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 | audit 21 condition:= base | lsm [option] 22 base: [[func=] [mask=] [fsmagic=] [fsuuid=] [uid=] 23 [euid=] [fowner=]] 24 lsm: [[subj_user=] [subj_role=] [subj_type=] 25 [obj_user=] [obj_role=] [obj_type=]] 26 option: [[appraise_type=]] [permit_directio] 27 28 base: func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK] 29 [FIRMWARE_CHECK] 30 [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] 31 mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] 32 [[^]MAY_EXEC] 33 fsmagic:= hex value 34 fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6) 35 uid:= decimal value 36 euid:= decimal value 37 fowner:=decimal value 38 lsm: are LSM specific 39 option: appraise_type:= [imasig] 40 41 default policy: 42 # PROC_SUPER_MAGIC 43 dont_measure fsmagic=0x9fa0 44 dont_appraise fsmagic=0x9fa0 45 # SYSFS_MAGIC 46 dont_measure fsmagic=0x62656572 47 dont_appraise fsmagic=0x62656572 48 # DEBUGFS_MAGIC 49 dont_measure fsmagic=0x64626720 50 dont_appraise fsmagic=0x64626720 51 # TMPFS_MAGIC 52 dont_measure fsmagic=0x01021994 53 dont_appraise fsmagic=0x01021994 54 # RAMFS_MAGIC 55 dont_appraise fsmagic=0x858458f6 56 # DEVPTS_SUPER_MAGIC 57 dont_measure fsmagic=0x1cd1 58 dont_appraise fsmagic=0x1cd1 59 # BINFMTFS_MAGIC 60 dont_measure fsmagic=0x42494e4d 61 dont_appraise fsmagic=0x42494e4d 62 # SECURITYFS_MAGIC 63 dont_measure fsmagic=0x73636673 64 dont_appraise fsmagic=0x73636673 65 # SELINUX_MAGIC 66 dont_measure fsmagic=0xf97cff8c 67 dont_appraise fsmagic=0xf97cff8c 68 # CGROUP_SUPER_MAGIC 69 dont_measure fsmagic=0x27e0eb 70 dont_appraise fsmagic=0x27e0eb 71 # NSFS_MAGIC 72 dont_measure fsmagic=0x6e736673 73 dont_appraise fsmagic=0x6e736673 74 75 measure func=BPRM_CHECK 76 measure func=FILE_MMAP mask=MAY_EXEC 77 measure func=FILE_CHECK mask=MAY_READ uid=0 78 measure func=MODULE_CHECK 79 measure func=FIRMWARE_CHECK 80 appraise fowner=0 81 82 The default policy measures all executables in bprm_check, 83 all files mmapped executable in file_mmap, and all files 84 open for read by root in do_filp_open. The default appraisal 85 policy appraises all files owned by root. 86 87 Examples of LSM specific definitions: 88 89 SELinux: 90 dont_measure obj_type=var_log_t 91 dont_appraise obj_type=var_log_t 92 dont_measure obj_type=auditd_log_t 93 dont_appraise obj_type=auditd_log_t 94 measure subj_user=system_u func=FILE_CHECK mask=MAY_READ 95 measure subj_role=system_r func=FILE_CHECK mask=MAY_READ 96 97 Smack: 98 measure subj_user=_ func=FILE_CHECK mask=MAY_READ 99