diff options
Diffstat (limited to 'security/nss/lib/util/secport.h')
| -rw-r--r-- | security/nss/lib/util/secport.h | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/security/nss/lib/util/secport.h b/security/nss/lib/util/secport.h index c682f5d11b..b3021afafe 100644 --- a/security/nss/lib/util/secport.h +++ b/security/nss/lib/util/secport.h @@ -126,6 +126,15 @@ SEC_END_PROTOS * ignored. See more details in Bug 1588015. */ #define PORT_AssertArg PR_ASSERT_ARG +/* Assert the current location can't be reached, passing a reason-string. */ +#define PORT_AssertNotReached(reasonStr) PR_NOT_REACHED(reasonStr) + +/* macros to handle endian based byte conversion */ +#define PORT_GET_BYTE_BE(value, offset, len) \ + ((unsigned char)(((len) - (offset)-1) >= sizeof(value) ? 0 : (((value) >> (((len) - (offset)-1) * PR_BITS_PER_BYTE)) & 0xff))) +#define PORT_GET_BYTE_LE(value, offset, len) \ + ((unsigned char)((offset) > sizeof(value) ? 0 : (((value) >> ((offset)*PR_BITS_PER_BYTE)) & 0xff))) + /* This runs a function that should return SECSuccess. * Intended for NSS internal use only. * The return value is asserted in a debug build, otherwise it is ignored. @@ -296,4 +305,69 @@ PORT_LoadLibraryFromOrigin(const char *existingShLibName, SEC_END_PROTOS +/* + * Constant time macros + */ +/* These macros use the fact that arithmetic shift shifts-in the sign bit. + * However, this is not ensured by the C standard so you may need to replace + * them with something else for odd compilers. These macros work for object + * sizes up to 32 bits. The inequalities will produce incorrect results if + * abs(a-b) >= PR_UINT32_MAX/2. This can be a voided if unsigned values stay + * within the range 0-PRUINT32_MAX/2 and signed values stay within the range + * -PRINT32_MAX/2-PRINT32_MAX/2. If these are insufficient, we can fix + * this by either expanding the PORT_CT_DUPLICATE_MSB_TO_ALL to PRUint64 + * or by creating the following new macros for inequality: + * + * PORT_CT_OVERFLOW prevents the overflow condition by handling the case + * where the high bits in a and b are different specially. Basically if + * the high bit in a and b differs we can just + * copy the high bit of one of the parameters to determine the result as + * follows: + * GxU if a has the high bit on, a>b, so d=a + * LxU if b has the high bit on, a<b, so d=b + * GxS if b has the high bit on, it's negative a>b so d=b + * LxS if a has the high bit on, it's negative a<b so d=a + * where PORT_CT_xxU() macros do unsigned compares and PORT_CT_xxS() do signed + * compares. + * + * #define PORT_CT_OVERFLOW(a,b,c,d) \ + * PORT_CT_SEL(PORT_CT_DUPLICATE_MSB_TO_ALL((a)^(b)), \ + * (PORT_CT_DUPLICATE_MSB_TO_ALL(d)),c) + * #define PORT_CT_GTU(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_GT(a,b),a) + * #define PORT_CT_LTU(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_LT(a,b),b) + * #define PORT_CT_GEU(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_GE(a,b),a) + * #define PORT_CT_LEU(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_LE(a,b),b) + * #define PORT_CT_GTS(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_GT(a,b),b) + * #define PORT_CT_LTS(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_LT(a,b),a) + * #define PORT_CT_GES(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_GE(a,b),b) + * #define PORT_CT_LES(a,b) PORT_CT_OVERFLOW(a,b,PORT_CT_LE(a,b),a) + * + * + * */ +/* Constant-time helper macro that copies the MSB of x to all other bits. */ +#define PORT_CT_DUPLICATE_MSB_TO_ALL(x) ((PRUint32)((PRInt32)(x) >> (sizeof(PRInt32) * 8 - 1))) + +/* Constant-time helper macro that selects l or r depending on all-1 or all-0 + * mask m */ +#define PORT_CT_SEL(m, l, r) (((m) & (l)) | (~(m) & (r))) + +/* Constant-time helper macro that returns all-1s if x is not 0; and all-0s + * otherwise. */ +#define PORT_CT_NOT_ZERO(x) (PORT_CT_DUPLICATE_MSB_TO_ALL(((x) | (0 - (x))))) + +/* Constant-time helper macro that returns all-1s if x is 0; and all-0s + * otherwise. */ +#define PORT_CT_ZERO(x) (~PORT_CT_DUPLICATE_MSB_TO_ALL(((x) | (0 - (x))))) + +/* Constant-time helper macro for equalities and inequalities. + * returns all-1's for true and all-0's for false */ +#define PORT_CT_EQ(a, b) PORT_CT_ZERO(((a) - (b))) +#define PORT_CT_NE(a, b) PORT_CT_NOT_ZERO(((a) - (b))) +#define PORT_CT_GT(a, b) PORT_CT_DUPLICATE_MSB_TO_ALL((b) - (a)) +#define PORT_CT_LT(a, b) PORT_CT_DUPLICATE_MSB_TO_ALL((a) - (b)) +#define PORT_CT_GE(a, b) (~PORT_CT_LT(a, b)) +#define PORT_CT_LE(a, b) (~PORT_CT_GT(a, b)) +#define PORT_CT_TRUE (~0) +#define PORT_CT_FALSE 0 + #endif /* _SECPORT_H_ */ |