Currently, IMA does not restrict random data sources from measuring their
data using ima_measure_critical_data(). Any kernel data source can call
the function, and it's data will get measured as long as the input
event_data_source is part of the IMA policy -
CRITICAL_DATA+critical_kernel_data_sources. This may result in IMA log
getting bloated by random data sources. Supporting random data sources
at run-time may also impact the reliability of the system.
To ensure that only data from supported sources are measured, the kernel
component needs to be added to a compile-time list of supported sources
(an "allowed list of components") in ima.h. IMA then validates the input
parameter - event_data_source passed to ima_measure_critical_data()
against this allowed list at run-time.
Provide an infrastructure for kernel data sources to be added to
the supported data sources list at compile-time. Update
ima_measure_critical_data() to validate, at run-time, that the data
source is supported before measuring the data.
Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
---
security/integrity/ima/ima.h | 29 +++++++++++++++++++++++++++++
security/integrity/ima/ima_main.c | 3 +++
2 files changed, 32 insertions(+)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 00b84052c8f1..ecb0a1e7378f 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -228,6 +228,35 @@ extern const char *const func_tokens[];
struct modsig;
+#define __ima_supported_kernel_data_sources(source) \
+ source(MIN_SOURCE, min_source) \
+ source(MAX_SOURCE, max_source)
+
+#define __ima_enum_stringify(ENUM, str) (#str),
+
+enum ima_supported_kernel_data_sources {
+ __ima_supported_kernel_data_sources(__ima_hook_enumify)
+};
+
+static const char * const ima_supported_kernel_data_sources_str[] = {
+ __ima_supported_kernel_data_sources(__ima_enum_stringify)
+};
+
+static inline bool ima_kernel_data_source_is_supported(const char *source)
+{
+ int i;
+
+ if (!source)
+ return false;
+
+ for (i = MIN_SOURCE + 1; i < MAX_SOURCE; i++) {
+ if (!strcmp(ima_supported_kernel_data_sources_str[i], source))
+ return true;
+ }
+
+ return false;
+}
+
#ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS
/*
* To track keys that need to be measured.
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index a889bf40cb7e..41be4d1d839e 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -888,6 +888,9 @@ int ima_measure_critical_data(const char *event_name,
if (!event_name || !event_data_source || !buf || !buf_len)
return -EINVAL;
+ if (!ima_kernel_data_source_is_supported(event_data_source))
+ return -EPERM;
+
return process_buffer_measurement(NULL, buf, buf_len, event_name,
CRITICAL_DATA, 0, event_data_source,
measure_buf_hash);
--
2.17.1
