posix1e/acl.3

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  30 .Dd December 18, 2002
  31 .Dt ACL 3
  32 .Os
  33 .Sh NAME
  34 .Nm acl
  35 .Nd introduction to the POSIX.1e ACL security API
  36 .Sh LIBRARY
  37 .Lb libc
  38 .Sh SYNOPSIS
  39 .In sys/types.h
  40 .In sys/acl.h
  41 .Sh DESCRIPTION
  42 The system permits file systems to export Access Control Lists via the VFS, and
  43 provides a library for userland access to and manipulation of these ACLs.
  44 Not all file systems provide support for ACLs, and some may require that
  45 ACL support be explicitly enabled by the administrator.
  46 The library calls include routines to allocate, duplicate, retrieve, set,
  47 and validate ACLs associated with file objects.
  48 .Pp
  49 This implementation of the POSIX.1e library differs from the standard
  50 in a number of non-portable ways in order to support the MacOS/Darwin
  51 ACL semantic.  Where possible, these differences are implemented using
  52 the mechanisms provided in the standard for such extensions.
  53 Where routines are non-standard, they are suffixed with _np to indicate that
  54 they are not portable.
  55 .Pp
  56 POSIX.1e describes a set of ACL manipulation routines to manage the
  57 contents of ACLs, as well as their relationships with files; almost
  58 all of these support routines are implemented.
  59 .Pp
  60 Available functions, sorted by behavior, include:
  61 .Bl -tag -width indent
  62 .It Fn acl_add_perm
  63 This function is described in
  64 .Xr acl_add_perm 3 ,
  65 and may be used to add permissions to a permission set.
  66 .It Fn acl_clear_perms
  67 This function is described in
  68 .Xr acl_clear_perms 3 ,
  69 and may be used to clear all permissions from a permission set.
  70 .It Fn acl_copy_entry
  71 This function is described in
  72 .Xr acl_copy_entry 3 ,
  73 and may be used to copy the contents of an ACL entry.
  74 .It Fn acl_create_entry
  75 This function is described in
  76 .Xr acl_create_entry 3 ,
  77 and may be used to create an empty entry in an ACL.
  78 .It Xo
  79 .Fn acl_delete_fd_np ,
  80 .Fn acl_delete_file_np ,
  81 .Fn acl_delete_link_np
  82 .Xc
  83 These functions are described in
  84 .Xr acl_delete 3 ,
  85 and may be used to delete ACLs from file system objects.
  86 .It Fn acl_delete_entry
  87 This function is described in
  88 .Xr acl_delete_entry 3 ,
  89 and may be used to delete an entry from an ACL.
  90 .It Fn acl_delete_perm
  91 This function is described in
  92 .Xr acl_delete_perm 3 ,
  93 and may be used to delete permissions from a permset.
  94 .It Fn acl_dup
  95 This function is described in
  96 .Xr acl_dup 3 ,
  97 and may be used to duplicate an ACL structure.
  98 .It Fn acl_free
  99 This function is described in
 100 .Xr acl_free 3 ,
 101 and may be used to free userland working ACL storage.
 102 .It Fn acl_from_text
 103 This function is described in
 104 .Xr acl_from_text 3 ,
 105 and may be used to convert a text-form ACL into working ACL state, if
 106 the ACL has POSIX.1e semantics.
 107 .It Fn acl_get_entry
 108 This function is described in
 109 .Xr acl_get_entry 3 ,
 110 and may be used to retrieve a designated ACL entry from an ACL.
 111 .It Xo
 112 .Fn acl_get_fd ,
 113 .Fn acl_get_fd_np ,
 114 .Fn acl_get_file ,
 115 .Fn acl_get_link_np
 116 .Xc
 117 These functions are described in
 118 .Xr acl_get 3 ,
 119 and may be used to retrieve ACLs from file system objects.
 120 .It Fn acl_get_permset
 121 This function is described in
 122 .Xr acl_get_permset 3 ,
 123 and may be used to retrieve a permset from an ACL entry.
 124 .It Fn acl_get_qualifier
 125 This function is described in
 126 .Xr acl_get_qualifier 3 ,
 127 and may be used to retrieve the qualifier from an ACL entry.
