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				[appraise_flag=] [keyrings=]
29		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
30				[FIRMWARE_CHECK]
31				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
32				[KEXEC_CMDLINE] [KEY_CHECK]
33			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
34			       [[^]MAY_EXEC]
35			fsmagic:= hex value
36			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
37			uid:= decimal value
38			euid:= decimal value
39			fowner:= decimal value
40		lsm:  	are LSM specific
41		option:	appraise_type:= [imasig] [imasig|modsig]
42			appraise_flag:= [check_blacklist]
43			Currently, blacklist check is only for files signed with appended
44			signature.
45			keyrings:= list of keyrings
46			(eg, .builtin_trusted_keys|.ima). Only valid
47			when action is "measure" and func is KEY_CHECK.
48			template:= name of a defined IMA template type
49			(eg, ima-ng). Only valid when action is "measure".
50			pcr:= decimal value
51
52		default policy:
53			# PROC_SUPER_MAGIC
54			dont_measure fsmagic=0x9fa0
55			dont_appraise fsmagic=0x9fa0
56			# SYSFS_MAGIC
57			dont_measure fsmagic=0x62656572
58			dont_appraise fsmagic=0x62656572
59			# DEBUGFS_MAGIC
60			dont_measure fsmagic=0x64626720
61			dont_appraise fsmagic=0x64626720
62			# TMPFS_MAGIC
63			dont_measure fsmagic=0x01021994
64			dont_appraise fsmagic=0x01021994
65			# RAMFS_MAGIC
66			dont_appraise fsmagic=0x858458f6
67			# DEVPTS_SUPER_MAGIC
68			dont_measure fsmagic=0x1cd1
69			dont_appraise fsmagic=0x1cd1
70			# BINFMTFS_MAGIC
71			dont_measure fsmagic=0x42494e4d
72			dont_appraise fsmagic=0x42494e4d
73			# SECURITYFS_MAGIC
74			dont_measure fsmagic=0x73636673
75			dont_appraise fsmagic=0x73636673
76			# SELINUX_MAGIC
77			dont_measure fsmagic=0xf97cff8c
78			dont_appraise fsmagic=0xf97cff8c
79			# CGROUP_SUPER_MAGIC
80			dont_measure fsmagic=0x27e0eb
81			dont_appraise fsmagic=0x27e0eb
82			# NSFS_MAGIC
83			dont_measure fsmagic=0x6e736673
84			dont_appraise fsmagic=0x6e736673
85
86			measure func=BPRM_CHECK
87			measure func=FILE_MMAP mask=MAY_EXEC
88			measure func=FILE_CHECK mask=MAY_READ uid=0
89			measure func=MODULE_CHECK
90			measure func=FIRMWARE_CHECK
91			appraise fowner=0
92
93		The default policy measures all executables in bprm_check,
94		all files mmapped executable in file_mmap, and all files
95		open for read by root in do_filp_open.  The default appraisal
96		policy appraises all files owned by root.
97
98		Examples of LSM specific definitions:
99
100		SELinux:
101			dont_measure obj_type=var_log_t
102			dont_appraise obj_type=var_log_t
103			dont_measure obj_type=auditd_log_t
104			dont_appraise obj_type=auditd_log_t
105			measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
106			measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
107
108		Smack:
109			measure subj_user=_ func=FILE_CHECK mask=MAY_READ
110
111		Example of measure rules using alternate PCRs:
112
113			measure func=KEXEC_KERNEL_CHECK pcr=4
114			measure func=KEXEC_INITRAMFS_CHECK pcr=5
115
116		Example of appraise rule allowing modsig appended signatures:
117
118			appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig
119
120		Example of measure rule using KEY_CHECK to measure all keys:
121
122			measure func=KEY_CHECK
123
124		Example of measure rule using KEY_CHECK to only measure
125		keys added to .builtin_trusted_keys or .ima keyring:
126
127			measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima
128