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/*
* Access vector cache interface for object managers.
*
* Author : Eamon Walsh <ewalsh@epoch.ncsc.mil>
*/
#ifndef _SELINUX_AVC_H_
#define _SELINUX_AVC_H_
#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <selinux/selinux.h>
#ifdef __cplusplus
extern "C"
{
#endif
/*
* SID format and operations
*/
struct security_id {
security_context_t ctx;
unsigned int refcnt;
};
typedef struct security_id *security_id_t;
#define SECSID_WILD (security_id_t)NULL /* unspecified SID */
/**
* avc_sid_to_context - get copy of context corresponding to SID.
* @sid: input SID
* @ctx: pointer to context reference
*
* Return a copy of the security context corresponding to the input
* @sid in the memory referenced by @ctx. The caller is expected to
* free the context with freecon(). Return %0 on success, -%1 on
* failure, with @errno set to %ENOMEM if insufficient memory was
* available to make the copy, or %EINVAL if the input SID is invalid.
*/
int avc_sid_to_context(security_id_t sid, security_context_t *ctx);
/**
* avc_context_to_sid - get SID for context.
* @ctx: input security context
* @sid: pointer to SID reference
*
* Look up security context @ctx in SID table, making
* a new entry if @ctx is not found. Increment the
* reference counter for the SID. Store a pointer
* to the SID structure into the memory referenced by @sid,
* returning %0 on success or -%1 on error with @errno set.
*/
int avc_context_to_sid(security_context_t ctx, security_id_t *sid);
/**
* sidget - increment SID reference counter.
* @sid: SID reference
*
* Increment the reference counter for @sid, indicating that
* @sid is in use by an (additional) object. Return the
* new reference count, or zero if @sid is invalid (has zero
* reference count). Note that avc_context_to_sid() also
* increments reference counts.
*/
int sidget(security_id_t sid);
/**
* sidput - decrement SID reference counter.
* @sid: SID reference
*
* Decrement the reference counter for @sid, indicating that
* a reference to @sid is no longer in use. Return the
* new reference count. When the reference count reaches
* zero, the SID is invalid, and avc_context_to_sid() must
* be called to obtain a new SID for the security context.
*/
int sidput(security_id_t sid);
/*
* AVC entry
*/
struct avc_entry;
struct avc_entry_ref {
struct avc_entry *ae;
};
/**
* avc_entry_ref_init - initialize an AVC entry reference.
* @aeref: pointer to avc entry reference structure
*
* Use this macro to initialize an avc entry reference structure
* before first use. These structures are passed to avc_has_perm(),
* which stores cache entry references in them. They can increase
* performance on repeated queries.
*/
#define avc_entry_ref_init(aeref) ((aeref)->ae = NULL)
/*
* User-provided callbacks for memory, auditing, and locking
*/
/* These structures are passed by reference to avc_init(). Passing
* a NULL reference will cause the AVC to use a default. The default
* memory callbacks are malloc() and free(). The default logging method
* is to print on stderr. If no thread callbacks are passed, a separate
* listening thread won't be started for kernel policy change messages.
* If no locking callbacks are passed, no locking will take place.
*/
struct avc_memory_callback {
/* malloc() equivalent. */
void *(*func_malloc)(size_t size);
/* free() equivalent. */
void (*func_free) (void *ptr);
/* Note that these functions should set errno on failure.
