selinux_set_mapping

Section: SELinux API documentation (3)
Updated: 12 Jun 2008
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NAME

selinux_set_mapping - establish dynamic object class and permission mapping.

SYNOPSIS

#include <selinux/selinux.h>

struct security_class_mapping {
        const char *name;
        const char *perms[];
};

int selinux_set_mapping(struct security_class_mapping *map);

DESCRIPTION

selinux_set_mapping establishes a mapping from a user-provided ordering of object classes and permissions to the numbers actually used by the loaded system policy. Use of this function is highly preferred over the generated constants in the libselinux header files, as this method allows the policy's class and permission values to change over time.

After the mapping is established, all libselinux functions that operate on class and permission values take the user-provided numbers, which are determined as follows:

The map argument consists of an array of security_class_mapping structures, which must be terminated by a structure having a NULL name field. Except for this last structure, the name field should refer to the string name of an object class, and the corresponding perms field should refer to an array of permission bit names terminated by a NULL string.

The object classes named in the mapping and the bit indexes of each set of permission bits named in the mapping are numbered in order starting from 1. These numbers are the values that should be passed to subsequent libselinux calls.

RETURN VALUE

Zero is returned on success. On error, -1 is returned and errno is set appropriately.

ERRORS

EINVAL: One of the class or permission names requested in the mapping is not present in the loaded policy.
ENOMEM: An attempt to allocate memory failed.

EXAMPLE

struct security_class_mapping map[] = {
    { "file", { "create", "unlink", "read", "write", NULL } },
    { "socket", { "bind", NULL } },
    { "process", { "signal", NULL } },
    { NULL }
};

if (selinux_set_mapping(map) < 0)
    exit(1);

In this example, after the call has succeeded, classes file, socket, and process will be identified by 1, 2 and 3, respectively. Permissions create, unlink, read, and write (for the file class) will be identified by 1, 2, 4, and 8 respectively. Classes and permissions not listed in the mapping cannot be used.

AUTHOR

Eamon Walsh <ewalsh@tycho.nsa.gov>