linux-headers (unknown)
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 /*
3 * Landlock - User space API
4 *
5 * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
6 * Copyright © 2018-2020 ANSSI
7 */
8
9 #ifndef _LINUX_LANDLOCK_H
10 #define _LINUX_LANDLOCK_H
11
12 #include <linux/types.h>
13
14 /**
15 * struct landlock_ruleset_attr - Ruleset definition
16 *
17 * Argument of sys_landlock_create_ruleset(). This structure can grow in
18 * future versions.
19 */
20 struct landlock_ruleset_attr {
21 /**
22 * @handled_access_fs: Bitmask of actions (cf. `Filesystem flags`_)
23 * that is handled by this ruleset and should then be forbidden if no
24 * rule explicitly allow them: it is a deny-by-default list that should
25 * contain as much Landlock access rights as possible. Indeed, all
26 * Landlock filesystem access rights that are not part of
27 * handled_access_fs are allowed. This is needed for backward
28 * compatibility reasons. One exception is the
29 * %LANDLOCK_ACCESS_FS_REFER access right, which is always implicitly
30 * handled, but must still be explicitly handled to add new rules with
31 * this access right.
32 */
33 __u64 handled_access_fs;
34 };
35
36 /*
37 * sys_landlock_create_ruleset() flags:
38 *
39 * - %LANDLOCK_CREATE_RULESET_VERSION: Get the highest supported Landlock ABI
40 * version.
41 */
42 /* clang-format off */
43 #define LANDLOCK_CREATE_RULESET_VERSION (1U << 0)
44 /* clang-format on */
45
46 /**
47 * enum landlock_rule_type - Landlock rule type
48 *
49 * Argument of sys_landlock_add_rule().
50 */
51 enum landlock_rule_type {
52 /**
53 * @LANDLOCK_RULE_PATH_BENEATH: Type of a &struct
54 * landlock_path_beneath_attr .
55 */
56 LANDLOCK_RULE_PATH_BENEATH = 1,
57 };
58
59 /**
60 * struct landlock_path_beneath_attr - Path hierarchy definition
61 *
62 * Argument of sys_landlock_add_rule().
63 */
64 struct landlock_path_beneath_attr {
65 /**
66 * @allowed_access: Bitmask of allowed actions for this file hierarchy
67 * (cf. `Filesystem flags`_).
68 */
69 __u64 allowed_access;
70 /**
71 * @parent_fd: File descriptor, preferably opened with ``O_PATH``,
72 * which identifies the parent directory of a file hierarchy, or just a
73 * file.
74 */
75 __s32 parent_fd;
76 /*
77 * This struct is packed to avoid trailing reserved members.
78 * Cf. security/landlock/syscalls.c:build_check_abi()
79 */
80 } __attribute__((packed));
81
82 /**
83 * DOC: fs_access
84 *
85 * A set of actions on kernel objects may be defined by an attribute (e.g.
86 * &struct landlock_path_beneath_attr) including a bitmask of access.
87 *
88 * Filesystem flags
89 * ~~~~~~~~~~~~~~~~
90 *
91 * These flags enable to restrict a sandboxed process to a set of actions on
92 * files and directories. Files or directories opened before the sandboxing
93 * are not subject to these restrictions.
94 *
95 * A file can only receive these access rights:
96 *
97 * - %LANDLOCK_ACCESS_FS_EXECUTE: Execute a file.
98 * - %LANDLOCK_ACCESS_FS_WRITE_FILE: Open a file with write access. Note that
99 * you might additionally need the %LANDLOCK_ACCESS_FS_TRUNCATE right in order
100 * to overwrite files with :manpage:`open(2)` using ``O_TRUNC`` or
101 * :manpage:`creat(2)`.
102 * - %LANDLOCK_ACCESS_FS_READ_FILE: Open a file with read access.
103 * - %LANDLOCK_ACCESS_FS_TRUNCATE: Truncate a file with :manpage:`truncate(2)`,
104 * :manpage:`ftruncate(2)`, :manpage:`creat(2)`, or :manpage:`open(2)` with
105 * ``O_TRUNC``. Whether an opened file can be truncated with
106 * :manpage:`ftruncate(2)` is determined during :manpage:`open(2)`, in the
107 * same way as read and write permissions are checked during
108 * :manpage:`open(2)` using %LANDLOCK_ACCESS_FS_READ_FILE and
109 * %LANDLOCK_ACCESS_FS_WRITE_FILE. This access right is available since the
110 * third version of the Landlock ABI.
