arc4random.h

/*  $OpenBSD: arc4random_linux.h,v 1.12 2019/07/11 10:37:28 inoguchi Exp $  */

/*
 * Copyright (c) 1996, David Mazieres <[email protected]>
 * Copyright (c) 2008, Damien Miller <[email protected]>
 * Copyright (c) 2013, Markus Friedl <[email protected]>
 * Copyright (c) 2014, Theo de Raadt <[email protected]>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Stub functions for portability.  From LibreSSL with some adaptations.
 */

#include <sys/mman.h>

#include <signal.h>

/* OpenSSH isn't multithreaded */
#define _ARC4_LOCK()
#define _ARC4_UNLOCK()
#define _ARC4_ATFORK(f)

static inline void
_getentropy_fail(void)
{
    fatal("getentropy failed");
}

static volatile sig_atomic_t _rs_forked;

static inline void
_rs_forkhandler(void)
{
    _rs_forked = 1;
}

static inline void
_rs_forkdetect(void)
{
    static pid_t _rs_pid = 0;
    pid_t pid = getpid();

    if (_rs_pid == 0 || _rs_pid == 1 || _rs_pid != pid || _rs_forked) {
        _rs_pid = pid;
        _rs_forked = 0;
        if (rs)
            memset(rs, 0, sizeof(*rs));
    }
}

static inline int
_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
{
#if defined(MAP_ANON) && defined(MAP_PRIVATE)
    if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
        MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
        return (-1);

    if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
        MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
        munmap(*rsp, sizeof(**rsp));
        *rsp = NULL;
        return (-1);
    }
#else
    if ((*rsp = calloc(1, sizeof(**rsp))) == NULL)
        return (-1);
    if ((*rsxp = calloc(1, sizeof(**rsxp))) == NULL) {
        free(*rsp);
        *rsp = NULL;
        return (-1);
    }
#endif

    _ARC4_ATFORK(_rs_forkhandler);
    return (0);
}