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NAME | SYNOPSIS | DESCRIPTION | SECURITY EVENTS | RETURN VALUE | ERRORS | NOTES | AUTHOR | SEE ALSO | COLOPHON |
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avc_add_callback(3) SELinux API documentation avc_add_callback(3)
avc_add_callback - additional event notification for SELinux
userspace object managers
#include <selinux/selinux.h>
#include <selinux/avc.h>
int avc_add_callback(int (*callback)(uint32_t event,
security_id_t ssid,
security_id_t tsid,
security_class_t tclass,
access_vector_t perms,
access_vector_t *out_retained),
uint32_t events, security_id_t ssid,
security_id_t tsid, security_class_t tclass,
access_vector_t perms);
avc_add_callback() is used to register callback functions on security
events. The purpose of this functionality is to allow userspace
object managers to take additional action when a policy change,
usually a policy reload, causes permissions to be granted or revoked.
events is the bitwise-or of security events on which to register the
callback; see SECURITY EVENTS below.
ssid, tsid, tclass, and perms specify the source and target SID's,
target class, and specific permissions that the callback wishes to
monitor. The special symbol SECSID_WILD may be passed as the source
or target and will cause any SID to match.
callback is the callback function provided by the userspace object
manager. The event argument indicates the security event which
occurred; the remaining arguments are interpreted according to the
event as described below. The return value of the callback should be
zero on success, -1 on error with errno set appropriately (but see
RETURN VALUE below).
In all cases below, ssid and/or tsid may be set to SECSID_WILD,
indicating that the change applies to all source and/or target SID's.
Unless otherwise indicated, the out_retained parameter is unused.
AVC_CALLBACK_GRANT
Previously denied permissions are now granted for ssid, tsid
with respect to tclass. perms indicates the permissions to
grant.
AVC_CALLBACK_TRY_REVOKE
Previously granted permissions are now conditionally revoked
for ssid, tsid with respect to tclass. perms indicates the
permissions to revoke. The callback should set out_retained
to the subset of perms which are retained as migrated
permissions. Note that out_retained is ignored if the
callback returns -1.
AVC_CALLBACK_REVOKE
Previously granted permissions are now unconditionally revoked
for ssid, tsid with respect to tclass. perms indicates the
permissions to revoke.
AVC_CALLBACK_RESET
Indicates that the cache was flushed. The SID, class, and
permission arguments are unused and are set to NULL.
AVC_CALLBACK_AUDITALLOW_ENABLE
The permissions given by perms should now be audited when
granted for ssid, tsid with respect to tclass.
AVC_CALLBACK_AUDITALLOW_DISABLE
The permissions given by perms should no longer be audited
when granted for ssid, tsid with respect to tclass.
AVC_CALLBACK_AUDITDENY_ENABLE
The permissions given by perms should now be audited when
denied for ssid, tsid with respect to tclass.
AVC_CALLBACK_AUDITDENY_DISABLE
The permissions given by perms should no longer be audited
when denied for ssid, tsid with respect to tclass.
On success, avc_add_callback() returns zero. On error, -1 is
returned and errno is set appropriately.
A return value of -1 from a callback is interpreted as a failed
policy operation. If such a return value is encountered, all
remaining callbacks registered on the event are called. In threaded
mode, the netlink handler thread may then terminate and cause the
userspace AVC to return EINVAL on all further permission checks until
avc_destroy(3) is called. In non-threaded mode, the permission check
on which the error occurred will return -1 and the value of errno
encountered to the caller. In both cases, a log message is produced
and the kernel may be notified of the error.
ENOMEM An attempt to allocate memory failed.
If the userspace AVC is running in threaded mode, callbacks
registered via avc_add_callback() may be executed in the context of
the netlink handler thread. This will likely introduce
synchronization issues requiring the use of locks. See avc_init(3).
Support for dynamic revocation and retained permissions is mostly
unimplemented in the SELinux kernel module. The only security event
that currently gets exercised is AVC_CALLBACK_RESET.
Eamon Walsh <ewalsh@tycho.nsa.gov>
avc_init(3), avc_has_perm(3), avc_context_to_sid(3),
avc_cache_stats(3), security_compute_av(3) selinux(8)
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 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2018-01-25.) 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 man-pages@man7.org
9 June 2004 avc_add_callback(3)
Pages that refer to this page: avc_cache_stats(3), avc_context_to_sid(3), avc_has_perm(3), avc_open(3)
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