avc_sid_to_context

avc_context_to_sid(3)	  SE Linux API documentation	avc_context_to_sid(3)



NAME
       avc_context_to_sid,  avc_sid_to_context,	 sidput,  sidget - obtain and
       manipulate security ID’s.

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

       int avc_context_to_sid(security_context_t ctx, security_id_t *sid);

       int avc_sid_to_context(security_id_t sid, security_context_t *ctx);

       int sidget(security_id_t sid);

       int sidput(security_id_t sid);

DESCRIPTION
       Security ID’s (SID’s) are reference-counted, opaque representations of
       security contexts.

       avc_context_to_sid  returns  a SID for the given context in the memory
       referenced by sid, incrementing its reference count by 1.

       avc_sid_to_context returns a copy of the context represented by sid in
       the  memory  referenced	by  ctx.   The	user  must free the copy with
       freecon(3).

       sidget increments the reference count of sid by 1.

       sidput decrements the reference count of sid by 1.  If the count	 ever
       reaches	zero,  the  SID becomes invalid and must not be used any fur-
       ther.


RETURN VALUE
       sidget and sidput return the new reference count.  A return  value  of
       zero indicates an invalid SID.

       avc_context_to_sid  and avc_sid_to_context return zero on success.  On
       error, -1 is returned and errno is set appropriately.


ERRORS
       EINVAL The provided sid has a zero reference count and is invalid.

       ENOMEM An attempt to allocate memory failed.


NOTES
       The expected usage  pattern  for	 these	functions  is  that  avc_con-
       text_to_sid  will  be  called once to obtain a SID for a newly created
       object, sidget will be called on a SID when its object is  duplicated,
       and  sidput  will  be  called  on  a SID when its object is destroyed.
       Proper reference counting is necessary to ensure that SID’s and	asso-
       ciated  cache entries are reclaimed from memory when no longer needed.


AUTHOR
       Eamon Walsh <ewalsh@epoch.ncsc.mil>


SEE ALSO
       avc_init(3), avc_has_perm(3), avc_cache_stats(3), avc_add_callback(3),
       getcon(3), freecon(3)



				 27 May 2004		avc_context_to_sid(3)