security/apparmor/resource.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor resource mediation and attachment
   5  *
   6  * Copyright (C) 1998-2008 Novell/SUSE
   7  * Copyright 2009-2010 Canonical Ltd.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation, version 2 of the
  12  * License.
  13  */
  14
  15 #include <linux/audit.h>
  16
  17 #include "include/audit.h"
  18 #include "include/resource.h"
  19 #include "include/policy.h"
  20
  21 /*
  22  * Table of rlimit names: we generate it from resource.h.
  23  */
  24 #include "rlim_names.h"
  25
  26 struct aa_fs_entry aa_fs_entry_rlimit[] = {
  27         AA_FS_FILE_STRING("mask", AA_FS_RLIMIT_MASK),
  28         { }
  29 };
  30
  31 /* audit callback for resource specific fields */
  32 static void audit_cb(struct audit_buffer *ab, void *va)
  33 {
  34         struct common_audit_data *sa = va;
  35
  36         audit_log_format(ab, " rlimit=%s value=%lu",
  37                          rlim_names[sa->aad.rlim.rlim], sa->aad.rlim.max);
  38 }
  39
  40 /**
  41  * audit_resource - audit setting resource limit
  42  * @profile: profile being enforced  (NOT NULL)
  43  * @resoure: rlimit being auditing
  44  * @value: value being set
  45  * @error: error value
  46  *
  47  * Returns: 0 or sa->error else other error code on failure
  48  */
  49 static int audit_resource(struct aa_profile *profile, unsigned int resource,
  50                           unsigned long value, int error)
  51 {
  52         struct common_audit_data sa;
  53
  54         COMMON_AUDIT_DATA_INIT(&sa, NONE);
  55         sa.aad.op = OP_SETRLIMIT,
  56         sa.aad.rlim.rlim = resource;
  57         sa.aad.rlim.max = value;
  58         sa.aad.error = error;
  59         return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_KERNEL, &sa,
  60                         audit_cb);
  61 }
  62
  63 /**
  64  * aa_map_resouce - map compiled policy resource to internal #
  65  * @resource: flattened policy resource number
  66  *
  67  * Returns: resource # for the current architecture.
  68  *
  69  * rlimit resource can vary based on architecture, map the compiled policy
  70  * resource # to the internal representation for the architecture.
  71  */
  72 int aa_map_resource(int resource)
  73 {
  74         return rlim_map[resource];
  75 }
  76
  77 /**
  78  * aa_task_setrlimit - test permission to set an rlimit
  79  * @profile - profile confining the task  (NOT NULL)
  80  * @task - task the resource is being set on
  81  * @resource - the resource being set
  82  * @new_rlim - the new resource limit  (NOT NULL)
  83  *
  84  * Control raising the processes hard limit.
  85  *
  86  * Returns: 0 or error code if setting resource failed
  87  */
  88 int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
  89                       unsigned int resource, struct rlimit *new_rlim)
  90 {
  91         int error = 0;
  92
  93         /* TODO: extend resource control to handle other (non current)
  94          * processes.  AppArmor rules currently have the implicit assumption
  95          * that the task is setting the resource of the current process
  96          */
  97         if ((task != current->group_leader) ||
  98             (profile->rlimits.mask & (1 << resource) &&
  99              new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
 100                 error = -EACCES;
 101
 102         return audit_resource(profile, resource, new_rlim->rlim_max, error);
 103 }
 104
 105 /**
 106  * __aa_transition_rlimits - apply new profile rlimits
 107  * @old: old profile on task  (NOT NULL)
 108  * @new: new profile with rlimits to apply  (NOT NULL)
 109  */
 110 void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
 111 {
 112         unsigned int mask = 0;
 113         struct rlimit *rlim, *initrlim;
 114         int i;
 115
 116         /* for any rlimits the profile controlled reset the soft limit
 117          * to the less of the tasks hard limit and the init tasks soft limit
 118          */
 119         if (old->rlimits.mask) {
 120                 for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 121                         if (old->rlimits.mask & mask) {
 122                                 rlim = current->signal->rlim + i;
 123                                 initrlim = init_task.signal->rlim + i;
 124                                 rlim->rlim_cur = min(rlim->rlim_max,
 125                                                      initrlim->rlim_cur);
 126                         }
 127                 }
 128         }
 129
 130         /* set any new hard limits as dictated by the new profile */
 131         if (!new->rlimits.mask)
 132                 return;
 133         for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 134                 if (!(new->rlimits.mask & mask))
 135                         continue;
 136
 137                 rlim = current->signal->rlim + i;
 138                 rlim->rlim_max = min(rlim->rlim_max,
 139                                      new->rlimits.limits[i].rlim_max);
 140                 /* soft limit should not exceed hard limit */
 141                 rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 142         }
 143 }