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		::
19
20		  rule format: action [condition ...]
21
22		  action: measure | dont_measure | appraise | dont_appraise |
23			  audit | hash | dont_hash
24		  condition:= base | lsm  [option]
25			base:	[[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
26				[euid=] [fowner=] [fsname=]]
27			lsm:	[[subj_user=] [subj_role=] [subj_type=]
28				 [obj_user=] [obj_role=] [obj_type=]]
29			option:	[[appraise_type=]] [template=] [permit_directio]
30				[appraise_flag=] [keyrings=]
31		  base:
32			func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
33			        [FIRMWARE_CHECK]
34				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
35				[KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA]
36			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
37			       [[^]MAY_EXEC]
38			fsmagic:= hex value
39			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
40			uid:= decimal value
41			euid:= decimal value
42			fowner:= decimal value
43		  lsm:  are LSM specific
44		  option:
45			appraise_type:= [imasig] [imasig|modsig]
46			appraise_flag:= [check_blacklist]
47			Currently, blacklist check is only for files signed with appended
48			signature.
49			keyrings:= list of keyrings
50			(eg, .builtin_trusted_keys|.ima). Only valid
51			when action is "measure" and func is KEY_CHECK.
52			template:= name of a defined IMA template type
53			(eg, ima-ng). Only valid when action is "measure".
54			pcr:= decimal value
55			label:= [selinux]|[kernel_info]|[data_label]
56			data_label:= a unique string used for grouping and limiting critical data.
57			For example, "selinux" to measure critical data for SELinux.
58
59		  default policy:
60			# PROC_SUPER_MAGIC
61			dont_measure fsmagic=0x9fa0
62			dont_appraise fsmagic=0x9fa0
63			# SYSFS_MAGIC
64			dont_measure fsmagic=0x62656572
65			dont_appraise fsmagic=0x62656572
66			# DEBUGFS_MAGIC
67			dont_measure fsmagic=0x64626720
68			dont_appraise fsmagic=0x64626720
69			# TMPFS_MAGIC
70			dont_measure fsmagic=0x01021994
71			dont_appraise fsmagic=0x01021994
72			# RAMFS_MAGIC
73			dont_appraise fsmagic=0x858458f6
74			# DEVPTS_SUPER_MAGIC
75			dont_measure fsmagic=0x1cd1
76			dont_appraise fsmagic=0x1cd1
77			# BINFMTFS_MAGIC
78			dont_measure fsmagic=0x42494e4d
79			dont_appraise fsmagic=0x42494e4d
80			# SECURITYFS_MAGIC
81			dont_measure fsmagic=0x73636673
82			dont_appraise fsmagic=0x73636673
83			# SELINUX_MAGIC
84			dont_measure fsmagic=0xf97cff8c
85			dont_appraise fsmagic=0xf97cff8c
86			# CGROUP_SUPER_MAGIC
87			dont_measure fsmagic=0x27e0eb
88			dont_appraise fsmagic=0x27e0eb
89			# NSFS_MAGIC
90			dont_measure fsmagic=0x6e736673
91			dont_appraise fsmagic=0x6e736673
92
93			measure func=BPRM_CHECK
94			measure func=FILE_MMAP mask=MAY_EXEC
95			measure func=FILE_CHECK mask=MAY_READ uid=0
96			measure func=MODULE_CHECK
97			measure func=FIRMWARE_CHECK
98			appraise fowner=0
99
100		The default policy measures all executables in bprm_check,
101		all files mmapped executable in file_mmap, and all files
102		open for read by root in do_filp_open.  The default appraisal
103		policy appraises all files owned by root.
104
105		Examples of LSM specific definitions:
106
107		SELinux::
108
109			dont_measure obj_type=var_log_t
110			dont_appraise obj_type=var_log_t
111			dont_measure obj_type=auditd_log_t
112			dont_appraise obj_type=auditd_log_t
113			measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
114			measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
115
116		Smack::
117
118			measure subj_user=_ func=FILE_CHECK mask=MAY_READ
119
120		Example of measure rules using alternate PCRs::
121
122			measure func=KEXEC_KERNEL_CHECK pcr=4
123			measure func=KEXEC_INITRAMFS_CHECK pcr=5
124
125		Example of appraise rule allowing modsig appended signatures:
126
127			appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig
128
129		Example of measure rule using KEY_CHECK to measure all keys:
130
131			measure func=KEY_CHECK
132
133		Example of measure rule using KEY_CHECK to only measure
134		keys added to .builtin_trusted_keys or .ima keyring:
135
136			measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima
137