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ima: per hook cache integrity appraisal status

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With the new IMA policy 'appraise_type=' option, different hooks
can require different methods for appraising a file's integrity.

For example, the existing 'ima_appraise_tcb' policy defines a
generic rule, requiring all root files to be appraised, without
specfying the appraisal method.  A more specific rule could require
all kernel modules, for example, to be signed.

appraise fowner=0 func=MODULE_CHECK appraise_type=imasig
appraise fowner=0

As a result, the integrity appraisal results for the same inode, but
for different hooks, could differ.  This patch caches the integrity
appraisal results on a per hook basis.

Changelog v2:
- Rename ima_cache_status() to ima_set_cache_status()
- Rename and move get_appraise_status() to ima_get_cache_status()
Changelog v0:
- include IMA_APPRAISE/APPRAISED_SUBMASK in IMA_DO/DONE_MASK (Dmitry)
- Support independent MODULE_CHECK appraise status.
- fixed IMA_XXXX_APPRAISE/APPRAISED flags

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
This commit is contained in:
Mimi Zohar 2012-12-03 17:08:11 -05:00
parent f578c08ec9
commit d79d72e024
6 changed files with 136 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
security/integrity/iint.c
View File

@ -72,7 +72,10 @@ static void iint_free(struct integrity_iint_cache *iint)
{
iint->version = 0;
iint->flags = 0UL;
iint->ima_status = INTEGRITY_UNKNOWN;
iint->ima_file_status = INTEGRITY_UNKNOWN;
iint->ima_mmap_status = INTEGRITY_UNKNOWN;
iint->ima_bprm_status = INTEGRITY_UNKNOWN;
iint->ima_module_status = INTEGRITY_UNKNOWN;
iint->evm_status = INTEGRITY_UNKNOWN;
kmem_cache_free(iint_cache, iint);
}
@ -149,7 +152,10 @@ static void init_once(void *foo)
memset(iint, 0, sizeof *iint);
iint->version = 0;
iint->flags = 0UL;
iint->ima_status = INTEGRITY_UNKNOWN;
iint->ima_file_status = INTEGRITY_UNKNOWN;
iint->ima_mmap_status = INTEGRITY_UNKNOWN;
iint->ima_bprm_status = INTEGRITY_UNKNOWN;
iint->ima_module_status = INTEGRITY_UNKNOWN;
iint->evm_status = INTEGRITY_UNKNOWN;
}

13
security/integrity/ima/ima.h
View File

@ -142,13 +142,16 @@ void ima_delete_rules(void);
#define IMA_APPRAISE_FIX 0x02
#ifdef CONFIG_IMA_APPRAISE
int ima_appraise_measurement(struct integrity_iint_cache *iint,
int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
struct file *file, const unsigned char *filename);
int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func);
void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);
enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
int func);
#else
static inline int ima_appraise_measurement(struct integrity_iint_cache *iint,
static inline int ima_appraise_measurement(int func,
struct integrity_iint_cache *iint,
struct file *file,
const unsigned char *filename)
{
@ -165,6 +168,12 @@ static inline void ima_update_xattr(struct integrity_iint_cache *iint,
struct file *file)
{
}
static inline enum integrity_status ima_get_cache_status(struct integrity_iint_cache
*iint, int func)
{
return INTEGRITY_UNKNOWN;
}
#endif
/* LSM based policy rules require audit */

71
security/integrity/ima/ima_appraise.c
View File

@ -51,6 +51,62 @@ static int ima_fix_xattr(struct dentry *dentry,
sizeof(iint->ima_xattr), 0);
}
/* Return specific func appraised cached result */
enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
int func)
{
switch(func) {
case MMAP_CHECK:
return iint->ima_mmap_status;
case BPRM_CHECK:
return iint->ima_bprm_status;
case MODULE_CHECK:
return iint->ima_module_status;
case FILE_CHECK:
default:
return iint->ima_file_status;
}
}
static void ima_set_cache_status(struct integrity_iint_cache *iint,
int func, enum integrity_status status)
{
switch(func) {
case MMAP_CHECK:
iint->ima_mmap_status = status;
break;
case BPRM_CHECK:
iint->ima_bprm_status = status;
break;
case MODULE_CHECK:
iint->ima_module_status = status;
break;
case FILE_CHECK:
default:
iint->ima_file_status = status;
break;
}
}
static void ima_cache_flags(struct integrity_iint_cache *iint, int func)
{
switch(func) {
case MMAP_CHECK:
iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
break;
case BPRM_CHECK:
iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
break;
case MODULE_CHECK:
iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED);
break;
case FILE_CHECK:
default:
iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
break;
}
}
/*
* ima_appraise_measurement - appraise file measurement
*
@ -59,7 +115,7 @@ static int ima_fix_xattr(struct dentry *dentry,
*
* Return 0 on success, error code otherwise
*/
int ima_appraise_measurement(struct integrity_iint_cache *iint,
int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
struct file *file, const unsigned char *filename)
{
struct dentry *dentry = file->f_dentry;
@ -75,9 +131,6 @@ int ima_appraise_measurement(struct integrity_iint_cache *iint,
if (!inode->i_op->getxattr)
return INTEGRITY_UNKNOWN;
if (iint->flags & IMA_APPRAISED)
return iint->ima_status;
rc = vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)&xattr_value,
0, GFP_NOFS);
if (rc <= 0) {
@ -99,7 +152,6 @@ int ima_appraise_measurement(struct integrity_iint_cache *iint,
cause = "invalid-HMAC";
goto out;
}
switch (xattr_value->type) {
case IMA_XATTR_DIGEST:
if (iint->flags & IMA_DIGSIG_REQUIRED) {
@ -148,9 +200,9 @@ out:
integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
op, cause, rc, 0);
} else {
iint->flags |= IMA_APPRAISED;
ima_cache_flags(iint, func);
}
iint->ima_status = status;
ima_set_cache_status(iint, func, status);
kfree(xattr_value);
return status;
}
@ -196,10 +248,11 @@ void ima_inode_post_setattr(struct dentry *dentry)
must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
iint = integrity_iint_find(inode);
if (iint) {
iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
IMA_ACTION_FLAGS);
if (must_appraise)
iint->flags |= IMA_APPRAISE;
else
iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED);
}
if (!must_appraise)
rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);

