Commit 630ce41e authored by Dr. Matthias St. Pierre's avatar Dr. Matthias St. Pierre
Browse files

rand_unix.c: don't discard entropy bytes from syscall_random() 



Fixes #6978

Don't discard partial reads from syscall_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 9b5f1c8f

crypto/rand/rand_unix.c

+17 −9
Original line number Diff line number Diff line
@@ -458,17 +458,25 @@ size_t rand_pool_acquire_entropy(RAND_POOL *pool) 
    unsigned char *buffer;



#   ifdef OPENSSL_RAND_SEED_GETRANDOM

    {

        ssize_t bytes;

        /* Maximum allowed number of consecutive unsuccessful attempts */

        int attempts = 3;



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

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

            buffer = rand_pool_add_begin(pool, bytes_needed);

    if (buffer != NULL) {

        size_t bytes = 0;



        if (syscall_random(buffer, bytes_needed) == (int)bytes_needed)

            bytes = bytes_needed;



            bytes = syscall_random(buffer, bytes_needed);

            if (bytes > 0) {

                rand_pool_add_end(pool, bytes, 8 * bytes);

        entropy_available = rand_pool_entropy_available(pool);

                bytes_needed -= bytes;

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

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

                break;

            }

        }

    }

    entropy_available = rand_pool_entropy_available(pool);

    if (entropy_available > 0)

        return entropy_available;

#   endif