[PATCH v8 15/19] ima: Namespace audit status flags

Stefan Berger
2022-01-04T17:04:53Z

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
none of the IMA_NS_STATUS_ACTIONS (currently only IMA_AUDIT) are 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>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
security/integrity/ima/ima.h | 27 ++++++++++++++++++++++++++-
security/integrity/ima/ima_api.c | 8 +++++---
security/integrity/ima/ima_main.c | 26 +++++++++++++++++++-------
security/integrity/ima/ima_ns.c | 20 ++++++++++++++++++++
4 files changed, 70 insertions(+), 11 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index e4804be6b524..1d7f140138be 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -318,7 +318,8 @@ int process_buffer_measurement(struct ima_namespace *ns,
int pcr, const char *func_data,
bool buf_hash, u8 *digest, size_t digest_len);
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,
struct ima_template_desc *template_desc);
@@ -530,6 +531,14 @@ struct ns_status *ima_get_ns_status(struct ima_namespace *ns,

void ima_free_ns_status_tree(struct ima_namespace *ns);

+#define IMA_NS_STATUS_ACTIONS IMA_AUDIT
+#define IMA_NS_STATUS_FLAGS IMA_AUDITED
+
+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 ima_namespace *
@@ -546,6 +555,22 @@ static inline struct ns_status *ima_get_ns_status(struct ima_namespace *ns,
return NULL;
}

+#define IMA_NS_STATUS_ACTIONS 0
+
+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 */

#endif /* __LINUX_IMA_H */
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index bee35ebb3a38..25163d64c057 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -348,14 +348,16 @@ void ima_store_measurement(struct ima_namespace *ns,
}

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;
const char *algo_name = hash_algo_name[iint->ima_hash->algo];
int i;
+ unsigned long flags = iint_flags(iint, status);

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

hash = kzalloc((iint->ima_hash->length * 2) + 1, GFP_KERNEL);
@@ -378,7 +380,7 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
audit_log_task_info(ab);
audit_log_end(ab);

- iint->flags |= IMA_AUDITED;
+ set_iint_flags(iint, status, flags | IMA_AUDITED);
out:
kfree(hash);
return;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 51b0ef1cebbe..99dc984b49c9 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -207,6 +207,7 @@ static int __process_measurement(struct ima_namespace *ns,
{
struct inode *inode = file_inode(file);
struct integrity_iint_cache *iint = NULL;
+ struct ns_status *status = NULL;
struct ima_template_desc *template_desc = NULL;
char *pathbuf = NULL;
char filename[NAME_MAX];
@@ -219,6 +220,7 @@ static int __process_measurement(struct ima_namespace *ns,
bool violation_check;
enum hash_algo hash_algo;
unsigned int allowed_algos = 0;
+ unsigned long flags;

if (!ns->ima_policy_flag || !S_ISREG(inode->i_mode))
return 0;
@@ -247,6 +249,14 @@ static int __process_measurement(struct ima_namespace *ns,
iint = integrity_inode_get(inode);
if (!iint)
rc = -ENOMEM;
+
+ if (!rc && (action & IMA_NS_STATUS_ACTIONS)) {
+ status = ima_get_ns_status(ns, inode, iint);
+ if (IS_ERR(status)) {
+ rc = PTR_ERR(status);
+ status = NULL;
+ }
+ }
}

if (!rc && violation_check)
@@ -262,11 +272,13 @@ static int __process_measurement(struct ima_namespace *ns,

mutex_lock(&iint->mutex);

+ flags = iint_flags(iint, status);
+
if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
/* reset appraisal flags if ima_inode_post_setattr was called */
- iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
- IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
- IMA_ACTION_FLAGS);
+ flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
+ IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
+ IMA_ACTION_FLAGS);

/*
* Re-evaulate the file if either the xattr has changed or the
@@ -277,7 +289,7 @@ static int __process_measurement(struct ima_namespace *ns,
((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
!(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
!(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
- iint->flags &= ~IMA_DONE_MASK;
+ flags &= ~IMA_DONE_MASK;
iint->measured_pcrs = 0;
}

@@ -285,9 +297,9 @@ static int __process_measurement(struct ima_namespace *ns,
* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
* IMA_AUDIT, IMA_AUDITED)
*/
- iint->flags |= action;
+ 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)))
@@ -362,7 +374,7 @@ static int __process_measurement(struct ima_namespace *ns,
&pathname, filename);
}
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 5a79fb6c10c0..205dd06ac41e 100644
--- a/security/integrity/ima/ima_ns.c
+++ b/security/integrity/ima/ima_ns.c
@@ -54,6 +54,26 @@ void free_ima_ns(struct user_namespace *user_ns)
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 int __init imans_cache_init(void)
{
imans_cachep = KMEM_CACHE(ima_namespace, SLAB_PANIC);
--
2.31.1