diff mbox

RFC: Add Apparmor policy matching to IMA

Message ID 20170829190401.18056-1-mjg59@google.com
State New, archived
Headers show

Commit Message

Matthew Garrett Aug. 29, 2017, 7:04 p.m. UTC
IMA has support for matching based on security context, but this is
currently limited to modules that implement the audit_rule_match hook.
The infrastructure around this seems to depend on having 32 bit security
IDs to reference the policy associated with tasks or files, which
doesn't seem to be a concept that Apparmor really has. So, this
implementation ignores the abstraction and calls through to Apparmor
directly.

This seems ugly, so is there a better way to achieve this?
---
 include/linux/apparmor.h            | 16 ++++++++++++++++
 security/apparmor/lib.c             | 32 ++++++++++++++++++++++++++++++++
 security/integrity/ima/ima_policy.c | 24 +++++++++++++++++++++---
 3 files changed, 69 insertions(+), 3 deletions(-)
 create mode 100644 include/linux/apparmor.h

Comments

John Johansen Aug. 29, 2017, 7:47 p.m. UTC | #1
On 08/29/2017 12:04 PM, Matthew Garrett wrote:
> IMA has support for matching based on security context, but this is
> currently limited to modules that implement the audit_rule_match hook.
> The infrastructure around this seems to depend on having 32 bit security
> IDs to reference the policy associated with tasks or files, which
> doesn't seem to be a concept that Apparmor really has. So, this
> implementation ignores the abstraction and calls through to Apparmor
> directly.
> 
> This seems ugly, so is there a better way to achieve this?

probably via secids :/

secid support in apparmor is a wip, and we are hoping to land full support
in 4.15

I'll see if I can't get a dev branch with them up for you this week.

that said if you wanted to land this sooner I am not opposed to this
going in with a minor change (see below) on the apparmor end

> ---
>  include/linux/apparmor.h            | 16 ++++++++++++++++
>  security/apparmor/lib.c             | 32 ++++++++++++++++++++++++++++++++
>  security/integrity/ima/ima_policy.c | 24 +++++++++++++++++++++---
>  3 files changed, 69 insertions(+), 3 deletions(-)
>  create mode 100644 include/linux/apparmor.h
> 
> diff --git a/include/linux/apparmor.h b/include/linux/apparmor.h
> new file mode 100644
> index 000000000000..d8ac3f706437
> --- /dev/null
> +++ b/include/linux/apparmor.h
> @@ -0,0 +1,16 @@
> +#ifndef _APPARMOR_H_
> +
> +struct linux_binprm;
> +
> +#ifdef CONFIG_SECURITY_APPARMOR
> +int aa_task_profile_match(struct linux_binprm *bprm, struct task_struct *tsk,
> +			  const char *profile);
> +#else
> +static int aa_task_profile_match(struct linux_binprm *bprm,
> +				 struct task_struct *tsk, const char *profile)
> +{
> +	return 0;
> +}
> +#endif
> +
> +#endif
> diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
> index 08ca26bcca77..04d087e4a1a3 100644
> --- a/security/apparmor/lib.c
> +++ b/security/apparmor/lib.c
> @@ -17,9 +17,11 @@
>  #include <linux/slab.h>
>  #include <linux/string.h>
>  #include <linux/vmalloc.h>
> +#include <linux/apparmor.h>
>  
>  #include "include/audit.h"
>  #include "include/apparmor.h"
> +#include "include/context.h"
>  #include "include/lib.h"
>  #include "include/perms.h"
>  #include "include/policy.h"
> @@ -385,6 +387,36 @@ void aa_profile_match_label(struct aa_profile *profile, struct aa_label *label,
>  	aa_label_match(profile, label, state, false, request, perms);
>  }
>  
> +/**
> + * aa_task_profile_match - check whether a task is using the specified profile
> + * @bprm - bprm structure to extract creds from.
> + * @tsk - task to verify. Ignored if @bprm is not NULL.
> + * @name - name of the profile to search for.
> + */
> +int aa_task_profile_match(struct linux_binprm *bprm, struct task_struct *tsk,
> +			   const char *name)
> +{
> +	struct aa_label *label;
> +	struct aa_profile *profile;
> +	struct aa_task_ctx *ctx;
> +	struct label_it i;
> +	const struct cred *cred;
> +
> +	if (bprm) {
> +		ctx = cred_ctx(bprm->cred);
> +		label = aa_get_newest_label(ctx->label);
> +	} else {
> +		cred = __task_cred(tsk);
> +		label = aa_get_newest_cred_label(cred);
> +	}
> +
> +	label_for_each(i, label, profile) {
> +		if (strcmp(name, profile->base.name) == 0)
> +			return 1;
> +	}
> +
you should be using
  profile->base.hname

its an stupid artefact of "hat" profile naming, which predates apparmor policy
namespace support

