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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>
54 lines
1.3 KiB
C
54 lines
1.3 KiB
C
#ifndef _ASM_SOCKET_H
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#define _ASM_SOCKET_H
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#include <asm/sockios.h>
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/* For setsockopt(2) */
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#define SOL_SOCKET 0xffff
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#define SO_DEBUG 0x0001
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#define SO_REUSEADDR 0x0004
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#define SO_KEEPALIVE 0x0008
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#define SO_DONTROUTE 0x0010
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#define SO_BROADCAST 0x0020
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#define SO_LINGER 0x0080
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#define SO_OOBINLINE 0x0100
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/* To add :#define SO_REUSEPORT 0x0200 */
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#define SO_SNDBUF 0x1001
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#define SO_RCVBUF 0x1002
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#define SO_SNDBUFFORCE 0x100a
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#define SO_RCVBUFFORCE 0x100b
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#define SO_SNDLOWAT 0x1003
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#define SO_RCVLOWAT 0x1004
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#define SO_SNDTIMEO 0x1005
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#define SO_RCVTIMEO 0x1006
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#define SO_ERROR 0x1007
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#define SO_TYPE 0x1008
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#define SO_PEERNAME 0x2000
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#define SO_NO_CHECK 0x400b
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#define SO_PRIORITY 0x400c
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#define SO_BSDCOMPAT 0x400e
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#define SO_PASSCRED 0x4010
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#define SO_PEERCRED 0x4011
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#define SO_TIMESTAMP 0x4012
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#define SCM_TIMESTAMP SO_TIMESTAMP
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/* Security levels - as per NRL IPv6 - don't actually do anything */
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#define SO_SECURITY_AUTHENTICATION 0x4016
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#define SO_SECURITY_ENCRYPTION_TRANSPORT 0x4017
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#define SO_SECURITY_ENCRYPTION_NETWORK 0x4018
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#define SO_BINDTODEVICE 0x4019
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/* Socket filtering */
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#define SO_ATTACH_FILTER 0x401a
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#define SO_DETACH_FILTER 0x401b
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#define SO_ACCEPTCONN 0x401c
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#define SO_PEERSEC 0x401d
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#define SO_PASSSEC 0x401e
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#endif /* _ASM_SOCKET_H */
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