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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
/*
* secport.c - portability interfaces for security libraries
*
* This file abstracts out libc functionality that libsec depends on
*
* NOTE - These are not public interfaces
*/
#include "seccomon.h"
#include "prmem.h"
#include "prerror.h"
#include "plarena.h"
#include "secerr.h"
#include "prmon.h"
#include "nssilock.h"
#include "secport.h"
#include "prenv.h"
#include "prinit.h"
#include <stdint.h>
#ifdef DEBUG
#define THREADMARK
#endif /* DEBUG */
#ifdef THREADMARK
#include "prthread.h"
#endif /* THREADMARK */
#if defined(XP_UNIX)
#include <stdlib.h>
#else
#include "wtypes.h"
#endif
#define SET_ERROR_CODE /* place holder for code to set PR error code. */
#ifdef THREADMARK
typedef struct threadmark_mark_str {
struct threadmark_mark_str *next;
void *mark;
} threadmark_mark;
#endif /* THREADMARK */
/* The value of this magic must change each time PORTArenaPool changes. */
#define ARENAPOOL_MAGIC 0xB8AC9BDF
#define CHEAP_ARENAPOOL_MAGIC 0x3F16BB09
typedef struct PORTArenaPool_str {
PLArenaPool arena;
PRUint32 magic;
PRLock *lock;
#ifdef THREADMARK
PRThread *marking_thread;
threadmark_mark *first_mark;
#endif
} PORTArenaPool;
/* locations for registering Unicode conversion functions.
* XXX is this the appropriate location? or should they be
* moved to client/server specific locations?
*/
PORTCharConversionFunc ucs4Utf8ConvertFunc;
PORTCharConversionFunc ucs2Utf8ConvertFunc;
PORTCharConversionWSwapFunc ucs2AsciiConvertFunc;
/* NSPR memory allocation functions (PR_Malloc, PR_Calloc, and PR_Realloc)
* use the PRUint32 type for the size parameter. Before we pass a size_t or
* unsigned long size to these functions, we need to ensure it is <= half of
* the maximum PRUint32 value to avoid truncation and catch a negative size.
*/
#define MAX_SIZE (PR_UINT32_MAX >> 1)
void *
PORT_Alloc(size_t bytes)
{
void *rv = NULL;
if (bytes <= MAX_SIZE) {
/* Always allocate a non-zero amount of bytes */
rv = PR_Malloc(bytes ? bytes : 1);
}
if (!rv) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
}
return rv;
}
void *
PORT_Realloc(void *oldptr, size_t bytes)
{
void *rv = NULL;
if (bytes <= MAX_SIZE) {
rv = PR_Realloc(oldptr, bytes);
}
if (!rv) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
}
return rv;
}
void *
PORT_ZAlloc(size_t bytes)
{
void *rv = NULL;
if (bytes <= MAX_SIZE) {
/* Always allocate a non-zero amount of bytes */
rv = PR_Calloc(1, bytes ? bytes : 1);
}
if (!rv) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
}
return rv;
}
/* aligned_alloc is C11. This is an alternative to get aligned memory. */
void *
PORT_ZAllocAligned(size_t bytes, size_t alignment, void **mem)
{
size_t x = alignment - 1;
/* This only works if alignment is a power of 2. */
if ((alignment == 0) || (alignment & (alignment - 1))) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return NULL;
}
if (!mem) {
return NULL;
}
/* Always allocate a non-zero amount of bytes */
*mem = PORT_ZAlloc((bytes ? bytes : 1) + x);
if (!*mem) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
return (void *)(((uintptr_t)*mem + x) & ~(uintptr_t)x);
}
void *
PORT_ZAllocAlignedOffset(size_t size, size_t alignment, size_t offset)
{
PORT_Assert(offset < size);
if (offset > size) {
return NULL;
}
void *mem = NULL;
void *v = PORT_ZAllocAligned(size, alignment, &mem);
if (!v) {
return NULL;
}
PORT_Assert(mem);
*((void **)((uintptr_t)v + offset)) = mem;
return v;
}
void
PORT_Free(void *ptr)
{
if (ptr) {
PR_Free(ptr);
}
}
void
PORT_ZFree(void *ptr, size_t len)
{
if (ptr) {
memset(ptr, 0, len);
PR_Free(ptr);
}
}
char *
PORT_Strdup(const char *str)
{
size_t len = PORT_Strlen(str) + 1;
char *newstr;
newstr = (char *)PORT_Alloc(len);
if (newstr) {
PORT_Memcpy(newstr, str, len);
}
return newstr;
}
void
PORT_SetError(int value)
{
PR_SetError(value, 0);
return;
}
int
PORT_GetError(void)
{
return (PR_GetError());
}
/********************* Arena code follows *****************************
* ArenaPools are like heaps. The memory in them consists of large blocks,
* called arenas, which are allocated from the/a system heap. Inside an
* ArenaPool, the arenas are organized as if they were in a stack. Newly
* allocated arenas are "pushed" on that stack. When you attempt to
* allocate memory from an ArenaPool, the code first looks to see if there
* is enough unused space in the top arena on the stack to satisfy your
* request, and if so, your request is satisfied from that arena.
