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ima: add support for measuring and appraising firmware

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The "security: introduce kernel_fw_from_file hook" patch defined a
new security hook to evaluate any loaded firmware that wasn't built
into the kernel.

This patch defines ima_fw_from_file(), which is called from the new
security hook, to measure and/or appraise the loaded firmware's
integrity.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Mimi Zohar 2014-07-22 10:39:48 -04:00 committed by Kees Cook
parent 6593d9245b
commit 5a9196d715
8 changed files with 50 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
Documentation/ABI/testing/ima_policy
View file

@ -26,6 +26,7 @@ Description:
option: [[appraise_type=]] [permit_directio]
base: func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
[FIRMWARE_CHECK]
mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC]
fsmagic:= hex value
fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
@ -57,7 +58,8 @@ Description:
measure func=BPRM_CHECK
measure func=FILE_MMAP mask=MAY_EXEC
measure func=FILE_CHECK mask=MAY_READ uid=0
measure func=MODULE_CHECK uid=0
measure func=MODULE_CHECK
measure func=FIRMWARE_CHECK
appraise fowner=0
The default policy measures all executables in bprm_check,

6
include/linux/ima.h
View file

@ -19,6 +19,7 @@ extern int ima_file_check(struct file *file, int mask);
extern void ima_file_free(struct file *file);
extern int ima_file_mmap(struct file *file, unsigned long prot);
extern int ima_module_check(struct file *file);
extern int ima_fw_from_file(struct file *file, char *buf, size_t size);
#else
static inline int ima_bprm_check(struct linux_binprm *bprm)
@ -46,6 +47,11 @@ static inline int ima_module_check(struct file *file)
return 0;
}
static inline int ima_fw_from_file(struct file *file, char *buf, size_t size)
{
return 0;
}
#endif /* CONFIG_IMA */
#ifdef CONFIG_IMA_APPRAISE

3
security/integrity/ima/ima.h
View file

@ -158,7 +158,7 @@ struct integrity_iint_cache *integrity_iint_insert(struct inode *inode);
struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
/* IMA policy related functions */
enum ima_hooks { FILE_CHECK = 1, MMAP_CHECK, BPRM_CHECK, MODULE_CHECK, POST_SETATTR };
enum ima_hooks { FILE_CHECK = 1, MMAP_CHECK, BPRM_CHECK, MODULE_CHECK, FIRMWARE_CHECK, POST_SETATTR };
int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
int flags);
@ -171,6 +171,7 @@ void ima_delete_rules(void);
#define IMA_APPRAISE_ENFORCE 0x01
#define IMA_APPRAISE_FIX 0x02
#define IMA_APPRAISE_MODULES 0x04
#define IMA_APPRAISE_FIRMWARE 0x08
#ifdef CONFIG_IMA_APPRAISE
int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,

8
security/integrity/ima/ima_appraise.c
View file

@ -75,6 +75,8 @@ enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
return iint->ima_bprm_status;
case MODULE_CHECK:
return iint->ima_module_status;
case FIRMWARE_CHECK:
return iint->ima_firmware_status;
case FILE_CHECK:
default:
return iint->ima_file_status;
@ -94,6 +96,9 @@ static void ima_set_cache_status(struct integrity_iint_cache *iint,
case MODULE_CHECK:
iint->ima_module_status = status;
break;
case FIRMWARE_CHECK:
iint->ima_firmware_status = status;
break;
case FILE_CHECK:
default:
iint->ima_file_status = status;
@ -113,6 +118,9 @@ static void ima_cache_flags(struct integrity_iint_cache *iint, int func)
case MODULE_CHECK:
iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED);
break;
case FIRMWARE_CHECK:
iint->flags |= (IMA_FIRMWARE_APPRAISED | IMA_APPRAISED);
break;
case FILE_CHECK:
default:
iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);

11
security/integrity/ima/ima_main.c
View file

@ -319,6 +319,17 @@ int ima_module_check(struct file *file)
return process_measurement(file, NULL, MAY_EXEC, MODULE_CHECK);
}
int ima_fw_from_file(struct file *file, char *buf, size_t size)
{
if (!file) {
if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
(ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES; /* INTEGRITY_UNKNOWN */
return 0;
}
return process_measurement(file, NULL, MAY_EXEC, FIRMWARE_CHECK);
}
static int __init init_ima(void)
{
int error;

7
security/integrity/ima/ima_policy.c
View file

@ -84,6 +84,7 @@ static struct ima_rule_entry default_rules[] = {
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID,
.flags = IMA_FUNC | IMA_MASK | IMA_UID},
{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
{.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
};
static struct ima_rule_entry default_appraise_rules[] = {
@ -241,6 +242,8 @@ static int get_subaction(struct ima_rule_entry *rule, int func)
return IMA_BPRM_APPRAISE;
case MODULE_CHECK:
return IMA_MODULE_APPRAISE;
case FIRMWARE_CHECK:
return IMA_FIRMWARE_APPRAISE;
case FILE_CHECK:
default:
return IMA_FILE_APPRAISE;
@ -486,6 +489,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
entry->func = FILE_CHECK;
else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
entry->func = MODULE_CHECK;
else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
entry->func = FIRMWARE_CHECK;
else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
|| (strcmp(args[0].from, "MMAP_CHECK") == 0))
entry->func = MMAP_CHECK;
@ -636,6 +641,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
result = -EINVAL;
else if (entry->func == MODULE_CHECK)
ima_appraise |= IMA_APPRAISE_MODULES;
else if (entry->func == FIRMWARE_CHECK)
ima_appraise |= IMA_APPRAISE_FIRMWARE;
audit_log_format(ab, "res=%d", !result);
audit_log_end(ab);
return result;

9
security/integrity/integrity.h
View file

@ -46,10 +46,14 @@
#define IMA_BPRM_APPRAISED 0x00002000
#define IMA_MODULE_APPRAISE 0x00004000
#define IMA_MODULE_APPRAISED 0x00008000
#define IMA_FIRMWARE_APPRAISE 0x00010000
#define IMA_FIRMWARE_APPRAISED 0x00020000
#define IMA_APPRAISE_SUBMASK (IMA_FILE_APPRAISE | IMA_MMAP_APPRAISE | \
IMA_BPRM_APPRAISE | IMA_MODULE_APPRAISE)
IMA_BPRM_APPRAISE | IMA_MODULE_APPRAISE | \
IMA_FIRMWARE_APPRAISE)
#define IMA_APPRAISED_SUBMASK (IMA_FILE_APPRAISED | IMA_MMAP_APPRAISED | \
IMA_BPRM_APPRAISED | IMA_MODULE_APPRAISED)
IMA_BPRM_APPRAISED | IMA_MODULE_APPRAISED | \
IMA_FIRMWARE_APPRAISED)
enum evm_ima_xattr_type {
IMA_XATTR_DIGEST = 0x01,
@ -104,6 +108,7 @@ struct integrity_iint_cache {
enum integrity_status ima_mmap_status:4;
enum integrity_status ima_bprm_status:4;
enum integrity_status ima_module_status:4;
enum integrity_status ima_firmware_status:4;
enum integrity_status evm_status:4;
struct ima_digest_data *ima_hash;
};

7
security/security.c
View file

@ -847,7 +847,12 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode)
int security_kernel_fw_from_file(struct file *file, char *buf, size_t size)
{
return security_ops->kernel_fw_from_file(file, buf, size);
int ret;
ret = security_ops->kernel_fw_from_file(file, buf, size);
if (ret)
return ret;
return ima_fw_from_file(file, buf, size);
}
EXPORT_SYMBOL_GPL(security_kernel_fw_from_file);