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 _UAPI_LINUX_LANDLOCK_H 10 #define _UAPI_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 * - %LANDLOCK_CREATE_RULESET_ERRATA: Get a bitmask of fixed issues. 42 */ 43 /* clang-format off */ 44 #define LANDLOCK_CREATE_RULESET_VERSION (1U << 0) 45 #define LANDLOCK_CREATE_RULESET_ERRATA (1U << 1) 46 /* clang-format on */ 47 48 /** 49 * enum landlock_rule_type - Landlock rule type 50 * 51 * Argument of sys_landlock_add_rule(). 52 */ 53 enum landlock_rule_type { 54 /** 55 * @LANDLOCK_RULE_PATH_BENEATH: Type of a &struct 56 * landlock_path_beneath_attr . 57 */ 58 LANDLOCK_RULE_PATH_BENEATH = 1, 59 }; 60 61 /** 62 * struct landlock_path_beneath_attr - Path hierarchy definition 63 * 64 * Argument of sys_landlock_add_rule(). 65 */ 66 struct landlock_path_beneath_attr { 67 /** 68 * @allowed_access: Bitmask of allowed actions for this file hierarchy 69 * (cf. `Filesystem flags`_). 70 */ 71 __u64 allowed_access; 72 /** 73 * @parent_fd: File descriptor, preferably opened with ``O_PATH``, 74 * which identifies the parent directory of a file hierarchy, or just a 75 * file. 76 */ 77 __s32 parent_fd; 78 /* 79 * This struct is packed to avoid trailing reserved members. 80 * Cf. security/landlock/syscalls.c:build_check_abi() 81 */ 82 } __attribute__((packed)); 83 84 /** 85 * DOC: fs_access 86 * 87 * A set of actions on kernel objects may be defined by an attribute (e.g. 88 * &struct landlock_path_beneath_attr) including a bitmask of access. 89 * 90 * Filesystem flags 91 * ~~~~~~~~~~~~~~~~ 92 * 93 * These flags enable to restrict a sandboxed process to a set of actions on 94 * files and directories. Files or directories opened before the sandboxing 95 * are not subject to these restrictions. 96 * 97 * A file can only receive these access rights: 98 * 99 * - %LANDLOCK_ACCESS_FS_EXECUTE: Execute a file. 100 * - %LANDLOCK_ACCESS_FS_WRITE_FILE: Open a file with write access. Note that 101 * you might additionally need the %LANDLOCK_ACCESS_FS_TRUNCATE right in order 102 * to overwrite files with :manpage:`open(2)` using ``O_TRUNC`` or 103 * :manpage:`creat(2)`. 104 * - %LANDLOCK_ACCESS_FS_READ_FILE: Open a file with read access. 105 * - %LANDLOCK_ACCESS_FS_TRUNCATE: Truncate a file with :manpage:`truncate(2)`, 106 * :manpage:`ftruncate(2)`, :manpage:`creat(2)`, or :manpage:`open(2)` with 107 * ``O_TRUNC``. Whether an opened file can be truncated with 108 * :manpage:`ftruncate(2)` is determined during :manpage:`open(2)`, in the 109 * same way as read and write permissions are checked during 110 * :manpage:`open(2)` using %LANDLOCK_ACCESS_FS_READ_FILE and 111 * %LANDLOCK_ACCESS_FS_WRITE_FILE. This access right is available since the 112 * third version of the Landlock ABI. 113 * 114 * A directory can receive access rights related to files or directories. The 115 * following access right is applied to the directory itself, and the 116 * directories beneath it: 117 * 118 * - %LANDLOCK_ACCESS_FS_READ_DIR: Open a directory or list its content. 119 * 120 * However, the following access rights only apply to the content of a 121 * directory, not the directory itself: 122 * 123 * - %LANDLOCK_ACCESS_FS_REMOVE_DIR: Remove an empty directory or rename one. 124 * - %LANDLOCK_ACCESS_FS_REMOVE_FILE: Unlink (or rename) a file. 125 * - %LANDLOCK_ACCESS_FS_MAKE_CHAR: Create (or rename or link) a character 126 * device. 