If not, some avc routines may return -1 without errno set. */
};
struct avc_log_callback {
/* log the printf-style format and arguments. */
void (*func_log)(const char *fmt, ...);
/* store a string representation of auditdata (corresponding
to the given security class) into msgbuf. */
void (*func_audit)(void *auditdata, security_class_t class,
char *msgbuf, size_t msgbufsize);
};
struct avc_thread_callback {
/* create and start a thread, returning an opaque pointer to it;
the thread should run the given function. */
void *(*func_create_thread)(void (*run)(void));
/* cancel a given thread and free its resources. */
void (*func_stop_thread)(void *thread);
};
struct avc_lock_callback {
/* create a lock and return an opaque pointer to it. */
void *(*func_alloc_lock)(void);
/* obtain a given lock, blocking if necessary. */
void (*func_get_lock)(void *lock);
/* release a given lock. */
void (*func_release_lock)(void *lock);
/* destroy a given lock (free memory, etc.) */
void (*func_free_lock)(void *lock);
};
/*
* AVC operations
*/
/**
* avc_init - Initialize the AVC.
* @msgprefix: prefix for log messages
* @mem_callbacks: user-supplied memory callbacks
* @log_callbacks: user-supplied logging callbacks
* @thread_callbacks: user-supplied threading callbacks
* @lock_callbacks: user-supplied locking callbacks
*
* Initialize the access vector cache. Return %0 on
* success or -%1 with @errno set on failure.
* If @msgprefix is NULL, use "uavc". If any callback
* structure references are NULL, use default methods
* for those callbacks (see the definition of the callback
* structures above).
*/
int avc_init(const char *msgprefix,
const struct avc_memory_callback *mem_callbacks,
const struct avc_log_callback *log_callbacks,
const struct avc_thread_callback *thread_callbacks,
const struct avc_lock_callback *lock_callbacks);
/**
* avc_cleanup - Remove unused SIDs and AVC entries.
*
* Search the SID table for SID structures with zero
* reference counts, and remove them along with all
* AVC entries that reference them. This can be used
* to return memory to the system.
*/
void avc_cleanup(void);
/**
* avc_reset - Flush the cache and reset statistics.
*
* Remove all entries from the cache and reset all access
* statistics (as returned by avc_cache_stats()) to zero.
* The SID mapping is not affected. Return %0 on success,
* -%1 with @errno set on error.
*/
int avc_reset(void);
/**
* avc_destroy - Free all AVC structures.
*
* Destroy all AVC structures and free all allocated
* memory. User-supplied locking, memory, and audit
* callbacks will be retained, but security-event
* callbacks will not. All SID's will be invalidated.
* User must call avc_init() if further use of AVC is desired.
*/
void avc_destroy(void);
/**
* avc_has_perm_noaudit - Check permissions but perform no auditing.
* @ssid: source security identifier
* @tsid: target security identifier
* @tclass: target security class
* @requested: requested permissions, interpreted based on @tclass
* @aeref: AVC entry reference
* @avd: access vector decisions
*
* Check the AVC to determine whether the @requested permissions are granted
* for the SID pair (@ssid, @tsid), interpreting the permissions
* based on @tclass, and call the security server on a cache miss to obtain
* a new decision and add it to the cache. Update @aeref to refer to an AVC
* entry with the resulting decisions, and return a copy of the decisions
* in @avd. Return %0 if all @requested permissions are granted, -%1 with
* @errno set to %EACCES if any permissions are denied, or to another value
* upon other errors. This function is typically called by avc_has_perm(),
* but may also be called directly to separate permission checking from
* auditing, e.g. in cases where a lock must be held for the check but
* should be released for the auditing.
*/
int avc_has_perm_noaudit(security_id_t ssid,
security_id_t tsid,
security_class_t tclass,
access_vector_t requested,
struct avc_entry_ref *aeref,
struct av_decision *avd);
/**
* avc_has_perm - Check permissions and perform any appropriate auditing.
* @ssid: source security identifier
* @tsid: target security identifier
* @tclass: target security class
* @requested: requested permissions, interpreted based on @tclass
* @aeref: AVC entry reference
* @auditdata: auxiliary audit data
*
* Check the AVC to determine whether the @requested permissions are granted
* for the SID pair (@ssid, @tsid), interpreting the permissions
* based on @tclass, and call the security server on a cache miss to obtain
* a new decision and add it to the cache. Update @aeref to refer to an AVC
* entry with the resulting decisions. Audit the granting or denial of
* permissions in accordance with the policy. Return %0 if all @requested
* permissions are granted, -%1 with @errno set to %EACCES if any permissions
* are denied or to another value upon other errors.
