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kernel-aes67/include/linux/in.h
Catherine Zhang 2c7946a7bf [SECURITY]: TCP/UDP getpeersec 
This patch implements an application of the LSM-IPSec networking
controls whereby an application can determine the label of the
security association its TCP or UDP sockets are currently connected to
via getsockopt and the auxiliary data mechanism of recvmsg.

Patch purpose:

This patch enables a security-aware application to retrieve the
security context of an IPSec security association a particular TCP or
UDP socket is using.  The application can then use this security
context to determine the security context for processing on behalf of
the peer at the other end of this connection.  In the case of UDP, the
security context is for each individual packet.  An example
application is the inetd daemon, which could be modified to start
daemons running at security contexts dependent on the remote client.

Patch design approach:

- Design for TCP
The patch enables the SELinux LSM to set the peer security context for
a socket based on the security context of the IPSec security
association.  The application may retrieve this context using
getsockopt.  When called, the kernel determines if the socket is a
connected (TCP_ESTABLISHED) TCP socket and, if so, uses the dst_entry
cache on the socket to retrieve the security associations.  If a
security association has a security context, the context string is
returned, as for UNIX domain sockets.

- Design for UDP
Unlike TCP, UDP is connectionless.  This requires a somewhat different
API to retrieve the peer security context.  With TCP, the peer
security context stays the same throughout the connection, thus it can
be retrieved at any time between when the connection is established
and when it is torn down.  With UDP, each read/write can have
different peer and thus the security context might change every time.
As a result the security context retrieval must be done TOGETHER with
the packet retrieval.

The solution is to 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).

Patch implementation details:

- Implementation for TCP
The security context can be retrieved by applications using getsockopt
with the existing SO_PEERSEC flag.  As an example (ignoring error
checking):

getsockopt(sockfd, SOL_SOCKET, SO_PEERSEC, optbuf, &optlen);
printf("Socket peer context is: %s\n", optbuf);

The SELinux function, selinux_socket_getpeersec, is extended to check
for labeled security associations for connected (TCP_ESTABLISHED ==
sk->sk_state) TCP sockets only.  If so, the socket has a dst_cache of
struct dst_entry values that may refer to security associations.  If
these have security associations with security contexts, the security
context is returned.

getsockopt returns a buffer that contains a security context string or
the buffer is unmodified.

- Implementation for UDP
To retrieve the security context, the application first indicates to
the kernel such desire by setting the IP_PASSSEC option via
getsockopt.  Then the application retrieves the security context using
the auxiliary data mechanism.

An example server application for UDP should look like this:

toggle = 1;
toggle_len = sizeof(toggle);

setsockopt(sockfd, SOL_IP, IP_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_IP &&
        cmsg_hdr->cmsg_type == SCM_SECURITY) {
        memcpy(&scontext, CMSG_DATA(cmsg_hdr), sizeof(scontext));
    }
}

ip_setsockopt is enhanced with a new socket option IP_PASSSEC to allow
a server socket to receive security context of the peer.  A new
ancillary message type SCM_SECURITY.

When the packet is received we get the security context from the
sec_path pointer which is contained in the sk_buff, and copy it to the
ancillary message space.  An additional LSM hook,
selinux_socket_getpeersec_udp, is defined to retrieve the security
context from the SELinux space.  The existing function,
selinux_socket_getpeersec does not suit our purpose, because the
security context is copied directly to user space, rather than to
kernel space.

Testing:

We have tested the patch by setting up TCP and UDP connections between
applications on two machines using the IPSec policies that result in
labeled security associations being built.  For TCP, we can then
extract the peer security context using getsockopt on either end.  For
UDP, the receiving end can retrieve the security context using the
auxiliary data mechanism of recvmsg.

Signed-off-by: Catherine Zhang <cxzhang@watson.ibm.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20 22:41:23 -08:00

