[Xen-devel] [PATCH] vtpmmgr: properly remove t_uint size dependency

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

Rather than using the internal MPI format for the Diffie-Hellman group,
whose representation depends on the size of the t_uint type, store the
value as a big-endian integer and use mpi_read_binary to convert it in
an architecture-independent manner.  This patch also removes the
unnecessary range check on the exponent which ended up being different
between 32- and 64-bit code.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
 stubdom/vtpmmgr/vtpm_cmd_handler.c | 65 ++++++++++++++++----------------------
 1 file changed, 28 insertions(+), 37 deletions(-)

diff --git a/stubdom/vtpmmgr/vtpm_cmd_handler.c 
b/stubdom/vtpmmgr/vtpm_cmd_handler.c
index 4ef1da8..8a42790 100644
--- a/stubdom/vtpmmgr/vtpm_cmd_handler.c
+++ b/stubdom/vtpmmgr/vtpm_cmd_handler.c
@@ -448,62 +448,52 @@ static TPM_RESULT vtpmmgr_GroupActivate(tpmcmd_t* tpmcmd)
 
 /* 2048-bit MODP Group from RFC3526:
  *   2^2048 - 2^1984 - 1 + 2^64 * { [2^1918 pi] + 124476 }
- * mpi objects use little endian word ordering
  */
-static t_uint Pp[256 / sizeof(t_uint)] = {
-#ifdef __x86_64__
-       0xFFFFFFFFFFFFFFFFUL, 0x15728E5A8AACAA68UL, 0x15D2261898FA0510UL,
-       0x3995497CEA956AE5UL, 0xDE2BCBF695581718UL, 0xB5C55DF06F4C52C9UL,
-       0x9B2783A2EC07A28FUL, 0xE39E772C180E8603UL, 0x32905E462E36CE3BUL,
-       0xF1746C08CA18217CUL, 0x670C354E4ABC9804UL, 0x9ED529077096966DUL,
-       0x1C62F356208552BBUL, 0x83655D23DCA3AD96UL, 0x69163FA8FD24CF5FUL,
-       0x98DA48361C55D39AUL, 0xC2007CB8A163BF05UL, 0x49286651ECE45B3DUL,
-       0xAE9F24117C4B1FE6UL, 0xEE386BFB5A899FA5UL, 0x0BFF5CB6F406B7EDUL,
-       0xF44C42E9A637ED6BUL, 0xE485B576625E7EC6UL, 0x4FE1356D6D51C245UL,
-       0x302B0A6DF25F1437UL, 0xEF9519B3CD3A431BUL, 0x514A08798E3404DDUL,
-       0x020BBEA63B139B22UL, 0x29024E088A67CC74UL, 0xC4C6628B80DC1CD1UL,
-       0xC90FDAA22168C234UL, 0xFFFFFFFFFFFFFFFFUL,
-#else
-       0xFFFFFFFF, 0xFFFFFFFF, 0x8AACAA68, 0x15728E5A, 0x98FA0510, 0x15D22618,
-       0xEA956AE5, 0x3995497C, 0x95581718, 0xDE2BCBF6, 0x6F4C52C9, 0xB5C55DF0,
-       0xEC07A28F, 0x9B2783A2, 0x180E8603, 0xE39E772C, 0x2E36CE3B, 0x32905E46,
-       0xCA18217C, 0xF1746C08, 0x4ABC9804, 0x670C354E, 0x7096966D, 0x9ED52907,
-       0x208552BB, 0x1C62F356, 0xDCA3AD96, 0x83655D23, 0xFD24CF5F, 0x69163FA8,
-       0x1C55D39A, 0x98DA4836, 0xA163BF05, 0xC2007CB8, 0xECE45B3D, 0x49286651,
-       0x7C4B1FE6, 0xAE9F2411, 0x5A899FA5, 0xEE386BFB, 0xF406B7ED, 0x0BFF5CB6,
-       0xA637ED6B, 0xF44C42E9, 0x625E7EC6, 0xE485B576, 0x6D51C245, 0x4FE1356D,
-       0xF25F1437, 0x302B0A6D, 0xCD3A431B, 0xEF9519B3, 0x8E3404DD, 0x514A0879,
-       0x3B139B22, 0x020BBEA6, 0x8A67CC74, 0x29024E08, 0x80DC1CD1, 0xC4C6628B,
-       0x2168C234, 0xC90FDAA2, 0xFFFFFFFF, 0xFFFFFFFF,
-#endif
+static uint8_t P_bytes[256] = {
+       0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
+       0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
+       0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
+       0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
+       0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
+       0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
+       0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
+       0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
+       0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
+       0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
+       0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
+       0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
+       0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
+       0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
+       0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
+       0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
+       0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
+       0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
+       0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
+       0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
+       0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
+       0xFF, 0xFF, 0xFF, 0xFF,
 };
 static t_uint Gp[] = { 2 };
 
 static void tm_dhkx_gen(void* dhkx1, void* dhkx2, void* out)
 {
        mpi GX = { 0 }, GY = { 0 }, K = { 0 }, RP = { 0 };
+       mpi P = { 0 };
 
-       int XpElts = 256 / sizeof(t_uint);
-       t_uint Xp[XpElts];
+       t_uint Xp[sizeof(P_bytes) / sizeof(t_uint)];
        mpi X = {
                .s = 1,
-               .n = XpElts,
+               .n = ARRAY_SIZE(Xp),
                .p = Xp
        };
-       mpi P = {
-               .s = 1,
-               .n = XpElts,
-               .p = Pp,
-       };
        mpi G = {
                .s = 1,
                .n = 1,
                .p = Gp,
        };
+       mpi_read_binary(&P, P_bytes, sizeof(P_bytes));
 
        do_random(Xp, sizeof(Xp));
-       while (Xp[XpElts - 1] == 0 || Xp[XpElts - 1] == -1UL)
-               do_random(Xp + XpElts - 1, sizeof(Xp[0]));
 
        mpi_exp_mod(&GX, &G, &X, &P, &RP);
        mpi_write_binary(&GX, dhkx2, 256);
@@ -511,6 +501,7 @@ static void tm_dhkx_gen(void* dhkx1, void* dhkx2, void* out)
 
        mpi_read_binary(&GY, dhkx1, 256);
        mpi_exp_mod(&K, &GY, &X, &P, &RP);
+       mpi_free(&P);
        mpi_free(&RP);
        mpi_free(&GY);
 
-- 
1.9.0


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