p); S(num,r[1]); M(den,num,D); Z(num,num,r[2]); A(den,r[2],den); S(den2,den); S(den4,den2); M(den6,den4,den2); M(t,den6,num); M(t,t,den); pow2523(t,t); M(t,t,num); M(t,t,den); M(t,t,den); M(r[0],t,den); S(chk,r[0]); M(chk,chk,den); if (neq25519(chk, num)) M(r[0],r[0],I); S(chk,r[0]); M(chk,chk,den); if (neq25519(chk, num)) return -1; if (par25519(r[0]) == (p[31]>>7)) Z(r[0],gf0,r[0]); M(r[3],r[0],r[1]); return 0; } int dropbear_ed25519_verify(const u8 *m,u32 mlen,const u8 *s,u32 slen,const u8 *pk) { hash_state hs; u8 t[32],h[64]; gf p[4],q[4]; if (slen < 64) return -1; if (unpackneg(q,pk)) return -1; sha512_init(&hs); sha512_process(&hs,s,32); sha512_process(&hs,pk,32); sha512_process(&hs,m,mlen); sha512_done(&hs,h); reduce(h); scalarmult(p,q,h); scalarbase(q,s + 32); add(p,q); pack(t,p); if (crypto_verify_32(s, t)) return -1; return 0; } #endif /* DROPBEAR_SIGNKEY_VERIFY */ #endif /* DROPBEAR_ED25519 */ #endif /* DROPBEAR_CURVE25519 || DROPBEAR_ED25519 */