kernel/capability.c

   1 /*
   2  * linux/kernel/capability.c
   3  *
   4  * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
   5  * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
   6  */
   7
   8 #include <linux/mm.h>
   9 #include <asm/uaccess.h>
  10
  11 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  12
  13 /* Note: never hold tasklist_lock while spinning for this one */
  14 spinlock_t task_capability_lock = SPIN_LOCK_UNLOCKED;
  15
  16 /*
  17  * For sys_getproccap() and sys_setproccap(), any of the three
  18  * capability set pointers may be NULL -- indicating that that set is
  19  * uninteresting and/or not to be changed.
  20  */
  21
  22 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  23 {
  24      int error, pid;
  25      __u32 version;
  26      struct task_struct *target;
  27      struct __user_cap_data_struct data;
  28
  29      if (get_user(version, &header->version))
  30              return -EFAULT;
  31
  32      error = -EINVAL;
  33      if (version != _LINUX_CAPABILITY_VERSION) {
  34              version = _LINUX_CAPABILITY_VERSION;
  35              if (put_user(version, &header->version))
  36                      error = -EFAULT;
  37              return error;
  38      }
  39
  40      if (get_user(pid, &header->pid))
  41              return -EFAULT;
  42
  43      if (pid < 0)
  44              return -EINVAL;
  45
  46      error = 0;
  47
  48      spin_lock(&task_capability_lock);
  49
  50      if (pid && pid != current->pid) {
  51              read_lock(&tasklist_lock);
  52              target = find_task_by_pid(pid);  /* identify target of query */
  53              if (!target)
  54                      error = -ESRCH;
  55      } else {
  56              target = current;
  57      }
  58
  59      if (!error) {
  60              data.permitted = cap_t(target->cap_permitted);
  61              data.inheritable = cap_t(target->cap_inheritable);
  62              data.effective = cap_t(target->cap_effective);
  63      }
  64
  65      if (target != current)
  66              read_unlock(&tasklist_lock);
  67      spin_unlock(&task_capability_lock);
  68
  69      if (!error) {
  70              if (copy_to_user(dataptr, &data, sizeof data))
  71                      return -EFAULT;
  72      }
  73
  74      return error;
  75 }
  76
  77 /* set capabilities for all processes in a given process group */
  78
  79 static void cap_set_pg(int pgrp,
  80                     kernel_cap_t *effective,
  81                     kernel_cap_t *inheritable,
  82                     kernel_cap_t *permitted)
  83 {
  84      struct task_struct *target;
  85
  86      /* FIXME: do we need to have a write lock here..? */
  87      read_lock(&tasklist_lock);
  88      for_each_task(target) {
  89              if (target->pgrp != pgrp)
  90                      continue;
  91              target->cap_effective   = *effective;
  92              target->cap_inheritable = *inheritable;
  93              target->cap_permitted   = *permitted;
  94      }
  95      read_unlock(&tasklist_lock);
  96 }
  97
  98 /* set capabilities for all processes other than 1 and self */
  99
 100 static void cap_set_all(kernel_cap_t *effective,
 101                      kernel_cap_t *inheritable,
 102                      kernel_cap_t *permitted)
 103 {
 104      struct task_struct *target;
 105
 106      /* FIXME: do we need to have a write lock here..? */
 107      read_lock(&tasklist_lock);
 108      /* ALL means everyone other than self or 'init' */
 109      for_each_task(target) {
 110              if (target == current || target->pid == 1)
 111                      continue;
 112              target->cap_effective   = *effective;
 113              target->cap_inheritable = *inheritable;
 114              target->cap_permitted   = *permitted;
 115      }
 116      read_unlock(&tasklist_lock);
 117 }
 118
 119 /*
 120  * The restrictions on setting capabilities are specified as:
 121  *
 122  * [pid is for the 'target' task.  'current' is the calling task.]
 123  *
 124  * I: any raised capabilities must be a subset of the (old current) Permitted
 125  * P: any raised capabilities must be a subset of the (old current) permitted
 126  * E: must be set to a subset of (new target) Permitted
 127  */
 128
 129 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 130 {
 131      kernel_cap_t inheritable, permitted, effective;
 132      __u32 version;
 133      struct task_struct *target;
 134      int error, pid;
 135
 136      if (get_user(version, &header->version))
 137              return -EFAULT;
 138
 139      if (version != _LINUX_CAPABILITY_VERSION) {
 140              version = _LINUX_CAPABILITY_VERSION;
 141              if (put_user(version, &header->version))
 142                      return -EFAULT;
 143              return -EINVAL;
 144      }
 145
 146      if (get_user(pid, &header->pid))
 147              return -EFAULT;
 148
 149      if (pid && !capable(CAP_SETPCAP))
 150              return -EPERM;
 151
 152      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 153          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 154          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 155              return -EFAULT;
 156
 157      error = -EPERM;
 158      spin_lock(&task_capability_lock);
 159
 160      if (pid > 0 && pid != current->pid) {
 161              read_lock(&tasklist_lock);
 162              target = find_task_by_pid(pid);  /* identify target of query */
 163              if (!target) {
 164                      error = -ESRCH;
 165                      goto out;
 166              }
 167      } else {
 168              target = current;
 169      }
 170
 171
 172      /* verify restrictions on target's new Inheritable set */
 173      if (!cap_issubset(inheritable,
 174                        cap_combine(target->cap_inheritable,
 175                                    current->cap_permitted))) {
 176              goto out;
 177      }
 178
 179      /* verify restrictions on target's new Permitted set */
 180      if (!cap_issubset(permitted,
 181                        cap_combine(target->cap_permitted,
 182                                    current->cap_permitted))) {
 183              goto out;
 184      }
 185
 186      /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
 187      if (!cap_issubset(effective, permitted)) {
 188              goto out;
 189      }
 190
 191      /* having verified that the proposed changes are legal,
 192            we now put them into effect. */
 193      error = 0;
 194
 195      if (pid < 0) {
 196              if (pid == -1)  /* all procs other than current and init */
 197                      cap_set_all(&effective, &inheritable, &permitted);
 198
 199              else            /* all procs in process group */
 200                      cap_set_pg(-pid, &effective, &inheritable, &permitted);
 201              goto spin_out;
 202      } else {
 203              /* FIXME: do we need to have a write lock here..? */
 204              target->cap_effective   = effective;
 205              target->cap_inheritable = inheritable;
 206              target->cap_permitted   = permitted;
 207      }
 208
 209 out:
 210      if (target != current) {
 211              read_unlock(&tasklist_lock);
 212      }
 213 spin_out:
 214      spin_unlock(&task_capability_lock);
 215      return error;
 216 }