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freebsd-dev/sys/compat/svr4/svr4_ioctl.c
Pawel Jakub Dawidek 7008be5bd7 Change the cap_rights_t type from uint64_t to a structure that we can extend 
in the future in a backward compatible (API and ABI) way.

The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.

The structure definition looks like this:

	struct cap_rights {
		uint64_t	cr_rights[CAP_RIGHTS_VERSION + 2];
	};

The initial CAP_RIGHTS_VERSION is 0.

The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.

The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.

To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.

	#define	CAP_PDKILL	CAPRIGHT(1, 0x0000000000000800ULL)

We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:

	#define	CAP_LOOKUP	CAPRIGHT(0, 0x0000000000000400ULL)
	#define	CAP_FCHMOD	CAPRIGHT(0, 0x0000000000002000ULL)

	#define	CAP_FCHMODAT	(CAP_FCHMOD | CAP_LOOKUP)

There is new API to manage the new cap_rights_t structure:

	cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
	void cap_rights_set(cap_rights_t *rights, ...);
	void cap_rights_clear(cap_rights_t *rights, ...);
	bool cap_rights_is_set(const cap_rights_t *rights, ...);

	bool cap_rights_is_valid(const cap_rights_t *rights);
	void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
	void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
	bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);

Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:

	cap_rights_t rights;

	cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);

There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:

	#define	cap_rights_set(rights, ...)				\
		__cap_rights_set((rights), __VA_ARGS__, 0ULL)
	void __cap_rights_set(cap_rights_t *rights, ...);

Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:

	cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);

Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.

This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.

Sponsored by:	The FreeBSD Foundation
2013-09-05 00:09:56 +00:00

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/*-
* Copyright (c) 1998 Mark Newton
* Copyright (c) 1994 Christos Zoulas
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/capability.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/fcntl.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <compat/svr4/svr4.h>
#include <compat/svr4/svr4_types.h>
#include <compat/svr4/svr4_util.h>
#include <compat/svr4/svr4_signal.h>
#include <compat/svr4/svr4_proto.h>
#include <compat/svr4/svr4_stropts.h>
#include <compat/svr4/svr4_ioctl.h>
#include <compat/svr4/svr4_termios.h>
#include <compat/svr4/svr4_filio.h>
#include <compat/svr4/svr4_sockio.h>
#ifdef DEBUG_SVR4
static void svr4_decode_cmd(u_long, char *, char *, int *, int *);
/*
* Decode an ioctl command symbolically
*/
static void
svr4_decode_cmd(cmd, dir, c, num, argsiz)
u_long cmd;
char *dir, *c;
int *num, *argsiz;
{
if (cmd & SVR4_IOC_VOID)
*dir++ = 'V';
if (cmd & SVR4_IOC_IN)
*dir++ = 'R';
if (cmd & SVR4_IOC_OUT)
*dir++ = 'W';
*dir = '\0';
if (cmd & SVR4_IOC_INOUT)
*argsiz = (cmd >> 16) & 0xff;
else
*argsiz = -1;
*c = (cmd >> 8) & 0xff;
*num = cmd & 0xff;
}
#endif
int
svr4_sys_ioctl(td, uap)
struct thread *td;
struct svr4_sys_ioctl_args *uap;
{
int *retval;
cap_rights_t rights;
struct file *fp;
u_long cmd;
int (*fun)(struct file *, struct thread *, register_t *,
int, u_long, caddr_t);
int error;
#ifdef DEBUG_SVR4
char dir[4];
char c;
int num;
int argsiz;
svr4_decode_cmd(uap->com, dir, &c, &num, &argsiz);
DPRINTF(("svr4_ioctl[%lx](%d, _IO%s(%c, %d, %d), %p);\n", uap->com, uap->fd,
dir, c, num, argsiz, uap->data));
#endif
retval = td->td_retval;
cmd = uap->com;
error = fget(td, uap->fd, cap_rights_init(&rights, CAP_IOCTL), &fp);
if (error != 0)
return (error);
if ((fp->f_flag & (FREAD | FWRITE)) == 0) {
fdrop(fp, td);
return EBADF;
}
#if defined(DEBUG_SVR4)
if (fp->f_type == DTYPE_SOCKET) {
struct socket *so = fp->f_data;
DPRINTF(("<<< IN: so_state = 0x%x\n", so->so_state));
}
#endif
switch (cmd & 0xff00) {
case SVR4_TIOC:
DPRINTF(("term\n"));
fun = svr4_term_ioctl;
break;
case SVR4_STR:
DPRINTF(("stream\n"));
fun = svr4_stream_ioctl;
break;
case SVR4_FIOC:
DPRINTF(("file\n"));
fun = svr4_fil_ioctl;
break;
case SVR4_SIOC:
DPRINTF(("socket\n"));
fun = svr4_sock_ioctl;
break;
case SVR4_XIOC:
/* We do not support those */
fdrop(fp, td);
return EINVAL;
default:
fdrop(fp, td);
DPRINTF(("Unimplemented ioctl %lx\n", cmd));
return 0; /* XXX: really ENOSYS */
}
#if defined(DEBUG_SVR4)
if (fp->f_type == DTYPE_SOCKET) {
struct socket *so;
so = fp->f_data;
DPRINTF((">>> OUT: so_state = 0x%x\n", so->so_state));
}
#endif
error = (*fun)(fp, td, retval, uap->fd, cmd, uap->data);
fdrop(fp, td);
return (error);
}
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