> +	return 0;
> +}
>  
>  /* currently unused */
>  int aa_profile_label_perm(struct aa_profile *profile, struct aa_profile *target,
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 93f6af4e3a20..556a1292734c 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -20,6 +20,7 @@
>  #include <linux/rculist.h>
>  #include <linux/genhd.h>
>  #include <linux/seq_file.h>
> +#include <linux/apparmor.h>
>  
>  #include "ima.h"
>  
> @@ -47,9 +48,9 @@
>  int ima_policy_flag;
>  static int temp_ima_appraise;
>  
> -#define MAX_LSM_RULES 6
> +#define MAX_LSM_RULES 7
>  enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
> -	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
> +       LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE, LSM_AA_PROFILE
>  };
>  
>  enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
> @@ -313,6 +314,11 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
>  							Audit_equal,
>  							rule->lsm[i].rule,
>  							NULL);
> +			break;
> +		case LSM_AA_PROFILE:
> +			rc = aa_task_profile_match(bprm, tsk,
> +						   rule->lsm[i].args_p);
> +			break;
>  		default:
>  			break;
>  		}
> @@ -527,7 +533,7 @@ enum {
>  	Opt_audit,
>  	Opt_obj_user, Opt_obj_role, Opt_obj_type,
>  	Opt_subj_user, Opt_subj_role, Opt_subj_type,
> -	Opt_func, Opt_mask, Opt_fsmagic,
> +	Opt_aa_profile, Opt_func, Opt_mask, Opt_fsmagic,
>  	Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq,
>  	Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
>  	Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
> @@ -547,6 +553,7 @@ static match_table_t policy_tokens = {
>  	{Opt_subj_user, "subj_user=%s"},
>  	{Opt_subj_role, "subj_role=%s"},
>  	{Opt_subj_type, "subj_type=%s"},
> +	{Opt_aa_profile, "aa_profile=%s"},
>  	{Opt_func, "func=%s"},
>  	{Opt_mask, "mask=%s"},
>  	{Opt_fsmagic, "fsmagic=%s"},
> @@ -847,6 +854,13 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>  						   LSM_SUBJ_TYPE,
>  						   AUDIT_SUBJ_TYPE);
>  			break;
> +		case Opt_aa_profile:
> +			ima_log_string(ab, "aa_profile", args[0].from);
> +			entry->lsm[LSM_AA_PROFILE].args_p = match_strdup(args);
> +			entry->lsm[LSM_AA_PROFILE].rule = 1;
> +			if (!entry->lsm[LSM_AA_PROFILE].args_p)
> +				result = -ENOMEM;
> +			break;
>  		case Opt_appraise_type:
>  			if (entry->action != APPRAISE) {
>  				result = -EINVAL;
> @@ -1138,6 +1152,10 @@ int ima_policy_show(struct seq_file *m, void *v)
>  				seq_printf(m, pt(Opt_subj_type),
>  					   (char *)entry->lsm[i].args_p);
>  				break;
> +			case LSM_AA_PROFILE:
> +				seq_printf(m, pt(Opt_aa_profile),
> +					   (char *)entry->lsm[i].args_p);
> +				break;
>  			}
>  		}
>  	}
> 

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Matthew Garrett Aug. 29, 2017, 7:50 p.m. UTC | #2
On Tue, Aug 29, 2017 at 12:47 PM, John Johansen
<john.johansen@canonical.com> wrote:
> On 08/29/2017 12:04 PM, Matthew Garrett wrote:
>> IMA has support for matching based on security context, but this is
>> currently limited to modules that implement the audit_rule_match hook.
>> The infrastructure around this seems to depend on having 32 bit security
>> IDs to reference the policy associated with tasks or files, which
>> doesn't seem to be a concept that Apparmor really has. So, this
>> implementation ignores the abstraction and calls through to Apparmor
>> directly.
>>
>> This seems ugly, so is there a better way to achieve this?
>
> probably via secids :/
>
> secid support in apparmor is a wip, and we are hoping to land full support
> in 4.15
>
> I'll see if I can't get a dev branch with them up for you this week.

Oh, that'd be great, thank you!

