vaccess_acl_posix1e (9)

Leading comments

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 Copyright (c) 2001 Robert N. M. Watson
 All rights reserved.

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(The comments found at the beginning of the groff file "man9/vaccess_acl_posix1e.9freebsd".)

NAME

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

SYNOPSIS

In sys/param.h In sys/vnode.h In sys/acl.h Ft int Fo vaccess_acl_posix1e Fa enum vtype type Fa uid_t file_uid Fa gid_t file_gid Fa struct acl *acl Fa accmode_t accmode Fa struct ucred *cred Fa int *privused Fc

DESCRIPTION

This call implements the logic for the UNIX discretionary file security model with POSIX.1e ACL extensions. It accepts the vnodes type Fa type , owning UID Fa file_uid , owning GID Fa file_gid , access ACL for the file Fa acl , desired access mode Fa accmode , requesting credential Fa cred , and an optional call-by-reference Vt int pointer returning whether or not privilege was required for successful evaluation of the call; the Fa 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_ACCESS9, which will use their own access methods to retrieve the vnode properties, and then invoke Fn vaccess_acl_posix1e in order to perform the actual check. Implementations of VOP_ACCESS9 may choose to implement additional security mechanisms whose results will be composed with the return value.

The algorithm used by Fn 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

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

ERRORS

Bq Er EACCES

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

Bq Er 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

vaccess(9), vnode(9), VOP_ACCESS9

AUTHORS

This manual page and the current implementation of Fn vaccess_acl_posix1e were written by An 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.