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Restore sysv_ipc.c:1.30, which was backed out due to interactions with

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System V shared memory, now believed fixed in sysv_shm.c:1.109:

  date: 2006/11/06 13:42:01;  author: rwatson;  state: Exp;  lines: +65 -37
  Sweep kernel replacing suser(9) calls with priv(9) calls, assigning
  specific privilege names to a broad range of privileges.  These may
  require some future tweaking.

  Sponsored by:           nCircle Network Security, Inc.
  Obtained from:          TrustedBSD Project
  Discussed on:           arch@
  Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
                          Alex Lyashkov <umka at sevcity dot net>,
                          Skip Ford <skip dot ford at verizon dot net>,
                          Antoine Brodin <antoine dot brodin at laposte dot net>

This restores fine-grained privilege support to System V IPC.

PR:	106078
This commit is contained in:
Robert Watson 2007-02-19 22:59:23 +00:00
parent 3d50b06b8e
commit b12c55ab92
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=166836
1 changed files with 65 additions and 37 deletions
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102
sys/kern/sysv_ipc.c
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@ -1,8 +1,12 @@
/* $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */
/*-
* Copyright (c) 1994 Herb Peyerl <hpeyerl@novatel.ca>
* Copyright (c) 2006 nCircle Network Security, Inc.
* All rights reserved.
*
* This software was developed by Robert N. M. Watson for the TrustedBSD
* Project under contract to nCircle Network Security, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
@ -39,6 +43,7 @@ __FBSDID("$FreeBSD$");
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/ipc.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/ucred.h>
@ -72,50 +77,73 @@ shmexit(struct vmspace *vm)
* Note: The MAC Framework does not require any modifications to the
* ipcperm() function, as access control checks are performed throughout the
* implementation of each primitive. Those entry point calls complement the
* ipcperm() discertionary checks.
* ipcperm() discertionary checks. Unlike file system discretionary access
* control, the original create of an object is given the same rights as the
* current owner.
*/
int
ipcperm(td, perm, mode)
struct thread *td;
struct ipc_perm *perm;
int mode;
ipcperm(struct thread *td, struct ipc_perm *perm, int acc_mode)
{
struct ucred *cred = td->td_ucred;
int error;
int error, obj_mode, dac_granted, priv_granted;
if (cred->cr_uid != perm->cuid && cred->cr_uid != perm->uid) {
/*
* For a non-create/owner, we require privilege to
* modify the object protections. Note: some other
* implementations permit IPC_M to be delegated to
* unprivileged non-creator/owner uids/gids.
*/
if (mode & IPC_M) {
error = suser(td);
if (error)
return (error);
}
/*
* Try to match against creator/owner group; if not, fall
* back on other.
*/
mode >>= 3;
if (!groupmember(perm->gid, cred) &&
!groupmember(perm->cgid, cred))
mode >>= 3;
dac_granted = 0;
if (cred->cr_uid == perm->cuid || cred->cr_uid == perm->uid) {
obj_mode = perm->mode;
dac_granted |= IPC_M;
} else if (groupmember(perm->gid, cred) ||
groupmember(perm->cgid, cred)) {
obj_mode = perm->mode;
obj_mode <<= 3;
} else {
/*
* Always permit the creator/owner to update the object
* protections regardless of whether the object mode
* permits it.
*/
if (mode & IPC_M)
return (0);
obj_mode = perm->mode;
obj_mode <<= 6;
}
if ((mode & perm->mode) != mode) {
if (suser(td) != 0)
return (EACCES);
/*
* While the System V IPC permission model allows IPC_M to be
* granted, as part of the mode, our implementation requires
* privilege to adminster the object if not the owner or creator.
*/
#if 0
if (obj_mode & IPC_M)
dac_granted |= IPC_M;
#endif
if (obj_mode & IPC_R)
dac_granted |= IPC_R;
if (obj_mode & IPC_W)
dac_granted |= IPC_W;
/*
* Simple case: all required rights are granted by DAC.
*/
if ((dac_granted & acc_mode) == acc_mode)
return (0);
/*
* Privilege is required to satisfy the request.
*/
priv_granted = 0;
if ((acc_mode & IPC_M) && !(dac_granted & IPC_M)) {
error = priv_check(td, PRIV_IPC_ADMIN);
if (error == 0)
priv_granted |= IPC_M;
}
return (0);
if ((acc_mode & IPC_R) && !(dac_granted & IPC_R)) {
error = priv_check(td, PRIV_IPC_READ);
if (error == 0)
priv_granted |= IPC_R;
}
if ((acc_mode & IPC_W) && !(dac_granted & IPC_W)) {
error = priv_check(td, PRIV_IPC_WRITE);
if (error == 0)
priv_granted |= IPC_W;
}
if (((dac_granted | priv_granted) & acc_mode) == acc_mode)
return (0);
else
return (EACCES);
}