> that said if you wanted to land this sooner I am not opposed to this
> going in with a minor change (see below) on the apparmor end

4.15 would be fine, I can use this implementation for internal testing.
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diff mbox

Patch

diff --git a/include/linux/apparmor.h b/include/linux/apparmor.h
new file mode 100644
index 000000000000..d8ac3f706437
--- /dev/null
+++ b/include/linux/apparmor.h
@@ -0,0 +1,16 @@ 
+#ifndef _APPARMOR_H_
+
+struct linux_binprm;
+
+#ifdef CONFIG_SECURITY_APPARMOR
+int aa_task_profile_match(struct linux_binprm *bprm, struct task_struct *tsk,
+			  const char *profile);
+#else
+static int aa_task_profile_match(struct linux_binprm *bprm,
+				 struct task_struct *tsk, const char *profile)
+{
+	return 0;
+}
+#endif
+
+#endif
diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
index 08ca26bcca77..04d087e4a1a3 100644
--- a/security/apparmor/lib.c
+++ b/security/apparmor/lib.c
@@ -17,9 +17,11 @@ 
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/vmalloc.h>
+#include <linux/apparmor.h>
 
 #include "include/audit.h"
 #include "include/apparmor.h"
+#include "include/context.h"
 #include "include/lib.h"
 #include "include/perms.h"
 #include "include/policy.h"
@@ -385,6 +387,36 @@  void aa_profile_match_label(struct aa_profile *profile, struct aa_label *label,
 	aa_label_match(profile, label, state, false, request, perms);
 }
 
+/**
+ * aa_task_profile_match - check whether a task is using the specified profile
+ * @bprm - bprm structure to extract creds from.
+ * @tsk - task to verify. Ignored if @bprm is not NULL.
+ * @name - name of the profile to search for.
+ */
+int aa_task_profile_match(struct linux_binprm *bprm, struct task_struct *tsk,
+			   const char *name)
+{
+	struct aa_label *label;
+	struct aa_profile *profile;
+	struct aa_task_ctx *ctx;
+	struct label_it i;
+	const struct cred *cred;
+
+	if (bprm) {
+		ctx = cred_ctx(bprm->cred);
+		label = aa_get_newest_label(ctx->label);
+	} else {
+		cred = __task_cred(tsk);
+		label = aa_get_newest_cred_label(cred);
+	}
+
+	label_for_each(i, label, profile) {
+		if (strcmp(name, profile->base.name) == 0)
+			return 1;
+	}
+
+	return 0;
+}
 
 /* currently unused */
 int aa_profile_label_perm(struct aa_profile *profile, struct aa_profile *target,
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 93f6af4e3a20..556a1292734c 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -20,6 +20,7 @@ 
 #include <linux/rculist.h>
 #include <linux/genhd.h>
 #include <linux/seq_file.h>
+#include <linux/apparmor.h>
 
 #include "ima.h"
 
@@ -47,9 +48,9 @@ 
 int ima_policy_flag;
 static int temp_ima_appraise;
 
-#define MAX_LSM_RULES 6
+#define MAX_LSM_RULES 7
 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
-	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
+       LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE, LSM_AA_PROFILE
 };
 
 enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
@@ -313,6 +314,11 @@  static bool ima_match_rules(struct ima_rule_entry *rule,
 							Audit_equal,
 							rule->lsm[i].rule,
 							NULL);
+			break;
+		case LSM_AA_PROFILE:
+			rc = aa_task_profile_match(bprm, tsk,
+						   rule->lsm[i].args_p);
+			break;
 		default:
 			break;
 		}
@@ -527,7 +533,7 @@  enum {
 	Opt_audit,
 	Opt_obj_user, Opt_obj_role, Opt_obj_type,
 	Opt_subj_user, Opt_subj_role, Opt_subj_type,
-	Opt_func, Opt_mask, Opt_fsmagic,
+	Opt_aa_profile, Opt_func, Opt_mask, Opt_fsmagic,
 	Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq,
 	Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
 	Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
@@ -547,6 +553,7 @@  static match_table_t policy_tokens = {
 	{Opt_subj_user, "subj_user=%s"},
 	{Opt_subj_role, "subj_role=%s"},
 	{Opt_subj_type, "subj_type=%s"},
+	{Opt_aa_profile, "aa_profile=%s"},
 	{Opt_func, "func=%s"},
 	{Opt_mask, "mask=%s"},
 	{Opt_fsmagic, "fsmagic=%s"},
@@ -847,6 +854,13 @@  static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 						   LSM_SUBJ_TYPE,
 						   AUDIT_SUBJ_TYPE);
 			break;
+		case Opt_aa_profile:
+			ima_log_string(ab, "aa_profile", args[0].from);
+			entry->lsm[LSM_AA_PROFILE].args_p = match_strdup(args);
+			entry->lsm[LSM_AA_PROFILE].rule = 1;
+			if (!entry->lsm[LSM_AA_PROFILE].args_p)
+				result = -ENOMEM;
+			break;
 		case Opt_appraise_type:
 			if (entry->action != APPRAISE) {
 				result = -EINVAL;
@@ -1138,6 +1152,10 @@  int ima_policy_show(struct seq_file *m, void *v)
 				seq_printf(m, pt(Opt_subj_type),
 					   (char *)entry->lsm[i].args_p);
 				break;
+			case LSM_AA_PROFILE:
+				seq_printf(m, pt(Opt_aa_profile),
+					   (char *)entry->lsm[i].args_p);
+				break;
 			}
 		}
 	}