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 | audit
21		condition:= base | lsm  [option]
22			base:	[[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
23				[euid=] [fowner=]]
24			lsm:	[[subj_user=] [subj_role=] [subj_type=]
25				 [obj_user=] [obj_role=] [obj_type=]]
26			option:	[[appraise_type=]] [permit_directio]
27
28		base: 	func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
29				[FIRMWARE_CHECK]
30				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
31			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
32			       [[^]MAY_EXEC]
33			fsmagic:= hex value
34			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
35			uid:= decimal value
36			euid:= decimal value
37			fowner:= decimal value
38		lsm:  	are LSM specific
39		option:	appraise_type:= [imasig]
40			pcr:= decimal value
41
42		default policy:
43			# PROC_SUPER_MAGIC
44			dont_measure fsmagic=0x9fa0
45			dont_appraise fsmagic=0x9fa0
46			# SYSFS_MAGIC
47			dont_measure fsmagic=0x62656572
48			dont_appraise fsmagic=0x62656572
49			# DEBUGFS_MAGIC
50			dont_measure fsmagic=0x64626720
51			dont_appraise fsmagic=0x64626720
52			# TMPFS_MAGIC
53			dont_measure fsmagic=0x01021994
54			dont_appraise fsmagic=0x01021994
55			# RAMFS_MAGIC
56			dont_appraise fsmagic=0x858458f6
57			# DEVPTS_SUPER_MAGIC
58			dont_measure fsmagic=0x1cd1
59			dont_appraise fsmagic=0x1cd1
60			# BINFMTFS_MAGIC
61			dont_measure fsmagic=0x42494e4d
62			dont_appraise fsmagic=0x42494e4d
63			# SECURITYFS_MAGIC
64			dont_measure fsmagic=0x73636673
65			dont_appraise fsmagic=0x73636673
66			# SELINUX_MAGIC
67			dont_measure fsmagic=0xf97cff8c
68			dont_appraise fsmagic=0xf97cff8c
69			# CGROUP_SUPER_MAGIC
70			dont_measure fsmagic=0x27e0eb
71			dont_appraise fsmagic=0x27e0eb
72			# NSFS_MAGIC
73			dont_measure fsmagic=0x6e736673
74			dont_appraise fsmagic=0x6e736673
75
76			measure func=BPRM_CHECK
77			measure func=FILE_MMAP mask=MAY_EXEC
78			measure func=FILE_CHECK mask=MAY_READ uid=0
79			measure func=MODULE_CHECK
80			measure func=FIRMWARE_CHECK
81			appraise fowner=0
82
83		The default policy measures all executables in bprm_check,
84		all files mmapped executable in file_mmap, and all files
85		open for read by root in do_filp_open.  The default appraisal
86		policy appraises all files owned by root.
87
88		Examples of LSM specific definitions:
89
90		SELinux:
91			dont_measure obj_type=var_log_t
92			dont_appraise obj_type=var_log_t
93			dont_measure obj_type=auditd_log_t
94			dont_appraise obj_type=auditd_log_t
95			measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
96			measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
97
98		Smack:
99			measure subj_user=_ func=FILE_CHECK mask=MAY_READ
100
101		Example of measure rules using alternate PCRs:
102
103			measure func=KEXEC_KERNEL_CHECK pcr=4
104			measure func=KEXEC_INITRAMFS_CHECK pcr=5
105