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/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Definitions of the Internet Protocol.
*
* Version: @(#)in.h 1.0.1 04/21/93
*
* Authors: Original taken from the GNU Project <netinet/in.h> file.
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _LINUX_IN_H
#define _LINUX_IN_H
#include <linux/types.h>
#include <linux/socket.h>
/* Standard well-defined IP protocols. */
enum {
IPPROTO_IP = 0, /* Dummy protocol for TCP */
IPPROTO_ICMP = 1, /* Internet Control Message Protocol */
IPPROTO_IGMP = 2, /* Internet Group Management Protocol */
IPPROTO_IPIP = 4, /* IPIP tunnels (older KA9Q tunnels use 94) */
IPPROTO_TCP = 6, /* Transmission Control Protocol */
IPPROTO_EGP = 8, /* Exterior Gateway Protocol */
IPPROTO_PUP = 12, /* PUP protocol */
IPPROTO_UDP = 17, /* User Datagram Protocol */
IPPROTO_IDP = 22, /* XNS IDP protocol */
IPPROTO_DCCP = 33, /* Datagram Congestion Control Protocol */
IPPROTO_RSVP = 46, /* RSVP protocol */
IPPROTO_GRE = 47, /* Cisco GRE tunnels (rfc 1701,1702) */
IPPROTO_IPV6 = 41, /* IPv6-in-IPv4 tunnelling */
IPPROTO_ESP = 50, /* Encapsulation Security Payload protocol */
IPPROTO_AH = 51, /* Authentication Header protocol */
IPPROTO_PIM = 103, /* Protocol Independent Multicast */
IPPROTO_COMP = 108, /* Compression Header protocol */
IPPROTO_SCTP = 132, /* Stream Control Transport Protocol */
IPPROTO_RAW = 255, /* Raw IP packets */
IPPROTO_MAX
};
/* Internet address. */
struct in_addr {
__u32 s_addr;
};
#define IP_TOS 1
#define IP_TTL 2
#define IP_HDRINCL 3
#define IP_OPTIONS 4
#define IP_ROUTER_ALERT 5
#define IP_RECVOPTS 6
#define IP_RETOPTS 7
#define IP_PKTINFO 8
#define IP_PKTOPTIONS 9
#define IP_MTU_DISCOVER 10
#define IP_RECVERR 11
#define IP_RECVTTL 12
#define IP_RECVTOS 13
#define IP_MTU 14
#define IP_FREEBIND 15
#define IP_IPSEC_POLICY 16
#define IP_XFRM_POLICY 17
#define IP_PASSSEC 18
/* BSD compatibility */
#define IP_RECVRETOPTS IP_RETOPTS
/* IP_MTU_DISCOVER values */
#define IP_PMTUDISC_DONT 0 /* Never send DF frames */
#define IP_PMTUDISC_WANT 1 /* Use per route hints */
#define IP_PMTUDISC_DO 2 /* Always DF */
#define IP_MULTICAST_IF 32
#define IP_MULTICAST_TTL 33
#define IP_MULTICAST_LOOP 34
#define IP_ADD_MEMBERSHIP 35
#define IP_DROP_MEMBERSHIP 36
#define IP_UNBLOCK_SOURCE 37
#define IP_BLOCK_SOURCE 38
#define IP_ADD_SOURCE_MEMBERSHIP 39
#define IP_DROP_SOURCE_MEMBERSHIP 40
#define IP_MSFILTER 41
#define MCAST_JOIN_GROUP 42
#define MCAST_BLOCK_SOURCE 43
#define MCAST_UNBLOCK_SOURCE 44
#define MCAST_LEAVE_GROUP 45
#define MCAST_JOIN_SOURCE_GROUP 46
#define MCAST_LEAVE_SOURCE_GROUP 47
#define MCAST_MSFILTER 48
#define MCAST_EXCLUDE 0
#define MCAST_INCLUDE 1
/* These need to appear somewhere around here */
#define IP_DEFAULT_MULTICAST_TTL 1
#define IP_DEFAULT_MULTICAST_LOOP 1
/* Request struct for multicast socket ops */
struct ip_mreq
{
struct in_addr imr_multiaddr; /* IP multicast address of group */
struct in_addr imr_interface; /* local IP address of interface */
};
struct ip_mreqn
{
struct in_addr imr_multiaddr; /* IP multicast address of group */
struct in_addr imr_address; /* local IP address of interface */
int imr_ifindex; /* Interface index */
};
struct ip_mreq_source {
__u32 imr_multiaddr;
__u32 imr_interface;
__u32 imr_sourceaddr;
};
struct ip_msfilter {
__u32 imsf_multiaddr;
__u32 imsf_interface;
__u32 imsf_fmode;
__u32 imsf_numsrc;
__u32 imsf_slist[1];
};
#define IP_MSFILTER_SIZE(numsrc) \
(sizeof(struct ip_msfilter) - sizeof(__u32) \
+ (numsrc) * sizeof(__u32))
struct group_req
{
__u32 gr_interface; /* interface index */
struct __kernel_sockaddr_storage gr_group; /* group address */
