| What: security/ima/policy |
| Date: May 2008 |
| Contact: Mimi Zohar <zohar@us.ibm.com> |
| Description: |
| The Trusted Computing Group(TCG) runtime Integrity |
| Measurement Architecture(IMA) maintains a list of hash |
| values of executables and other sensitive system files |
| loaded into the run-time of this system. At runtime, |
| the policy can be constrained based on LSM specific data. |
| Policies are loaded into the securityfs file ima/policy |
| by opening the file, writing the rules one at a time and |
| then closing the file. The new policy takes effect after |
| the file ima/policy is closed. |
| |
| rule format: action [condition ...] |
| |
| action: measure | dont_measure |
| condition:= base | lsm |
| base: [[func=] [mask=] [fsmagic=] [uid=]] |
| lsm: [[subj_user=] [subj_role=] [subj_type=] |
| [obj_user=] [obj_role=] [obj_type=]] |
| |
| base: func:= [BPRM_CHECK][FILE_MMAP][INODE_PERMISSION] |
| mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC] |
| fsmagic:= hex value |
| uid:= decimal value |
| lsm: are LSM specific |
| |
| default policy: |
| # PROC_SUPER_MAGIC |
| dont_measure fsmagic=0x9fa0 |
| # SYSFS_MAGIC |
| dont_measure fsmagic=0x62656572 |
| # DEBUGFS_MAGIC |
| dont_measure fsmagic=0x64626720 |
| # TMPFS_MAGIC |
| dont_measure fsmagic=0x01021994 |
| # SECURITYFS_MAGIC |
| dont_measure fsmagic=0x73636673 |
| |
| measure func=BPRM_CHECK |
| measure func=FILE_MMAP mask=MAY_EXEC |
| measure func=INODE_PERM mask=MAY_READ uid=0 |
| |
| The default policy measures all executables in bprm_check, |
| all files mmapped executable in file_mmap, and all files |
| open for read by root in inode_permission. |
| |
| Examples of LSM specific definitions: |
| |
| SELinux: |
| # SELINUX_MAGIC |
| dont_measure fsmagic=0xF97CFF8C |
| |
| dont_measure obj_type=var_log_t |
| dont_measure obj_type=auditd_log_t |
| measure subj_user=system_u func=INODE_PERM mask=MAY_READ |
| measure subj_role=system_r func=INODE_PERM mask=MAY_READ |
| |
| Smack: |
| measure subj_user=_ func=INODE_PERM mask=MAY_READ |
