diff mbox series

[3/3] IMA: add support to measure duplicate buffer for critical data hook

Message ID 20210130004519.25106-4-tusharsu@linux.microsoft.com (mailing list archive)
State New, archived
Headers show
Series support for duplicate measurement of integrity critical data | expand

Commit Message

Tushar Sugandhi Jan. 30, 2021, 12:45 a.m. UTC 
process_buffer_measurement() and the underlying functions do not use the
policy condition to measure duplicate buffer entries for integrity
critical data.

Update process_buffer_measurement(), ima_add_template_entry(), and
ima_store_template() to use the policy condition to decide if a
duplicate buffer entry for integrity critical data should be measured.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
---
 security/integrity/ima/ima.h       | 4 ++--
 security/integrity/ima/ima_api.c   | 9 +++++----
 security/integrity/ima/ima_init.c  | 2 +-
 security/integrity/ima/ima_main.c  | 5 +++--
 security/integrity/ima/ima_queue.c | 5 +++--
 5 files changed, 14 insertions(+), 11 deletions(-)

Comments

Mimi Zohar Feb. 8, 2021, 8:24 p.m. UTC | #1 
Hi Tushar,

On Fri, 2021-01-29 at 16:45 -0800, Tushar Sugandhi wrote:

> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
> 
> index c096ef8945c7..fbf359495fa8 100644
> --- a/security/integrity/ima/ima_queue.c
> +++ b/security/integrity/ima/ima_queue.c
> @@ -158,7 +158,7 @@ static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
>   */
>  int ima_add_template_entry(struct ima_template_entry *entry, int violation,
>  			   const char *op, struct inode *inode,
> -			   const unsigned char *filename)
> +			   const unsigned char *filename, bool allow_dup)
>  {
>  	u8 *digest = entry->digests[ima_hash_algo_idx].digest;
> 
 	struct tpm_digestate_entry(struct ima_template_entry *entry, int violation,
>  
>  	mutex_lock(&ima_extend_list_mutex);
>  	if (!violation) {
> -		if (ima_lookup_digest_entry(digest, entry->pcr)) {
> +		if (!allow_dup &&
> +		    ima_lookup_digest_entry(digest, entry->pcr)) {

Can't this change be simplified to "if (!violation && !allow_dup)"?

Also perhaps instead of passing another variable "allow_dup" to each of
these functions, pass a mask containing violation and allow_dup.

>  			audit_cause = "hash_exists";
>  			result = -EEXIST;
>  			goto out;

thanks,

Mimi
Tushar Sugandhi Feb. 9, 2021, 6:31 p.m. UTC | #2 
On 2021-02-08 12:24 p.m., Mimi Zohar wrote:
> Hi Tushar,
> 
> On Fri, 2021-01-29 at 16:45 -0800, Tushar Sugandhi wrote:
> 
>> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
>>
>> index c096ef8945c7..fbf359495fa8 100644
>> --- a/security/integrity/ima/ima_queue.c
>> +++ b/security/integrity/ima/ima_queue.c
>> @@ -158,7 +158,7 @@ static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
>>    */
>>   int ima_add_template_entry(struct ima_template_entry *entry, int violation,
>>   			   const char *op, struct inode *inode,
>> -			   const unsigned char *filename)
>> +			   const unsigned char *filename, bool allow_dup)
>>   {
>>   	u8 *digest = entry->digests[ima_hash_algo_idx].digest;
>>
>   	struct tpm_digestate_entry(struct ima_template_entry *entry, int violation,
Not sure I understand this.  Maybe a typo?  Could you please explain?

>>   
>>   	mutex_lock(&ima_extend_list_mutex);
>>   	if (!violation) {
>> -		if (ima_lookup_digest_entry(digest, entry->pcr)) {
>> +		if (!allow_dup &&
>> +		    ima_lookup_digest_entry(digest, entry->pcr)) {
> 
> Can't this change be simplified to "if (!violation && !allow_dup)"?
> 
Sure.  Will do.

Earlier I wasn't sure if 'violation' would touch any other use-cases 
inadvertently.  That's why I localized the change as above.

But now since we are supporting other scenarios as well,
I believe "if (!violation && !allow_dup)" would be cleaner.

> Also perhaps instead of passing another variable "allow_dup" to each of
> these functions, pass a mask containing violation and allow_dup.
> 
There were examples of both approaches in ima_match_policy().
  - int *pcr/ima_template_desc **template_desc as an out-param;
  - and various actions as flags in return int.

Earlier I couldn't decide one way or the other, so I picked the 
out-param approach.

But since allow_dup is just a single bit info, returning it as a bit in 
the action flag is a cleaner solution.
Will implement it with flag in the next iteration.

Thanks again for reviewing the series.  Really appreciate it.

