xref: /openbmc/linux/include/uapi/linux/securebits.h (revision 6f52b16c)
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _UAPI_LINUX_SECUREBITS_H
3 #define _UAPI_LINUX_SECUREBITS_H
4 
5 /* Each securesetting is implemented using two bits. One bit specifies
6    whether the setting is on or off. The other bit specify whether the
7    setting is locked or not. A setting which is locked cannot be
8    changed from user-level. */
9 #define issecure_mask(X)	(1 << (X))
10 
11 #define SECUREBITS_DEFAULT 0x00000000
12 
13 /* When set UID 0 has no special privileges. When unset, we support
14    inheritance of root-permissions and suid-root executable under
15    compatibility mode. We raise the effective and inheritable bitmasks
16    *of the executable file* if the effective uid of the new process is
17    0. If the real uid is 0, we raise the effective (legacy) bit of the
18    executable file. */
19 #define SECURE_NOROOT			0
20 #define SECURE_NOROOT_LOCKED		1  /* make bit-0 immutable */
21 
22 #define SECBIT_NOROOT		(issecure_mask(SECURE_NOROOT))
23 #define SECBIT_NOROOT_LOCKED	(issecure_mask(SECURE_NOROOT_LOCKED))
24 
25 /* When set, setuid to/from uid 0 does not trigger capability-"fixup".
26    When unset, to provide compatiblility with old programs relying on
27    set*uid to gain/lose privilege, transitions to/from uid 0 cause
28    capabilities to be gained/lost. */
29 #define SECURE_NO_SETUID_FIXUP		2
30 #define SECURE_NO_SETUID_FIXUP_LOCKED	3  /* make bit-2 immutable */
31 
32 #define SECBIT_NO_SETUID_FIXUP	(issecure_mask(SECURE_NO_SETUID_FIXUP))
33 #define SECBIT_NO_SETUID_FIXUP_LOCKED \
34 			(issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED))
35 
36 /* When set, a process can retain its capabilities even after
37    transitioning to a non-root user (the set-uid fixup suppressed by
38    bit 2). Bit-4 is cleared when a process calls exec(); setting both
39    bit 4 and 5 will create a barrier through exec that no exec()'d
40    child can use this feature again. */
41 #define SECURE_KEEP_CAPS		4
42 #define SECURE_KEEP_CAPS_LOCKED		5  /* make bit-4 immutable */
43 
44 #define SECBIT_KEEP_CAPS	(issecure_mask(SECURE_KEEP_CAPS))
45 #define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED))
46 
47 /* When set, a process cannot add new capabilities to its ambient set. */
48 #define SECURE_NO_CAP_AMBIENT_RAISE		6
49 #define SECURE_NO_CAP_AMBIENT_RAISE_LOCKED	7  /* make bit-6 immutable */
50 
51 #define SECBIT_NO_CAP_AMBIENT_RAISE (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE))
52 #define SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED \
53 			(issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE_LOCKED))
54 
55 #define SECURE_ALL_BITS		(issecure_mask(SECURE_NOROOT) | \
56 				 issecure_mask(SECURE_NO_SETUID_FIXUP) | \
57 				 issecure_mask(SECURE_KEEP_CAPS) | \
58 				 issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE))
59 #define SECURE_ALL_LOCKS	(SECURE_ALL_BITS << 1)
60 
61 #endif /* _UAPI_LINUX_SECUREBITS_H */
62