* Otherwise, a new arena is allocated (or taken from NSPR's list of freed
* arenas) and pushed on to the stack. The new arena is always big enough
* to satisfy the request, and is also at least a minimum size that is
* established at the time that the ArenaPool is created.
*
* The ArenaMark function returns the address of a marker in the arena at
* the top of the arena stack. It is the address of the place in the arena
* on the top of the arena stack from which the next block of memory will
* be allocated. Each ArenaPool has its own separate stack, and hence
* marks are only relevant to the ArenaPool from which they are gotten.
* Marks may be nested. That is, a thread can get a mark, and then get
* another mark.
*
* It is intended that all the marks in an ArenaPool may only be owned by a
* single thread. In DEBUG builds, this is enforced. In non-DEBUG builds,
* it is not. In DEBUG builds, when a thread gets a mark from an
* ArenaPool, no other thread may acquire a mark in that ArenaPool while
* that mark exists, that is, until that mark is unmarked or released.
* Therefore, it is important that every mark be unmarked or released when
* the creating thread has no further need for exclusive ownership of the
* right to manage the ArenaPool.
*
* The ArenaUnmark function discards the ArenaMark at the address given,
* and all marks nested inside that mark (that is, acquired from that same
* ArenaPool while that mark existed). It is an error for a thread other
* than the mark's creator to try to unmark it. When a thread has unmarked
* all its marks from an ArenaPool, then another thread is able to set
* marks in that ArenaPool. ArenaUnmark does not deallocate (or "pop") any
* memory allocated from the ArenaPool since the mark was created.
*
* ArenaRelease "pops" the stack back to the mark, deallocating all the
* memory allocated from the arenas in the ArenaPool since that mark was
* created, and removing any arenas from the ArenaPool that have no
* remaining active allocations when that is done. It implicitly releases
* any marks nested inside the mark being explicitly released. It is the
* only operation, other than destroying the arenapool, that potentially
* reduces the number of arenas on the stack. Otherwise, the stack grows
* until the arenapool is destroyed, at which point all the arenas are
* freed or returned to a "free arena list", depending on their sizes.
*/
PLArenaPool *
PORT_NewArena(unsigned long chunksize)
{
PORTArenaPool *pool;
if (chunksize > MAX_SIZE) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
pool = PORT_ZNew(PORTArenaPool);
if (!pool) {
return NULL;
}
pool->magic = ARENAPOOL_MAGIC;
pool->lock = PZ_NewLock(nssILockArena);
if (!pool->lock) {
PORT_Free(pool);
return NULL;
}
PL_InitArenaPool(&pool->arena, "security", chunksize, sizeof(double));
return (&pool->arena);
}
void
PORT_InitCheapArena(PORTCheapArenaPool *pool, unsigned long chunksize)
{
pool->magic = CHEAP_ARENAPOOL_MAGIC;
PL_InitArenaPool(&pool->arena, "security", chunksize, sizeof(double));
}
void *
PORT_ArenaAlloc(PLArenaPool *arena, size_t size)
{
void *p = NULL;
PORTArenaPool *pool = (PORTArenaPool *)arena;
if (size <= 0) {
size = 1;
}
if (size > MAX_SIZE) {
/* you lose. */
} else
/* Is it one of ours? Assume so and check the magic */
if (ARENAPOOL_MAGIC == pool->magic) {
PZ_Lock(pool->lock);
#ifdef THREADMARK
/* Most likely one of ours. Is there a thread id? */
if (pool->marking_thread &&
pool->marking_thread != PR_GetCurrentThread()) {
/* Another thread holds a mark in this arena */
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_Assert(0);
return NULL;
} /* tid != null */
#endif /* THREADMARK */
PL_ARENA_ALLOCATE(p, arena, size);
PZ_Unlock(pool->lock);
} else {
PL_ARENA_ALLOCATE(p, arena, size);
}
if (!p) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
}
return (p);
}
void *
PORT_ArenaZAlloc(PLArenaPool *arena, size_t size)
{
void *p;
if (size <= 0)
size = 1;
p = PORT_ArenaAlloc(arena, size);
if (p) {
PORT_Memset(p, 0, size);
}
return (p);
}
static PRCallOnceType setupUseFreeListOnce;
static PRBool useFreeList;
static PRStatus
SetupUseFreeList(void)
{
useFreeList = (PR_GetEnvSecure("NSS_DISABLE_ARENA_FREE_LIST") == NULL);
return PR_SUCCESS;
}
/*
* If zero is true, zeroize the arena memory before freeing it.
