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author | markm <markm@FreeBSD.org> | 2015-07-19 16:05:23 +0000 |
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committer | markm <markm@FreeBSD.org> | 2015-07-19 16:05:23 +0000 |
commit | 3ed54293a28be84e3e5841a06f90394843e9b52d (patch) | |
tree | 808d52d87730a039d4790819cd20e8c656ebae58 /sys/dev/random/randomdev.c | |
parent | 8672831bb490f98611d0eafad6252403cd7b5618 (diff) | |
download | FreeBSD-src-3ed54293a28be84e3e5841a06f90394843e9b52d.zip FreeBSD-src-3ed54293a28be84e3e5841a06f90394843e9b52d.tar.gz |
Optimise the buffer-size calculation. It was possible to get one block too many.
Approved by: so (/dev/random blanket)
Diffstat (limited to 'sys/dev/random/randomdev.c')
-rw-r--r-- | sys/dev/random/randomdev.c | 35 |
1 files changed, 16 insertions, 19 deletions
diff --git a/sys/dev/random/randomdev.c b/sys/dev/random/randomdev.c index 43f905e..8a12777 100644 --- a/sys/dev/random/randomdev.c +++ b/sys/dev/random/randomdev.c @@ -64,6 +64,9 @@ __FBSDID("$FreeBSD$"); #define RANDOM_UNIT 0 +/* Return the largest number >= x that is a multiple of m */ +#define CEIL_TO_MULTIPLE(x, m) ((((x) + (m) - 1)/(m))*(m)) + static d_read_t randomdev_read; static d_write_t randomdev_write; static d_poll_t randomdev_poll; @@ -191,15 +194,15 @@ read_random_uio(struct uio *uio, bool nonblock) * 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 = CEIL_TO_MULTIPLE(read_len, RANDOM_BLOCKSIZE); + /* Work in chunks page-sized or less */ 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 (total_read != uio->uio_resid && (error == ERESTART || error == EINTR) ) + if (total_read != uio->uio_resid && (error == ERESTART || error == EINTR)) /* Return partial read, not error. */ error = 0; } @@ -217,7 +220,7 @@ read_random_uio(struct uio *uio, bool nonblock) u_int read_random(void *random_buf, u_int len) { - u_int read_len, total_read, c; + u_int read_len; uint8_t local_buf[len + RANDOM_BLOCKSIZE]; KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__)); @@ -228,22 +231,16 @@ read_random(void *random_buf, u_int len) /* XXX: FIX!! Next line as an atomic operation? */ 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); - random_alg_context.ra_read(&local_buf[total_read], c); - read_len -= c; - total_read += c; + if (len > 0) { + /* + * Belt-and-braces. + * Round up the read length to a crypto block size multiple, + * which is what the underlying generator is expecting. + */ + read_len = CEIL_TO_MULTIPLE(len, RANDOM_BLOCKSIZE); + random_alg_context.ra_read(local_buf, read_len); + memcpy(random_buf, local_buf, len); } - memcpy(random_buf, local_buf, len); } else len = 0; return (len); |