1 What: security/ima/policy
3 Contact: Mimi Zohar <zohar@us.ibm.com>
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.
15 IMA appraisal, if configured, uses these file measurements
16 for local measurement appraisal.
20 rule format: action [condition ...]
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=]
32 func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
34 [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
35 [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA]
36 mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
39 fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
42 fowner:= decimal value
45 appraise_type:= [imasig] [imasig|modsig]
46 appraise_flag:= [check_blacklist]
47 Currently, blacklist check is only for files signed with appended
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".
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.
61 dont_measure fsmagic=0x9fa0
62 dont_appraise fsmagic=0x9fa0
64 dont_measure fsmagic=0x62656572
65 dont_appraise fsmagic=0x62656572
67 dont_measure fsmagic=0x64626720
68 dont_appraise fsmagic=0x64626720
70 dont_measure fsmagic=0x01021994
71 dont_appraise fsmagic=0x01021994
73 dont_appraise fsmagic=0x858458f6
75 dont_measure fsmagic=0x1cd1
76 dont_appraise fsmagic=0x1cd1
78 dont_measure fsmagic=0x42494e4d
79 dont_appraise fsmagic=0x42494e4d
81 dont_measure fsmagic=0x73636673
82 dont_appraise fsmagic=0x73636673
84 dont_measure fsmagic=0xf97cff8c
85 dont_appraise fsmagic=0xf97cff8c
87 dont_measure fsmagic=0x27e0eb
88 dont_appraise fsmagic=0x27e0eb
90 dont_measure fsmagic=0x6e736673
91 dont_appraise fsmagic=0x6e736673
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
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.
105 Examples of LSM specific definitions:
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
118 measure subj_user=_ func=FILE_CHECK mask=MAY_READ
120 Example of measure rules using alternate PCRs::
122 measure func=KEXEC_KERNEL_CHECK pcr=4
123 measure func=KEXEC_INITRAMFS_CHECK pcr=5
125 Example of appraise rule allowing modsig appended signatures:
127 appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig
129 Example of measure rule using KEY_CHECK to measure all keys:
131 measure func=KEY_CHECK
133 Example of measure rule using KEY_CHECK to only measure
134 keys added to .builtin_trusted_keys or .ima keyring:
136 measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima