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35 .Nd introduction to the POSIX.1e ACL security API
43 permits file systems to export Access Control Lists via the VFS, and
44 provides a library for userland access to and manipulation of these ACLs.
45 Not all file systems provide support for ACLs, and some may require that
46 ACL support be explicitly enabled by the administrator.
47 The library calls include routines to allocate, duplicate, retrieve, set,
48 and validate ACLs associated with file objects.
49 As well as the POSIX.1e routines, there are a number of non-portable
50 extensions defined that allow for alternative ACL semantics than the
51 POSIX.1e semantics, such as NFSv4, AFS, NTFS, Coda, and NWFS semantics.
52 Where routines are non-standard, they are suffixed with _np to indicate that
53 they are not portable.
55 POSIX.1e describes a set of ACL manipulation routines to manage the
56 contents of ACLs, as well as their relationships with files; almost
57 all of these support routines are implemented in
60 Available functions, sorted by behavior, include:
61 .Bl -tag -width indent
62 .It Fn acl_add_flag_np
63 This function is described in
64 .Xr acl_add_flag_np 3 ,
65 and may be used to add flags to a flagset.
67 This function is described in
69 and may be used to add permissions to a permission set.
71 This function is described in
73 and may be used to calculate and set the permissions associated with
77 .It Fn acl_clear_flags_np
78 This function is described in
79 .Xr acl_clear_flags_np 3 ,
80 and may be used to clear all flags from a flagset.
81 .It Fn acl_clear_perms
82 This function is described in
83 .Xr acl_clear_perms 3 ,
84 and may be used to clear all permissions from a permission set.
86 This function is described in
87 .Xr acl_copy_entry 3 ,
88 and may be used to copy the contents of an ACL entry.
90 .Fn acl_create_entry ,
91 .Fn acl_create_entry_np
93 These functions are described in
94 .Xr acl_create_entry 3 ,
95 and may be used to create an empty entry in an ACL.
97 .Fn acl_delete_def_file ,
98 .Fn acl_delete_def_link_np ,
99 .Fn acl_delete_fd_np ,
100 .Fn acl_delete_file_np ,
101 .Fn acl_delete_link_np
103 These functions are described in
105 and may be used to delete ACLs from file system objects.
107 .Fn acl_delete_entry ,
108 .Fn acl_delete_entry_np ,
110 This functions are described in
111 .Xr acl_delete_entry 3 ,
112 and may be used to delete an entry from an ACL.
113 .It Fn acl_delete_flag_np
114 This function is described in
115 .Xr acl_delete_flag_np 3 ,
116 and may be used to delete flags from a flagset.
117 .It Fn acl_delete_perm
118 This function is described in
119 .Xr acl_delete_perm 3 ,
120 and may be used to delete permissions from a permset.
122 This function is described in
124 and may be used to duplicate an ACL structure.
126 This function is described in
128 and may be used to free userland working ACL storage.
130 This function is described in
131 .Xr acl_from_text 3 ,
132 and may be used to convert a text-form ACL into working ACL state, if
133 the ACL has POSIX.1e or NFSv4 semantics.
134 .It Fn acl_get_brand_np
135 This function is described in
136 .Xr acl_get_brand_np 3
137 and may be used to determine whether the ACL has POSIX.1e or NFSv4 semantics.
139 This function is described in
140 .Xr acl_get_entry 3 ,
141 and may be used to retrieve a designated ACL entry from an ACL.
148 These functions are described in
150 and may be used to retrieve ACLs from file system objects.
151 .It Fn acl_get_entry_type_np
152 This function is described in
153 .Xr acl_get_entry_type_np 3 ,
154 and may be used to retrieve an ACL type from an ACL entry.
155 .It Fn acl_get_flagset_np
156 This function is described in
157 .Xr acl_get_flagset_np 3 ,
158 and may be used to retrieve a flagset from an ACL entry.
159 .It Fn acl_get_permset
160 This function is described in
161 .Xr acl_get_permset 3 ,
162 and may be used to retrieve a permset from an ACL entry.