*/
void
PORT_FreeArena(PLArenaPool *arena, PRBool zero)
{
PORTArenaPool *pool = (PORTArenaPool *)arena;
PRLock *lock = (PRLock *)0;
size_t len = sizeof *arena;
if (!pool)
return;
if (ARENAPOOL_MAGIC == pool->magic) {
len = sizeof *pool;
lock = pool->lock;
PZ_Lock(lock);
}
if (zero) {
PL_ClearArenaPool(arena, 0);
}
(void)PR_CallOnce(&setupUseFreeListOnce, &SetupUseFreeList);
if (useFreeList) {
PL_FreeArenaPool(arena);
} else {
PL_FinishArenaPool(arena);
}
PORT_ZFree(arena, len);
if (lock) {
PZ_Unlock(lock);
PZ_DestroyLock(lock);
}
}
void
PORT_DestroyCheapArena(PORTCheapArenaPool *pool)
{
(void)PR_CallOnce(&setupUseFreeListOnce, &SetupUseFreeList);
if (useFreeList) {
PL_FreeArenaPool(&pool->arena);
} else {
PL_FinishArenaPool(&pool->arena);
}
}
void *
PORT_ArenaGrow(PLArenaPool *arena, void *ptr, size_t oldsize, size_t newsize)
{
PORTArenaPool *pool = (PORTArenaPool *)arena;
PORT_Assert(newsize >= oldsize);
if (newsize > MAX_SIZE) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
if (ARENAPOOL_MAGIC == pool->magic) {
PZ_Lock(pool->lock);
/* Do we do a THREADMARK check here? */
PL_ARENA_GROW(ptr, arena, oldsize, (newsize - oldsize));
PZ_Unlock(pool->lock);
} else {
PL_ARENA_GROW(ptr, arena, oldsize, (newsize - oldsize));
}
return (ptr);
}
void *
PORT_ArenaMark(PLArenaPool *arena)
{
void *result;
PORTArenaPool *pool = (PORTArenaPool *)arena;
if (ARENAPOOL_MAGIC == pool->magic) {
PZ_Lock(pool->lock);
#ifdef THREADMARK
{
threadmark_mark *tm, **pw;
PRThread *currentThread = PR_GetCurrentThread();
if (!pool->marking_thread) {
/* First mark */
pool->marking_thread = currentThread;
} else if (currentThread != pool->marking_thread) {
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_Assert(0);
return NULL;
}
result = PL_ARENA_MARK(arena);
PL_ARENA_ALLOCATE(tm, arena, sizeof(threadmark_mark));
if (!tm) {
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
return NULL;
}
tm->mark = result;
tm->next = (threadmark_mark *)NULL;
pw = &pool->first_mark;
while (*pw) {
pw = &(*pw)->next;
}
*pw = tm;
}
#else /* THREADMARK */
result = PL_ARENA_MARK(arena);
#endif /* THREADMARK */
PZ_Unlock(pool->lock);
} else {
/* a "pure" NSPR arena */
result = PL_ARENA_MARK(arena);
}
return result;
}
/*
* This function accesses the internals of PLArena, which is why it needs
* to use the NSPR internal macro PL_MAKE_MEM_UNDEFINED before the memset
* calls.
*
* We should move this function to NSPR as PL_ClearArenaAfterMark or add
* a PL_ARENA_CLEAR_AND_RELEASE macro.
*
* TODO: remove the #ifdef PL_MAKE_MEM_UNDEFINED tests when NSPR 4.10+ is
* widely available.
