NAME

       aa_policy_cache - an opaque object representing an AppArmor policy cache

       aa_policy_cache_new - create a new aa_policy_cache object from a path

       aa_policy_cache_ref - increments the ref count of an aa_policy_cache object

       aa_policy_cache_unref - decrements the ref count and frees the aa_policy_cache object when
       0

       aa_policy_cache_remove - removes all policy cache files under a path

       aa_policy_cache_replace_all - performs a kernel policy replacement of all cached policies

       aa_policy_cache_dir_path - returns the path to the aa_policy_cache directory

       aa_policy_cache_dir_path_preview - returns a preview of the path to the aa_policy_cache
       directory without an existing aa_policy_cache object

SYNOPSIS

       #include <sys/apparmor.h>

       typedef struct aa_policy_cache aa_policy_cache;

       int aa_policy_cache_new(aa_policy_cache **policy_cache, aa_features *kernel_features, int
       dirfd, const char *path, uint16_t max_caches);

       int aa_policy_cache_add_ro_dir(aa_policy_cache *policy_cache, int dirfd, const char
       *path);

       aa_policy_cache *aa_policy_cache_ref(aa_policy_cache *policy_cache);

       void aa_policy_cache_unref(aa_policy_cache *policy_cache);

       int aa_policy_cache_remove(int dirfd, const char *path);

       int aa_policy_cache_replace_all(aa_policy_cache *policy_cache, aa_kernel_interface
       *kernel_interface);

       char *aa_policy_cache_dir_path(aa_policy_cache *policy_cache, int level);

       char *aa_policy_cache_dir_path_preview(aa_features *kernel_features, int dirfd, const char
       *path);

       Link with -lapparmor when compiling.

DESCRIPTION

       The aa_policy_cache object contains information about a set of AppArmor policy cache
       files. The policy cache files are the binary representation of a human-readable AppArmor
       profile. The binary representation is the form that is loaded into the kernel.

       The aa_policy_cache_new() function creates an aa_policy_cache object based upon a
       directory file descriptor and path. See the openat(2) man page for examples of dirfd and
       path. The path must point to a directory and it will be used as the basis for the location
       of policy cache files. See aa_policy_cache_dir_path to find out which directory will be
       used to store the binary policy cache files. If additional overlay cache directories are
       used (see aa_policy_cache_add_ro_dir) the directory specified in aa_policy_cache_new is
       the first directory searched and is the writable overlay. If kernel_features is NULL, then
       the features of the current kernel are used. When specifying a valid kernel_features
       object, it must be compatible with the features of the kernel of interest.  The value of
       max_caches should be equal to the number of caches that should be allowed before old
       caches are automatically reaped. The definition of what is considered to be an old cache
       is private to libapparmor. Specifying 0 means that no new caches should be created and
       only existing, valid caches may be used.  Specifying UINT16_MAX means that a new cache may
       be created and that the reaping of old caches is disabled. The allocated aa_policy_cache
       object must be freed using aa_policy_cache_unref().

       The aa_policy_cache_add_ro_dir() function adds an existing cache directory to the policy
       cache, as a readonly layer under the primary directory the cache was created with. When
       the cache is searched for an existing cache file the primary directory will be searched
       and then the readonly directories in the order that they were added to the policy cache.
       This allows the policy cache to be seeded with precompiled policy that can be updated by
       overlaying the read only cache file with one written to the primary cache dir.

       aa_policy_cache_ref() increments the reference count on the policy_cache object.

       aa_policy_cache_unref() decrements the reference count on the policy_cache object and
       releases all corresponding resources when the reference count reaches zero.

       The aa_policy_cache_remove() function deletes all of the policy cache files based upon a
       directory file descriptor and path. The path must point to a directory. See the openat(2)
       man page for examples of dirfd and path.

       The aa_policy_cache_replace_all() function can be used to perform a policy replacement of
       all of the cache policies in the cache directory represented by the policy_cache object.
       If kernel_interface is NULL, then the current kernel interface is used. When specifying a
       valid kernel_interface object, it must be the interface of the currently running kernel.

       The aa_policy_cache_dir_path() function provides the path to the cache directory for a
       policy_cache object at level in the policy cache overlay of cache directories. A level of
       0 will always be present and is the first directory to search in an overlay of cache
       directories, and will also be the writable cache directory layer. Binary policy cache
       files will be located in the directory returned by this function.

       The aa_policy_cache_dir_levels() function provides access to the number of directories
       that are being overlaid to create the policy cache.

RETURN VALUE

       The aa_policy_cache_new() function returns 0 on success and *policy_cache will point to an
       aa_policy_cache object that must be freed by aa_policy_cache_unref(). -1 is returned on
       error, with errno set appropriately, and *policy_cache will be set to NULL.

       aa_policy_cache_ref() returns the value of policy_cache.

       aa_policy_cache_remove() and aa_policy_cache_replace_all() return 0 on success.  -1 is
       returned on error, with errno set appropriately.

       aa_policy_cache_dir_path() returns a path string which must be freed by the caller. NULL
       is returned on error, with errno set appropriately.

       aa_policy_cache_dir_levels() returns a number indicating the number of directory levels
       there are associated with the policy_cache.

       aa_policy_cache_dir_path_preview() is the same as aa_policy_cache_dir_path() except that
       it doesn't require an existing aa_policy_cache object. This is useful if the calling
       program cannot create an aa_policy_cache object due to lack of privileges needed to create
       the cache directory.

ERRORS

       The errno value will be set according to the underlying error in the aa_policy_cache
       family of functions that return -1 or NULL on error.

NOTES

       All aa_policy_cache functions described above, except for the aa_policy_cache_dir_path()
       function was added in libapparmor version 2.13. All the other aa_policy_cache functions
       described above are present in libapparmor version 2.10.

       aa_policy_cache_unref() saves the value of errno when called and restores errno before
       exiting in libapparmor version 2.12 and newer.

BUGS

       None known. If you find any, please report them at
       <https://gitlab.com/apparmor/apparmor/-/issues>.

SEE ALSO

       aa_features(3), aa_kernel_interface(3), openat(2) and <https://wiki.apparmor.net>.