111 *
112 * A directory can receive access rights related to files or directories. The
113 * following access right is applied to the directory itself, and the
114 * directories beneath it:
115 *
116 * - %LANDLOCK_ACCESS_FS_READ_DIR: Open a directory or list its content.
117 *
118 * However, the following access rights only apply to the content of a
119 * directory, not the directory itself:
120 *
121 * - %LANDLOCK_ACCESS_FS_REMOVE_DIR: Remove an empty directory or rename one.
122 * - %LANDLOCK_ACCESS_FS_REMOVE_FILE: Unlink (or rename) a file.
123 * - %LANDLOCK_ACCESS_FS_MAKE_CHAR: Create (or rename or link) a character
124 * device.
125 * - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory.
126 * - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file.
127 * - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain
128 * socket.
129 * - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe.
130 * - %LANDLOCK_ACCESS_FS_MAKE_BLOCK: Create (or rename or link) a block device.
131 * - %LANDLOCK_ACCESS_FS_MAKE_SYM: Create (or rename or link) a symbolic link.
132 * - %LANDLOCK_ACCESS_FS_REFER: Link or rename a file from or to a different
133 * directory (i.e. reparent a file hierarchy).
134 *
135 * This access right is available since the second version of the Landlock
136 * ABI.
137 *
138 * This is the only access right which is denied by default by any ruleset,
139 * even if the right is not specified as handled at ruleset creation time.
140 * The only way to make a ruleset grant this right is to explicitly allow it
141 * for a specific directory by adding a matching rule to the ruleset.
142 *
143 * In particular, when using the first Landlock ABI version, Landlock will
144 * always deny attempts to reparent files between different directories.
145 *
146 * In addition to the source and destination directories having the
147 * %LANDLOCK_ACCESS_FS_REFER access right, the attempted link or rename
148 * operation must meet the following constraints:
149 *
150 * * The reparented file may not gain more access rights in the destination
151 * directory than it previously had in the source directory. If this is
152 * attempted, the operation results in an ``EXDEV`` error.
153 *
154 * * When linking or renaming, the ``LANDLOCK_ACCESS_FS_MAKE_*`` right for the
155 * respective file type must be granted for the destination directory.
156 * Otherwise, the operation results in an ``EACCES`` error.
157 *
158 * * When renaming, the ``LANDLOCK_ACCESS_FS_REMOVE_*`` right for the
159 * respective file type must be granted for the source directory. Otherwise,
160 * the operation results in an ``EACCES`` error.
161 *
162 * If multiple requirements are not met, the ``EACCES`` error code takes
163 * precedence over ``EXDEV``.
164 *
165 * .. warning::
166 *
167 * It is currently not possible to restrict some file-related actions
168 * accessible through these syscall families: :manpage:`chdir(2)`,
169 * :manpage:`stat(2)`, :manpage:`flock(2)`, :manpage:`chmod(2)`,
170 * :manpage:`chown(2)`, :manpage:`setxattr(2)`, :manpage:`utime(2)`,
171 * :manpage:`ioctl(2)`, :manpage:`fcntl(2)`, :manpage:`access(2)`.
172 * Future Landlock evolutions will enable to restrict them.
173 */
174 /* clang-format off */
175 #define LANDLOCK_ACCESS_FS_EXECUTE (1ULL << 0)
176 #define LANDLOCK_ACCESS_FS_WRITE_FILE (1ULL << 1)
177 #define LANDLOCK_ACCESS_FS_READ_FILE (1ULL << 2)
178 #define LANDLOCK_ACCESS_FS_READ_DIR (1ULL << 3)
179 #define LANDLOCK_ACCESS_FS_REMOVE_DIR (1ULL << 4)
180 #define LANDLOCK_ACCESS_FS_REMOVE_FILE (1ULL << 5)
181 #define LANDLOCK_ACCESS_FS_MAKE_CHAR (1ULL << 6)
182 #define LANDLOCK_ACCESS_FS_MAKE_DIR (1ULL << 7)
183 #define LANDLOCK_ACCESS_FS_MAKE_REG (1ULL << 8)
184 #define LANDLOCK_ACCESS_FS_MAKE_SOCK (1ULL << 9)
185 #define LANDLOCK_ACCESS_FS_MAKE_FIFO (1ULL << 10)
186 #define LANDLOCK_ACCESS_FS_MAKE_BLOCK (1ULL << 11)
187 #define LANDLOCK_ACCESS_FS_MAKE_SYM (1ULL << 12)
188 #define LANDLOCK_ACCESS_FS_REFER (1ULL << 13)
189 #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14)
190 /* clang-format on */
191
192 #endif /* _LINUX_LANDLOCK_H */
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