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 #include <linux/security.h>
  17
  18 #include "include/audit.h"
  19 #include "include/context.h"
  20 #include "include/resource.h"
  21 #include "include/policy.h"
  22
  23 /*
  24  * Table of rlimit names: we generate it from resource.h.
  25  */
  26 #include "rlim_names.h"
  27
  28 struct aa_sfs_entry aa_sfs_entry_rlimit[] = {
  29         AA_SFS_FILE_STRING("mask", AA_SFS_RLIMIT_MASK),
  30         { }
  31 };
  32
  33 /* audit callback for resource specific fields */
  34 static void audit_cb(struct audit_buffer *ab, void *va)
  35 {
  36         struct common_audit_data *sa = va;
  37
  38         audit_log_format(ab, " rlimit=%s value=%lu",
  39                          rlim_names[aad(sa)->rlim.rlim], aad(sa)->rlim.max);
  40         if (aad(sa)->peer) {
  41                 audit_log_format(ab, " peer=");
  42                 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
  43                                 FLAGS_NONE, GFP_ATOMIC);
  44         }
  45 }
  46
  47 /**
  48  * audit_resource - audit setting resource limit
  49  * @profile: profile being enforced  (NOT NULL)
  50  * @resource: rlimit being auditing
  51  * @value: value being set
  52  * @error: error value
  53  *
  54  * Returns: 0 or sa->error else other error code on failure
  55  */
  56 static int audit_resource(struct aa_profile *profile, unsigned int resource,
  57                           unsigned long value, struct aa_label *peer,
  58                           const char *info, int error)
  59 {
  60         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SETRLIMIT);
  61
  62         aad(&sa)->rlim.rlim = resource;
  63         aad(&sa)->rlim.max = value;
  64         aad(&sa)->peer = peer;
  65         aad(&sa)->info = info;
  66         aad(&sa)->error = error;
  67
  68         return aa_audit(AUDIT_APPARMOR_AUTO, profile, &sa, audit_cb);
  69 }
  70
  71 /**
  72  * aa_map_resouce - map compiled policy resource to internal #
  73  * @resource: flattened policy resource number
  74  *
  75  * Returns: resource # for the current architecture.
  76  *
  77  * rlimit resource can vary based on architecture, map the compiled policy
  78  * resource # to the internal representation for the architecture.
  79  */
  80 int aa_map_resource(int resource)
  81 {
  82         return rlim_map[resource];
  83 }
  84
  85 static int profile_setrlimit(struct aa_profile *profile, unsigned int resource,
  86                              struct rlimit *new_rlim)
  87 {
  88         int e = 0;
  89
  90         if (profile->rlimits.mask & (1 << resource) && new_rlim->rlim_max >
  91             profile->rlimits.limits[resource].rlim_max)
  92                 e = -EACCES;
  93         return audit_resource(profile, resource, new_rlim->rlim_max, NULL, NULL,
  94                               e);
  95 }
  96
  97 /**
  98  * aa_task_setrlimit - test permission to set an rlimit
  99  * @label - label confining the task  (NOT NULL)
 100  * @task - task the resource is being set on
 101  * @resource - the resource being set
 102  * @new_rlim - the new resource limit  (NOT NULL)
 103  *
 104  * Control raising the processes hard limit.
 105  *
 106  * Returns: 0 or error code if setting resource failed
 107  */
 108 int aa_task_setrlimit(struct aa_label *label, struct task_struct *task,
 109                       unsigned int resource, struct rlimit *new_rlim)
 110 {
 111         struct aa_profile *profile;
 112         struct aa_label *peer;
 113         int error = 0;
 114
 115         rcu_read_lock();
 116         peer = aa_get_newest_cred_label(__task_cred(task));
 117         rcu_read_unlock();
 118
 119         /* TODO: extend resource control to handle other (non current)
 120          * profiles.  AppArmor rules currently have the implicit assumption
 121          * that the task is setting the resource of a task confined with
 122          * the same profile or that the task setting the resource of another
 123          * task has CAP_SYS_RESOURCE.
 124          */
 125
 126         if (label != peer &&
 127             !aa_capable(label, CAP_SYS_RESOURCE, SECURITY_CAP_NOAUDIT))
 128                 error = fn_for_each(label, profile,
 129                                 audit_resource(profile, resource,
 130                                                new_rlim->rlim_max, peer,
 131                                                "cap_sys_resource", -EACCES));
 132         else
 133                 error = fn_for_each_confined(label, profile,
 134                                 profile_setrlimit(profile, resource, new_rlim));
 135         aa_put_label(peer);
 136
 137         return error;
 138 }
 139
 140 /**
 141  * __aa_transition_rlimits - apply new profile rlimits
 142  * @old_l: old label on task  (NOT NULL)
 143  * @new_l: new label with rlimits to apply  (NOT NULL)
 144  */
 145 void __aa_transition_rlimits(struct aa_label *old_l, struct aa_label *new_l)
 146 {
 147         unsigned int mask = 0;
 148         struct rlimit *rlim, *initrlim;
 149         struct aa_profile *old, *new;
 150         struct label_it i;
 151
 152         old = labels_profile(old_l);
 153         new = labels_profile(new_l);
 154
 155         /* for any rlimits the profile controlled, reset the soft limit
 156          * to the lesser of the tasks hard limit and the init tasks soft limit
 157          */
 158         label_for_each_confined(i, old_l, old) {
 159                 if (old->rlimits.mask) {
 160                         int j;
 161
 162                         for (j = 0, mask = 1; j < RLIM_NLIMITS; j++,
 163                                      mask <<= 1) {
 164                                 if (old->rlimits.mask & mask) {
 165                                         rlim = current->signal->rlim + j;
 166                                         initrlim = init_task.signal->rlim + j;
 167                                         rlim->rlim_cur = min(rlim->rlim_max,
 168                                                             initrlim->rlim_cur);
 169                                 }
 170                         }
 171                 }
 172         }
 173
 174         /* set any new hard limits as dictated by the new profile */
 175         label_for_each_confined(i, new_l, new) {
 176                 int j;
 177
 178                 if (!new->rlimits.mask)
 179                         continue;
 180                 for (j = 0, mask = 1; j < RLIM_NLIMITS; j++, mask <<= 1) {
 181                         if (!(new->rlimits.mask & mask))
 182                                 continue;
 183
 184                         rlim = current->signal->rlim + j;
 185                         rlim->rlim_max = min(rlim->rlim_max,
 186                                              new->rlimits.limits[j].rlim_max);
 187                         /* soft limit should not exceed hard limit */
 188                         rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 189                 }
 190         }
 191 }