*/
int avc_has_perm(security_id_t ssid, security_id_t tsid,
security_class_t tclass, access_vector_t requested,
struct avc_entry_ref *aeref, void *auditdata);
/**
* avc_audit - Audit the granting or denial of permissions.
* @ssid: source security identifier
* @tsid: target security identifier
* @tclass: target security class
* @requested: requested permissions
* @avd: access vector decisions
* @result: result from avc_has_perm_noaudit
* @auditdata: auxiliary audit data
*
* Audit the granting or denial of permissions in accordance
* with the policy. This function is typically called by
* avc_has_perm() after a permission check, but can also be
* called directly by callers who use avc_has_perm_noaudit()
* in order to separate the permission check from the auditing.
* For example, this separation is useful when the permission check must
* be performed under a lock, to allow the lock to be released
* before calling the auditing code.
*/
void avc_audit(security_id_t ssid, security_id_t tsid,
security_class_t tclass, access_vector_t requested,
struct av_decision *avd, int result, void *auditdata);
/*
* security event callback facility
*/
/* security events */
#define AVC_CALLBACK_GRANT 1
#define AVC_CALLBACK_TRY_REVOKE 2
#define AVC_CALLBACK_REVOKE 4
#define AVC_CALLBACK_RESET 8
#define AVC_CALLBACK_AUDITALLOW_ENABLE 16
#define AVC_CALLBACK_AUDITALLOW_DISABLE 32
#define AVC_CALLBACK_AUDITDENY_ENABLE 64
#define AVC_CALLBACK_AUDITDENY_DISABLE 128
/**
* avc_add_callback - Register a callback for security events.
* @callback: callback function
* @events: bitwise OR of desired security events
* @ssid: source security identifier or %SECSID_WILD
* @tsid: target security identifier or %SECSID_WILD
* @tclass: target security class
* @perms: permissions
*
* Register a callback function for events in the set @events
* related to the SID pair (@ssid, @tsid) and
* and the permissions @perms, interpreting
* @perms based on @tclass. Returns %0 on success or
* -%1 if insufficient memory exists to add the callback.
*/
int avc_add_callback(int (*callback)(u_int32_t event, security_id_t ssid,
security_id_t tsid,
security_class_t tclass,
access_vector_t perms,
access_vector_t *out_retained),
u_int32_t events, security_id_t ssid,
security_id_t tsid,
security_class_t tclass, access_vector_t perms);
/*
* AVC statistics
*/
/* If set, cache statistics are tracked. This may
* become a compile-time option in the future.
*/
#define AVC_CACHE_STATS 1
struct avc_cache_stats {
unsigned entry_lookups;
unsigned entry_hits;
unsigned entry_misses;
unsigned entry_discards;
unsigned cav_lookups;
unsigned cav_hits;
unsigned cav_probes;
unsigned cav_misses;
};
/**
* avc_cache_stats - get cache access statistics.
* @stats: reference to statistics structure
*
* Fill the supplied structure with information about AVC
* activity since the last call to avc_init() or
* avc_reset(). See the structure definition for
* details.
*/
void avc_cache_stats(struct avc_cache_stats *stats);
/**
* avc_av_stats - log av table statistics.
*
* Log a message with information about the size and
* distribution of the access vector table. The audit
* callback is used to print the message.
*/
void avc_av_stats(void);
/**
* avc_sid_stats - log SID table statistics.
*
* Log a message with information about the size and
* distribution of the SID table. The audit callback
* is used to print the message.
*/
void avc_sid_stats(void);
#ifdef __cplusplus
}
#endif
#endif /* _SELINUX_AVC_H_ */
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