};
struct group_source_req
{
__u32 gsr_interface; /* interface index */
struct __kernel_sockaddr_storage gsr_group; /* group address */
struct __kernel_sockaddr_storage gsr_source; /* source address */
};
struct group_filter
{
__u32 gf_interface; /* interface index */
struct __kernel_sockaddr_storage gf_group; /* multicast address */
__u32 gf_fmode; /* filter mode */
__u32 gf_numsrc; /* number of sources */
struct __kernel_sockaddr_storage gf_slist[1]; /* interface index */
};
#define GROUP_FILTER_SIZE(numsrc) \
(sizeof(struct group_filter) - sizeof(struct __kernel_sockaddr_storage) \
+ (numsrc) * sizeof(struct __kernel_sockaddr_storage))
struct in_pktinfo
{
int ipi_ifindex;
struct in_addr ipi_spec_dst;
struct in_addr ipi_addr;
};
/* Structure describing an Internet (IP) socket address. */
#define __SOCK_SIZE__ 16 /* sizeof(struct sockaddr) */
struct sockaddr_in {
sa_family_t sin_family; /* Address family */
unsigned short int sin_port; /* Port number */
struct in_addr sin_addr; /* Internet address */
/* Pad to size of `struct sockaddr'. */
unsigned char __pad[__SOCK_SIZE__ - sizeof(short int) -
sizeof(unsigned short int) - sizeof(struct in_addr)];
};
#define sin_zero __pad /* for BSD UNIX comp. -FvK */
/*
* Definitions of the bits in an Internet address integer.
* On subnets, host and network parts are found according
* to the subnet mask, not these masks.
*/
#define IN_CLASSA(a) ((((long int) (a)) & 0x80000000) == 0)
#define IN_CLASSA_NET 0xff000000
#define IN_CLASSA_NSHIFT 24
#define IN_CLASSA_HOST (0xffffffff & ~IN_CLASSA_NET)
#define IN_CLASSA_MAX 128
#define IN_CLASSB(a) ((((long int) (a)) & 0xc0000000) == 0x80000000)
#define IN_CLASSB_NET 0xffff0000
#define IN_CLASSB_NSHIFT 16
#define IN_CLASSB_HOST (0xffffffff & ~IN_CLASSB_NET)
#define IN_CLASSB_MAX 65536
#define IN_CLASSC(a) ((((long int) (a)) & 0xe0000000) == 0xc0000000)
#define IN_CLASSC_NET 0xffffff00
#define IN_CLASSC_NSHIFT 8
#define IN_CLASSC_HOST (0xffffffff & ~IN_CLASSC_NET)
#define IN_CLASSD(a) ((((long int) (a)) & 0xf0000000) == 0xe0000000)
#define IN_MULTICAST(a) IN_CLASSD(a)
#define IN_MULTICAST_NET 0xF0000000
#define IN_EXPERIMENTAL(a) ((((long int) (a)) & 0xf0000000) == 0xf0000000)
#define IN_BADCLASS(a) IN_EXPERIMENTAL((a))
/* Address to accept any incoming messages. */
#define INADDR_ANY ((unsigned long int) 0x00000000)
/* Address to send to all hosts. */
#define INADDR_BROADCAST ((unsigned long int) 0xffffffff)
/* Address indicating an error return. */
#define INADDR_NONE ((unsigned long int) 0xffffffff)
/* Network number for local host loopback. */
#define IN_LOOPBACKNET 127
/* Address to loopback in software to local host. */
#define INADDR_LOOPBACK 0x7f000001 /* 127.0.0.1 */
#define IN_LOOPBACK(a) ((((long int) (a)) & 0xff000000) == 0x7f000000)
/* Defines for Multicast INADDR */
#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */
#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */
#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */
#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */
/* <asm/byteorder.h> contains the htonl type stuff.. */
#include <asm/byteorder.h>
#ifdef __KERNEL__
/* Some random defines to make it easier in the kernel.. */
#define LOOPBACK(x) (((x) & htonl(0xff000000)) == htonl(0x7f000000))
#define MULTICAST(x) (((x) & htonl(0xf0000000)) == htonl(0xe0000000))
#define BADCLASS(x) (((x) & htonl(0xf0000000)) == htonl(0xf0000000))
#define ZERONET(x) (((x) & htonl(0xff000000)) == htonl(0x00000000))
#define LOCAL_MCAST(x) (((x) & htonl(0xFFFFFF00)) == htonl(0xE0000000))
#endif
#endif /* _LINUX_IN_H */
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