19
security/integrity/ima/ima_main.c
View File

@ -151,8 +151,10 @@ static int process_measurement(struct file *file, const char *filename,
if (!ima_initialized || !S_ISREG(inode->i_mode))
return 0;
/* Determine if in appraise/audit/measurement policy,
* returns IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT bitmask. */
/* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
* bitmask based on the appraise/audit/measurement policy.
* Included is the appraise submask.
*/
action = ima_get_action(inode, mask, function);
if (!action)
return 0;
@ -166,16 +168,17 @@ static int process_measurement(struct file *file, const char *filename,
goto out;
/* Determine if already appraised/measured based on bitmask
* (IMA_MEASURE, IMA_MEASURED, IMA_APPRAISE, IMA_APPRAISED,
* IMA_AUDIT, IMA_AUDITED) */
* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
* IMA_AUDIT, IMA_AUDITED)
*/
iint->flags |= action;
action &= IMA_DO_MASK;
action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
/* Nothing to do, just return existing appraised status */
if (!action) {
if (iint->flags & IMA_APPRAISED)
rc = iint->ima_status;
if (must_appraise)
rc = ima_get_cache_status(iint, function);
goto out_digsig;
}
@ -191,8 +194,8 @@ static int process_measurement(struct file *file, const char *filename,
if (action & IMA_MEASURE)
ima_store_measurement(iint, file, pathname);
if (action & IMA_APPRAISE)
rc = ima_appraise_measurement(iint, file, pathname);
if (action & IMA_APPRAISE_SUBMASK)
rc = ima_appraise_measurement(function, iint, file, pathname);
if (action & IMA_AUDIT)
ima_audit_measurement(iint, pathname);
kfree(pathbuf);

22
security/integrity/ima/ima_policy.c
View File

@ -218,6 +218,25 @@ retry:
return true;
}
/*
* In addition to knowing that we need to appraise the file in general,
* we need to differentiate between calling hooks.
*/
static int get_subaction(int func)
{
switch(func) {
case MMAP_CHECK:
return IMA_MMAP_APPRAISE;
case BPRM_CHECK:
return IMA_BPRM_APPRAISE;
case MODULE_CHECK:
return IMA_MODULE_APPRAISE;
case FILE_CHECK:
default:
return IMA_FILE_APPRAISE;
}
}
/**
* ima_match_policy - decision based on LSM and other conditions
* @inode: pointer to an inode for which the policy decision is being made
@ -248,6 +267,9 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
action |= entry->flags & IMA_ACTION_FLAGS;
action |= entry->action & IMA_DO_MASK;
if (entry->action & IMA_APPRAISE)
action |= get_subaction(func);
if (entry->action & IMA_DO_MASK)
actmask &= ~(entry->action | entry->action << 1);
else

26
security/integrity/integrity.h
View File

@ -30,9 +30,24 @@
#define IMA_DIGSIG 0x01000000
#define IMA_DIGSIG_REQUIRED 0x02000000
#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT)
#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_AUDITED \
| IMA_COLLECTED)
#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \
IMA_APPRAISE_SUBMASK)
#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_AUDITED | \
IMA_COLLECTED | IMA_APPRAISED_SUBMASK)
/* iint subaction appraise cache flags */
#define IMA_FILE_APPRAISE 0x00000100
#define IMA_FILE_APPRAISED 0x00000200
#define IMA_MMAP_APPRAISE 0x00000400
#define IMA_MMAP_APPRAISED 0x00000800
#define IMA_BPRM_APPRAISE 0x00001000
#define IMA_BPRM_APPRAISED 0x00002000
#define IMA_MODULE_APPRAISE 0x00004000
#define IMA_MODULE_APPRAISED 0x00008000
#define IMA_APPRAISE_SUBMASK (IMA_FILE_APPRAISE | IMA_MMAP_APPRAISE | \
IMA_BPRM_APPRAISE | IMA_MODULE_APPRAISE)
#define IMA_APPRAISED_SUBMASK (IMA_FILE_APPRAISED | IMA_MMAP_APPRAISED | \
IMA_BPRM_APPRAISED | IMA_MODULE_APPRAISED)
enum evm_ima_xattr_type {
IMA_XATTR_DIGEST = 0x01,
@ -52,7 +67,10 @@ struct integrity_iint_cache {
u64 version; /* track inode changes */
unsigned long flags;
struct evm_ima_xattr_data ima_xattr;
enum integrity_status ima_status:4;
enum integrity_status ima_file_status:4;
enum integrity_status ima_mmap_status:4;
enum integrity_status ima_bprm_status:4;
enum integrity_status ima_module_status:4;
enum integrity_status evm_status:4;
};