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
#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);
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.
Returns zero on success or -1 on error.
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)