NAME
vaccess_acl_posix1e —
generate a POSIX.1e ACL access control
decision using vnode parameters
SYNOPSIS
#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,
accmode_t accmode, struct ucred
*cred, int *privused);
DESCRIPTION
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 accmode, 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 toNULL 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 super-user privilege, if available for the credential, will also be considered.
RETURN VALUES
vaccess_acl_posix1e() will return 0 on
success, or a non-zero error value on failure.
ERRORS
- [
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
AUTHORS
This manual page and the current implementation of
vaccess_acl_posix1e() were written by
Robert Watson.
BUGS
This manual page should include a full description of the POSIX.1e ACL evaluation algorithm, or cross reference another page that does.