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/*

 * linux/kernel/capability.c

 *

 * Copyright (C) 1997  Andrew Main <zefram@fysh.org>

 * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>

 */

#include <linux/mm.h>

#include <asm/uaccess.h>

kernel_cap_t cap_bset = CAP_INIT_EFF_SET;

/* Note: never hold tasklist_lock while spinning for this one */

spinlock_t task_capability_lock = SPIN_LOCK_UNLOCKED;

/*

 * 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.

 */

asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)

{

     int error, pid;

     __u32 version;

     struct task_struct *target;

     struct __user_cap_data_struct data;

     if (get_user(version, &header->version))

             return -EFAULT;

     error = -EINVAL;

     if (version != _LINUX_CAPABILITY_VERSION) {

             version = _LINUX_CAPABILITY_VERSION;

             if (put_user(version, &header->version))

                     error = -EFAULT;

             return error;

     }

     if (get_user(pid, &header->pid))

             return -EFAULT;

     if (pid < 0)

             return -EINVAL;

     error = 0;

     spin_lock(&task_capability_lock);

     if (pid && pid != current->pid) {

             read_lock(&tasklist_lock);

             target = find_task_by_pid(pid);  /* identify target of query */

             if (!target)

                     error = -ESRCH;

     } else {

             target = current;

     }

     if (!error) {

             data.permitted = cap_t(target->cap_permitted);

             data.inheritable = cap_t(target->cap_inheritable);

             data.effective = cap_t(target->cap_effective);

     }

     if (target != current)

             read_unlock(&tasklist_lock);

     spin_unlock(&task_capability_lock);

     if (!error) {

             if (copy_to_user(dataptr, &data, sizeof data))

                     return -EFAULT;

     }

     return error;

}

/* set capabilities for all processes in a given process group */

static void cap_set_pg(int pgrp,

                    kernel_cap_t *effective,

                    kernel_cap_t *inheritable,

                    kernel_cap_t *permitted)

{

     struct task_struct *target;

     /* FIXME: do we need to have a write lock here..? */

     read_lock(&tasklist_lock);

     for_each_task(target) {

             if (target->pgrp != pgrp)

                     continue;

             target->cap_effective   = *effective;

             target->cap_inheritable = *inheritable;

             target->cap_permitted   = *permitted;

     }

     read_unlock(&tasklist_lock);

}

/* set capabilities for all processes other than 1 and self */

static void cap_set_all(kernel_cap_t *effective,

                     kernel_cap_t *inheritable,

                     kernel_cap_t *permitted)

{

     struct task_struct *target;

     /* FIXME: do we need to have a write lock here..? */

     read_lock(&tasklist_lock);

     /* ALL means everyone other than self or 'init' */

     for_each_task(target) {

             if (target == current || target->pid == 1)

                     continue;

             target->cap_effective   = *effective;

             target->cap_inheritable = *inheritable;

             target->cap_permitted   = *permitted;

     }

     read_unlock(&tasklist_lock);

}

/*

 * 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

 */

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 error, pid;

     if (get_user(version, &header->version))

             return -EFAULT;

     if (version != _LINUX_CAPABILITY_VERSION) {

             version = _LINUX_CAPABILITY_VERSION;

             if (put_user(version, &header->version))

                     return -EFAULT;

             return -EINVAL;

     }

     if (get_user(pid, &header->pid))

             return -EFAULT;

     if (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;

     error = -EPERM;

     spin_lock(&task_capability_lock);

     if (pid > 0 && pid != current->pid) {

             read_lock(&tasklist_lock);

             target = find_task_by_pid(pid);  /* identify target of query */

             if (!target) {

                     error = -ESRCH;

                     goto out;

             }

     } else {

             target = current;

     }

     /* verify restrictions on target's new Inheritable set */

     if (!cap_issubset(inheritable,

                       cap_combine(target->cap_inheritable,

                                   current->cap_permitted))) {

             goto out;

     }

     /* verify restrictions on target's new Permitted set */

     if (!cap_issubset(permitted,

                       cap_combine(target->cap_permitted,

                                   current->cap_permitted))) {

             goto out;

     }

     /* verify the _new_Effective_ is a subset of the _new_Permitted_ */

     if (!cap_issubset(effective, permitted)) {

             goto out;

     }

     /* having verified that the proposed changes are legal,

           we now put them into effect. */

     error = 0;

     if (pid < 0) {

             if (pid == -1)  /* all procs other than current and init */

                     cap_set_all(&effective, &inheritable, &permitted);

             else            /* all procs in process group */

                     cap_set_pg(-pid, &effective, &inheritable, &permitted);

             goto spin_out;

     } else {

             /* FIXME: do we need to have a write lock here..? */

             target->cap_effective   = effective;

             target->cap_inheritable = inheritable;

             target->cap_permitted   = permitted;

     }

out:

     if (target != current) {

             read_unlock(&tasklist_lock);

     }

spin_out:

     spin_unlock(&task_capability_lock);

     return error;

}