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GENFS_CAN_ACCESS_ACL_POSIX1E(9)                      Kernel Developer's Manual

NAME
     genfs_can_access_acl_posix1e - generate a POSIX.1e ACL access control
     decision using vnode parameters

SYNOPSIS
     #include <miscfs/genfs/genfs.h>

     int
     genfs_can_access_acl_posix1e(struct vnode *vp, kauth_cred_t cred,
         uid_t file_uid, gid_t file_gid, mode_t file_mode, struct acl *acl,
         accmode_t accmode);

DESCRIPTION
     This call implements the logic for the UNIX discretionary file security
     model with POSIX.1e ACL extensions.  It accepts the vnode vp, requesting
     credential cred, owning UID file_uid, owning GID file_gid, file
     permissions file_mode, access ACL for the file acl, and desired access
     mode accmode.

     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 genfs_can_access_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 genfs_can_access_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
     genfs_can_access_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
     genfs_can_access(9), vnode(9), VOP_ACCESS(9)

AUTHORS
     This manual page and the current implementation of
     genfs_can_access_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.

NetBSD 10.99                   January 17, 2022                   NetBSD 10.99