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linux-next/security/capability.c
Serge Hallyn aedb60a67c file capabilities: remove cap_task_kill()
The original justification for cap_task_kill() was as follows:

	check_kill_permission() does appropriate uid equivalence checks.
	However with file capabilities it becomes possible for an
	unprivileged user to execute a file with file capabilities
	resulting in a more privileged task with the same uid.

However now that cap_task_kill() always returns 0 (permission
granted) when p->uid==current->uid, the whole hook is worthless,
and only likely to create more subtle problems in the corner cases
where it might still be called but return -EPERM.  Those cases
are basically when uids are different but euid/suid is equivalent
as per the check in check_kill_permission().

One example of a still-broken application is 'at' for non-root users.

This patch removes cap_task_kill().

Signed-off-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Earlier-version-tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-20 09:46:36 -07:00

82 lines
2.3 KiB
C

/*
* Capabilities Linux Security Module
*
* 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.
*
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/security.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/ptrace.h>
#include <linux/moduleparam.h>
static struct security_operations capability_ops = {
.ptrace = cap_ptrace,
.capget = cap_capget,
.capset_check = cap_capset_check,
.capset_set = cap_capset_set,
.capable = cap_capable,
.settime = cap_settime,
.netlink_send = cap_netlink_send,
.netlink_recv = cap_netlink_recv,
.bprm_apply_creds = cap_bprm_apply_creds,
.bprm_set_security = cap_bprm_set_security,
.bprm_secureexec = cap_bprm_secureexec,
.inode_setxattr = cap_inode_setxattr,
.inode_removexattr = cap_inode_removexattr,
.inode_need_killpriv = cap_inode_need_killpriv,
.inode_killpriv = cap_inode_killpriv,
.task_setscheduler = cap_task_setscheduler,
.task_setioprio = cap_task_setioprio,
.task_setnice = cap_task_setnice,
.task_post_setuid = cap_task_post_setuid,
.task_reparent_to_init = cap_task_reparent_to_init,
.syslog = cap_syslog,
.vm_enough_memory = cap_vm_enough_memory,
};
/* flag to keep track of how we were registered */
static int secondary;
static int capability_disable;
module_param_named(disable, capability_disable, int, 0);
static int __init capability_init (void)
{
if (capability_disable) {
printk(KERN_INFO "Capabilities disabled at initialization\n");
return 0;
}
/* register ourselves with the security framework */
if (register_security (&capability_ops)) {
/* try registering with primary module */
if (mod_reg_security (KBUILD_MODNAME, &capability_ops)) {
printk (KERN_INFO "Failure registering capabilities "
"with primary security module.\n");
return -EINVAL;
}
secondary = 1;
}
printk (KERN_INFO "Capability LSM initialized%s\n",
secondary ? " as secondary" : "");
return 0;
}
security_initcall (capability_init);