sys_getrandom.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2018 Conrad Meyer <cem@FreeBSD.org>
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: releng/12.0/sys/kern/sys_getrandom.c 332122 2018-04-06 17:35:35Z brooks $");
   31 
   32 #include <sys/param.h>
   33 #include <sys/errno.h>
   34 #include <sys/limits.h>
   35 #include <sys/proc.h>
   36 #include <sys/random.h>
   37 #include <sys/sysproto.h>
   38 #include <sys/systm.h>
   39 #include <sys/uio.h>
   40 
   41 #define GRND_VALIDFLAGS (GRND_NONBLOCK | GRND_RANDOM)
   42 
   43 /*
   44  * random_read_uio(9) returns EWOULDBLOCK if a nonblocking request would block,
   45  * but the Linux API name is EAGAIN.  On FreeBSD, they have the same numeric
   46  * value for now.
   47  */
   48 CTASSERT(EWOULDBLOCK == EAGAIN);
   49 
   50 static int
   51 kern_getrandom(struct thread *td, void *user_buf, size_t buflen,
   52     unsigned int flags)
   53 {
   54         struct uio auio;
   55         struct iovec aiov;
   56         int error;
   57 
   58         if ((flags & ~GRND_VALIDFLAGS) != 0)
   59                 return (EINVAL);
   60         if (buflen > IOSIZE_MAX)
   61                 return (EINVAL);
   62 
   63         if (buflen == 0) {
   64                 td->td_retval[0] = 0;
   65                 return (0);
   66         }
   67 
   68         aiov.iov_base = user_buf;
   69         aiov.iov_len = buflen;
   70         auio.uio_iov = &aiov;
   71         auio.uio_iovcnt = 1;
   72         auio.uio_offset = 0;
   73         auio.uio_resid = buflen;
   74         auio.uio_segflg = UIO_USERSPACE;
   75         auio.uio_rw = UIO_READ;
   76         auio.uio_td = td;
   77 
   78         error = read_random_uio(&auio, (flags & GRND_NONBLOCK) != 0);
   79         if (error == 0)
   80                 td->td_retval[0] = buflen - auio.uio_resid;
   81         return (error);
   82 }
   83 
   84 #ifndef _SYS_SYSPROTO_H_
   85 struct getrandom_args {
   86         void            *buf;
   87         size_t          buflen;
   88         unsigned int    flags;
   89 };
   90 #endif
   91 
   92 int
   93 sys_getrandom(struct thread *td, struct getrandom_args *uap)
   94 {
   95         return (kern_getrandom(td, uap->buf, uap->buflen, uap->flags));
   96 }

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FreeBSD/Linux Kernel Cross Reference sys/kern/sys_getrandom.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_getrandom.c