/* * linux/kernel/capability.c * * Copyright (C) 1997  Andrew Main <zefram@fysh.org> * * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@kernel.org> * 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 <linux/pid_namespace.h>#include <asm/uaccess.h> /* * This lock protects task->cap_* for all tasks including current. * Locking rule: acquire this prior to tasklist_lock. */static DEFINE_SPINLOCK(task_capability_lock); /* * Leveraged for setting/resetting capabilities */ const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;const kernel_cap_t __cap_full_set = CAP_FULL_SET;const kernel_cap_t __cap_init_eff_set = CAP_INIT_EFF_SET; EXPORT_SYMBOL(__cap_empty_set);EXPORT_SYMBOL(__cap_full_set);EXPORT_SYMBOL(__cap_init_eff_set); /* * More recent versions of libcap are available from: * *   http://www.kernel.org/pub/linux/libs/security/linux-privs/ */ static void warn_legacy_capability_use(void){	static int warned;	if (!warned) {		char name[sizeof(current->comm)]; 		printk(KERN_INFO "warning: `%s' uses 32-bit capabilities"		       " (legacy support in use)\n",		       get_task_comm(name, current));		warned = 1;	}} /* * Version 2 capabilities worked fine, but the linux/capability.h file * that accompanied their introduction encouraged their use without * the necessary user-space source code changes. As such, we have * created a version 3 with equivalent functionality to version 2, but * with a header change to protect legacy source code from using * version 2 when it wanted to use version 1. If your system has code * that trips the following warning, it is using version 2 specific * capabilities and may be doing so insecurely. * * The remedy is to either upgrade your version of libcap (to 2.10+, * if the application is linked against it), or recompile your * application with modern kernel headers and this warning will go * away. */ static void warn_deprecated_v2(void){	static int warned; 	if (!warned) {		char name[sizeof(current->comm)]; 		printk(KERN_INFO "warning: `%s' uses deprecated v2"		       " capabilities in a way that may be insecure.\n",		       get_task_comm(name, current));		warned = 1;	}} /* * Version check. Return the number of u32s in each capability flag * array, or a negative value on error. */static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy){	__u32 version; 	if (get_user(version, &header->version))		return -EFAULT; 	switch (version) {	case _LINUX_CAPABILITY_VERSION_1:		warn_legacy_capability_use();		*tocopy = _LINUX_CAPABILITY_U32S_1;		break;	case _LINUX_CAPABILITY_VERSION_2:		warn_deprecated_v2();		/*		 * fall through - v3 is otherwise equivalent to v2.		 */	case _LINUX_CAPABILITY_VERSION_3:		*tocopy = _LINUX_CAPABILITY_U32S_3;		break;	default:		if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))			return -EFAULT;		return -EINVAL;	} 	return 0;} /* * 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. */ /* * Atomically modify the effective capabilities returning the original * value. No permission check is performed here - it is assumed that the * caller is permitted to set the desired effective capabilities. */kernel_cap_t cap_set_effective(const kernel_cap_t pE_new){	kernel_cap_t pE_old; 	spin_lock(&task_capability_lock); 	pE_old = current->cap_effective;	current->cap_effective = pE_new; 	spin_unlock(&task_capability_lock); 	return pE_old;} EXPORT_SYMBOL(cap_set_effective); /** * 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;	struct task_struct *target;	unsigned tocopy;	kernel_cap_t pE, pI, pP; 	ret = cap_validate_magic(header, &tocopy);	if (ret != 0)		return ret; 	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 != task_pid_vnr(current)) {		target = find_task_by_vpid(pid);		if (!target) {			ret = -ESRCH;			goto out;		}	} else		target = current; 	ret = security_capget(target, &pE, &pI, &pP); out:	read_unlock(&tasklist_lock);	spin_unlock(&task_capability_lock); 	if (!ret) {		struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];		unsigned i; 		for (i = 0; i < tocopy; i++) {			kdata[i].effective = pE.cap[i];			kdata[i].permitted = pP.cap[i];			kdata[i].inheritable = pI.cap[i];		} 		/*		 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,		 * we silently drop the upper capabilities here. This		 * has the effect of making older libcap		 * implementations implicitly drop upper capability		 * bits when they perform a: capget/modify/capset		 * sequence.		 *		 * This behavior is considered fail-safe		 * behavior. Upgrading the application to a newer		 * version of libcap will enable access to the newer		 * capabilities.		 *		 * An alternative would be to return an error here		 * (-ERANGE), but that causes legacy applications to		 * unexpectidly fail; the capget/modify/capset aborts		 * before modification is attempted and the application		 * fails.		 */ 		if (copy_to_user(dataptr, kdata, tocopy				 * sizeof(struct __user_cap_data_struct))) {			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_nr, kernel_cap_t *effective,			      kernel_cap_t *inheritable,			      kernel_cap_t *permitted){	struct task_struct *g, *target;	int ret = -EPERM;	int found = 0;	struct pid *pgrp; 	pgrp = find_vpid(pgrp_nr);	do_each_pid_task(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_pid_task(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_container_init(target->group_leader))                     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){	struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];	unsigned i, tocopy;	kernel_cap_t inheritable, permitted, effective;	struct task_struct *target;	int ret;	pid_t pid; 	ret = cap_validate_magic(header, &tocopy);	if (ret != 0)		return ret; 	if (get_user(pid, &header->pid))		return -EFAULT; 	if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP))		return -EPERM; 	if (copy_from_user(&kdata, data, tocopy			   * sizeof(struct __user_cap_data_struct))) {		return -EFAULT;	} 	for (i = 0; i < tocopy; i++) {		effective.cap[i] = kdata[i].effective;		permitted.cap[i] = kdata[i].permitted;		inheritable.cap[i] = kdata[i].inheritable;	}	while (i < _KERNEL_CAPABILITY_U32S) {		effective.cap[i] = 0;		permitted.cap[i] = 0;		inheritable.cap[i] = 0;		i++;	} 	spin_lock(&task_capability_lock);	read_lock(&tasklist_lock); 	if (pid > 0 && pid != task_pid_vnr(current)) {		target = find_task_by_vpid(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;} int capable(int cap){	return __capable(current, cap);}EXPORT_SYMBOL(capable);