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Add IMA policy support for measuring/appraising the kexec image and
initramfs. Two new IMA policy identifiers KEXEC_KERNEL_CHECK and
KEXEC_INITRAMFS_CHECK are defined.
Example policy rules:
measure func=KEXEC_KERNEL_CHECK
appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig
measure func=KEXEC_INITRAMFS_CHECK
appraise func=KEXEC_INITRAMFS_CHECK appraise_type=imasig
Moving the enumeration to the vfs layer simplified the patches, allowing
the IMA changes, for the most part, to be separated from the other
changes. Unfortunately, passing either a kernel_read_file_id or a
ima_hooks enumeration within IMA is messy.
Option 1: duplicate kernel_read_file enumeration in ima_hooks
enum kernel_read_file_id {
...
READING_KEXEC_IMAGE,
READING_KEXEC_INITRAMFS,
READING_MAX_ID
enum ima_hooks {
...
KEXEC_KERNEL_CHECK
KEXEC_INITRAMFS_CHECK
Option 2: define ima_hooks as extension of kernel_read_file
eg: enum ima_hooks {
FILE_CHECK = READING_MAX_ID,
MMAP_CHECK,
In order to pass both kernel_read_file_id and ima_hooks values, we
would need to specify a struct containing a union.
struct caller_id {
union {
enum ima_hooks func_id;
enum kernel_read_file_id read_id;
};
};
Option 3: incorportate the ima_hooks enumeration into kernel_read_file_id,
perhaps changing the enumeration name.
For now, duplicate the new READING_KEXEC_IMAGE/INITRAMFS in the ima_hooks.
Changelog v4:
- replaced switch statement with a kernel_read_file_id to an ima_hooks
id mapping array - Dmitry
- renamed ima_hook tokens KEXEC_CHECK and INITRAMFS_CHECK to
KEXEC_KERNEL_CHECK and KEXEC_INITRAMFS_CHECK respectively - Dave Young
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Petko Manolov <petkan@mip-labs.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cc: Dave Young <dyoung@redhat.com>
99 lines
3.2 KiB
Plaintext
99 lines
3.2 KiB
Plaintext
What: security/ima/policy
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Date: May 2008
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Contact: Mimi Zohar <zohar@us.ibm.com>
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Description:
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The Trusted Computing Group(TCG) runtime Integrity
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Measurement Architecture(IMA) maintains a list of hash
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values of executables and other sensitive system files
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loaded into the run-time of this system. At runtime,
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the policy can be constrained based on LSM specific data.
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Policies are loaded into the securityfs file ima/policy
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by opening the file, writing the rules one at a time and
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then closing the file. The new policy takes effect after
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the file ima/policy is closed.
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IMA appraisal, if configured, uses these file measurements
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for local measurement appraisal.
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rule format: action [condition ...]
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action: measure | dont_measure | appraise | dont_appraise | audit
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condition:= base | lsm [option]
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base: [[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
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[euid=] [fowner=]]
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lsm: [[subj_user=] [subj_role=] [subj_type=]
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[obj_user=] [obj_role=] [obj_type=]]
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option: [[appraise_type=]] [permit_directio]
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base: func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
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[FIRMWARE_CHECK]
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[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
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mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
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[[^]MAY_EXEC]
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fsmagic:= hex value
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fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
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uid:= decimal value
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euid:= decimal value
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fowner:=decimal value
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lsm: are LSM specific
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option: appraise_type:= [imasig]
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default policy:
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# PROC_SUPER_MAGIC
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dont_measure fsmagic=0x9fa0
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dont_appraise fsmagic=0x9fa0
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# SYSFS_MAGIC
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dont_measure fsmagic=0x62656572
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dont_appraise fsmagic=0x62656572
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# DEBUGFS_MAGIC
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dont_measure fsmagic=0x64626720
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dont_appraise fsmagic=0x64626720
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# TMPFS_MAGIC
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dont_measure fsmagic=0x01021994
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dont_appraise fsmagic=0x01021994
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# RAMFS_MAGIC
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dont_appraise fsmagic=0x858458f6
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# DEVPTS_SUPER_MAGIC
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dont_measure fsmagic=0x1cd1
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dont_appraise fsmagic=0x1cd1
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# BINFMTFS_MAGIC
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dont_measure fsmagic=0x42494e4d
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dont_appraise fsmagic=0x42494e4d
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# SECURITYFS_MAGIC
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dont_measure fsmagic=0x73636673
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dont_appraise fsmagic=0x73636673
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# SELINUX_MAGIC
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dont_measure fsmagic=0xf97cff8c
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dont_appraise fsmagic=0xf97cff8c
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# CGROUP_SUPER_MAGIC
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dont_measure fsmagic=0x27e0eb
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dont_appraise fsmagic=0x27e0eb
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# NSFS_MAGIC
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dont_measure fsmagic=0x6e736673
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dont_appraise fsmagic=0x6e736673
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measure func=BPRM_CHECK
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measure func=FILE_MMAP mask=MAY_EXEC
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measure func=FILE_CHECK mask=MAY_READ uid=0
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measure func=MODULE_CHECK
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measure func=FIRMWARE_CHECK
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appraise fowner=0
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The default policy measures all executables in bprm_check,
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all files mmapped executable in file_mmap, and all files
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open for read by root in do_filp_open. The default appraisal
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policy appraises all files owned by root.
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Examples of LSM specific definitions:
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SELinux:
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dont_measure obj_type=var_log_t
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dont_appraise obj_type=var_log_t
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dont_measure obj_type=auditd_log_t
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dont_appraise obj_type=auditd_log_t
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measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
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measure subj_role=system_r func=FILE_CHECK mask=MAY_READ
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Smack:
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measure subj_user=_ func=FILE_CHECK mask=MAY_READ
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