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ACL(9) BSD Kernel Developer's Manual ACL(9) NAME acl -- virtual file system access control lists SYNOPSIS #include <sys/param.h> #include <sys/vnode.h> #include <sys/acl.h> In the kernel configuration file: options UFS_ACL DESCRIPTION Access control lists, or ACLs, allow fine-grained specification of rights for vnodes representing files and directories. However, as there are a plethora of file systems with differing ACL semantics, the vnode inter- face is aware only of the syntax of ACLs, relying on the underlying file system to implement the details. Depending on the underlying file sys- tem, each file or directory may have zero or more ACLs associated with it, named using the type field of the appropriate vnode ACL calls: VOP_ACLCHECK(9), VOP_GETACL(9), and VOP_SETACL(9). Currently, each ACL is represented in-kernel by a fixed-size acl struc- ture, defined as follows: struct acl { unsigned int acl_maxcnt; unsigned int acl_cnt; int acl_spare[4]; struct acl_entry acl_entry[ACL_MAX_ENTRIES]; }; An ACL is constructed from a fixed size array of ACL entries, each of which consists of a set of permissions, principal namespace, and princi- pal identifier. In this implementation, the acl_maxcnt field is always set to ACL_MAX_ENTRIES. Each individual ACL entry is of the type acl_entry_t, which is a struc- ture with the following members: acl_tag_t ae_tag The following is a list of definitions of ACL types to be set in ae_tag: ACL_UNDEFINED_FIELD Undefined ACL type. ACL_USER_OBJ Discretionary access rights for processes whose effective user ID matches the user ID of the file's owner. ACL_USER Discretionary access rights for processes whose effective user ID matches the ACL entry qualifier. ACL_GROUP_OBJ Discretionary access rights for processes whose effective group ID or any supplemen- tal groups match the group ID of the file's owner. ACL_GROUP Discretionary access rights for processes whose effective group ID or any supplemen- tal groups match the ACL entry qualifier. ACL_MASK The maximum discretionary access rights that can be granted to a process in the file group class. This is only valid for POSIX.1e ACLs. ACL_OTHER Discretionary access rights for processes not covered by any other ACL entry. This is only valid for POSIX.1e ACLs. ACL_OTHER_OBJ Same as ACL_OTHER. ACL_EVERYONE Discretionary access rights for all users. This is only valid for NFSv4 ACLs. Each POSIX.1e ACL must contain exactly one ACL_USER_OBJ, one ACL_GROUP_OBJ, and one ACL_OTHER. If any of ACL_USER, ACL_GROUP, or ACL_OTHER are present, then exactly one ACL_MASK entry should be present. uid_t ae_id The ID of user for whom this ACL describes access permissions. For entries other than ACL_USER and ACL_GROUP, this field should be set to ACL_UNDEFINED_ID. acl_perm_t ae_perm This field defines what kind of access the process matching this ACL has for accessing the associated file. For POSIX.1e ACLs, the fol- lowing are valid: ACL_EXECUTE The process may execute the associated file. ACL_WRITE The process may write to the associated file. ACL_READ The process may read from the associated file. ACL_PERM_NONE The process has no read, write or execute per- missions to the associated file. For NFSv4 ACLs, the following are valid: ACL_READ_DATA The process may read from the associated file. ACL_LIST_DIRECTORY Same as ACL_READ_DATA. ACL_WRITE_DATA The process may write to the associated file. ACL_ADD_FILE Same as ACL_ACL_WRITE_DATA. ACL_APPEND_DATA ACL_ADD_SUBDIRECTORY Same as ACL_APPEND_DATA. ACL_READ_NAMED_ATTRS Ignored. ACL_WRITE_NAMED_ATTRS Ignored. ACL_EXECUTE The process may execute the associated file. ACL_DELETE_CHILD ACL_READ_ATTRIBUTES ACL_WRITE_ATTRIBUTES ACL_DELETE ACL_READ_ACL ACL_WRITE_ACL ACL_WRITE_OWNER ACL_SYNCHRONIZE Ignored. acl_entry_type_t ae_entry_type This field defines the type of NFSv4 ACL entry. It is not used with POSIX.1e ACLs. The following values are valid: ACL_ENTRY_TYPE_ALLOW ACL_ENTRY_TYPE_DENY acl_flag_t ae_flags This field defines the inheritance flags of NFSv4 ACL entry. It is not used with POSIX.1e ACLs. The following values are valid: ACL_ENTRY_FILE_INHERIT ACL_ENTRY_DIRECTORY_INHERIT ACL_ENTRY_NO_PROPAGATE_INHERIT ACL_ENTRY_INHERIT_ONLY SEE ALSO acl(3), vaccess_acl_nfs4(9), vaccess_acl_posix1e(9), VFS(9), vnaccess(9), VOP_ACLCHECK(9), VOP_GETACL(9), VOP_SETACL(9) AUTHORS This manual page was written by Robert Watson. BSD September 18, 2009 BSD
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | AUTHORS
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