Initial commit
This commit is contained in:
Sergey Kishchenko
342
kernel/capability.c
Executable file
342
kernel/capability.c
Executable file
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/*
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* linux/kernel/capability.c
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*
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* Copyright (C) 1997 Andrew Main <zefram@fysh.org>
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*
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* Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org>
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* 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
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*/
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#include <linux/capability.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/pid_namespace.h>
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#include <asm/uaccess.h>
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/*
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* This lock protects task->cap_* for all tasks including current.
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* Locking rule: acquire this prior to tasklist_lock.
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*/
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static DEFINE_SPINLOCK(task_capability_lock);
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/*
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* Leveraged for setting/resetting capabilities
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*/
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const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
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const kernel_cap_t __cap_full_set = CAP_FULL_SET;
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const kernel_cap_t __cap_init_eff_set = CAP_INIT_EFF_SET;
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EXPORT_SYMBOL(__cap_empty_set);
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EXPORT_SYMBOL(__cap_full_set);
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EXPORT_SYMBOL(__cap_init_eff_set);
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/*
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* More recent versions of libcap are available from:
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*
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* http://www.kernel.org/pub/linux/libs/security/linux-privs/
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*/
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static void warn_legacy_capability_use(void)
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{
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static int warned;
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if (!warned) {
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char name[sizeof(current->comm)];
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printk(KERN_INFO "warning: `%s' uses 32-bit capabilities"
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" (legacy support in use)\n",
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get_task_comm(name, current));
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warned = 1;
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}
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}
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/*
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* For sys_getproccap() and sys_setproccap(), any of the three
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* capability set pointers may be NULL -- indicating that that set is
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* uninteresting and/or not to be changed.
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*/
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/**
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* sys_capget - get the capabilities of a given process.
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* @header: pointer to struct that contains capability version and
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* target pid data
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* @dataptr: pointer to struct that contains the effective, permitted,
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* and inheritable capabilities that are returned
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*
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* Returns 0 on success and < 0 on error.
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*/
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asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
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{
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int ret = 0;
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pid_t pid;
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__u32 version;
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struct task_struct *target;
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unsigned tocopy;
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kernel_cap_t pE, pI, pP;
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if (get_user(version, &header->version))
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return -EFAULT;
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switch (version) {
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case _LINUX_CAPABILITY_VERSION_1:
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warn_legacy_capability_use();
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tocopy = _LINUX_CAPABILITY_U32S_1;
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break;
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case _LINUX_CAPABILITY_VERSION_2:
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tocopy = _LINUX_CAPABILITY_U32S_2;
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break;
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default:
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if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
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return -EFAULT;
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return -EINVAL;
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}
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if (get_user(pid, &header->pid))
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return -EFAULT;
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if (pid < 0)
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return -EINVAL;
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spin_lock(&task_capability_lock);
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read_lock(&tasklist_lock);
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if (pid && pid != task_pid_vnr(current)) {
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target = find_task_by_vpid(pid);
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if (!target) {
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ret = -ESRCH;
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goto out;
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}
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} else
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target = current;
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ret = security_capget(target, &pE, &pI, &pP);
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out:
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read_unlock(&tasklist_lock);
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spin_unlock(&task_capability_lock);
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if (!ret) {
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struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S];
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unsigned i;
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for (i = 0; i < tocopy; i++) {
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kdata[i].effective = pE.cap[i];
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kdata[i].permitted = pP.cap[i];
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kdata[i].inheritable = pI.cap[i];
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}
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/*
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* Note, in the case, tocopy < _LINUX_CAPABILITY_U32S,
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* we silently drop the upper capabilities here. This
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* has the effect of making older libcap
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* implementations implicitly drop upper capability
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* bits when they perform a: capget/modify/capset
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* sequence.
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*
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* This behavior is considered fail-safe
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* behavior. Upgrading the application to a newer
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* version of libcap will enable access to the newer
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* capabilities.
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*
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* An alternative would be to return an error here
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* (-ERANGE), but that causes legacy applications to
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* unexpectidly fail; the capget/modify/capset aborts
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* before modification is attempted and the application
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* fails.
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*/
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if (copy_to_user(dataptr, kdata, tocopy
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* sizeof(struct __user_cap_data_struct))) {
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return -EFAULT;
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}
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}
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return ret;
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}
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/*
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* cap_set_pg - set capabilities for all processes in a given process
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* group. We call this holding task_capability_lock and tasklist_lock.