Thanks,
Tushar

>>   			audit_cause = "hash_exists";
>>   			result = -EEXIST;
>>   			goto out;
> 
> thanks,
> 
> Mimi
>
diff mbox series

Patch

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 59324173497f..b06732560949 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -139,7 +139,7 @@  int ima_init(void);
 int ima_fs_init(void);
 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
 			   const char *op, struct inode *inode,
-			   const unsigned char *filename);
+			   const unsigned char *filename, bool allow_dup);
 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash);
 int ima_calc_buffer_hash(const void *buf, loff_t len,
 			 struct ima_digest_data *hash);
@@ -278,7 +278,7 @@  int ima_alloc_init_template(struct ima_event_data *event_data,
 			    struct ima_template_desc *template_desc);
 int ima_store_template(struct ima_template_entry *entry, int violation,
 		       struct inode *inode,
-		       const unsigned char *filename, int pcr);
+		       const unsigned char *filename, int pcr, bool allow_dup);
 void ima_free_template_entry(struct ima_template_entry *entry);
 const char *ima_d_path(const struct path *path, char **pathbuf, char *filename);
 
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index d273373e6be9..f84369f9905e 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -101,7 +101,7 @@  int ima_alloc_init_template(struct ima_event_data *event_data,
  */
 int ima_store_template(struct ima_template_entry *entry,
 		       int violation, struct inode *inode,
-		       const unsigned char *filename, int pcr)
+		       const unsigned char *filename, int pcr, bool allow_dup)
 {
 	static const char op[] = "add_template_measure";
 	static const char audit_cause[] = "hashing_error";
@@ -119,7 +119,8 @@  int ima_store_template(struct ima_template_entry *entry,
 		}
 	}
 	entry->pcr = pcr;
-	result = ima_add_template_entry(entry, violation, op, inode, filename);
+	result = ima_add_template_entry(entry, violation, op, inode, filename,
+					allow_dup);
 	return result;
 }
 
@@ -152,7 +153,7 @@  void ima_add_violation(struct file *file, const unsigned char *filename,
 		goto err_out;
 	}
 	result = ima_store_template(entry, violation, inode,
-				    filename, CONFIG_IMA_MEASURE_PCR_IDX);
+				    filename, CONFIG_IMA_MEASURE_PCR_IDX, false);
 	if (result < 0)
 		ima_free_template_entry(entry);
 err_out:
@@ -330,7 +331,7 @@  void ima_store_measurement(struct integrity_iint_cache *iint,
 		return;
 	}
 
-	result = ima_store_template(entry, violation, inode, filename, pcr);
+	result = ima_store_template(entry, violation, inode, filename, pcr, false);
 	if ((!result || result == -EEXIST) && !(file->f_flags & O_DIRECT)) {
 		iint->flags |= IMA_MEASURED;
 		iint->measured_pcrs |= (0x1 << pcr);
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 6e8742916d1d..d0a79d7b8d89 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -88,7 +88,7 @@  static int __init ima_add_boot_aggregate(void)
 
 	result = ima_store_template(entry, violation, NULL,
 				    boot_aggregate_name,
-				    CONFIG_IMA_MEASURE_PCR_IDX);
+				    CONFIG_IMA_MEASURE_PCR_IDX, false);
 	if (result < 0) {
 		ima_free_template_entry(entry);
 		audit_cause = "store_entry";
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 2774139845b6..ff6d15d7594c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -843,6 +843,7 @@  void process_buffer_measurement(struct inode *inode, const void *buf, int size,
 	int digest_hash_len = hash_digest_size[ima_hash_algo];
 	int violation = 0;
 	int action = 0;
+	bool allow_dup = false;
 	u32 secid;
 
 	if (!ima_policy_flag)
@@ -865,7 +866,7 @@  void process_buffer_measurement(struct inode *inode, const void *buf, int size,
 	if (func) {
 		security_task_getsecid(current, &secid);
 		action = ima_get_action(inode, current_cred(), secid, 0, func,
-					&pcr, &template, func_data, NULL);
+					&pcr, &template, func_data, &allow_dup);
 		if (!(action & IMA_MEASURE))
 			return;
 	}
@@ -903,7 +904,7 @@  void process_buffer_measurement(struct inode *inode, const void *buf, int size,
 		goto out;
 	}
 
-	ret = ima_store_template(entry, violation, NULL, event_data.buf, pcr);
+	ret = ima_store_template(entry, violation, NULL, event_data.buf, pcr, allow_dup);
 	if (ret < 0) {
 		audit_cause = "store_entry";
 		ima_free_template_entry(entry);
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index c096ef8945c7..fbf359495fa8 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -158,7 +158,7 @@  static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
  */
 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
 			   const char *op, struct inode *inode,
-			   const unsigned char *filename)
+			   const unsigned char *filename, bool allow_dup)
 {
 	u8 *digest = entry->digests[ima_hash_algo_idx].digest;
 	struct tpm_digest *digests_arg = entry->digests;
@@ -169,7 +169,8 @@  int ima_add_template_entry(struct ima_template_entry *entry, int violation,
 
 	mutex_lock(&ima_extend_list_mutex);
 	if (!violation) {
-		if (ima_lookup_digest_entry(digest, entry->pcr)) {
+		if (!allow_dup &&
+		    ima_lookup_digest_entry(digest, entry->pcr)) {
 			audit_cause = "hash_exists";
 			result = -EEXIST;
 			goto out;