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Rework the read routines to keep the PRNG sources happy. These work

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in units of crypto blocks, so must have adequate space to write.
This means needing to be careful about buffers and keeping track
of external read request length.

Approved by:	so (/dev/random blanket)
This commit is contained in:
markm 2015-07-13 08:38:21 +00:00
parent 610f9926f9
commit 054d3d8bb0
1 changed files with 24 additions and 7 deletions
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31
sys/dev/random/randomdev.c
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@ -153,8 +153,8 @@ static int
randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags)
{
uint8_t *random_buf;
int c, error;
ssize_t nbytes;
int error;
ssize_t read_len, total_read, c;
random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
random_alg_context.ra_pre_read();
@ -175,14 +175,24 @@ randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags)
/* XXX: FIX!! Next line as an atomic operation? */
read_rate += (uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t);
#endif
nbytes = uio->uio_resid;
total_read = 0;
while (uio->uio_resid && !error) {
c = MIN(uio->uio_resid, PAGE_SIZE);
/* See the random_buf size requirements in the Yarrow/Fortuna code */
random_alg_context.ra_read(random_buf, c);
read_len = uio->uio_resid;
/*
* Belt-and-braces.
* Round up the read length to a crypto block size multiple,
* which is what the underlying generator is expecting.
* See the random_buf size requirements in the Yarrow/Fortuna code.
*/
read_len += RANDOM_BLOCKSIZE;
read_len -= read_len % RANDOM_BLOCKSIZE;
read_len = MIN(read_len, PAGE_SIZE);
random_alg_context.ra_read(random_buf, read_len);
c = MIN(uio->uio_resid, read_len);
error = uiomove(random_buf, c, uio);
total_read += c;
}
if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR) )
if (total_read != uio->uio_resid && (error == ERESTART || error == EINTR) )
/* Return partial read, not error. */
error = 0;
}
@ -212,6 +222,13 @@ read_random(void *random_buf, u_int len)
read_rate += (len + sizeof(uint32_t))/sizeof(uint32_t);
#endif
read_len = len;
/*
* Belt-and-braces.
* Round up the read length to a crypto block size multiple,
* which is what the underlying generator is expecting.
*/
read_len += RANDOM_BLOCKSIZE;
read_len -= read_len % RANDOM_BLOCKSIZE;
total_read = 0;
while (read_len) {
c = MIN(read_len, PAGE_SIZE);