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*/
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static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
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kernel_cap_t *inheritable,
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kernel_cap_t *permitted)
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{
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struct task_struct *g, *target;
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int ret = -EPERM;
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int found = 0;
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struct pid *pgrp;
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pgrp = find_vpid(pgrp_nr);
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do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
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target = g;
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while_each_thread(g, target) {
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if (!security_capset_check(target, effective,
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inheritable,
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permitted)) {
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security_capset_set(target, effective,
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inheritable,
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permitted);
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ret = 0;
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}
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found = 1;
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}
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} while_each_pid_task(pgrp, PIDTYPE_PGID, g);
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if (!found)
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ret = 0;
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return ret;
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}
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/*
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* cap_set_all - set capabilities for all processes other than init
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* and self. We call this holding task_capability_lock and tasklist_lock.
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*/
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static inline int cap_set_all(kernel_cap_t *effective,
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kernel_cap_t *inheritable,
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kernel_cap_t *permitted)
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{
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struct task_struct *g, *target;
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int ret = -EPERM;
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int found = 0;
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do_each_thread(g, target) {
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if (target == current || is_container_init(target->group_leader))
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continue;
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found = 1;
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if (security_capset_check(target, effective, inheritable,
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permitted))
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continue;
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ret = 0;
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security_capset_set(target, effective, inheritable, permitted);
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} while_each_thread(g, target);
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if (!found)
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ret = 0;
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return ret;
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}
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/**
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* sys_capset - set capabilities for a process or a group of processes
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* @header: pointer to struct that contains capability version and
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* target pid data
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* @data: pointer to struct that contains the effective, permitted,
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* and inheritable capabilities
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*
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* Set capabilities for a given process, all processes, or all
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* processes in a given process group.
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*
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* The restrictions on setting capabilities are specified as:
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*
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* [pid is for the 'target' task. 'current' is the calling task.]
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*
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* I: any raised capabilities must be a subset of the (old current) permitted
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* P: any raised capabilities must be a subset of the (old current) permitted
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* E: must be set to a subset of (new target) permitted
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*
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* Returns 0 on success and < 0 on error.
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*/
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asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
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{
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struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S];
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unsigned i, tocopy;
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kernel_cap_t inheritable, permitted, effective;
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__u32 version;
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struct task_struct *target;
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int ret;
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pid_t pid;
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if (get_user(version, &header->version))
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return -EFAULT;
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switch (version) {
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case _LINUX_CAPABILITY_VERSION_1:
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warn_legacy_capability_use();
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tocopy = _LINUX_CAPABILITY_U32S_1;
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break;
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case _LINUX_CAPABILITY_VERSION_2:
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tocopy = _LINUX_CAPABILITY_U32S_2;
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break;
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default:
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if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
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return -EFAULT;
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return -EINVAL;
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}
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if (get_user(pid, &header->pid))
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return -EFAULT;
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if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP))
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return -EPERM;
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if (copy_from_user(&kdata, data, tocopy
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* sizeof(struct __user_cap_data_struct))) {
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return -EFAULT;
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}
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for (i = 0; i < tocopy; i++) {
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effective.cap[i] = kdata[i].effective;
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permitted.cap[i] = kdata[i].permitted;
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inheritable.cap[i] = kdata[i].inheritable;
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}
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while (i < _LINUX_CAPABILITY_U32S) {
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effective.cap[i] = 0;
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permitted.cap[i] = 0;
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inheritable.cap[i] = 0;
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i++;
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}
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spin_lock(&task_capability_lock);
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read_lock(&tasklist_lock);
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if (pid > 0 && pid != task_pid_vnr(current)) {
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target = find_task_by_vpid(pid);
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if (!target) {
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ret = -ESRCH;
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goto out;
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}
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} else
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target = current;
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ret = 0;
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/* having verified that the proposed changes are legal,
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we now put them into effect. */
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if (pid < 0) {
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if (pid == -1) /* all procs other than current and init */
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ret = cap_set_all(&effective, &inheritable, &permitted);
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else /* all procs in process group */
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ret = cap_set_pg(-pid, &effective, &inheritable,
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&permitted);
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} else {
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ret = security_capset_check(target, &effective, &inheritable,
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&permitted);
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if (!ret)
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security_capset_set(target, &effective, &inheritable,
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&permitted);
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}
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out:
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read_unlock(&tasklist_lock);
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spin_unlock(&task_capability_lock);
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return ret;
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}
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int __capable(struct task_struct *t, int cap)
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{
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if (security_capable(t, cap) == 0) {
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t->flags |= PF_SUPERPRIV;
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return 1;
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}
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return 0;
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}
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int capable(int cap)
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{
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return __capable(current, cap);
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}
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EXPORT_SYMBOL(capable);
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