kernel/capability.c

   1 /*
   2  * linux/kernel/capability.c
   3  *
   4  * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
   5  *
   6  * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
   7  * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
   8  */
   9
  10 #include <linux/mm.h>
  11 #include <linux/module.h>
  12 #include <linux/security.h>
  13 #include <linux/syscalls.h>
  14 #include <linux/vs_cvirt.h>
  15 #include <asm/uaccess.h>
  16
  17 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  18 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  19
  20 EXPORT_SYMBOL(securebits);
  21 EXPORT_SYMBOL(cap_bset);
  22
  23 /*
  24  * This lock protects task->cap_* for all tasks including current.
  25  * Locking rule: acquire this prior to tasklist_lock.
  26  */
  27 static DEFINE_SPINLOCK(task_capability_lock);
  28
  29 /*
  30  * For sys_getproccap() and sys_setproccap(), any of the three
  31  * capability set pointers may be NULL -- indicating that that set is
  32  * uninteresting and/or not to be changed.
  33  */
  34
  35 /*
  36  * sys_capget - get the capabilities of a given process.
  37  */
  38 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  39 {
  40      int ret = 0;
  41      pid_t pid;
  42      __u32 version;
  43      task_t *target;
  44      struct __user_cap_data_struct data;
  45
  46      if (get_user(version, &header->version))
  47              return -EFAULT;
  48
  49      if (version != _LINUX_CAPABILITY_VERSION) {
  50              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  51                      return -EFAULT;
  52              return -EINVAL;
  53      }
  54
  55      if (get_user(pid, &header->pid))
  56              return -EFAULT;
  57
  58      if (pid < 0)
  59              return -EINVAL;
  60
  61      spin_lock(&task_capability_lock);
  62      read_lock(&tasklist_lock);
  63
  64      if (pid && pid != current->pid) {
  65              target = find_task_by_pid(pid);
  66              if (!target) {
  67                   ret = -ESRCH;
  68                   goto out;
  69              }
  70      } else
  71              target = current;
  72
  73      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  74
  75 out:
  76      read_unlock(&tasklist_lock);
  77      spin_unlock(&task_capability_lock);
  78
  79      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  80           return -EFAULT;
  81
  82      return ret;
  83 }
  84
  85 /*
  86  * cap_set_pg - set capabilities for all processes in a given process
  87  * group.  We call this holding task_capability_lock and tasklist_lock.
  88  */
  89 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  90                               kernel_cap_t *inheritable,
  91                               kernel_cap_t *permitted)
  92 {
  93         task_t *g, *target;
  94         int ret = -EPERM;
  95         int found = 0;
  96
  97         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
  98                 target = g;
  99                 while_each_thread(g, target) {
 100                         if (!security_capset_check(target, effective,
 101                                                         inheritable,
 102                                                         permitted)) {
 103                                 security_capset_set(target, effective,
 104                                                         inheritable,
 105                                                         permitted);
 106                                 ret = 0;
 107                         }
 108                         found = 1;
 109                 }
 110         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 111
 112         if (!found)
 113              ret = 0;
 114         return ret;
 115 }
 116
 117 /*
 118  * cap_set_all - set capabilities for all processes other than init
 119  * and self.  We call this holding task_capability_lock and tasklist_lock.
 120  */
 121 static inline int cap_set_all(kernel_cap_t *effective,
 122                                kernel_cap_t *inheritable,
 123                                kernel_cap_t *permitted)
 124 {
 125      task_t *g, *target;
 126      int ret = -EPERM;
 127      int found = 0;
 128
 129      do_each_thread(g, target) {
 130              if (target == current || target->pid == 1)
 131                      continue;
 132              found = 1;
 133              if (security_capset_check(target, effective, inheritable,
 134                                                 permitted))
 135                      continue;
 136              ret = 0;
 137              security_capset_set(target, effective, inheritable, permitted);
 138      } while_each_thread(g, target);
 139
 140      if (!found)
 141              ret = 0;
 142      return ret;
 143 }
 144
 145 /*
 146  * sys_capset - set capabilities for a given process, all processes, or all
 147  * processes in a given process group.
 148  *
 149  * The restrictions on setting capabilities are specified as:
 150  *
 151  * [pid is for the 'target' task.  'current' is the calling task.]
 152  *
 153  * I: any raised capabilities must be a subset of the (old current) permitted
 154  * P: any raised capabilities must be a subset of the (old current) permitted
 155  * E: must be set to a subset of (new target) permitted
 156  */
 157 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 158 {
 159      kernel_cap_t inheritable, permitted, effective;
 160      __u32 version;
 161      task_t *target;
 162      int ret;
 163      pid_t pid;
 164
 165      if (get_user(version, &header->version))
 166              return -EFAULT;
 167
 168      if (version != _LINUX_CAPABILITY_VERSION) {
 169              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 170                      return -EFAULT;
 171              return -EINVAL;
 172      }
 173
 174      if (get_user(pid, &header->pid))
 175              return -EFAULT;
 176
 177      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 178              return -EPERM;
 179
 180      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 181          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 182          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 183              return -EFAULT;
 184
 185      spin_lock(&task_capability_lock);
 186      read_lock(&tasklist_lock);
 187
 188      if (pid > 0 && pid != current->pid) {
 189           target = find_task_by_pid(pid);
 190           if (!target) {
 191                ret = -ESRCH;
 192                goto out;
 193           }
 194      } else
 195                target = current;
 196
 197      ret = 0;
 198
 199      /* having verified that the proposed changes are legal,
 200            we now put them into effect. */
 201      if (pid < 0) {
 202              if (pid == -1)  /* all procs other than current and init */
 203                      ret = cap_set_all(&effective, &inheritable, &permitted);
 204
 205              else            /* all procs in process group */
 206                      ret = cap_set_pg(-pid, &effective, &inheritable,
 207                                                         &permitted);
 208      } else {
 209              ret = security_capset_check(target, &effective, &inheritable,
 210                                                         &permitted);
 211              if (!ret)
 212                      security_capset_set(target, &effective, &inheritable,
 213                                                         &permitted);
 214      }
 215
 216 out:
 217      read_unlock(&tasklist_lock);
 218      spin_unlock(&task_capability_lock);
 219
 220      return ret;
 221 }