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/capability.h>
  11 #include <linux/mm.h>
  12 #include <linux/module.h>
  13 #include <linux/security.h>
  14 #include <linux/syscalls.h>
  15 #include <linux/vs_cvirt.h>
  16 #include <asm/uaccess.h>
  17
  18 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  19 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  20
  21 EXPORT_SYMBOL(securebits);
  22 EXPORT_SYMBOL(cap_bset);
  23
  24 /*
  25  * This lock protects task->cap_* for all tasks including current.
  26  * Locking rule: acquire this prior to tasklist_lock.
  27  */
  28 static DEFINE_SPINLOCK(task_capability_lock);
  29
  30 /*
  31  * For sys_getproccap() and sys_setproccap(), any of the three
  32  * capability set pointers may be NULL -- indicating that that set is
  33  * uninteresting and/or not to be changed.
  34  */
  35
  36 /**
  37  * sys_capget - get the capabilities of a given process.
  38  * @header: pointer to struct that contains capability version and
  39  *      target pid data
  40  * @dataptr: pointer to struct that contains the effective, permitted,
  41  *      and inheritable capabilities that are returned
  42  *
  43  * Returns 0 on success and < 0 on error.
  44  */
  45 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  46 {
  47      int ret = 0;
  48      pid_t pid;
  49      __u32 version;
  50      task_t *target;
  51      struct __user_cap_data_struct data;
  52
  53      if (get_user(version, &header->version))
  54              return -EFAULT;
  55
  56      if (version != _LINUX_CAPABILITY_VERSION) {
  57              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  58                      return -EFAULT;
  59              return -EINVAL;
  60      }
  61
  62      if (get_user(pid, &header->pid))
  63              return -EFAULT;
  64
  65      if (pid < 0)
  66              return -EINVAL;
  67
  68      spin_lock(&task_capability_lock);
  69      read_lock(&tasklist_lock);
  70
  71      if (pid && pid != current->pid) {
  72              target = find_task_by_pid(pid);
  73              if (!target) {
  74                   ret = -ESRCH;
  75                   goto out;
  76              }
  77      } else
  78              target = current;
  79
  80      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  81
  82 out:
  83      read_unlock(&tasklist_lock);
  84      spin_unlock(&task_capability_lock);
  85
  86      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  87           return -EFAULT;
  88
  89      return ret;
  90 }
  91
  92 /*
  93  * cap_set_pg - set capabilities for all processes in a given process
  94  * group.  We call this holding task_capability_lock and tasklist_lock.
  95  */
  96 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  97                               kernel_cap_t *inheritable,
  98                               kernel_cap_t *permitted)
  99 {
 100         task_t *g, *target;
 101         int ret = -EPERM;
 102         int found = 0;
 103
 104         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
 105                 target = g;
 106                 while_each_thread(g, target) {
 107                         if (!security_capset_check(target, effective,
 108                                                         inheritable,
 109                                                         permitted)) {
 110                                 security_capset_set(target, effective,
 111                                                         inheritable,
 112                                                         permitted);
 113                                 ret = 0;
 114                         }
 115                         found = 1;
 116                 }
 117         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 118
 119         if (!found)
 120              ret = 0;
 121         return ret;
 122 }
 123
 124 /*
 125  * cap_set_all - set capabilities for all processes other than init
 126  * and self.  We call this holding task_capability_lock and tasklist_lock.
 127  */
 128 static inline int cap_set_all(kernel_cap_t *effective,
 129                                kernel_cap_t *inheritable,
 130                                kernel_cap_t *permitted)
 131 {
 132      task_t *g, *target;
 133      int ret = -EPERM;
 134      int found = 0;
 135
 136      do_each_thread(g, target) {
 137              if (target == current || target->pid == 1)
 138                      continue;
 139              found = 1;
 140              if (security_capset_check(target, effective, inheritable,
 141                                                 permitted))
 142                      continue;
 143              ret = 0;
 144              security_capset_set(target, effective, inheritable, permitted);
 145      } while_each_thread(g, target);
 146
 147      if (!found)
 148              ret = 0;
 149      return ret;
 150 }
 151
 152 /**
 153  * sys_capset - set capabilities for a process or a group of processes
 154  * @header: pointer to struct that contains capability version and
 155  *      target pid data
 156  * @data: pointer to struct that contains the effective, permitted,
 157  *      and inheritable capabilities
 158  *
 159  * Set capabilities for a given process, all processes, or all
 160  * processes in a given process group.
 161  *
 162  * The restrictions on setting capabilities are specified as:
 163  *
 164  * [pid is for the 'target' task.  'current' is the calling task.]
 165  *
 166  * I: any raised capabilities must be a subset of the (old current) permitted
 167  * P: any raised capabilities must be a subset of the (old current) permitted
 168  * E: must be set to a subset of (new target) permitted
 169  *
 170  * Returns 0 on success and < 0 on error.
 171  */
 172 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 173 {
 174      kernel_cap_t inheritable, permitted, effective;
 175      __u32 version;
 176      task_t *target;
 177      int ret;
 178      pid_t pid;
 179
 180      if (get_user(version, &header->version))
 181              return -EFAULT;
 182
 183      if (version != _LINUX_CAPABILITY_VERSION) {
 184              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 185                      return -EFAULT;
 186              return -EINVAL;
 187      }
 188
 189      if (get_user(pid, &header->pid))
 190              return -EFAULT;
 191
 192      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 193              return -EPERM;
 194
 195      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 196          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 197          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 198              return -EFAULT;
 199
 200      spin_lock(&task_capability_lock);
 201      read_lock(&tasklist_lock);
 202
 203      if (pid > 0 && pid != current->pid) {
 204           target = find_task_by_pid(pid);
 205           if (!target) {
 206                ret = -ESRCH;
 207                goto out;
 208           }
 209      } else
 210                target = current;
 211
 212      ret = 0;
 213
 214      /* having verified that the proposed changes are legal,
 215            we now put them into effect. */
 216      if (pid < 0) {
 217              if (pid == -1)  /* all procs other than current and init */
 218                      ret = cap_set_all(&effective, &inheritable, &permitted);
 219
 220              else            /* all procs in process group */
 221                      ret = cap_set_pg(-pid, &effective, &inheritable,
 222                                                         &permitted);
 223      } else {
 224              ret = security_capset_check(target, &effective, &inheritable,
 225                                                         &permitted);
 226              if (!ret)
 227                      security_capset_set(target, &effective, &inheritable,
 228                                                         &permitted);
 229      }
 230
 231 out:
 232      read_unlock(&tasklist_lock);
 233      spin_unlock(&task_capability_lock);
 234
 235      return ret;
 236 }
 237
 238 int __capable(struct task_struct *t, int cap)
 239 {
 240         if (security_capable(t, cap) == 0) {
 241                 t->flags |= PF_SUPERPRIV;
 242                 return 1;
 243         }
 244         return 0;
 245 }
 246 EXPORT_SYMBOL(__capable);
 247
 248 int capable(int cap)
 249 {
 250         /* here for now so we don't require task locking */
 251         if (vx_check_bit(VXC_CAP_MASK, cap) && !vx_mcaps(1L << cap))
 252                 return 0;
 253         return __capable(current, cap);
 254 }
 255 EXPORT_SYMBOL(capable);
 256