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_context.h>
  16 #include <asm/uaccess.h>
  17 #include <linux/vs_base.h>
  18
  19 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  20 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  21
  22 EXPORT_SYMBOL(securebits);
  23 EXPORT_SYMBOL(cap_bset);
  24
  25 /*
  26  * This lock protects task->cap_* for all tasks including current.
  27  * Locking rule: acquire this prior to tasklist_lock.
  28  */
  29 static DEFINE_SPINLOCK(task_capability_lock);
  30
  31 /*
  32  * For sys_getproccap() and sys_setproccap(), any of the three
  33  * capability set pointers may be NULL -- indicating that that set is
  34  * uninteresting and/or not to be changed.
  35  */
  36
  37 /**
  38  * sys_capget - get the capabilities of a given process.
  39  * @header: pointer to struct that contains capability version and
  40  *      target pid data
  41  * @dataptr: pointer to struct that contains the effective, permitted,
  42  *      and inheritable capabilities that are returned
  43  *
  44  * Returns 0 on success and < 0 on error.
  45  */
  46 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  47 {
  48      int ret = 0;
  49      pid_t pid;
  50      __u32 version;
  51      struct task_struct *target;
  52      struct __user_cap_data_struct data;
  53
  54      if (get_user(version, &header->version))
  55              return -EFAULT;
  56
  57      if (version != _LINUX_CAPABILITY_VERSION) {
  58              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  59                      return -EFAULT;
  60              return -EINVAL;
  61      }
  62
  63      if (get_user(pid, &header->pid))
  64              return -EFAULT;
  65
  66      if (pid < 0)
  67              return -EINVAL;
  68
  69      spin_lock(&task_capability_lock);
  70      read_lock(&tasklist_lock);
  71
  72      if (pid && pid != current->pid) {
  73              target = find_task_by_pid(pid);
  74              if (!target) {
  75                   ret = -ESRCH;
  76                   goto out;
  77              }
  78      } else
  79              target = current;
  80
  81      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  82
  83 out:
  84      read_unlock(&tasklist_lock);
  85      spin_unlock(&task_capability_lock);
  86
  87      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  88           return -EFAULT;
  89
  90      return ret;
  91 }
  92
  93 /*
  94  * cap_set_pg - set capabilities for all processes in a given process
  95  * group.  We call this holding task_capability_lock and tasklist_lock.
  96  */
  97 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  98                               kernel_cap_t *inheritable,
  99                               kernel_cap_t *permitted)
 100 {
 101         struct task_struct *g, *target;
 102         int ret = -EPERM;
 103         int found = 0;
 104
 105         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
 106                 if (!vx_check(g->xid, VS_ADMIN_P | VS_IDENT))
 107                         continue;
 108                 target = g;
 109                 while_each_thread(g, target) {
 110                         if (!security_capset_check(target, effective,
 111                                                         inheritable,
 112                                                         permitted)) {
 113                                 security_capset_set(target, effective,
 114                                                         inheritable,
 115                                                         permitted);
 116                                 ret = 0;
 117                         }
 118                         found = 1;
 119                 }
 120         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 121
 122         if (!found)
 123              ret = 0;
 124         return ret;
 125 }
 126
 127 /*
 128  * cap_set_all - set capabilities for all processes other than init
 129  * and self.  We call this holding task_capability_lock and tasklist_lock.
 130  */
 131 static inline int cap_set_all(kernel_cap_t *effective,
 132                                kernel_cap_t *inheritable,
 133                                kernel_cap_t *permitted)
 134 {
 135      struct task_struct *g, *target;
 136      int ret = -EPERM;
 137      int found = 0;
 138
 139      do_each_thread(g, target) {
 140              if (target == current || is_init(target))
 141                      continue;
 142              found = 1;
 143              if (security_capset_check(target, effective, inheritable,
 144                                                 permitted))
 145                      continue;
 146              ret = 0;
 147              security_capset_set(target, effective, inheritable, permitted);
 148      } while_each_thread(g, target);
 149
 150      if (!found)
 151              ret = 0;
 152      return ret;
 153 }
 154
 155 /**
 156  * sys_capset - set capabilities for a process or a group of processes
 157  * @header: pointer to struct that contains capability version and
 158  *      target pid data
 159  * @data: pointer to struct that contains the effective, permitted,
 160  *      and inheritable capabilities
 161  *
 162  * Set capabilities for a given process, all processes, or all
 163  * processes in a given process group.
 164  *
 165  * The restrictions on setting capabilities are specified as:
 166  *
 167  * [pid is for the 'target' task.  'current' is the calling task.]
 168  *
 169  * I: any raised capabilities must be a subset of the (old current) permitted
 170  * P: any raised capabilities must be a subset of the (old current) permitted
 171  * E: must be set to a subset of (new target) permitted
 172  *
 173  * Returns 0 on success and < 0 on error.
 174  */
 175 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 176 {
 177      kernel_cap_t inheritable, permitted, effective;
 178      __u32 version;
 179      struct task_struct *target;
 180      int ret;
 181      pid_t pid;
 182
 183      if (get_user(version, &header->version))
 184              return -EFAULT;
 185
 186      if (version != _LINUX_CAPABILITY_VERSION) {
 187              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 188                      return -EFAULT;
 189              return -EINVAL;
 190      }
 191
 192      if (get_user(pid, &header->pid))
 193              return -EFAULT;
 194
 195      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 196              return -EPERM;
 197
 198      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 199          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 200          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 201              return -EFAULT;
 202
 203      spin_lock(&task_capability_lock);
 204      read_lock(&tasklist_lock);
 205
 206      if (pid > 0 && pid != current->pid) {
 207           target = find_task_by_pid(pid);
 208           if (!target) {
 209                ret = -ESRCH;
 210                goto out;
 211           }
 212      } else
 213                target = current;
 214
 215      ret = 0;
 216
 217      /* having verified that the proposed changes are legal,
 218            we now put them into effect. */
 219      if (pid < 0) {
 220              if (pid == -1)  /* all procs other than current and init */
 221                      ret = cap_set_all(&effective, &inheritable, &permitted);
 222
 223              else            /* all procs in process group */
 224                      ret = cap_set_pg(-pid, &effective, &inheritable,
 225                                                         &permitted);
 226      } else {
 227              ret = security_capset_check(target, &effective, &inheritable,
 228                                                         &permitted);
 229              if (!ret)
 230                      security_capset_set(target, &effective, &inheritable,
 231                                                         &permitted);
 232      }
 233
 234 out:
 235      read_unlock(&tasklist_lock);
 236      spin_unlock(&task_capability_lock);
 237
 238      return ret;
 239 }
 240
 241 int __capable(struct task_struct *t, int cap)
 242 {
 243         if (security_capable(t, cap) == 0) {
 244                 t->flags |= PF_SUPERPRIV;
 245                 return 1;
 246         }
 247         return 0;
 248 }
 249 EXPORT_SYMBOL(__capable);
 250
 251 #include <linux/vserver/base.h>
 252 int capable(int cap)
 253 {
 254         /* here for now so we don't require task locking */
 255         if (vs_check_bit(VXC_CAP_MASK, cap) && !vx_mcaps(1L << cap))
 256                 return 0;
 257         return __capable(current, cap);
 258 }
 259 EXPORT_SYMBOL(capable);