877ce7c1b3
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
1.1 KiB
C
54 lines
1.1 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 1
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#define SO_DEBUG 1
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#define SO_REUSEADDR 2
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#define SO_TYPE 3
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#define SO_ERROR 4
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#define SO_DONTROUTE 5
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#define SO_BROADCAST 6
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#define SO_SNDBUF 7
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#define SO_RCVBUF 8
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#define SO_SNDBUFFORCE 32
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#define SO_RCVBUFFORCE 33
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#define SO_KEEPALIVE 9
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#define SO_OOBINLINE 10
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#define SO_NO_CHECK 11
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#define SO_PRIORITY 12
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#define SO_LINGER 13
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#define SO_BSDCOMPAT 14
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/* To add :#define SO_REUSEPORT 15 */
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#define SO_PASSCRED 16
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#define SO_PEERCRED 17
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#define SO_RCVLOWAT 18
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#define SO_SNDLOWAT 19
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#define SO_RCVTIMEO 20
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#define SO_SNDTIMEO 21
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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_ACCEPTCONN 30
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#define SO_PEERSEC 31
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#define SO_PASSSEC 34
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#endif /* _ASM_SOCKET_H */
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