*/
static void
port_ArenaZeroAfterMark(PLArenaPool *arena, void *mark)
{
PLArena *a = arena->current;
if (a->base <= (PRUword)mark && (PRUword)mark <= a->avail) {
/* fast path: mark falls in the current arena */
#ifdef PL_MAKE_MEM_UNDEFINED
PL_MAKE_MEM_UNDEFINED(mark, a->avail - (PRUword)mark);
#endif
memset(mark, 0, a->avail - (PRUword)mark);
} else {
/* slow path: need to find the arena that mark falls in */
for (a = arena->first.next; a; a = a->next) {
PR_ASSERT(a->base <= a->avail && a->avail <= a->limit);
if (a->base <= (PRUword)mark && (PRUword)mark <= a->avail) {
#ifdef PL_MAKE_MEM_UNDEFINED
PL_MAKE_MEM_UNDEFINED(mark, a->avail - (PRUword)mark);
#endif
memset(mark, 0, a->avail - (PRUword)mark);
a = a->next;
break;
}
}
for (; a; a = a->next) {
PR_ASSERT(a->base <= a->avail && a->avail <= a->limit);
#ifdef PL_MAKE_MEM_UNDEFINED
PL_MAKE_MEM_UNDEFINED((void *)a->base, a->avail - a->base);
#endif
memset((void *)a->base, 0, a->avail - a->base);
}
}
}
static void
port_ArenaRelease(PLArenaPool *arena, void *mark, PRBool zero)
{
PORTArenaPool *pool = (PORTArenaPool *)arena;
if (ARENAPOOL_MAGIC == pool->magic) {
PZ_Lock(pool->lock);
#ifdef THREADMARK
{
threadmark_mark **pw;
if (PR_GetCurrentThread() != pool->marking_thread) {
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_Assert(0);
return /* no error indication available */;
}
pw = &pool->first_mark;
while (*pw && (mark != (*pw)->mark)) {
pw = &(*pw)->next;
}
if (!*pw) {
/* bad mark */
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_Assert(0);
return /* no error indication available */;
}
*pw = (threadmark_mark *)NULL;
if (zero) {
port_ArenaZeroAfterMark(arena, mark);
}
PL_ARENA_RELEASE(arena, mark);
if (!pool->first_mark) {
pool->marking_thread = (PRThread *)NULL;
}
}
#else /* THREADMARK */
if (zero) {
port_ArenaZeroAfterMark(arena, mark);
}
PL_ARENA_RELEASE(arena, mark);
#endif /* THREADMARK */
PZ_Unlock(pool->lock);
} else {
if (zero) {
port_ArenaZeroAfterMark(arena, mark);
}
PL_ARENA_RELEASE(arena, mark);
}
}
void
PORT_ArenaRelease(PLArenaPool *arena, void *mark)
{
port_ArenaRelease(arena, mark, PR_FALSE);
}
/*
* Zeroize the arena memory before releasing it.
*/
void
PORT_ArenaZRelease(PLArenaPool *arena, void *mark)
{
port_ArenaRelease(arena, mark, PR_TRUE);
}
void
PORT_ArenaUnmark(PLArenaPool *arena, void *mark)
{
#ifdef THREADMARK
PORTArenaPool *pool = (PORTArenaPool *)arena;
if (ARENAPOOL_MAGIC == pool->magic) {
threadmark_mark **pw;
PZ_Lock(pool->lock);
if (PR_GetCurrentThread() != pool->marking_thread) {
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_Assert(0);
return /* no error indication available */;
}
pw = &pool->first_mark;
while (((threadmark_mark *)NULL != *pw) && (mark != (*pw)->mark)) {
pw = &(*pw)->next;
}
if ((threadmark_mark *)NULL == *pw) {
/* bad mark */
PZ_Unlock(pool->lock);
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_Assert(0);
return /* no error indication available */;
}
*pw = (threadmark_mark *)NULL;
if (!pool->first_mark) {
pool->marking_thread = (PRThread *)NULL;
}
PZ_Unlock(pool->lock);
}
#endif /* THREADMARK */
}
char *
PORT_ArenaStrdup(PLArenaPool *arena, const char *str)
{
int len = PORT_Strlen(str) + 1;
char *newstr;
newstr = (char *)PORT_ArenaAlloc(arena, len);
if (newstr) {
PORT_Memcpy(newstr, str, len);
}
return newstr;
}
/********************** end of arena functions ***********************/
/****************** unicode conversion functions ***********************/
/*
* NOTE: These conversion functions all assume that the multibyte
* characters are going to be in NETWORK BYTE ORDER, not host byte
* order. This is because the only time we deal with UCS-2 and UCS-4
* are when the data was received from or is going to be sent out
* over the wire (in, e.g. certificates).
