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=]] [template=] [permit_directio]
28		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
29				[FIRMWARE_CHECK]
30				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
31				[KEXEC_CMDLINE]
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] [imasig|modsig]
41			template:= name of a defined IMA template type
42			(eg, ima-ng). Only valid when action is "measure".
43			pcr:= decimal value
44
45		default policy:
46			# PROC_SUPER_MAGIC
47			dont_measure fsmagic=0x9fa0
48			dont_appraise fsmagic=0x9fa0
49			# SYSFS_MAGIC
50			dont_measure fsmagic=0x62656572
51			dont_appraise fsmagic=0x62656572
52			# DEBUGFS_MAGIC
53			dont_measure fsmagic=0x64626720
54			dont_appraise fsmagic=0x64626720
55			# TMPFS_MAGIC
56			dont_measure fsmagic=0x01021994
57			dont_appraise fsmagic=0x01021994
58			# RAMFS_MAGIC
59			dont_appraise fsmagic=0x858458f6
60			# DEVPTS_SUPER_MAGIC
61			dont_measure fsmagic=0x1cd1
62			dont_appraise fsmagic=0x1cd1
63			# BINFMTFS_MAGIC
64			dont_measure fsmagic=0x42494e4d
65			dont_appraise fsmagic=0x42494e4d
66			# SECURITYFS_MAGIC
67			dont_measure fsmagic=0x73636673
68			dont_appraise fsmagic=0x73636673
69			# SELINUX_MAGIC
70			dont_measure fsmagic=0xf97cff8c
71			dont_appraise fsmagic=0xf97cff8c
72			# CGROUP_SUPER_MAGIC
73			dont_measure fsmagic=0x27e0eb
74			dont_appraise fsmagic=0x27e0eb
75			# NSFS_MAGIC
76			dont_measure fsmagic=0x6e736673
77			dont_appraise fsmagic=0x6e736673
78
79			measure func=BPRM_CHECK
80			measure func=FILE_MMAP mask=MAY_EXEC
81			measure func=FILE_CHECK mask=MAY_READ uid=0
82			measure func=MODULE_CHECK
83			measure func=FIRMWARE_CHECK
84			appraise fowner=0
85
86		The default policy measures all executables in bprm_check,
87		all files mmapped executable in file_mmap, and all files
88		open for read by root in do_filp_open.  The default appraisal
89		policy appraises all files owned by root.
90
91		Examples of LSM specific definitions:
92
93		SELinux:
94			dont_measure obj_type=var_log_t
95			dont_appraise obj_type=var_log_t
96			dont_measure obj_type=auditd_log_t
97			dont_appraise obj_type=auditd_log_t
98			measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
99			measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
100
101		Smack:
102			measure subj_user=_ func=FILE_CHECK mask=MAY_READ
103
104		Example of measure rules using alternate PCRs:
105
106			measure func=KEXEC_KERNEL_CHECK pcr=4
107			measure func=KEXEC_INITRAMFS_CHECK pcr=5
108
109		Example of appraise rule allowing modsig appended signatures:
110
111			appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig
112