linux/kernel/capability.c
Sukadev Bhattiprolu f400e198b2 [PATCH] pidspace: is_init()
This is an updated version of Eric Biederman's is_init() patch.
(http://lkml.org/lkml/2006/2/6/280).  It applies cleanly to 2.6.18-rc3 and
replaces a few more instances of ->pid == 1 with is_init().

Further, is_init() checks pid and thus removes dependency on Eric's other
patches for now.

Eric's original description:

	There are a lot of places in the kernel where we test for init
	because we give it special properties.  Most  significantly init
	must not die.  This results in code all over the kernel test
	->pid == 1.

	Introduce is_init to capture this case.

	With multiple pid spaces for all of the cases affected we are
	looking for only the first process on the system, not some other
	process that has pid == 1.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: <lxc-devel@lists.sourceforge.net>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:12 -07:00

252 lines
6.6 KiB
C

/*
* linux/kernel/capability.c
*
* Copyright (C) 1997 Andrew Main <zefram@fysh.org>
*
* Integrated into 2.1.97+, Andrew G. Morgan <morgan@transmeta.com>
* 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
*/
#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <asm/uaccess.h>
unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
EXPORT_SYMBOL(securebits);
EXPORT_SYMBOL(cap_bset);
/*
* This lock protects task->cap_* for all tasks including current.
* Locking rule: acquire this prior to tasklist_lock.
*/
static DEFINE_SPINLOCK(task_capability_lock);
/*
* For sys_getproccap() and sys_setproccap(), any of the three
* capability set pointers may be NULL -- indicating that that set is
* uninteresting and/or not to be changed.
*/
/**
* sys_capget - get the capabilities of a given process.
* @header: pointer to struct that contains capability version and
* target pid data
* @dataptr: pointer to struct that contains the effective, permitted,
* and inheritable capabilities that are returned
*
* Returns 0 on success and < 0 on error.
*/
asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
{
int ret = 0;
pid_t pid;
__u32 version;
struct task_struct *target;
struct __user_cap_data_struct data;
if (get_user(version, &header->version))
return -EFAULT;
if (version != _LINUX_CAPABILITY_VERSION) {
if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
return -EFAULT;
return -EINVAL;
}
if (get_user(pid, &header->pid))
return -EFAULT;
if (pid < 0)
return -EINVAL;
spin_lock(&task_capability_lock);
read_lock(&tasklist_lock);
if (pid && pid != current->pid) {
target = find_task_by_pid(pid);
if (!target) {
ret = -ESRCH;
goto out;
}
} else
target = current;
ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
out:
read_unlock(&tasklist_lock);
spin_unlock(&task_capability_lock);
if (!ret && copy_to_user(dataptr, &data, sizeof data))
return -EFAULT;
return ret;
}
/*
* cap_set_pg - set capabilities for all processes in a given process
* group. We call this holding task_capability_lock and tasklist_lock.
*/
static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
kernel_cap_t *inheritable,
kernel_cap_t *permitted)
{
struct task_struct *g, *target;
int ret = -EPERM;
int found = 0;
do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
target = g;
while_each_thread(g, target) {
if (!security_capset_check(target, effective,
inheritable,
permitted)) {
security_capset_set(target, effective,
inheritable,
permitted);
ret = 0;
}
found = 1;
}
} while_each_task_pid(pgrp, PIDTYPE_PGID, g);
if (!found)
ret = 0;
return ret;
}
/*
* cap_set_all - set capabilities for all processes other than init
* and self. We call this holding task_capability_lock and tasklist_lock.
*/
static inline int cap_set_all(kernel_cap_t *effective,
kernel_cap_t *inheritable,
kernel_cap_t *permitted)
{
struct task_struct *g, *target;
int ret = -EPERM;
int found = 0;
do_each_thread(g, target) {
if (target == current || is_init(target))
continue;
found = 1;
if (security_capset_check(target, effective, inheritable,
permitted))
continue;
ret = 0;
security_capset_set(target, effective, inheritable, permitted);
} while_each_thread(g, target);
if (!found)
ret = 0;
return ret;
}
/**
* sys_capset - set capabilities for a process or a group of processes
* @header: pointer to struct that contains capability version and
* target pid data
* @data: pointer to struct that contains the effective, permitted,
* and inheritable capabilities
*
* Set capabilities for a given process, all processes, or all
* processes in a given process group.
*
* The restrictions on setting capabilities are specified as:
*
* [pid is for the 'target' task. 'current' is the calling task.]
*
* I: any raised capabilities must be a subset of the (old current) permitted
* P: any raised capabilities must be a subset of the (old current) permitted
* E: must be set to a subset of (new target) permitted
*
* Returns 0 on success and < 0 on error.
*/
asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
{
kernel_cap_t inheritable, permitted, effective;
__u32 version;
struct task_struct *target;
int ret;
pid_t pid;
if (get_user(version, &header->version))
return -EFAULT;
if (version != _LINUX_CAPABILITY_VERSION) {
if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
return -EFAULT;
return -EINVAL;
}
if (get_user(pid, &header->pid))
return -EFAULT;
if (pid && pid != current->pid && !capable(CAP_SETPCAP))
return -EPERM;
if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
return -EFAULT;
spin_lock(&task_capability_lock);
read_lock(&tasklist_lock);
if (pid > 0 && pid != current->pid) {
target = find_task_by_pid(pid);
if (!target) {
ret = -ESRCH;
goto out;
}
} else
target = current;
ret = 0;
/* having verified that the proposed changes are legal,
we now put them into effect. */
if (pid < 0) {
if (pid == -1) /* all procs other than current and init */
ret = cap_set_all(&effective, &inheritable, &permitted);
else /* all procs in process group */
ret = cap_set_pg(-pid, &effective, &inheritable,
&permitted);
} else {
ret = security_capset_check(target, &effective, &inheritable,
&permitted);
if (!ret)
security_capset_set(target, &effective, &inheritable,
&permitted);
}
out:
read_unlock(&tasklist_lock);
spin_unlock(&task_capability_lock);
return ret;
}
int __capable(struct task_struct *t, int cap)
{
if (security_capable(t, cap) == 0) {
t->flags |= PF_SUPERPRIV;
return 1;
}
return 0;
}
EXPORT_SYMBOL(__capable);
int capable(int cap)
{
return __capable(current, cap);
}
EXPORT_SYMBOL(capable);