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Subject[RFC PATCH v4 5/5] ima: namespace audit status flags
Date
From: Mehmet Kayaalp <mkayaalp@linux.vnet.ibm.com>

The iint cache stores whether the file is measured, appraised, audited
etc. This patch moves the IMA_AUDITED flag into the per-namespace
ns_status, enabling IMA audit mechanism to audit the same file each time
it is accessed in a new namespace.

The ns_status is not looked up if the CONFIG_IMA_NS is disabled or if
any of the IMA_NS_STATUS_ACTIONS (currently only IMA_AUDIT) is not
enabled.

Read and write operations on the iint flags is replaced with function
calls. For reading, iint_flags() returns the bitwise AND of iint->flags
and ns_status->flags. The ns_status flags are masked with
IMA_NS_STATUS_FLAGS (currently only IMA_AUDITED). Similarly
set_iint_flags() only writes the masked portion to the ns_status flags,
while the iint flags is set as before. The ns_status parameter added to
ima_audit_measurement() is used with the above functions to query and
set the ns_status flags.

Signed-off-by: Mehmet Kayaalp <mkayaalp@linux.vnet.ibm.com>

Changelog:
v2:
* fixed flag calculation in iint_flags()
---
init/Kconfig | 3 +++
security/integrity/ima/ima.h | 24 +++++++++++++++++++++++-
security/integrity/ima/ima_api.c | 8 +++++---
security/integrity/ima/ima_main.c | 15 ++++++++++++---
security/integrity/ima/ima_ns.c | 20 ++++++++++++++++++++
5 files changed, 63 insertions(+), 7 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 2ae532aa12a0..a71a2901dac3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -939,6 +939,9 @@ config IMA_NS
help
Allow the creation of IMA namespaces. Namespaced IMA data
enables having IMA features work separately in each IMA namespace.
+ Currently, only the audit status flags are stored in the namespace,
+ which allows the same file to be audited each time it is accessed
+ in a new namespace.

endif # NAMESPACES

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index a23f4b0b21f4..d73757984563 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -212,7 +212,8 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
struct evm_ima_xattr_data *xattr_value,
int xattr_len, int pcr);
void ima_audit_measurement(struct integrity_iint_cache *iint,
- const unsigned char *filename);
+ const unsigned char *filename,
+ struct ns_status *status);
int ima_alloc_init_template(struct ima_event_data *event_data,
struct ima_template_entry **entry);
int ima_store_template(struct ima_template_entry *entry, int violation,
@@ -301,6 +302,9 @@ static inline int ima_read_xattr(struct dentry *dentry,

#endif /* CONFIG_IMA_APPRAISE */

+#define IMA_NS_STATUS_ACTIONS IMA_AUDIT
+#define IMA_NS_STATUS_FLAGS IMA_AUDITED
+
int ima_ns_init(void);
struct ima_namespace;
int ima_init_namespace(struct ima_namespace *ns);
@@ -308,12 +312,30 @@ int ima_init_namespace(struct ima_namespace *ns);
#ifdef CONFIG_IMA_NS
struct ns_status *ima_get_ns_status(struct ima_namespace *ns,
struct inode *inode);
+unsigned long iint_flags(struct integrity_iint_cache *iint,
+ struct ns_status *status);
+unsigned long set_iint_flags(struct integrity_iint_cache *iint,
+ struct ns_status *status, unsigned long flags);
#else
static inline struct ns_status *ima_get_ns_status(struct ima_namespace *ns,
struct inode *inode)
{
return NULL;
}
+
+static inline unsigned long iint_flags(struct integrity_iint_cache *iint,
+ struct ns_status *status)
+{
+ return iint->flags;
+}
+
+static inline unsigned long set_iint_flags(struct integrity_iint_cache *iint,
+ struct ns_status *status,
+ unsigned long flags)
+{
+ iint->flags = flags;
+ return flags;
+}
#endif /* CONFIG_IMA_NS */

/* LSM based policy rules require audit */
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 85ca995b9bb7..0b302d829554 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -307,15 +307,17 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
}

void ima_audit_measurement(struct integrity_iint_cache *iint,
- const unsigned char *filename)
+ const unsigned char *filename,
+ struct ns_status *status)
{
struct audit_buffer *ab;
char hash[(iint->ima_hash->length * 2) + 1];
const char *algo_name = hash_algo_name[iint->ima_hash->algo];
char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
int i;
+ unsigned long flags = iint_flags(iint, status);

- if (iint->flags & IMA_AUDITED)
+ if (flags & IMA_AUDITED)
return;

for (i = 0; i < iint->ima_hash->length; i++)
@@ -336,7 +338,7 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
audit_log_task_info(ab, current);
audit_log_end(ab);

- iint->flags |= IMA_AUDITED;
+ set_iint_flags(iint, status, flags | IMA_AUDITED);
}

/*
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index ad9acac98526..1d1f5dffb186 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -172,6 +172,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
{
struct inode *inode = file_inode(file);
struct integrity_iint_cache *iint = NULL;
+ struct ns_status *status = NULL;
struct ima_template_desc *template_desc;
char *pathbuf = NULL;
char filename[NAME_MAX];
@@ -182,6 +183,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
int xattr_len = 0;
bool violation_check;
enum hash_algo hash_algo;
+ unsigned long flags;

if (!ima_policy_flag || !S_ISREG(inode->i_mode))
return 0;
@@ -209,6 +211,12 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
iint = integrity_inode_get(inode);
if (!iint)
rc = -ENOMEM;
+
+ if (!rc && (action & IMA_NS_STATUS_ACTIONS)) {
+ status = ima_get_ns_status(get_current_ns(), inode);
+ if (IS_ERR(status))
+ rc = PTR_ERR(status);
+ }
}

if (!rc && violation_check)
@@ -238,9 +246,10 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
* IMA_AUDIT, IMA_AUDITED)
*/
- iint->flags |= action;
+ flags = iint_flags(iint, status);
+ flags = set_iint_flags(iint, status, flags | action);
action &= IMA_DO_MASK;
- action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
+ action &= ~((flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);

/* If target pcr is already measured, unset IMA_MEASURE action */
if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
@@ -290,7 +299,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
inode_unlock(inode);
}
if (action & IMA_AUDIT)
- ima_audit_measurement(iint, pathname);
+ ima_audit_measurement(iint, pathname, status);

if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
rc = 0;
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
index e0c4d66aab79..cbd0c33c8107 100644
--- a/security/integrity/ima/ima_ns.c
+++ b/security/integrity/ima/ima_ns.c
@@ -114,6 +114,26 @@ void free_ima_ns(struct kref *kref)
destroy_ima_ns(ns);
}

+unsigned long iint_flags(struct integrity_iint_cache *iint,
+ struct ns_status *status)
+{
+ if (!status)
+ return iint->flags;
+
+ return (iint->flags & ~IMA_NS_STATUS_FLAGS) |
+ (status->flags & IMA_NS_STATUS_FLAGS);
+}
+
+unsigned long set_iint_flags(struct integrity_iint_cache *iint,
+ struct ns_status *status, unsigned long flags)
+{
+ iint->flags = flags;
+ if (status)
+ status->flags = flags & IMA_NS_STATUS_FLAGS;
+
+ return flags;
+}
+
static struct ns_common *imans_get(struct task_struct *task)
{
struct ima_namespace *ns = NULL;
--
2.14.3
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