[PATCH v2 05/10] dm-ima: Fix UAF errors and measuring incorrect context

Benjamin Marzinski
2026-04-29T20:21:18Z

the dm-ima code did not keep the dm_ima_measure_on_* functions from
running at the same time. This could lead to various errors. If two
processes were updating the device state, one could update the state
first, but the other could measure the state first, causing the the
current device state to appear incorrect. If a table load happened while
a device was resuming, the IMA measurement could report the wrong table
being active. And if two dm_ima_measure_on_* functions ran at the same
time, one of them could free data that the other was accessing, causing
a crash.

All the core dm functions that call a dm_ima_measure_on_* function
update the device state they want to measure under the _hash_lock,
except for do_resume(). But holding the _hash_lock is not a good way to
synchronize these functions. It's a global mutex, that is needed in many
dm operations, and the dm_ima_measure_* functions can sleep, blocking
any dm operation on any device that needs the _hash_lock.

To serialize and order the IMA measurement functions, the
dm_ima_measurements now has two counters, update_idx and measure_idx.
update_idx is incremented while holding the _hash_lock and saved, along
with the device name and uuid, in a dm_ima_context struct. Once the
_hash_lock is dropped, the dm_ima_measure_* function is called. It waits
until measure_idx matches the saved value of update_idx, ensuring that
the updates and measurements happen in the same order if there are
multiple processes changing the device at the same time. Then it
measures the device, updates measure_idx, and wakes up any other
process waiting to do a measurement. This makes sure that the
measurements are serialized and done in the order that the _hash_lock
was acquired in. But they only block other measurements for the same
device, which are unlikely to happen at the same time.

do_resume() is trickier, because it removes the inactive table while
holding the _hash_lock, but doesn't hold it while updating md->map. To
make sure it is also ordered, the IMA code grabs the _hash_lock after
md->map is updated. Then it makes sure that the device isn't being
removed and that another do_resume() hasn't already changed the active
table again, and serializes like the other functions do.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
drivers/md/dm-ima.c | 259 ++++++++++++++++++++++++------------------
drivers/md/dm-ima.h | 65 +++++++++--
drivers/md/dm-ioctl.c | 144 +++++++++++++++++++++--
drivers/md/dm.c | 2 +
4 files changed, 340 insertions(+), 130 deletions(-)

diff --git a/drivers/md/dm-ima.c b/drivers/md/dm-ima.c
index c141068bc6b4..096c664d855c 100644
--- a/drivers/md/dm-ima.c
+++ b/drivers/md/dm-ima.c
@@ -21,25 +21,32 @@
* character, so that they don't interfere with the construction of key-value pairs,
* and clients can split the key1=val1,key2=val2,key3=val3; pairs properly.
*/
-static void fix_separator_chars(char **buf)
+static void fix_separator_chars(char *buf)
{
- int l = strlen(*buf);
+ int l = strlen(buf);
int i, j, sp = 0;

for (i = 0; i < l; i++)
- if ((*buf)[i] == '\\' || (*buf)[i] == ';' || (*buf)[i] == '=' || (*buf)[i] == ',')
+ if (buf[i] == '\\' || buf[i] == ';' || buf[i] == '=' || buf[i] == ',')
sp++;

if (!sp)
return;

+ buf[l + sp] = '\0';
for (i = l-1, j = i+sp; i >= 0; i--) {
- (*buf)[j--] = (*buf)[i];
- if ((*buf)[i] == '\\' || (*buf)[i] == ';' || (*buf)[i] == '=' || (*buf)[i] == ',')
- (*buf)[j--] = '\\';
+ buf[j--] = buf[i];
+ if (buf[i] == '\\' || buf[i] == ';' || buf[i] == '=' || buf[i] == ',')
+ buf[j--] = '\\';
}
}

