NAME    [Toc]    [Back]

     vaccess_acl_posix1e -- generate a POSIX.1e ACL access control decision
     using vnode parameters

SYNOPSIS    [Toc]    [Back]

     #include <sys/param.h>
     #include <sys/vnode.h>
     #include <sys/acl.h>

     int
     vaccess_acl_posix1e(enum vtype type, uid_t file_uid, gid_t file_gid,
	 struct acl *acl, mode_t acc_mode, struct ucred *cred, int *privused);

DESCRIPTION    [Toc]    [Back]

     This call implements the logic for the UNIX discretionary file security
     model with POSIX.1e ACL extensions.  It accepts the vnodes type type,
     owning UID file_uid, owning GID file_gid, access ACL for the file acl,
     desired access mode acc_mode, requesting credential cred, and an optional
     call-by-reference int pointer returning whether or not privilege was
     required for successful evaluation of the call; the privused pointer may
     be set to NULL by the caller in order not to be informed of privilege
     information, or it may point to an integer that will be set to 1 if privilege
 is used, and 0 otherwise.

     This call is intended to support implementations of VOP_ACCESS(9), which
     will use their own access methods to retrieve the vnode properties, and
     then invoke vaccess_acl_posix1e() in order to perform the actual check.
     Implementations of VOP_ACCESS(9) may choose to implement additional security
 mechanisms whose results will be composed with the return value.

     The algorithm used by vaccess_acl_posix1e() is based on the POSIX.1e ACL
     evaluation algorithm.  The algorithm selects a matching entry from the
     access ACL, which may then be composed with an available ACL mask entry,
     providing UNIX security compatibility.

     Once appropriate protections are selected for the current credential, the
     requested access mode, in combination with the vnode type, will be compared
 with the discretionary rights available for the credential.	If the
     rights granted by discretionary protections are insufficient, then superuser
 privilege, if available for the credential, will also be considered.

RETURN VALUES    [Toc]    [Back]

     vaccess_acl_posix1e() will return 0 on success, or a non-zero error value
     on failure.

ERRORS    [Toc]    [Back]

     [EACCES]		Permission denied.  An attempt was made to access a
			file in a way forbidden by its file access permissions.


     [EPERM]		Operation not permitted.  An attempt was made to perform
 an operation limited to processes with appropriate
 privileges or to the owner of a file or other
			resource.

SEE ALSO    [Toc]    [Back]

     vaccess(9), vnode(9), VOP_ACCESS(9)

AUTHORS    [Toc]    [Back]

     This man page and the current implementation of vaccess_acl_posix1e()
     were written by Robert Watson.

BUGS    [Toc]    [Back]

     This man page should include a full description of the POSIX.1e ACL evaluation
 algorithm, or cross reference another page that does.


FreeBSD 5.2.1			August 22, 2001 		 FreeBSD 5.2.1