security/selinux/include/avc.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Access vector cache interface for object managers.
   4  *
   5  * Author : Stephen Smalley, <sds@tycho.nsa.gov>
   6  */
   7 #ifndef _SELINUX_AVC_H_
   8 #define _SELINUX_AVC_H_
   9
  10 #include <linux/stddef.h>
  11 #include <linux/errno.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kdev_t.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/init.h>
  16 #include <linux/audit.h>
  17 #include <linux/lsm_audit.h>
  18 #include <linux/in6.h>
  19 #include "flask.h"
  20 #include "av_permissions.h"
  21 #include "security.h"
  22
  23 /*
  24  * An entry in the AVC.
  25  */
  26 struct avc_entry;
  27
  28 struct task_struct;
  29 struct inode;
  30 struct sock;
  31 struct sk_buff;
  32
  33 /*
  34  * AVC statistics
  35  */
  36 struct avc_cache_stats {
  37         unsigned int lookups;
  38         unsigned int misses;
  39         unsigned int allocations;
  40         unsigned int reclaims;
  41         unsigned int frees;
  42 };
  43
  44 /*
  45  * We only need this data after we have decided to send an audit message.
  46  */
  47 struct selinux_audit_data {
  48         u32 ssid;
  49         u32 tsid;
  50         u16 tclass;
  51         u32 requested;
  52         u32 audited;
  53         u32 denied;
  54         int result;
  55         struct selinux_state *state;
  56 };
  57
  58 /*
  59  * AVC operations
  60  */
  61
  62 void __init avc_init(void);
  63
  64 static inline u32 avc_audit_required(u32 requested,
  65                               struct av_decision *avd,
  66                               int result,
  67                               u32 auditdeny,
  68                               u32 *deniedp)
  69 {
  70         u32 denied, audited;
  71         denied = requested & ~avd->allowed;
  72         if (unlikely(denied)) {
  73                 audited = denied & avd->auditdeny;
  74                 /*
  75                  * auditdeny is TRICKY!  Setting a bit in
  76                  * this field means that ANY denials should NOT be audited if
  77                  * the policy contains an explicit dontaudit rule for that
  78                  * permission.  Take notice that this is unrelated to the
  79                  * actual permissions that were denied.  As an example lets
  80                  * assume:
  81                  *
  82                  * denied == READ
  83                  * avd.auditdeny & ACCESS == 0 (not set means explicit rule)
  84                  * auditdeny & ACCESS == 1
  85                  *
  86                  * We will NOT audit the denial even though the denied
  87                  * permission was READ and the auditdeny checks were for
  88                  * ACCESS
  89                  */
  90                 if (auditdeny && !(auditdeny & avd->auditdeny))
  91                         audited = 0;
  92         } else if (result)
  93                 audited = denied = requested;
  94         else
  95                 audited = requested & avd->auditallow;
  96         *deniedp = denied;
  97         return audited;
  98 }
  99
 100 int slow_avc_audit(struct selinux_state *state,
 101                    u32 ssid, u32 tsid, u16 tclass,
 102                    u32 requested, u32 audited, u32 denied, int result,
 103                    struct common_audit_data *a,
 104                    unsigned flags);
 105
 106 /**
 107  * avc_audit - Audit the granting or denial of permissions.
 108  * @ssid: source security identifier
 109  * @tsid: target security identifier
 110  * @tclass: target security class
 111  * @requested: requested permissions
 112  * @avd: access vector decisions
 113  * @result: result from avc_has_perm_noaudit
 114  * @a:  auxiliary audit data
 115  * @flags: VFS walk flags
 116  *
 117  * Audit the granting or denial of permissions in accordance
 118  * with the policy.  This function is typically called by
 119  * avc_has_perm() after a permission check, but can also be
 120  * called directly by callers who use avc_has_perm_noaudit()
 121  * in order to separate the permission check from the auditing.
 122  * For example, this separation is useful when the permission check must
 123  * be performed under a lock, to allow the lock to be released
 124  * before calling the auditing code.
 125  */
 126 static inline int avc_audit(struct selinux_state *state,
 127                             u32 ssid, u32 tsid,
 128                             u16 tclass, u32 requested,
 129                             struct av_decision *avd,
 130                             int result,
 131                             struct common_audit_data *a,
 132                             int flags)
 133 {
 134         u32 audited, denied;
 135         audited = avc_audit_required(requested, avd, result, 0, &denied);
 136         if (likely(!audited))
 137                 return 0;
 138         return slow_avc_audit(state, ssid, tsid, tclass,
 139                               requested, audited, denied, result,
 140                               a, flags);
 141 }
 142
 143 #define AVC_STRICT 1 /* Ignore permissive mode. */
 144 #define AVC_EXTENDED_PERMS 2    /* update extended permissions */
 145 #define AVC_NONBLOCKING    4    /* non blocking */
 146 int avc_has_perm_noaudit(struct selinux_state *state,
 147                          u32 ssid, u32 tsid,
 148                          u16 tclass, u32 requested,
 149                          unsigned flags,
 150                          struct av_decision *avd);
 151
 152 int avc_has_perm(struct selinux_state *state,
 153                  u32 ssid, u32 tsid,
 154                  u16 tclass, u32 requested,
 155                  struct common_audit_data *auditdata);
 156
 157 int avc_has_extended_perms(struct selinux_state *state,
 158                            u32 ssid, u32 tsid, u16 tclass, u32 requested,
 159                            u8 driver, u8 perm, struct common_audit_data *ad);
 160
 161
 162 u32 avc_policy_seqno(struct selinux_state *state);
 163
 164 #define AVC_CALLBACK_GRANT              1
 165 #define AVC_CALLBACK_TRY_REVOKE         2
 166 #define AVC_CALLBACK_REVOKE             4
 167 #define AVC_CALLBACK_RESET              8
 168 #define AVC_CALLBACK_AUDITALLOW_ENABLE  16
 169 #define AVC_CALLBACK_AUDITALLOW_DISABLE 32
 170 #define AVC_CALLBACK_AUDITDENY_ENABLE   64
 171 #define AVC_CALLBACK_AUDITDENY_DISABLE  128
 172 #define AVC_CALLBACK_ADD_XPERMS         256
 173
 174 int avc_add_callback(int (*callback)(u32 event), u32 events);
 175
 176 /* Exported to selinuxfs */
 177 struct selinux_avc;
 178 int avc_get_hash_stats(struct selinux_avc *avc, char *page);
 179 unsigned int avc_get_cache_threshold(struct selinux_avc *avc);
 180 void avc_set_cache_threshold(struct selinux_avc *avc,
 181                              unsigned int cache_threshold);
 182
 183 /* Attempt to free avc node cache */
 184 void avc_disable(void);
 185
 186 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
 187 DECLARE_PER_CPU(struct avc_cache_stats, avc_cache_stats);
 188 #endif
 189
 190 #endif /* _SELINUX_AVC_H_ */
 191