+static void fix_context_strings(struct dm_ima_context *context)
+{
+ fix_separator_chars(context->dev_name);
+ fix_separator_chars(context->dev_uuid);
+}
+
/*
* Internal function to allocate memory for IMA measurements.
*/
@@ -59,68 +66,89 @@ static void *dm_ima_alloc(size_t len, bool noio)
return ptr;
}

+void dm_ima_init(struct mapped_device *md)
+{
+ md->ima.update_idx = 0;
+ md->ima.measure_idx = 0;
+ init_waitqueue_head(&md->ima.ima_wq);
+ spin_lock_init(&md->ima.ima_lock);
+}
+
+void dm_ima_alloc_context(struct dm_ima_context **context, bool noio)
+{
+ *context = dm_ima_alloc(sizeof(struct dm_ima_context), noio);
+}
+
+void dm_ima_free_context(struct dm_ima_context *context)
+{
+ if (likely(context)) {
+ kfree(context->table.device_metadata);
+ kfree(context->table.hash);
+ kfree(context);
+ }
+}
+
+static void wait_to_measure(struct dm_ima_measurements *ima,
+ unsigned int update_idx)
+{
+ spin_lock_irq(&ima->ima_lock);
+ wait_event_lock_irq(ima->ima_wq,
+ ima->measure_idx == update_idx,
+ ima->ima_lock);
+ spin_unlock_irq(&ima->ima_lock);
+}
+
+static void wake_next_measure(struct dm_ima_measurements *ima)
+{
+ spin_lock_irq(&ima->ima_lock);
+ ima->measure_idx++;
+ spin_unlock_irq(&ima->ima_lock);
+ wake_up_all(&ima->ima_wq);
+}
+
/*
- * Internal function to allocate and copy name and uuid for IMA measurements.
+ * Helper function for swapping the table, to make sure that the
+ * correct table metadata is saved and restored.
*/
-static int dm_ima_alloc_and_copy_name_uuid(struct mapped_device *md, char **dev_name,
- char **dev_uuid, bool noio)
+void dm_ima_context_table_op(struct mapped_device *md,
+ struct dm_ima_context *context,
+ enum dm_ima_table_op op)
{
- int r;
- *dev_name = dm_ima_alloc(DM_NAME_LEN*2, noio);
- if (!(*dev_name)) {
- r = -ENOMEM;
- goto error;
- }
+ struct dm_ima_measurements *ima = &md->ima;

- *dev_uuid = dm_ima_alloc(DM_UUID_LEN*2, noio);
- if (!(*dev_uuid)) {
- r = -ENOMEM;
- goto error;
- }
+ if (unlikely(!context))
+ return;

- r = dm_copy_name_and_uuid(md, *dev_name, *dev_uuid);
- if (r)
- goto error;
+ wait_to_measure(ima, context->update_idx);

- fix_separator_chars(dev_name);
- fix_separator_chars(dev_uuid);
+ if (op == DM_IMA_TABLE_SAVE) {
+ context->table = ima->inactive_table;
+ memset(&ima->inactive_table, 0, sizeof(ima->inactive_table));
+ } else {
+ ima->inactive_table = context->table;
+ memset(&context->table, 0, sizeof(context->table));
+ }

- return 0;
-error:
- kfree(*dev_name);
- kfree(*dev_uuid);
- *dev_name = NULL;
- *dev_uuid = NULL;
- return r;
+ wake_next_measure(ima);
}

/*
* Internal function to allocate and copy device data for IMA measurements.
*/
static int dm_ima_alloc_and_copy_device_data(struct mapped_device *md, char **device_data,
+ struct dm_ima_context *context,
unsigned int num_targets, bool noio)
{
- char *dev_name = NULL, *dev_uuid = NULL;
- int r;
-
- r = dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio);
- if (r)
- return r;
-
*device_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN, noio);
- if (!(*device_data)) {
- r = -ENOMEM;
- goto error;
- }
+ if (!(*device_data))
+ return -ENOMEM;

scnprintf(*device_data, DM_IMA_DEVICE_BUF_LEN,
"name=%s,uuid=%s,major=%d,minor=%d,minor_count=%d,num_targets=%u;",
- dev_name, dev_uuid, md->disk->major, md->disk->first_minor,
- md->disk->minors, num_targets);
-error:
- kfree(dev_name);
- kfree(dev_uuid);
- return r;
+ context->dev_name, context->dev_uuid, md->disk->major,
+ md->disk->first_minor, md->disk->minors, num_targets);
+
+ return 0;
}

