security_compute_av(3) — Linux manual page


security_compute_av(3)  SELinux API documentation security_compute_av(3)

NAME         top

       security_compute_av, security_compute_av_flags,
       security_compute_create, security_compute_create_name,
       security_compute_relabel, security_compute_member,
       security_compute_user, security_validatetrans,
       security_get_initial_context - query the SELinux policy database
       in the kernel

SYNOPSIS         top

       #include <selinux/selinux.h>

       int security_compute_av(char *scon, char *tcon, security_class_t
       tclass, access_vector_t requested, struct av_decision *avd);

       int security_compute_av_raw(char *scon, char *tcon,
       security_class_t tclass, access_vector_t requested, struct
       av_decision *avd);

       int security_compute_av_flags(char *scon, char *tcon,
       security_class_t tclass, access_vector_t requested, struct
       av_decision *avd);

       int security_compute_av_flags_raw(char *scon, char *tcon,
       security_class_t tclass, access_vector_t requested, struct
       av_decision *avd);

       int security_compute_create(char *scon, char *tcon,
       security_class_t tclass, char **newcon);

       int security_compute_create_raw(char *scon, char *tcon,
       security_class_t tclass, char **newcon);

       int security_compute_create_name(char *scon, char *tcon,
       security_class_t tclass, const char *objname, char **newcon);

       int security_compute_create_name_raw(char *scon, char *tcon,
       security_class_t tclass, const char *objname, char **newcon);

       int security_compute_relabel(char *scon, char *tcon,
       security_class_t tclass, char **newcon);

       int security_compute_relabel_raw(char *scon, char *tcon,
       security_class_t tclass, char **newcon);

       int security_compute_member(char *scon, char *tcon,
       security_class_t tclass, char **newcon);

       int security_compute_member_raw(char *scon, char *tcon,
       security_class_t tclass, char **newcon);

       int security_compute_user(char *scon, const char *username, char

       int security_compute_user_raw(char *scon, const char *username,
       char ***con);

       int security_validatetrans(char *scon, const char *tcon,
       security_class_t tclass, char *newcon);

       int security_validatetrans_raw(char *scon, const char *tcon,
       security_class_t tclass, char *newcon);

       int security_get_initial_context(const char *name, char **con);

       int security_get_initial_context_raw(const char *name, char

       int selinux_check_access(const char *scon, const char *tcon,
       const char *class, const char *perm, void *auditdata);

       int selinux_check_passwd_access(access_vector_t requested);

       int checkPasswdAccess(access_vector_t requested);

DESCRIPTION         top

       This family of functions is used to obtain policy decisions from
       the SELinux kernel security server (policy engine).  In general,
       direct use of security_compute_av() and its variant interfaces is
       discouraged in favor of using selinux_check_access() since the
       latter automatically handles the dynamic mapping of class and
       permission names to their policy values, initialization and use
       of the Access Vector Cache (AVC), and proper handling of per-
       domain and global permissive mode and allow_unknown.

       When using any of the functions that take policy integer values
       for classes or permissions as inputs, use
       string_to_security_class(3) and string_to_av_perm(3) to map the
       class and permission names to their policy values.  These values
       may change across a policy reload, so they should be re-acquired
       on every use or using a SELINUX_CB_POLICYLOAD callback set via

       An alternative approach is to use selinux_set_mapping(3) to
       create a mapping from class and permission index values used by
       the application to the policy values, thereby allowing the
       application to pass its own fixed constants for the classes and
       permissions to these functions and internally mapping them on
       demand.  However, this also requires setting up a callback as
       above to address policy reloads.

       security_compute_av() queries whether the policy permits the
       source context scon to access the target context tcon via class
       tclass with the requested access vector.  The decision is
       returned in avd.

       security_compute_av_flags() is identical to security_compute_av
       but additionally sets the flags field of avd.  Currently one flag
       is supported: SELINUX_AVD_FLAGS_PERMISSIVE, which indicates the
       decision is computed on a permissive domain.

       security_compute_create() is used to compute a context to use for
       labeling a new object in a particular class based on a SID pair.

       security_compute_create_name() is identical to
       security_compute_create() but also takes name of the new object
       in creation as an argument.  When TYPE_TRANSITION rule on the
       given class and a SID pair has object name extension, we shall be
       able to obtain a correct newcon according to the security policy.
       Note that this interface is only supported on the linux 2.6.40 or
       later.  In the older kernel, the object name will be simply

       security_compute_relabel() is used to compute the new context to
       use when relabeling an object, it is used in the
       source and the newrole source to determine the correct label for
       the tty at login time, but can be used for other things.

       security_compute_member() is used to compute the context to use
       when labeling a polyinstantiated object instance.

       security_compute_user() is used to determine the set of user
       contexts that can be reached from a source context. This function
       is deprecated; use get_ordered_context_list(3) instead.

       security_validatetrans() is used to determine if a transition
       from scon to newcon using tcon as the object is valid for object
       class tclass. This checks against the mlsvalidatetrans and
       validatetrans constraints in the loaded policy. Returns 0 if
       allowed, and -1 if an error occurred with errno set.

       security_get_initial_context() is used to get the context of a
       kernel initial security identifier specified by name

       security_compute_av_raw(), security_compute_av_flags_raw(),
       security_compute_relabel_raw(), security_compute_member_raw(),
       security_compute_user_raw() security_validatetrans_raw() and
       security_get_initial_context_raw() behave identically to their
       non-raw counterparts but do not perform context translation.

       selinux_check_access() is used to check if the source context has
       the access permission for the specified class on the target

       selinux_check_passwd_access() is used to check for a permission
       in the passwd class.  selinux_check_passwd_access() uses
       getprevcon(3) for the source and target security contexts.

       checkPasswdAccess() is a deprecated alias of the
       selinux_check_passwd_access() function.

RETURN VALUE         top

       Returns zero on success or -1 on error.

SEE ALSO         top

       string_to_security_class(3), string_to_av_perm(3),
       selinux_set_callback(3), selinux_set_mapping(3), getprevcon(3),
       get_ordered_context_list(3), selinux(8)

COLOPHON         top

       This page is part of the selinux (Security-Enhanced Linux user-
       space libraries and tools) project.  Information about the
       project can be found at 
       ⟨⟩.  If you have a
       bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2023-05-11.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to         1 January 2004       security_compute_av(3)

Pages that refer to this page: avc_add_callback(3)avc_compute_create(3)avc_has_perm(3)avc_init(3)avc_open(3)get_ordered_context_list(3)selinux_set_mapping(3)