NAME

       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

       #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 ***con);

       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 **con);

       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

       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 selinux_set_callback(3).

       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 ignored.

       security_compute_relabel() is used to compute the new context to use when relabeling  an  object,  it  is
       used  in  the  pam_selinux.so 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_create_raw(),
       security_compute_create_name_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 context.

       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

       Returns zero on success or -1 on error.

SEE ALSO

       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)