1What:		security/ima/policy
2Date:		May 2008
3Contact:	Mimi Zohar <zohar@us.ibm.com>
4Description:
5		The Trusted Computing Group(TCG) runtime Integrity
6		Measurement Architecture(IMA) maintains a list of hash
7		values of executables and other sensitive system files
8		loaded into the run-time of this system.  At runtime,
9		the policy can be constrained based on LSM specific data.
10		Policies are loaded into the securityfs file ima/policy
11		by opening the file, writing the rules one at a time and
12		then closing the file.  The new policy takes effect after
13		the file ima/policy is closed.
14
15		IMA appraisal, if configured, uses these file measurements
16		for local measurement appraisal.
17
18		rule format: action [condition ...]
19
20		action: measure | dont_measure | appraise | dont_appraise |
21			audit | hash | dont_hash
22		condition:= base | lsm  [option]
23			base:	[[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
24				[euid=] [fowner=] [fsname=]]
25			lsm:	[[subj_user=] [subj_role=] [subj_type=]
26				 [obj_user=] [obj_role=] [obj_type=]]
27			option:	[[appraise_type=]] [permit_directio]
28
29		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
30				[FIRMWARE_CHECK]
31				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
32			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
33			       [[^]MAY_EXEC]
34			fsmagic:= hex value
35			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
36			uid:= decimal value
37			euid:= decimal value
38			fowner:= decimal value
39		lsm:  	are LSM specific
40		option:	appraise_type:= [imasig]
41			pcr:= decimal value
42
43		default policy:
44			# PROC_SUPER_MAGIC
45			dont_measure fsmagic=0x9fa0
46			dont_appraise fsmagic=0x9fa0
47			# SYSFS_MAGIC
48			dont_measure fsmagic=0x62656572
49			dont_appraise fsmagic=0x62656572
50			# DEBUGFS_MAGIC
51			dont_measure fsmagic=0x64626720
52			dont_appraise fsmagic=0x64626720
53			# TMPFS_MAGIC
54			dont_measure fsmagic=0x01021994
55			dont_appraise fsmagic=0x01021994
56			# RAMFS_MAGIC
57			dont_appraise fsmagic=0x858458f6
58			# DEVPTS_SUPER_MAGIC
59			dont_measure fsmagic=0x1cd1
60			dont_appraise fsmagic=0x1cd1
61			# BINFMTFS_MAGIC
62			dont_measure fsmagic=0x42494e4d
63			dont_appraise fsmagic=0x42494e4d
64			# SECURITYFS_MAGIC
65			dont_measure fsmagic=0x73636673
66			dont_appraise fsmagic=0x73636673
67			# SELINUX_MAGIC
68			dont_measure fsmagic=0xf97cff8c
69			dont_appraise fsmagic=0xf97cff8c
70			# CGROUP_SUPER_MAGIC
71			dont_measure fsmagic=0x27e0eb
72			dont_appraise fsmagic=0x27e0eb
73			# NSFS_MAGIC
74			dont_measure fsmagic=0x6e736673
75			dont_appraise fsmagic=0x6e736673
76
77			measure func=BPRM_CHECK
78			measure func=FILE_MMAP mask=MAY_EXEC
79			measure func=FILE_CHECK mask=MAY_READ uid=0
80			measure func=MODULE_CHECK
81			measure func=FIRMWARE_CHECK
82			appraise fowner=0
83
84		The default policy measures all executables in bprm_check,
85		all files mmapped executable in file_mmap, and all files
86		open for read by root in do_filp_open.  The default appraisal
87		policy appraises all files owned by root.
88
89		Examples of LSM specific definitions:
90
91		SELinux:
92			dont_measure obj_type=var_log_t
93			dont_appraise obj_type=var_log_t
94			dont_measure obj_type=auditd_log_t
95			dont_appraise obj_type=auditd_log_t
96			measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
97			measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
98
99		Smack:
100			measure subj_user=_ func=FILE_CHECK mask=MAY_READ
101
102		Example of measure rules using alternate PCRs:
103
104			measure func=KEXEC_KERNEL_CHECK pcr=4
105			measure func=KEXEC_INITRAMFS_CHECK pcr=5
106