security/apparmor/resource.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor resource mediation and attachment
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2010 Canonical Ltd.
   9  */
  10
  11 #include <linux/audit.h>
  12 #include <linux/security.h>
  13
  14 #include "include/audit.h"
  15 #include "include/cred.h"
  16 #include "include/resource.h"
  17 #include "include/policy.h"
  18
  19 /*
  20  * Table of rlimit names: we generate it from resource.h.
  21  */
  22 #include "rlim_names.h"
  23
  24 struct aa_sfs_entry aa_sfs_entry_rlimit[] = {
  25         AA_SFS_FILE_STRING("mask", AA_SFS_RLIMIT_MASK),
  26         { }
  27 };
  28
  29 /* audit callback for resource specific fields */
  30 static void audit_cb(struct audit_buffer *ab, void *va)
  31 {
  32         struct common_audit_data *sa = va;
  33
  34         audit_log_format(ab, " rlimit=%s value=%lu",
  35                          rlim_names[aad(sa)->rlim.rlim], aad(sa)->rlim.max);
  36         if (aad(sa)->peer) {
  37                 audit_log_format(ab, " peer=");
  38                 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
  39                                 FLAGS_NONE, GFP_ATOMIC);
  40         }
  41 }
  42
  43 /**
  44  * audit_resource - audit setting resource limit
  45  * @profile: profile being enforced  (NOT NULL)
  46  * @resource: rlimit being auditing
  47  * @value: value being set
  48  * @peer: aa_albel of the task being set
  49  * @info: info being auditing
  50  * @error: error value
  51  *
  52  * Returns: 0 or sa->error else other error code on failure
  53  */
  54 static int audit_resource(struct aa_profile *profile, unsigned int resource,
  55                           unsigned long value, struct aa_label *peer,
  56                           const char *info, int error)
  57 {
  58         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, AA_CLASS_RLIMITS,
  59                           OP_SETRLIMIT);
  60
  61         aad(&sa)->rlim.rlim = resource;
  62         aad(&sa)->rlim.max = value;
  63         aad(&sa)->peer = peer;
  64         aad(&sa)->info = info;
  65         aad(&sa)->error = error;
  66
  67         return aa_audit(AUDIT_APPARMOR_AUTO, profile, &sa, audit_cb);
  68 }
  69
  70 /**
  71  * aa_map_resource - map compiled policy resource to internal #
  72  * @resource: flattened policy resource number
  73  *
  74  * Returns: resource # for the current architecture.
  75  *
  76  * rlimit resource can vary based on architecture, map the compiled policy
  77  * resource # to the internal representation for the architecture.
  78  */
  79 int aa_map_resource(int resource)
  80 {
  81         return rlim_map[resource];
  82 }
  83
  84 static int profile_setrlimit(struct aa_profile *profile, unsigned int resource,
  85                              struct rlimit *new_rlim)
  86 {
  87         struct aa_ruleset *rules = list_first_entry(&profile->rules,
  88                                                     typeof(*rules), list);
  89         int e = 0;
  90
  91         if (rules->rlimits.mask & (1 << resource) && new_rlim->rlim_max >
  92             rules->rlimits.limits[resource].rlim_max)
  93                 e = -EACCES;
  94         return audit_resource(profile, resource, new_rlim->rlim_max, NULL, NULL,
  95                               e);
  96 }
  97
  98 /**
  99  * aa_task_setrlimit - test permission to set an rlimit
 100  * @label - label confining the task  (NOT NULL)
 101  * @task - task the resource is being set on
 102  * @resource - the resource being set
 103  * @new_rlim - the new resource limit  (NOT NULL)
 104  *
 105  * Control raising the processes hard limit.
 106  *
 107  * Returns: 0 or error code if setting resource failed
 108  */
 109 int aa_task_setrlimit(struct aa_label *label, struct task_struct *task,
 110                       unsigned int resource, struct rlimit *new_rlim)
 111 {
 112         struct aa_profile *profile;
 113         struct aa_label *peer;
 114         int error = 0;
 115
 116         rcu_read_lock();
 117         peer = aa_get_newest_cred_label(__task_cred(task));
 118         rcu_read_unlock();
 119
 120         /* TODO: extend resource control to handle other (non current)
 121          * profiles.  AppArmor rules currently have the implicit assumption
 122          * that the task is setting the resource of a task confined with
 123          * the same profile or that the task setting the resource of another
 124          * task has CAP_SYS_RESOURCE.
 125          */
 126
 127         if (label != peer &&
 128             aa_capable(label, CAP_SYS_RESOURCE, CAP_OPT_NOAUDIT) != 0)
 129                 error = fn_for_each(label, profile,
 130                                 audit_resource(profile, resource,
 131                                                new_rlim->rlim_max, peer,
 132                                                "cap_sys_resource", -EACCES));
 133         else
 134                 error = fn_for_each_confined(label, profile,
 135                                 profile_setrlimit(profile, resource, new_rlim));
 136         aa_put_label(peer);
 137
 138         return error;
 139 }
 140
 141 /**
 142  * __aa_transition_rlimits - apply new profile rlimits
 143  * @old_l: old label on task  (NOT NULL)
 144  * @new_l: new label with rlimits to apply  (NOT NULL)
 145  */
 146 void __aa_transition_rlimits(struct aa_label *old_l, struct aa_label *new_l)
 147 {
 148         unsigned int mask = 0;
 149         struct rlimit *rlim, *initrlim;
 150         struct aa_profile *old, *new;
 151         struct label_it i;
 152
 153         old = labels_profile(old_l);
 154         new = labels_profile(new_l);
 155
 156         /* for any rlimits the profile controlled, reset the soft limit
 157          * to the lesser of the tasks hard limit and the init tasks soft limit
 158          */
 159         label_for_each_confined(i, old_l, old) {
 160                 struct aa_ruleset *rules = list_first_entry(&old->rules,
 161                                                             typeof(*rules),
 162                                                             list);
 163                 if (rules->rlimits.mask) {
 164                         int j;
 165
 166                         for (j = 0, mask = 1; j < RLIM_NLIMITS; j++,
 167                                      mask <<= 1) {
 168                                 if (rules->rlimits.mask & mask) {
 169                                         rlim = current->signal->rlim + j;
 170                                         initrlim = init_task.signal->rlim + j;
 171                                         rlim->rlim_cur = min(rlim->rlim_max,
 172                                                             initrlim->rlim_cur);
 173                                 }
 174                         }
 175                 }
 176         }
 177
 178         /* set any new hard limits as dictated by the new profile */
 179         label_for_each_confined(i, new_l, new) {
 180                 struct aa_ruleset *rules = list_first_entry(&new->rules,
 181                                                             typeof(*rules),
 182                                                             list);
 183                 int j;
 184
 185                 if (!rules->rlimits.mask)
 186                         continue;
 187                 for (j = 0, mask = 1; j < RLIM_NLIMITS; j++, mask <<= 1) {
 188                         if (!(rules->rlimits.mask & mask))
 189                                 continue;
 190
 191                         rlim = current->signal->rlim + j;
 192                         rlim->rlim_max = min(rlim->rlim_max,
 193                                              rules->rlimits.limits[j].rlim_max);
 194                         /* soft limit should not exceed hard limit */
 195                         rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 196                 }
 197         }
 198 }