diff mbox series

[v7,7/8] IMA: define a builtin critical data measurement policy

Message ID 20201209194212.5131-8-tusharsu@linux.microsoft.com (mailing list archive)
State New, archived
Headers show
Series IMA: support for measuring kernel integrity critical data | expand

Commit Message

Tushar Sugandhi Dec. 9, 2020, 7:42 p.m. UTC 
From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>

Define a new critical data builtin policy to allow measuring
early kernel integrity critical data before a custom IMA policy
is loaded.

Add critical data to built-in IMA rules if the kernel command line
contains "ima_policy=critical_data".

Update the documentation on kernel parameters to document
the new critical data builtin policy.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  5 ++++-
 security/integrity/ima/ima_policy.c             | 12 ++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

Comments

Tyler Hicks Dec. 10, 2020, 11:22 p.m. UTC | #1 
On 2020-12-09 11:42:11, Tushar Sugandhi wrote:
> From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> 
> Define a new critical data builtin policy to allow measuring
> early kernel integrity critical data before a custom IMA policy
> is loaded.
> 
> Add critical data to built-in IMA rules if the kernel command line
> contains "ima_policy=critical_data".
> 
> Update the documentation on kernel parameters to document
> the new critical data builtin policy.
> 
> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>

Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>

Tyler

> ---
>  Documentation/admin-guide/kernel-parameters.txt |  5 ++++-
>  security/integrity/ima/ima_policy.c             | 12 ++++++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 526d65d8573a..6034d75c3ca0 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1746,7 +1746,7 @@
>  	ima_policy=	[IMA]
>  			The builtin policies to load during IMA setup.
>  			Format: "tcb | appraise_tcb | secure_boot |
> -				 fail_securely"
> +				 fail_securely | critical_data"
>  
>  			The "tcb" policy measures all programs exec'd, files
>  			mmap'd for exec, and all files opened with the read
> @@ -1765,6 +1765,9 @@
>  			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
>  			flag.
>  
> +			The "critical_data" policy measures kernel integrity
> +			critical data.
> +
>  	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
>  			Load a policy which meets the needs of the Trusted
>  			Computing Base.  This means IMA will measure all
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 7486d09a3f60..37ca16a9e65f 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -206,6 +206,10 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
>  	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
>  };
>  
> +static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
> +	{.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
> +};
> +
>  /* An array of architecture specific rules */
>  static struct ima_rule_entry *arch_policy_entry __ro_after_init;
>  
> @@ -228,6 +232,7 @@ __setup("ima_tcb", default_measure_policy_setup);
>  
>  static bool ima_use_appraise_tcb __initdata;
>  static bool ima_use_secure_boot __initdata;
> +static bool ima_use_critical_data __initdata;
>  static bool ima_fail_unverifiable_sigs __ro_after_init;
>  static int __init policy_setup(char *str)
>  {
> @@ -242,6 +247,8 @@ static int __init policy_setup(char *str)
>  			ima_use_appraise_tcb = true;
>  		else if (strcmp(p, "secure_boot") == 0)
>  			ima_use_secure_boot = true;
> +		else if (strcmp(p, "critical_data") == 0)
> +			ima_use_critical_data = true;
>  		else if (strcmp(p, "fail_securely") == 0)
>  			ima_fail_unverifiable_sigs = true;
>  		else
> @@ -875,6 +882,11 @@ void __init ima_init_policy(void)
>  			  ARRAY_SIZE(default_appraise_rules),
>  			  IMA_DEFAULT_POLICY);
>  
> +	if (ima_use_critical_data)
> +		add_rules(critical_data_rules,
> +			  ARRAY_SIZE(critical_data_rules),
> +			  IMA_DEFAULT_POLICY);
> +
>  	ima_update_policy_flag();
>  }
>  
> -- 
> 2.17.1
>
Tushar Sugandhi Dec. 11, 2020, 1:30 a.m. UTC | #2 
On 2020-12-10 3:22 p.m., Tyler Hicks wrote:
> On 2020-12-09 11:42:11, Tushar Sugandhi wrote:
>> From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
>>
>> Define a new critical data builtin policy to allow measuring
>> early kernel integrity critical data before a custom IMA policy
>> is loaded.
>>
>> Add critical data to built-in IMA rules if the kernel command line
>> contains "ima_policy=critical_data".
>>
>> Update the documentation on kernel parameters to document
>> the new critical data builtin policy.
>>
>> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> 
> Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
> 
> Tyler
> 
Thanks for the review.

~Tushar
diff mbox series

Patch

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 526d65d8573a..6034d75c3ca0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1746,7 +1746,7 @@ 
 	ima_policy=	[IMA]
 			The builtin policies to load during IMA setup.
 			Format: "tcb | appraise_tcb | secure_boot |
-				 fail_securely"
+				 fail_securely | critical_data"
 
 			The "tcb" policy measures all programs exec'd, files
 			mmap'd for exec, and all files opened with the read
@@ -1765,6 +1765,9 @@ 
 			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
 			flag.
 
+			The "critical_data" policy measures kernel integrity
+			critical data.
+
 	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
 			Load a policy which meets the needs of the Trusted
 			Computing Base.  This means IMA will measure all
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 7486d09a3f60..37ca16a9e65f 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -206,6 +206,10 @@  static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
 	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 };
 
+static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
+	{.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
+};
+
 /* An array of architecture specific rules */
 static struct ima_rule_entry *arch_policy_entry __ro_after_init;
 
@@ -228,6 +232,7 @@  __setup("ima_tcb", default_measure_policy_setup);
 
 static bool ima_use_appraise_tcb __initdata;
 static bool ima_use_secure_boot __initdata;
+static bool ima_use_critical_data __initdata;
 static bool ima_fail_unverifiable_sigs __ro_after_init;
 static int __init policy_setup(char *str)
 {
@@ -242,6 +247,8 @@  static int __init policy_setup(char *str)
 			ima_use_appraise_tcb = true;
 		else if (strcmp(p, "secure_boot") == 0)
 			ima_use_secure_boot = true;
+		else if (strcmp(p, "critical_data") == 0)
+			ima_use_critical_data = true;
 		else if (strcmp(p, "fail_securely") == 0)
 			ima_fail_unverifiable_sigs = true;
 		else
@@ -875,6 +882,11 @@  void __init ima_init_policy(void)
 			  ARRAY_SIZE(default_appraise_rules),
 			  IMA_DEFAULT_POLICY);
 
+	if (ima_use_critical_data)
+		add_rules(critical_data_rules,
+			  ARRAY_SIZE(critical_data_rules),
+			  IMA_DEFAULT_POLICY);
+
 	ima_update_policy_flag();
 }