*/
void
PORT_SetUCS4_UTF8ConversionFunction(PORTCharConversionFunc convFunc)
{
ucs4Utf8ConvertFunc = convFunc;
}
void
PORT_SetUCS2_ASCIIConversionFunction(PORTCharConversionWSwapFunc convFunc)
{
ucs2AsciiConvertFunc = convFunc;
}
void
PORT_SetUCS2_UTF8ConversionFunction(PORTCharConversionFunc convFunc)
{
ucs2Utf8ConvertFunc = convFunc;
}
PRBool
PORT_UCS4_UTF8Conversion(PRBool toUnicode, unsigned char *inBuf,
unsigned int inBufLen, unsigned char *outBuf,
unsigned int maxOutBufLen, unsigned int *outBufLen)
{
if (!ucs4Utf8ConvertFunc) {
return sec_port_ucs4_utf8_conversion_function(toUnicode,
inBuf, inBufLen, outBuf, maxOutBufLen, outBufLen);
}
return (*ucs4Utf8ConvertFunc)(toUnicode, inBuf, inBufLen, outBuf,
maxOutBufLen, outBufLen);
}
PRBool
PORT_UCS2_UTF8Conversion(PRBool toUnicode, unsigned char *inBuf,
unsigned int inBufLen, unsigned char *outBuf,
unsigned int maxOutBufLen, unsigned int *outBufLen)
{
if (!ucs2Utf8ConvertFunc) {
return sec_port_ucs2_utf8_conversion_function(toUnicode,
inBuf, inBufLen, outBuf, maxOutBufLen, outBufLen);
}
return (*ucs2Utf8ConvertFunc)(toUnicode, inBuf, inBufLen, outBuf,
maxOutBufLen, outBufLen);
}
PRBool
PORT_ISO88591_UTF8Conversion(const unsigned char *inBuf,
unsigned int inBufLen, unsigned char *outBuf,
unsigned int maxOutBufLen, unsigned int *outBufLen)
{
return sec_port_iso88591_utf8_conversion_function(inBuf, inBufLen,
outBuf, maxOutBufLen, outBufLen);
}
PRBool
PORT_UCS2_ASCIIConversion(PRBool toUnicode, unsigned char *inBuf,
unsigned int inBufLen, unsigned char *outBuf,
unsigned int maxOutBufLen, unsigned int *outBufLen,
PRBool swapBytes)
{
if (!ucs2AsciiConvertFunc) {
return PR_FALSE;
}
return (*ucs2AsciiConvertFunc)(toUnicode, inBuf, inBufLen, outBuf,
maxOutBufLen, outBufLen, swapBytes);
}
/* Portable putenv. Creates/replaces an environment variable of the form
* envVarName=envValue
*/
int
NSS_PutEnv(const char *envVarName, const char *envValue)
{
SECStatus result = SECSuccess;
#ifdef _WIN32
PRBool setOK;
setOK = SetEnvironmentVariable(envVarName, envValue);
if (!setOK) {
SET_ERROR_CODE
return SECFailure;
}
#elif defined(__GNUC__) && __GNUC__ >= 7
int setEnvFailed;
setEnvFailed = setenv(envVarName, envValue, 1);
if (setEnvFailed) {
SET_ERROR_CODE
return SECFailure;
}
#else
char *encoded = (char *)PORT_ZAlloc(strlen(envVarName) + 2 + strlen(envValue));
if (!encoded) {
return SECFailure;
}
strcpy(encoded, envVarName);
strcat(encoded, "=");
strcat(encoded, envValue);
int putEnvFailed = putenv(encoded); /* adopt. */
if (putEnvFailed) {
SET_ERROR_CODE
result = SECFailure;
PORT_Free(encoded);
}
#endif
return result;
}
/*
* Perform a constant-time compare of two memory regions. The return value is
* 0 if the memory regions are equal and non-zero otherwise.
*/
int
NSS_SecureMemcmp(const void *ia, const void *ib, size_t n)
{
const unsigned char *a = (const unsigned char *)ia;
const unsigned char *b = (const unsigned char *)ib;
int r = 0;
for (size_t i = 0; i < n; ++i) {
r |= a[i] ^ b[i];
}
/* 0 <= r < 256, so -r has bit 8 set when r != 0 */
return 1 & (-r >> 8);
}
/*
* Perform a constant-time check if a memory region is all 0. The return value
* is 0 if the memory region is all zero.
