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/* Copyright (C) 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <asm/posix_types.h>
/* The kernel expects this structure in SCM_CREDS messages.
* Note: sizeof(struct __kernel_ucred) <= sizeof(struct cmsgcred) must hold.
*/
struct kernel_ucred
{
__kernel_pid_t pid;
__kernel_uid_t uid;
__kernel_gid_t gid;
};
struct credmsg
{
struct cmsghdr cm;
struct cmsgcred cc;
};
struct kcredmsg
{
struct cmsghdr cm;
struct kernel_ucred cc;
};
extern int __syscall_sendmsg (int, const struct msghdr *, int);
/* Send a message described by MESSAGE on socket FD.
Returns the number of bytes sent, or -1 for errors. */
int
__libc_sendmsg (int fd, const struct msghdr *message, int flags)
{
struct msghdr m;
char *buf, *a, *b;
struct credmsg *cred = 0;
struct kcredmsg *kcred;
struct cmsghdr *cm;
long int offset = 0;
pid_t pid;
/* Preprocess the message control block for SCM_CREDS. */
if (message->msg_controllen)
{
cm = CMSG_FIRSTHDR (message);
while (cm)
{
if (cm->cmsg_type == SCM_CREDS)
{
if (cred ||
cm->cmsg_len < CMSG_LEN (sizeof (struct cmsgcred)))
{
__set_errno (EINVAL);
return -1;
}
else
{
cred = (struct credmsg *) cm;
offset = (char *) cm - (char *) message->msg_control;
}
}
cm = CMSG_NXTHDR ((struct msghdr *) message, cm);
}
if (cred)
{
buf = alloca (message->msg_controllen);
memcpy (buf, message->msg_control, message->msg_controllen);
kcred = (struct kcredmsg *) (buf + offset);
a = (char *) kcred + CMSG_LEN (sizeof (struct kernel_ucred));
b = (char *) kcred + CMSG_LEN (sizeof (struct cmsgcred));
memmove (a, b, message->msg_controllen - (b - buf));
kcred->cm.cmsg_len = CMSG_LEN (sizeof (struct kernel_ucred));
/* Linux expects the calling process to pass in
its credentials, and sanity checks them.
You can send real, effective, or set- uid and gid.
If the user hasn't filled in the buffer, we default to
real uid and gid. */
pid = __getpid ();
if (cred->cc.cmcred_pid != pid)
{
kcred->cc.pid = pid;
kcred->cc.uid = __getuid ();
kcred->cc.gid = __getgid ();
}
else
{
kcred->cc.uid = cred->cc.cmcred_uid;
kcred->cc.gid = cred->cc.cmcred_gid;
}
memcpy (&m, message, sizeof (struct msghdr));
m.msg_control = buf;
m.msg_controllen -= b - a;
return __syscall_sendmsg (fd, &m, flags);
}
}
return __syscall_sendmsg (fd, message, flags);
}
weak_alias (__libc_sendmsg, sendmsg)
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