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review.trustedfirmware.org / hafnium / third_party / linux.git / 3a0ad55d848b50499b68d7141d4eca997fce28ef / . / Documentation / ABI / testing / ima_policy
blob: 74c6702de74e24369bc4d3e314d534898052ec2b [file] [log] [blame]
Andrew Scullb4b6d4a2019-01-02 15:54:55 +0000[diff] [blame]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=]] [permit_directio]
28
29 base: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
30 [FIRMWARE_CHECK]
31 [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
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]
41 pcr:= decimal value
42
43 default policy:
44 # PROC_SUPER_MAGIC
45 dont_measure fsmagic=0x9fa0
46 dont_appraise fsmagic=0x9fa0
47 # SYSFS_MAGIC
48 dont_measure fsmagic=0x62656572
49 dont_appraise fsmagic=0x62656572
50 # DEBUGFS_MAGIC
51 dont_measure fsmagic=0x64626720
52 dont_appraise fsmagic=0x64626720
53 # TMPFS_MAGIC
54 dont_measure fsmagic=0x01021994
55 dont_appraise fsmagic=0x01021994
56 # RAMFS_MAGIC
57 dont_appraise fsmagic=0x858458f6
58 # DEVPTS_SUPER_MAGIC
59 dont_measure fsmagic=0x1cd1
60 dont_appraise fsmagic=0x1cd1
61 # BINFMTFS_MAGIC
62 dont_measure fsmagic=0x42494e4d
63 dont_appraise fsmagic=0x42494e4d
64 # SECURITYFS_MAGIC
65 dont_measure fsmagic=0x73636673
66 dont_appraise fsmagic=0x73636673
67 # SELINUX_MAGIC
68 dont_measure fsmagic=0xf97cff8c
69 dont_appraise fsmagic=0xf97cff8c
70 # CGROUP_SUPER_MAGIC
71 dont_measure fsmagic=0x27e0eb
72 dont_appraise fsmagic=0x27e0eb
73 # NSFS_MAGIC
74 dont_measure fsmagic=0x6e736673
75 dont_appraise fsmagic=0x6e736673
76
77 measure func=BPRM_CHECK
78 measure func=FILE_MMAP mask=MAY_EXEC
79 measure func=FILE_CHECK mask=MAY_READ uid=0
80 measure func=MODULE_CHECK
81 measure func=FIRMWARE_CHECK
82 appraise fowner=0
83
84 The default policy measures all executables in bprm_check,
85 all files mmapped executable in file_mmap, and all files
86 open for read by root in do_filp_open. The default appraisal
87 policy appraises all files owned by root.
88
89 Examples of LSM specific definitions:
90
91 SELinux:
92 dont_measure obj_type=var_log_t
93 dont_appraise obj_type=var_log_t
94 dont_measure obj_type=auditd_log_t
95 dont_appraise obj_type=auditd_log_t
96 measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
97 measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
98
99 Smack:
100 measure subj_user=_ func=FILE_CHECK mask=MAY_READ
101
102 Example of measure rules using alternate PCRs:
103
104 measure func=KEXEC_KERNEL_CHECK pcr=4
105 measure func=KEXEC_INITRAMFS_CHECK pcr=5