/*
@@ -162,7 +190,8 @@ static int dm_ima_alloc_and_copy_capacity_str(struct mapped_device *md, char **c
/*
* Build up the IMA data for each target, and finally measure.
*/
-void dm_ima_measure_on_table_load(struct dm_table *table)
+void dm_ima_measure_on_table_load(struct dm_table *table,
+ struct dm_ima_context *context)
{
size_t device_data_buf_len, target_metadata_buf_len, target_data_buf_len, l = 0;
char *target_metadata_buf = NULL, *target_data_buf = NULL, *digest_buf = NULL;
@@ -175,9 +204,14 @@ void dm_ima_measure_on_table_load(struct dm_table *table)
bool noio = false;
char table_load_event_name[] = "dm_table_load";

+ if (unlikely(!context))
+ return;
+
+ wait_to_measure(&table->md->ima, context->update_idx);
+
ima_buf = dm_ima_alloc(DM_IMA_MEASUREMENT_BUF_LEN, noio);
if (!ima_buf)
- return;
+ goto error;

target_metadata_buf = dm_ima_alloc(DM_IMA_TARGET_METADATA_BUF_LEN, noio);
if (!target_metadata_buf)
@@ -189,7 +223,9 @@ void dm_ima_measure_on_table_load(struct dm_table *table)

num_targets = table->num_targets;

- if (dm_ima_alloc_and_copy_device_data(table->md, &device_data_buf, num_targets, noio))
+ fix_context_strings(context);
+ if (dm_ima_alloc_and_copy_device_data(table->md, &device_data_buf,
+ context, num_targets, noio))
goto error;

sha256_init(&hash_ctx);
@@ -299,14 +335,17 @@ void dm_ima_measure_on_table_load(struct dm_table *table)
kfree(ima_buf);
kfree(target_metadata_buf);
kfree(target_data_buf);
+
+ wake_next_measure(&table->md->ima);
}

/*
* Measure IMA data on device resume.
*/
-void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)
+void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap,
+ struct dm_ima_context *context)
{
- char *device_table_data, *dev_name = NULL, *dev_uuid = NULL, *capacity_str = NULL;
+ char *device_table_data = NULL, *capacity_str = NULL;
char active[] = "active_table_hash=";
unsigned int active_len = strlen(active);
unsigned int l = 0;
@@ -314,9 +353,14 @@ void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)
bool nodata = true;
int capacity_len;

+ if (unlikely(!context))
+ return;
+
+ wait_to_measure(&md->ima, context->update_idx);
+
device_table_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN, noio);
if (!device_table_data)
- return;
+ goto error;

capacity_len = dm_ima_alloc_and_copy_capacity_str(md, &capacity_str, noio);
if (capacity_len < 0)
@@ -328,25 +372,8 @@ void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)
if (swap) {
kfree(md->ima.active_table.hash);
kfree(md->ima.active_table.device_metadata);
- memset(&md->ima.active_table, 0, sizeof(md->ima.active_table));
-
- if (md->ima.inactive_table.hash) {
- md->ima.active_table.hash = md->ima.inactive_table.hash;
- md->ima.active_table.hash_len = md->ima.inactive_table.hash_len;
- md->ima.inactive_table.hash = NULL;
- md->ima.inactive_table.hash_len = 0;
- }
-
- if (md->ima.inactive_table.device_metadata) {
- md->ima.active_table.device_metadata =
- md->ima.inactive_table.device_metadata;
- md->ima.active_table.device_metadata_len =
- md->ima.inactive_table.device_metadata_len;
- md->ima.active_table.num_targets = md->ima.inactive_table.num_targets;
- md->ima.inactive_table.device_metadata = NULL;
- md->ima.inactive_table.device_metadata_len = 0;
- md->ima.inactive_table.num_targets = 0;
- }
+ md->ima.active_table = context->table;
+ memset(&context->table, 0, sizeof(context->table));
}

