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This patch implements an API whereby an application can determine the
label of its peer's Unix datagram sockets via the auxiliary data mechanism of
recvmsg.
Patch purpose:
This patch enables a security-aware application to retrieve the
security context of the peer of a Unix datagram socket. The application
can then use this security context to determine the security context for
processing on behalf of the peer who sent the packet.
Patch design and implementation:
The design and implementation is very similar to the UDP case for INET
sockets. Basically we build upon the existing Unix domain socket API for
retrieving user credentials. Linux offers the API for obtaining user
credentials via ancillary messages (i.e., out of band/control messages
that are bundled together with a normal message). To retrieve the security
context, the application first indicates to the kernel such desire by
setting the SO_PASSSEC option via getsockopt. Then the application
retrieves the security context using the auxiliary data mechanism.
An example server application for Unix datagram socket should look like this:
toggle = 1;
toggle_len = sizeof(toggle);
setsockopt(sockfd, SOL_SOCKET, SO_PASSSEC, &toggle, &toggle_len);
recvmsg(sockfd, &msg_hdr, 0);
if (msg_hdr.msg_controllen > sizeof(struct cmsghdr)) {
cmsg_hdr = CMSG_FIRSTHDR(&msg_hdr);
if (cmsg_hdr->cmsg_len <= CMSG_LEN(sizeof(scontext)) &&
cmsg_hdr->cmsg_level == SOL_SOCKET &&
cmsg_hdr->cmsg_type == SCM_SECURITY) {
memcpy(&scontext, CMSG_DATA(cmsg_hdr), sizeof(scontext));
}
}
sock_setsockopt is enhanced with a new socket option SOCK_PASSSEC to allow
a server socket to receive security context of the peer.
Testing:
We have tested the patch by setting up Unix datagram client and server
applications. We verified that the server can retrieve the security context
using the auxiliary data mechanism of recvmsg.
Signed-off-by: Catherine Zhang <cxzhang@watson.ibm.com>
Acked-by: Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
107 lines
3.1 KiB
C
107 lines
3.1 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1997, 1999, 2000, 2001 Ralf Baechle
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* Copyright (C) 2000, 2001 Silicon Graphics, Inc.
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*/
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#ifndef _ASM_SOCKET_H
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#define _ASM_SOCKET_H
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#include <asm/sockios.h>
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/*
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* For setsockopt(2)
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*
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* This defines are ABI conformant as far as Linux supports these ...
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*/
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#define SOL_SOCKET 0xffff
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#define SO_DEBUG 0x0001 /* Record debugging information. */
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#define SO_REUSEADDR 0x0004 /* Allow reuse of local addresses. */
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#define SO_KEEPALIVE 0x0008 /* Keep connections alive and send
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SIGPIPE when they die. */
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#define SO_DONTROUTE 0x0010 /* Don't do local routing. */
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#define SO_BROADCAST 0x0020 /* Allow transmission of
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broadcast messages. */
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#define SO_LINGER 0x0080 /* Block on close of a reliable
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socket to transmit pending data. */
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#define SO_OOBINLINE 0x0100 /* Receive out-of-band data in-band. */
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#if 0
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To add: #define SO_REUSEPORT 0x0200 /* Allow local address and port reuse. */
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#endif
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#define SO_TYPE 0x1008 /* Compatible name for SO_STYLE. */
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#define SO_STYLE SO_TYPE /* Synonym */
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#define SO_ERROR 0x1007 /* get error status and clear */
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#define SO_SNDBUF 0x1001 /* Send buffer size. */
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#define SO_RCVBUF 0x1002 /* Receive buffer. */
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#define SO_SNDLOWAT 0x1003 /* send low-water mark */
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#define SO_RCVLOWAT 0x1004 /* receive low-water mark */
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#define SO_SNDTIMEO 0x1005 /* send timeout */
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#define SO_RCVTIMEO 0x1006 /* receive timeout */
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#define SO_ACCEPTCONN 0x1009
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/* linux-specific, might as well be the same as on i386 */
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#define SO_NO_CHECK 11
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#define SO_PRIORITY 12
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#define SO_BSDCOMPAT 14
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#define SO_PASSCRED 17
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#define SO_PEERCRED 18
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/* Security levels - as per NRL IPv6 - don't actually do anything */
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#define SO_SECURITY_AUTHENTICATION 22
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#define SO_SECURITY_ENCRYPTION_TRANSPORT 23
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#define SO_SECURITY_ENCRYPTION_NETWORK 24
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#define SO_BINDTODEVICE 25
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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#define SCM_TIMESTAMP SO_TIMESTAMP
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#define SO_PEERSEC 30
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#define SO_SNDBUFFORCE 31
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#define SO_RCVBUFFORCE 33
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#define SO_PASSSEC 34
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#ifdef __KERNEL__
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/** sock_type - Socket types
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*
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* Please notice that for binary compat reasons MIPS has to
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* override the enum sock_type in include/linux/net.h, so
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* we define ARCH_HAS_SOCKET_TYPES here.
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*
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* @SOCK_DGRAM - datagram (conn.less) socket
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* @SOCK_STREAM - stream (connection) socket
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* @SOCK_RAW - raw socket
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* @SOCK_RDM - reliably-delivered message
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* @SOCK_SEQPACKET - sequential packet socket
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* @SOCK_PACKET - linux specific way of getting packets at the dev level.
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* For writing rarp and other similar things on the user level.
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*/
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enum sock_type {
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SOCK_DGRAM = 1,
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SOCK_STREAM = 2,
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SOCK_RAW = 3,
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SOCK_RDM = 4,
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SOCK_SEQPACKET = 5,
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SOCK_DCCP = 6,
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SOCK_PACKET = 10,
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};
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#define SOCK_MAX (SOCK_PACKET + 1)
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#define ARCH_HAS_SOCKET_TYPES 1
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#endif /* __KERNEL__ */
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#endif /* _ASM_SOCKET_H */
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