163 .It Fn acl_get_qualifier
164 This function is described in
165 .Xr acl_get_qualifier 3 ,
166 and may be used to retrieve the qualifier from an ACL entry.
167 .It Fn acl_get_tag_type
168 This function is described in
169 .Xr acl_get_tag_type 3 ,
170 and may be used to retrieve the tag type from an ACL entry.
172 This function is described in
174 and may be used to allocate a fresh (empty) ACL structure.
175 .It Fn acl_is_trivial_np
176 This function is described in
177 .Xr acl_is_trivial_np 3 ,
178 and may be used to find out whether ACL is trivial.
185 These functions are described in
187 and may be used to assign an ACL to a file system object.
188 .It Fn acl_set_entry_type_np
189 This function is described in
190 .Xr acl_set_entry_type_np 3 ,
191 and may be used to set the ACL type of an ACL entry.
192 .It Fn acl_set_flagset_np
193 This function is described in
194 .Xr acl_set_flagset_np 3 ,
195 and may be used to set the flags of an ACL entry from a flagset.
196 .It Fn acl_set_permset
197 This function is described in
198 .Xr acl_set_permset 3 ,
199 and may be used to set the permissions of an ACL entry from a permset.
200 .It Fn acl_set_qualifier
201 This function is described in
202 .Xr acl_set_qualifier 3 ,
203 and may be used to set the qualifier of an ACL.
204 .It Fn acl_set_tag_type
205 This function is described in
206 .Xr acl_set_tag_type 3 ,
207 and may be used to set the tag type of an ACL.
209 This function is described in
211 and may be used to remove extended entries from an ACL.
216 These functions are described in
218 and may be used to generate a text-form of a POSIX.1e or NFSv4 semantics ACL.
221 .Fn acl_valid_fd_np ,
222 .Fn acl_valid_file_np ,
223 .Fn acl_valid_link_np
225 These functions are described in
227 and may be used to validate an ACL as correct POSIX.1e-semantics, or
228 as appropriate for a particular file system object regardless of semantics.
231 Documentation of the internal kernel interfaces backing these calls may
234 The syscalls between the internal interfaces and the public library
235 routines may change over time, and as such are not documented.
236 They are not intended to be called directly without going through the
241 .Xr acl_add_flag_np 3 ,
243 .Xr acl_calc_mask 3 ,
244 .Xr acl_clear_flags_np 3 ,
245 .Xr acl_clear_perms 3 ,
246 .Xr acl_copy_entry 3 ,
247 .Xr acl_create_entry 3 ,
248 .Xr acl_delete_entry 3 ,
249 .Xr acl_delete_flag_np 3 ,
250 .Xr acl_delete_perm 3 ,
253 .Xr acl_from_text 3 ,
255 .Xr acl_get_brand_np 3 ,
256 .Xr acl_get_entry_type_np 3 ,
257 .Xr acl_get_flagset_np 3 ,
258 .Xr acl_get_permset 3 ,
259 .Xr acl_get_qualifier 3 ,
260 .Xr acl_get_tag_type 3 ,
262 .Xr acl_is_trivial_np 3 ,
264 .Xr acl_set_entry_type_np 3 ,
265 .Xr acl_set_flagset_np 3 ,
266 .Xr acl_set_permset 3 ,
267 .Xr acl_set_qualifier 3 ,
268 .Xr acl_set_tag_type 3 ,
275 POSIX.1e assigns security labels to all objects, extending the security
276 functionality described in POSIX.1.
277 These additional labels provide fine-grained discretionary access control,
278 fine-grained capabilities, and labels necessary for mandatory access
280 POSIX.2c describes a set of userland utilities for manipulating these
283 POSIX.1e is described in IEEE POSIX.1e draft 17.
284 Discussion of the draft continues on the cross-platform POSIX.1e
285 implementation mailing list.
286 To join this list, see the
288 POSIX.1e implementation page for more information.
290 POSIX.1e support was introduced in
293 was the first version to include a complete ACL implementation based
294 on extended attributes for the UFS and UFS2 file systems.
300 utilities describe the user tools that permit direct manipulation of complete
303 .An Robert N M Watson