[PATCH v4 3/3] ima: Add digest and digest_len params to the functions to measure a buffer
From: Roberto Sassu
Date: Fri Jul 23 2021 - 04:53:43 EST
This patch performs the final modification necessary to pass the buffer
measurement to callers, so that they provide a functionality similar to
ima_file_hash(). It adds the 'digest' and 'digest_len' parameters to
ima_measure_critical_data() and process_buffer_measurement().
These functions calculate the digest even if there is no suitable rule in
the IMA policy and, in this case, they simply return 1 before generating a
new measurement entry.
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Reviewed-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
---
include/linux/ima.h | 5 +--
security/integrity/ima/ima.h | 2 +-
security/integrity/ima/ima_appraise.c | 2 +-
security/integrity/ima/ima_asymmetric_keys.c | 2 +-
security/integrity/ima/ima_init.c | 3 +-
security/integrity/ima/ima_main.c | 36 ++++++++++++++------
security/integrity/ima/ima_queue_keys.c | 2 +-
security/selinux/ima.c | 6 ++--
8 files changed, 39 insertions(+), 19 deletions(-)
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 60492263aa64..b6ab66a546ae 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -38,7 +38,7 @@ extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
extern int ima_measure_critical_data(const char *event_label,
const char *event_name,
const void *buf, size_t buf_len,
- bool hash);
+ bool hash, u8 *digest, size_t digest_len);
#ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
extern void ima_appraise_parse_cmdline(void);
@@ -147,7 +147,8 @@ static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {
static inline int ima_measure_critical_data(const char *event_label,
const char *event_name,
const void *buf, size_t buf_len,
- bool hash)
+ bool hash, u8 *digest,
+ size_t digest_len)
{
return -ENOENT;
}
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 03db221324c3..2f4c20b16ad7 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -268,7 +268,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
struct inode *inode, const void *buf, int size,
const char *eventname, enum ima_hooks func,
int pcr, const char *func_data,
- bool buf_hash);
+ bool buf_hash, u8 *digest, size_t digest_len);
void ima_audit_measurement(struct integrity_iint_cache *iint,
const unsigned char *filename);
int ima_alloc_init_template(struct ima_event_data *event_data,
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ef9dcfce45d4..63bec42c353f 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -357,7 +357,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
process_buffer_measurement(&init_user_ns, NULL, digest, digestsize,
"blacklisted-hash", NONE,
- pcr, NULL, false);
+ pcr, NULL, false, NULL, 0);
}
return rc;
diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
index c985418698a4..f6aa0b47a772 100644
--- a/security/integrity/ima/ima_asymmetric_keys.c
+++ b/security/integrity/ima/ima_asymmetric_keys.c
@@ -62,5 +62,5 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
*/
process_buffer_measurement(&init_user_ns, NULL, payload, payload_len,
keyring->description, KEY_CHECK, 0,
- keyring->description, false);
+ keyring->description, false, NULL, 0);
}
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 5076a7d9d23e..b26fa67476b4 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -154,7 +154,8 @@ int __init ima_init(void)
ima_init_key_queue();
ima_measure_critical_data("kernel_info", "kernel_version",
- UTS_RELEASE, strlen(UTS_RELEASE), false);
+ UTS_RELEASE, strlen(UTS_RELEASE), false,
+ NULL, 0);
return rc;
}
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index b512c06d8ee1..360266da5a10 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -838,17 +838,20 @@ int ima_post_load_data(char *buf, loff_t size,
* @pcr: pcr to extend the measurement
* @func_data: func specific data, may be NULL
* @buf_hash: measure buffer data hash
+ * @digest: buffer digest will be written to
+ * @digest_len: buffer length
*
* Based on policy, either the buffer data or buffer data hash is measured
*
- * Return: 0 if the buffer has been successfully measured, a negative value
- * otherwise.
+ * Return: 0 if the buffer has been successfully measured, 1 if the digest
+ * has been written to the passed location but not added to a measurement entry,
+ * a negative value otherwise.
*/
int process_buffer_measurement(struct user_namespace *mnt_userns,
struct inode *inode, const void *buf, int size,
const char *eventname, enum ima_hooks func,
int pcr, const char *func_data,
- bool buf_hash)
+ bool buf_hash, u8 *digest, size_t digest_len)
{
int ret = 0;
const char *audit_cause = "ENOMEM";
@@ -869,7 +872,10 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
int action = 0;
u32 secid;
- if (!ima_policy_flag)
+ if (digest && digest_len < digest_hash_len)
+ return -EINVAL;
+
+ if (!ima_policy_flag && !digest)
return -ENOENT;
template = ima_template_desc_buf();
@@ -891,7 +897,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
action = ima_get_action(mnt_userns, inode, current_cred(),
secid, 0, func, &pcr, &template,
func_data);
- if (!(action & IMA_MEASURE))
+ if (!(action & IMA_MEASURE) && !digest)
return -ENOENT;
}
@@ -922,6 +928,12 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
event_data.buf_len = digest_hash_len;
}
+ if (digest)
+ memcpy(digest, iint.ima_hash->digest, digest_hash_len);
+
+ if (!ima_policy_flag || (func && !(action & IMA_MEASURE)))
+ return 1;
+
ret = ima_alloc_init_template(&event_data, &entry, template);
if (ret < 0) {
audit_cause = "alloc_entry";
@@ -964,7 +976,7 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file),
buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0,
- NULL, false);
+ NULL, false, NULL, 0);
fdput(f);
}
@@ -975,26 +987,30 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
* @buf: pointer to buffer data
* @buf_len: length of buffer data (in bytes)
* @hash: measure buffer data hash
+ * @digest: buffer digest will be written to
+ * @digest_len: buffer length
*
* Measure data critical to the integrity of the kernel into the IMA log
* and extend the pcr. Examples of critical data could be various data
* structures, policies, and states stored in kernel memory that can
* impact the integrity of the system.
*
- * Return: 0 if the buffer has been successfully measured, a negative value
- * otherwise.
+ * Return: 0 if the buffer has been successfully measured, 1 if the digest
+ * has been written to the passed location but not added to a measurement entry,
+ * a negative value otherwise.
*/
int ima_measure_critical_data(const char *event_label,
const char *event_name,
const void *buf, size_t buf_len,
- bool hash)
+ bool hash, u8 *digest, size_t digest_len)
{
if (!event_name || !event_label || !buf || !buf_len)
return -ENOPARAM;
return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
event_name, CRITICAL_DATA, 0,
- event_label, hash);
+ event_label, hash, digest,
+ digest_len);
}
static int __init init_ima(void)
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index 979ef6c71f3d..93056c03bf5a 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -165,7 +165,7 @@ void ima_process_queued_keys(void)
entry->keyring_name,
KEY_CHECK, 0,
entry->keyring_name,
- false);
+ false, NULL, 0);
list_del(&entry->list);
ima_free_key_entry(entry);
}
diff --git a/security/selinux/ima.c b/security/selinux/ima.c
index 34d421861bfc..727c4e43219d 100644
--- a/security/selinux/ima.c
+++ b/security/selinux/ima.c
@@ -86,7 +86,8 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
}
ima_measure_critical_data("selinux", "selinux-state",
- state_str, strlen(state_str), false);
+ state_str, strlen(state_str), false,
+ NULL, 0);
kfree(state_str);
@@ -103,7 +104,8 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
}
ima_measure_critical_data("selinux", "selinux-policy-hash",
- policy, policy_len, true);
+ policy, policy_len, true,
+ NULL, 0);
vfree(policy);
}
--
2.25.1