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