Commit cca99621 authored by Dr. Matthias St. Pierre's avatar Dr. Matthias St. Pierre
Browse files

rand_unix.c: don't discard entropy bytes from /dev/*random 



Don't discard partial reads from /dev/*random and retry instead.

Reviewed-by: default avatarAndy Polyakov <appro@openssl.org>
Reviewed-by: default avatarPaul Dale <paul.dale@oracle.com>
Reviewed-by: default avatarTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6990)
parent 630ce41e

crypto/rand/rand_unix.c

+14 −9
Original line number Diff line number Diff line
@@ -493,22 +493,27 @@ size_t rand_pool_acquire_entropy(RAND_POOL *pool) 
        size_t i;



        for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths); i++) {

            ssize_t bytes = 0;

            /* Maximum allowed number of consecutive unsuccessful attempts */

            int attempts = 3;

            const int fd = get_random_device(i);



            if (fd == -1)

                continue;



            while (bytes_needed != 0 && attempts-- > 0) {

                buffer = rand_pool_add_begin(pool, bytes_needed);

            if (buffer != NULL) {

                const ssize_t n = read(fd, buffer, bytes_needed);

                bytes = read(fd, buffer, bytes_needed);



                if (n <= 0) {

                    close_random_device(i);

                    continue;

                if (bytes > 0) {

                    rand_pool_add_end(pool, bytes, 8 * bytes);

                    bytes_needed -= bytes;

                    attempts = 3; /* reset counter after successful attempt */

                } else if (bytes < 0 && errno != EINTR) {

                    break;

                }



                rand_pool_add_end(pool, n, 8 * n);

            }

            if (!keep_random_devices_open)

            if (bytes < 0 || !keep_random_devices_open)

                close_random_device(i);



            bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);