*/
unsigned int
NSS_SecureMemcmpZero(const void *mem, size_t n)
{
const unsigned char *a = (const unsigned char *)mem;
int r = 0;
for (size_t i = 0; i < n; ++i) {
r |= a[i];
}
/* 0 <= r < 256, so -r has bit 8 set when r != 0 */
return 1 & (-r >> 8);
}
/*
* A "value barrier" prevents the compiler from making optimizations based on
* the value that a variable takes.
*
* Standard C does not have value barriers, so C implementations of them are
* compiler-specific and are not guaranteed to be effective. Thus, the value
* barriers here are a best-effort, defense-in-depth, strategy. They are not a
* substitute for standard constant-time programming discipline.
*
* Some implementations have a performance penalty, so value barriers should
* be used sparingly.
*/
static inline int
value_barrier_int(int x)
{
#if defined(__GNUC__) || defined(__clang__)
/* This inline assembly trick from Chandler Carruth's CppCon 2015 talk
* generates no instructions.
*
* "+r"(x) means that x will be mapped to a register that is both an input
* and an output to the assembly routine (""). The compiler will not
* inspect the assembly routine itself, so it cannot assume anything about
* the value of x after this line.
*/
__asm__(""
: "+r"(x)
: /* no other inputs */);
return x;
#else
/* If the compiler does not support the inline assembly trick above, we can
* put x in `volatile` storage and read it out again. This will generate
* explict store and load instructions, and possibly more depending on the
* target.
*/
volatile int y = x;
return y;
#endif
}
/*
* A branch-free implementation of
* if (!b) {
* memmove(dest, src0, n);
* } else {
* memmove(dest, src1, n);
* }
*
* The memmove is performed with src0 if `b == 0` and with src1
* otherwise.
*
* As with memmove, the selected src can overlap dest.
*
* Each of dest, src0, and src1 must point to an allocated buffer
* of at least n bytes.
*/
void
NSS_SecureSelect(void *dest, const void *src0, const void *src1, size_t n, unsigned char b)
{
// This value barrier makes it safe for the compiler to inline
// NSS_SecureSelect into a routine where it could otherwise infer something
// about the value of b, e.g. that b is 0/1 valued.
int w = value_barrier_int(b);
// 0 <= b < 256, and int is at least 16 bits, so -w has bits 8-15
// set when w != 0.
unsigned char mask = 0xff & (-w >> 8);
for (size_t i = 0; i < n; ++i) {
unsigned char s0i = ((unsigned char *)src0)[i];
unsigned char s1i = ((unsigned char *)src1)[i];
// if mask == 0 this simplifies to s0 ^ 0
// if mask == -1 this simplifies to s0 ^ s0 ^ s1
((unsigned char *)dest)[i] = s0i ^ (mask & (s0i ^ s1i));
}
}
/*
* consolidate all the calls to get the system FIPS status in one spot.
* This function allows an environment variable to override what is returned.
*/
PRBool
NSS_GetSystemFIPSEnabled(void)
{
/* if FIPS is disabled in NSS, always return FALSE, even if the environment
* variable is set, or the system is in FIPS mode */
#ifndef NSS_FIPS_DISABLED
const char *env;
/* The environment variable is active for all platforms */
env = PR_GetEnvSecure("NSS_FIPS");
/* we generally accept y, Y, 1, FIPS, TRUE, and ON as turning on FIPS
* mode. Anything else is considered 'off' */
if (env && (*env == 'y' || *env == '1' || *env == 'Y' ||
(PORT_Strcasecmp(env, "fips") == 0) ||
(PORT_Strcasecmp(env, "true") == 0) ||
(PORT_Strcasecmp(env, "on") == 0))) {
return PR_TRUE;
}
/* currently only Linux has a system FIPS indicator. Add others here
* as they become available/known */
#ifdef LINUX
{
FILE *f;
char d;
size_t size;
f = fopen("/proc/sys/crypto/fips_enabled", "r");
if (!f)
return PR_FALSE;
size = fread(&d, 1, 1, f);
fclose(f);
if (size != 1)
return PR_FALSE;
if (d == '1')
return PR_TRUE;
}
#endif /* LINUX */
#endif /* NSS_FIPS_DISABLED == 0 */
return PR_FALSE;
}