127 * - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory. 128 * - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file. 129 * - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain 130 * socket. 131 * - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe. 132 * - %LANDLOCK_ACCESS_FS_MAKE_BLOCK: Create (or rename or link) a block device. 133 * - %LANDLOCK_ACCESS_FS_MAKE_SYM: Create (or rename or link) a symbolic link. 134 * - %LANDLOCK_ACCESS_FS_REFER: Link or rename a file from or to a different 135 * directory (i.e. reparent a file hierarchy). 136 * 137 * This access right is available since the second version of the Landlock 138 * ABI. 139 * 140 * This is the only access right which is denied by default by any ruleset, 141 * even if the right is not specified as handled at ruleset creation time. 142 * The only way to make a ruleset grant this right is to explicitly allow it 143 * for a specific directory by adding a matching rule to the ruleset. 144 * 145 * In particular, when using the first Landlock ABI version, Landlock will 146 * always deny attempts to reparent files between different directories. 147 * 148 * In addition to the source and destination directories having the 149 * %LANDLOCK_ACCESS_FS_REFER access right, the attempted link or rename 150 * operation must meet the following constraints: 151 * 152 * * The reparented file may not gain more access rights in the destination 153 * directory than it previously had in the source directory. If this is 154 * attempted, the operation results in an ``EXDEV`` error. 155 * 156 * * When linking or renaming, the ``LANDLOCK_ACCESS_FS_MAKE_*`` right for the 157 * respective file type must be granted for the destination directory. 158 * Otherwise, the operation results in an ``EACCES`` error. 159 * 160 * * When renaming, the ``LANDLOCK_ACCESS_FS_REMOVE_*`` right for the 161 * respective file type must be granted for the source directory. Otherwise, 162 * the operation results in an ``EACCES`` error. 163 * 164 * If multiple requirements are not met, the ``EACCES`` error code takes 165 * precedence over ``EXDEV``. 166 * 167 * .. warning:: 168 * 169 * It is currently not possible to restrict some file-related actions 170 * accessible through these syscall families: :manpage:`chdir(2)`, 171 * :manpage:`stat(2)`, :manpage:`flock(2)`, :manpage:`chmod(2)`, 172 * :manpage:`chown(2)`, :manpage:`setxattr(2)`, :manpage:`utime(2)`, 173 * :manpage:`ioctl(2)`, :manpage:`fcntl(2)`, :manpage:`access(2)`. 174 * Future Landlock evolutions will enable to restrict them. 175 */ 176 /* clang-format off */ 177 #define LANDLOCK_ACCESS_FS_EXECUTE (1ULL << 0) 178 #define LANDLOCK_ACCESS_FS_WRITE_FILE (1ULL << 1) 179 #define LANDLOCK_ACCESS_FS_READ_FILE (1ULL << 2) 180 #define LANDLOCK_ACCESS_FS_READ_DIR (1ULL << 3) 181 #define LANDLOCK_ACCESS_FS_REMOVE_DIR (1ULL << 4) 182 #define LANDLOCK_ACCESS_FS_REMOVE_FILE (1ULL << 5) 183 #define LANDLOCK_ACCESS_FS_MAKE_CHAR (1ULL << 6) 184 #define LANDLOCK_ACCESS_FS_MAKE_DIR (1ULL << 7) 185 #define LANDLOCK_ACCESS_FS_MAKE_REG (1ULL << 8) 186 #define LANDLOCK_ACCESS_FS_MAKE_SOCK (1ULL << 9) 187 #define LANDLOCK_ACCESS_FS_MAKE_FIFO (1ULL << 10) 188 #define LANDLOCK_ACCESS_FS_MAKE_BLOCK (1ULL << 11) 189 #define LANDLOCK_ACCESS_FS_MAKE_SYM (1ULL << 12) 190 #define LANDLOCK_ACCESS_FS_REFER (1ULL << 13) 191 #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14) 192 /* clang-format on */ 193 194 #endif /* _UAPI_LINUX_LANDLOCK_H */ 195