avc_cleanup(3) — Linux manual page


avc_open(3)               SELinux API documentation              avc_open(3)

NAME         top

       avc_open, avc_destroy, avc_reset, avc_cleanup - userspace SELinux AVC
       setup and teardown

SYNOPSIS         top

       #include <selinux/selinux.h>
       #include <selinux/avc.h>

       int avc_open(struct selinux_opt *options, unsigned nopt);

       void avc_destroy(void);

       int avc_reset(void);

       void avc_cleanup(void);

DESCRIPTION         top

       avc_open() initializes the userspace AVC and must be called before
       any other AVC operation can be performed.

       avc_destroy() destroys the userspace AVC, freeing all internal memory
       structures.  After this call has been made, avc_open() must be called
       again before any AVC operations can be performed.

       avc_reset() flushes the userspace AVC, causing it to forget any
       cached access decisions.  The userspace AVC normally calls this
       function automatically when needed, see NETLINK NOTIFICATION below.

       avc_cleanup() attempts to free unused memory within the userspace
       AVC, but does not flush any cached access decisions.  Under normal
       operation, calling this function should not be necessary.

OPTIONS         top

       The userspace AVC obeys callbacks set via selinux_set_callback(3), in
       particular the logging and audit callbacks.

       The options which may be passed to avc_open() include the following:

              This option forces the userspace AVC into enforcing mode if
              the option value is non-NULL; permissive mode otherwise.  The
              system enforcing mode will be ignored.


       Linux kernel version 2.6.37 supports the SELinux kernel status page,
       enabling userspace applications to mmap(2) SELinux status state in
       read-only mode to avoid system calls during the cache hit code path.

       avc_open() calls selinux_status_open(3) to initialize the selinux
       status state.

       avc_has_perm(3) and selinux_check_access(3) both check for status
       updates through calls to selinux_status_updated(3) at the start of
       each permission query and take the appropriate action.

       Two status types are currently implemented.  setenforce events will
       change the effective enforcing state used within the AVC, and
       policyload events will result in a cache flush.


       In the event that the kernel status page is not successfully
       mmap(2)'ed the AVC will default to the netlink fallback mechanism,
       which opens a netlink socket for receiving status updates.
       setenforce and policyload events will have the same results as for
       the status page implementation, but all status update checks will now
       require a system call.

RETURN VALUE         top

       Functions with a return value return zero on success.  On error, -1
       is returned and errno is set appropriately.

AUTHOR         top

       Eamon Walsh <ewalsh@tycho.nsa.gov>

SEE ALSO         top

       selinux(8), selinux_check_access(3), avc_has_perm(3),
       avc_context_to_sid(3), avc_cache_stats(3), avc_add_callback(3),
       selinux_status_open(3), selinux_status_updated(3),
       selinux_set_callback(3), security_compute_av(3)

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 ⟨https://github.com/SELinuxProject/selinux/wiki⟩.  If you
       have a bug report for this manual page, see
       ⟨https://github.com/SELinuxProject/selinux/wiki/Contributing⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨https://github.com/SELinuxProject/selinux⟩ on 2020-11-01.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-10-31.)  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 im‐
       provements to the information in this COLOPHON (which is not part of
       the original manual page), send a mail to man-pages@man7.org

                                 12 Jun 2008                     avc_open(3)