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