linux/arch/mips/include/uapi/asm/socket.h
David Herrmann 28b5ba2aa0 net: introduce SO_PEERGROUPS getsockopt
This adds the new getsockopt(2) option SO_PEERGROUPS on SOL_SOCKET to
retrieve the auxiliary groups of the remote peer. It is designed to
naturally extend SO_PEERCRED. That is, the underlying data is from the
same credentials. Regarding its syntax, it is based on SO_PEERSEC. That
is, if the provided buffer is too small, ERANGE is returned and @optlen
is updated. Otherwise, the information is copied, @optlen is set to the
actual size, and 0 is returned.

While SO_PEERCRED (and thus `struct ucred') already returns the primary
group, it lacks the auxiliary group vector. However, nearly all access
controls (including kernel side VFS and SYSVIPC, but also user-space
polkit, DBus, ...) consider the entire set of groups, rather than just
the primary group. But this is currently not possible with pure
SO_PEERCRED. Instead, user-space has to work around this and query the
system database for the auxiliary groups of a UID retrieved via
SO_PEERCRED.

Unfortunately, there is no race-free way to query the auxiliary groups
of the PID/UID retrieved via SO_PEERCRED. Hence, the current user-space
solution is to use getgrouplist(3p), which itself falls back to NSS and
whatever is configured in nsswitch.conf(3). This effectively checks
which groups we *would* assign to the user if it logged in *now*. On
normal systems it is as easy as reading /etc/group, but with NSS it can
resort to quering network databases (eg., LDAP), using IPC or network
communication.

Long story short: Whenever we want to use auxiliary groups for access
checks on IPC, we need further IPC to talk to the user/group databases,
rather than just relying on SO_PEERCRED and the incoming socket. This
is unfortunate, and might even result in dead-locks if the database
query uses the same IPC as the original request.

So far, those recursions / dead-locks have been avoided by using
primitive IPC for all crucial NSS modules. However, we want to avoid
re-inventing the wheel for each NSS module that might be involved in
user/group queries. Hence, we would preferably make DBus (and other IPC
that supports access-management based on groups) work without resorting
to the user/group database. This new SO_PEERGROUPS ioctl would allow us
to make dbus-daemon work without ever calling into NSS.

Cc: Michal Sekletar <msekleta@redhat.com>
Cc: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-21 11:38:41 -04:00

124 lines
3.2 KiB
C

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1997, 1999, 2000, 2001 Ralf Baechle
* Copyright (C) 2000, 2001 Silicon Graphics, Inc.
*/
#ifndef _UAPI_ASM_SOCKET_H
#define _UAPI_ASM_SOCKET_H
#include <asm/sockios.h>
/*
* For setsockopt(2)
*
* This defines are ABI conformant as far as Linux supports these ...
*/
#define SOL_SOCKET 0xffff
#define SO_DEBUG 0x0001 /* Record debugging information. */
#define SO_REUSEADDR 0x0004 /* Allow reuse of local addresses. */
#define SO_KEEPALIVE 0x0008 /* Keep connections alive and send
SIGPIPE when they die. */
#define SO_DONTROUTE 0x0010 /* Don't do local routing. */
#define SO_BROADCAST 0x0020 /* Allow transmission of
broadcast messages. */
#define SO_LINGER 0x0080 /* Block on close of a reliable
socket to transmit pending data. */
#define SO_OOBINLINE 0x0100 /* Receive out-of-band data in-band. */
#define SO_REUSEPORT 0x0200 /* Allow local address and port reuse. */
#define SO_TYPE 0x1008 /* Compatible name for SO_STYLE. */
#define SO_STYLE SO_TYPE /* Synonym */
#define SO_ERROR 0x1007 /* get error status and clear */
#define SO_SNDBUF 0x1001 /* Send buffer size. */
#define SO_RCVBUF 0x1002 /* Receive buffer. */
#define SO_SNDLOWAT 0x1003 /* send low-water mark */
#define SO_RCVLOWAT 0x1004 /* receive low-water mark */
#define SO_SNDTIMEO 0x1005 /* send timeout */
#define SO_RCVTIMEO 0x1006 /* receive timeout */
#define SO_ACCEPTCONN 0x1009
#define SO_PROTOCOL 0x1028 /* protocol type */
#define SO_DOMAIN 0x1029 /* domain/socket family */
/* linux-specific, might as well be the same as on i386 */
#define SO_NO_CHECK 11
#define SO_PRIORITY 12
#define SO_BSDCOMPAT 14
#define SO_PASSCRED 17
#define SO_PEERCRED 18
/* Security levels - as per NRL IPv6 - don't actually do anything */
#define SO_SECURITY_AUTHENTICATION 22
#define SO_SECURITY_ENCRYPTION_TRANSPORT 23
#define SO_SECURITY_ENCRYPTION_NETWORK 24
#define SO_BINDTODEVICE 25
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
#define SCM_TIMESTAMP SO_TIMESTAMP
#define SO_PEERSEC 30
#define SO_SNDBUFFORCE 31
#define SO_RCVBUFFORCE 33
#define SO_PASSSEC 34
#define SO_TIMESTAMPNS 35
#define SCM_TIMESTAMPNS SO_TIMESTAMPNS
#define SO_MARK 36
#define SO_TIMESTAMPING 37
#define SCM_TIMESTAMPING SO_TIMESTAMPING
#define SO_RXQ_OVFL 40
#define SO_WIFI_STATUS 41
#define SCM_WIFI_STATUS SO_WIFI_STATUS
#define SO_PEEK_OFF 42
/* Instruct lower device to use last 4-bytes of skb data as FCS */
#define SO_NOFCS 43
#define SO_LOCK_FILTER 44
#define SO_SELECT_ERR_QUEUE 45
#define SO_BUSY_POLL 46
#define SO_MAX_PACING_RATE 47
#define SO_BPF_EXTENSIONS 48
#define SO_INCOMING_CPU 49
#define SO_ATTACH_BPF 50
#define SO_DETACH_BPF SO_DETACH_FILTER
#define SO_ATTACH_REUSEPORT_CBPF 51
#define SO_ATTACH_REUSEPORT_EBPF 52
#define SO_CNX_ADVICE 53
#define SCM_TIMESTAMPING_OPT_STATS 54
#define SO_MEMINFO 55
#define SO_INCOMING_NAPI_ID 56
#define SO_COOKIE 57
#define SCM_TIMESTAMPING_PKTINFO 58
#define SO_PEERGROUPS 59
#endif /* _UAPI_ASM_SOCKET_H */