 128 .It Fn acl_get_tag_type
 129 This function is described in
 130 .Xr acl_get_tag_type 3 ,
 131 and may be used to retrieve the tag type from an ACL entry.
 132 .It Fn acl_init
 133 This function is described in
 134 .Xr acl_init 3 ,
 135 and may be used to allocate a fresh (empty) ACL structure.
 136 .It Xo
 137 .Fn acl_set_fd ,
 138 .Fn acl_set_fd_np ,
 139 .Fn acl_set_file ,
 140 .Fn acl_set_link_np
 141 .Xc
 142 These functions are described in
 143 .Xr acl_set 3 ,
 144 and may be used to assign an ACL to a file system object.
 145 .It Fn acl_set_permset
 146 This function is described in
 147 .Xr acl_set_permset 3 ,
 148 and may be used to set the permissions of an ACL entry from a permset.
 149 .It Fn acl_set_qualifier
 150 This function is described in
 151 .Xr acl_set_qualifier 3 ,
 152 and may be used to set the qualifier of an ACL.
 153 .It Fn acl_set_tag_type
 154 This function is described in
 155 .Xr acl_set_tag_type 3 ,
 156 and may be used to set the tag type of an ACL.
 157 .It Fn acl_to_text
 158 This function is described in
 159 .Xr acl_to_text 3 ,
 160 and may be used to generate a text-form of a POSIX.1e semantics ACL.
 161 .It Xo
 162 .Fn acl_valid ,
 163 .Fn acl_valid_fd_np ,
 164 .Fn acl_valid_file_np ,
 165 .Fn acl_valid_link_np
 166 .Xc
 167 These functions are described in
 168 .Xr acl_valid 3 ,
 169 and may be used to validate an ACL as correct POSIX.1e-semantics, or
 170 as appropriate for a particular file system object regardless of semantics.
 171 .El
 172 .Pp
 173 Documentation of the internal kernel interfaces backing these calls may
 174 be found in
 175 .Xr acl 9 .
 176 The syscalls between the internal interfaces and the public library
 177 routines may change over time, and as such are not documented.
 178 They are not intended to be called directly without going through the
 179 library.
 180 .Sh SEE ALSO
 181 .\".Xr getfacl 1 ,
 182 .\".Xr setfacl 1 ,
 183 .Xr ls 1 ,
 184 .Xr chmod 1 ,
 185 .Xr acl_add_perm 3 ,
 186 .Xr acl_clear_perms 3 ,
 187 .Xr acl_copy_entry 3 ,
 188 .Xr acl_create_entry 3 ,
 189 .Xr acl_delete_entry 3 ,
 190 .Xr acl_delete_perm 3 ,
 191 .Xr acl_dup 3 ,
 192 .Xr acl_free 3 ,
 193 .Xr acl_from_text 3 ,
 194 .Xr acl_get 3 ,
 195 .Xr acl_get_permset 3 ,
 196 .Xr acl_get_qualifier 3 ,
 197 .Xr acl_get_tag_type 3 ,
 198 .Xr acl_init 3 ,
 199 .Xr acl_set 3 ,
 200 .Xr acl_set_permset 3 ,
 201 .Xr acl_set_qualifier 3 ,
 202 .Xr acl_set_tag_type 3 ,
 203 .Xr acl_to_text 3 ,
 204 .Xr acl_valid 3 ,
 205 .Xr posix1e 3 ,
 206 .Xr acl 9
 207 .Sh UNSUPPORTED FUNCTIONS
 208 .Xr acl_calc_mask 3 ,
 209 .Fn acl_delete_def_file
 210 .Sh STANDARDS
 211 POSIX.1e assigns security labels to all objects, extending the security
 212 functionality described in POSIX.1.
 213 These additional labels provide fine-grained discretionary access control,
 214 fine-grained capabilities, and labels necessary for mandatory access
 215 control.
 216 POSIX.2c describes a set of userland utilities for manipulating these
 217 labels.
 218 .Pp
 219 POSIX.1e is described in IEEE POSIX.1e draft 17.
 220 .Sh HISTORY
 221 This manpage is closely derived from the
 222 .Fx
 223 manpage by
 224 .An Robert N M Watson
 225 .Sh AUTHORS
 226 .An Michael Smith
 227 .An Robert N M Watson