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
 105 /**
 106  * avc_audit - Audit the granting or denial of permissions.
 107  * @ssid: source security identifier
 108  * @tsid: target security identifier
 109  * @tclass: target security class
 110  * @requested: requested permissions
 111  * @avd: access vector decisions
 112  * @result: result from avc_has_perm_noaudit
 113  * @a:  auxiliary audit data
 114  * @flags: VFS walk flags
 115  *
 116  * Audit the granting or denial of permissions in accordance
 117  * with the policy.  This function is typically called by
 118  * avc_has_perm() after a permission check, but can also be
 119  * called directly by callers who use avc_has_perm_noaudit()
 120  * in order to separate the permission check from the auditing.
 121  * For example, this separation is useful when the permission check must
 122  * be performed under a lock, to allow the lock to be released
 123  * before calling the auditing code.
 124  */
 125 static inline int avc_audit(struct selinux_state *state,
 126                             u32 ssid, u32 tsid,
 127                             u16 tclass, u32 requested,
 128                             struct av_decision *avd,
 129                             int result,
 130                             struct common_audit_data *a,
 131                             int flags)
 132 {
 133         u32 audited, denied;
 134         audited = avc_audit_required(requested, avd, result, 0, &denied);
 135         if (likely(!audited))
 136                 return 0;
 137         /* fall back to ref-walk if we have to generate audit */
 138         if (flags & MAY_NOT_BLOCK)
 139                 return -ECHILD;
 140         return slow_avc_audit(state, ssid, tsid, tclass,
 141                               requested, audited, denied, result,
 142                               a);
 143 }
 144
 145 #define AVC_STRICT 1 /* Ignore permissive mode. */
 146 #define AVC_EXTENDED_PERMS 2    /* update extended permissions */
 147 #define AVC_NONBLOCKING    4    /* non blocking */
 148 int avc_has_perm_noaudit(struct selinux_state *state,
 149                          u32 ssid, u32 tsid,
 150                          u16 tclass, u32 requested,
 151                          unsigned flags,
 152                          struct av_decision *avd);
 153
 154 int avc_has_perm(struct selinux_state *state,
 155                  u32 ssid, u32 tsid,
 156                  u16 tclass, u32 requested,
 157                  struct common_audit_data *auditdata);
 158 int avc_has_perm_flags(struct selinux_state *state,
 159                        u32 ssid, u32 tsid,
 160                        u16 tclass, u32 requested,
 161                        struct common_audit_data *auditdata,
 162                        int flags);
 163
 164 int avc_has_extended_perms(struct selinux_state *state,
 165                            u32 ssid, u32 tsid, u16 tclass, u32 requested,
 166                            u8 driver, u8 perm, struct common_audit_data *ad);
 167
 168
 169 u32 avc_policy_seqno(struct selinux_state *state);
 170
 171 #define AVC_CALLBACK_GRANT              1
 172 #define AVC_CALLBACK_TRY_REVOKE         2
 173 #define AVC_CALLBACK_REVOKE             4
 174 #define AVC_CALLBACK_RESET              8
 175 #define AVC_CALLBACK_AUDITALLOW_ENABLE  16
 176 #define AVC_CALLBACK_AUDITALLOW_DISABLE 32
 177 #define AVC_CALLBACK_AUDITDENY_ENABLE   64
 178 #define AVC_CALLBACK_AUDITDENY_DISABLE  128
 179 #define AVC_CALLBACK_ADD_XPERMS         256
 180
 181 int avc_add_callback(int (*callback)(u32 event), u32 events);
 182
 183 /* Exported to selinuxfs */
 184 struct selinux_avc;
 185 int avc_get_hash_stats(struct selinux_avc *avc, char *page);
 186 unsigned int avc_get_cache_threshold(struct selinux_avc *avc);
 187 void avc_set_cache_threshold(struct selinux_avc *avc,
 188                              unsigned int cache_threshold);
 189
 190 /* Attempt to free avc node cache */
 191 void avc_disable(void);
 192
 193 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
 194 DECLARE_PER_CPU(struct avc_cache_stats, avc_cache_stats);
 195 #endif
 196
 197 #endif /* _SELINUX_AVC_H_ */
 198