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This commit is contained in:
Michael Graff
2000-06-08 23:42:17 +00:00
parent 5c14b1acbe
commit 118332fc5c
1 changed files with 98 additions and 5 deletions
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103
lib/isc/unix/entropy.c
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@@ -65,6 +65,7 @@
typedef struct {
isc_uint32_t cursor; /* current add point in the pool */
isc_uint32_t entropy; /* current entropy estimate in bits */
isc_uint32_t pseudo; /* bits extracted in pseudorandom */
isc_uint32_t rotate; /* how many bits to rotate by */
isc_uint32_t pool[RND_POOLWORDS]; /* random pool data */
} isc_entropypool_t;
@@ -219,12 +220,88 @@ entropypool_adddata(isc_entropypool_t *rp, void *p, unsigned int len,
rp->entropy = RND_POOLBITS;
}
static isc_uint32_t
get_from_filesource(isc_entropysource_t *source, isc_uint32_t desired) {
isc_entropypool_t *pool = &source->ent->pool;
unsigned char buf[128];
int fd = source->sources.file.fd;
ssize_t n, ndesired;
u_int32_t added = 0;
if (fd == -1)
return (0);
desired = desired / 8 + (((desired & 0x07) == 1) ? 0 : 1);
while (desired > 0) {
ndesired = ISC_MIN(desired, sizeof(buf));
n = read(fd, buf, ndesired);
if (n < 0) {
if (errno == EAGAIN)
goto out;
close(fd);
source->sources.file.fd = -1;
}
if (n == 0)
goto out;
entropypool_adddata(pool, buf, n, n * 8);
added += n * 8;
}
out:
return (added);
}
/*
* Poll each source, trying to get data from it to stuff into the entropy
* pool.
*/
static void
fillpool(isc_entropy_t *ent, unsigned int needed, isc_boolean_t blocking) {
isc_uint32_t added, desired;
isc_entropysource_t *source;
if (needed < RND_ENTROPY_THRESHOLD * 8)
needed = RND_ENTROPY_THRESHOLD * 8;
if (needed > RND_POOLBITS)
needed = RND_POOLBITS;
added = 0;
/*
* Poll each file source to see if we can read anything useful from
* it. XXXMLG When where are multiple sources, we should keep a
* record of which one we last used so we can start from it (or the
* next one) to avoid letting some sources build up entropy while
* others are always drained.
*/
source = ISC_LIST_HEAD(ent->sources);
while (source != NULL) {
desired = ISC_MIN(needed, RND_POOLBITS - ent->pool.entropy);
if (source->type == ENTROPY_SOURCETYPE_FILE)
added += get_from_filesource(source, desired);
if (added > needed)
break;
source = ISC_LIST_NEXT(source, link);
}
/*
* If we added any data, decrement the pseudo variable by
* how much we added.
*/
if (ent->pool.pseudo <= added)
ent->pool.pseudo = 0;
else
ent->pool.pseudo -= added;
/*
* Increment the amount of entropy we have in the pool.
*/
ent->pool.entropy = ISC_MIN(ent->pool.entropy + added, RND_POOLBITS);
}
/*
@@ -287,11 +364,24 @@ isc_entropy_getdata(isc_entropy_t *ent, void *data, unsigned int length,
while (remain != 0) {
count = ISC_MIN(remain, RND_ENTROPY_THRESHOLD);
/* Try to get more entropy if we need it. */
/*
* If we are extracting good data only, make certain we
* have enough data in our pool for this pass. If we don't,
* get some, and fail if we can't, and partial returns
* are not ok.
*/
if (goodonly) {
fillpool(ent, remain * 8, blocking);
if (!partial && (ENTROPY(ent) < count * 8))
fillpool(ent, count * 8, blocking);
if (!partial
&& ((ENTROPY(ent) < count * 8)
|| (ENTROPY(ent) < RND_ENTROPY_THRESHOLD * 8)))
goto zeroize;
} else {
/*
* If we've extracted half our pool size in bits
* since the last refresh, try to refresh here.
*/
fillpool(ent, 0, ISC_FALSE);
}
isc_sha1_init(&hash);
@@ -320,13 +410,14 @@ isc_entropy_getdata(isc_entropy_t *ent, void *data, unsigned int length,
memset(digest, 0, sizeof(digest));
if (*returned != NULL)
*returned = length;
*returned = (length - remain);
return (ISC_R_SUCCESS);
zeroize:
/* put the entropy we almost extracted back */
entropypool_adddata(&ent->pool, data, length, total);
ent->pool.entropy += total;
ent->pool.entropy = ISC_MIN(ent->pool.entropy, RND_POOLBITS);
memset(data, 0, length);
memset(digest, 0, sizeof(digest));
if (*returned != NULL)
@@ -339,6 +430,7 @@ static void
isc_entropypool_init(isc_entropypool_t *pool) {
pool->cursor = RND_POOLWORDS - 1;
pool->entropy = 0;
pool->pseudo = 0;
pool->rotate = 0;
memset(pool->pool, 0, RND_POOLWORDS);
}
@@ -347,6 +439,7 @@ static void
isc_entropypool_invalidate(isc_entropypool_t *pool) {
pool->cursor = 0;
pool->entropy = 0;
pool->pseudo = 0;
pool->rotate = 0;
memset(pool->pool, 0, RND_POOLWORDS);
}