if (md->ima.active_table.device_metadata) {
@@ -372,12 +399,11 @@ void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)
}

if (nodata) {
- if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
- goto error;
-
+ fix_context_strings(context);
l = scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
"%sname=%s,uuid=%s;device_resume=no_data;",
- DM_IMA_VERSION_STR, dev_name, dev_uuid);
+ DM_IMA_VERSION_STR, context->dev_name,
+ context->dev_uuid);
}

memcpy(device_table_data + l, capacity_str, capacity_len);
@@ -385,19 +411,21 @@ void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)

dm_ima_measure_data("dm_device_resume", device_table_data, l, noio);

- kfree(dev_name);
- kfree(dev_uuid);
error:
kfree(capacity_str);
kfree(device_table_data);
+
+ wake_next_measure(&md->ima);
}

/*
* Measure IMA data on remove.
*/
-void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)
+void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all,
+ struct dm_ima_context *context,
+ unsigned int idx)
{
- char *device_table_data, *dev_name = NULL, *dev_uuid = NULL, *capacity_str = NULL;
+ char *device_table_data, *capacity_str = NULL;
char active_table_str[] = "active_table_hash=";
char inactive_table_str[] = "inactive_table_hash=";
char device_active_str[] = "device_active_metadata=";
@@ -413,6 +441,11 @@ void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)
bool nodata = true;
int capacity_len;

+ wait_to_measure(&md->ima, idx);
+
+ if (unlikely(!context))
+ goto exit;
+
device_table_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN*2, noio);
if (!device_table_data)
goto exit;
@@ -481,12 +514,11 @@ void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)
* in IMA measurements.
*/
if (nodata) {
- if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
- goto error;
-
+ fix_context_strings(context);
l = scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
"%sname=%s,uuid=%s;device_remove=no_data;",
- DM_IMA_VERSION_STR, dev_name, dev_uuid);
+ DM_IMA_VERSION_STR, context->dev_name,
+ context->dev_uuid);
}

memcpy(device_table_data + l, remove_all_str, remove_all_len);
@@ -499,7 +531,6 @@ void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)

dm_ima_measure_data("dm_device_remove", device_table_data, l, noio);

-error:
kfree(device_table_data);
kfree(capacity_str);
exit:
@@ -512,30 +543,35 @@ void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)
memset(&md->ima.active_table, 0, sizeof(md->ima.active_table));
memset(&md->ima.inactive_table, 0, sizeof(md->ima.inactive_table));

- kfree(dev_name);
- kfree(dev_uuid);
+ wake_next_measure(&md->ima);
}

/*
* Measure ima data on table clear.
*/
-void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map)
+void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map,
+ struct dm_ima_context *context)
{
unsigned int l = 0;
- char *device_table_data = NULL, *dev_name = NULL, *dev_uuid = NULL, *capacity_str = NULL;
+ char *device_table_data = NULL, *capacity_str = NULL;
char inactive_str[] = "inactive_table_hash=";
unsigned int inactive_len = strlen(inactive_str);
bool noio = true;
bool nodata = true;
int capacity_len;

+ if (unlikely(!context))
+ return;
+
+ wait_to_measure(&md->ima, context->update_idx);
+
device_table_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN, noio);
if (!device_table_data)
- return;
+ goto error;

capacity_len = dm_ima_alloc_and_copy_capacity_str(md, &capacity_str, noio);
if (capacity_len < 0)
- goto error1;
+ goto error;

memcpy(device_table_data + l, DM_IMA_VERSION_STR, strlen(DM_IMA_VERSION_STR));
l += strlen(DM_IMA_VERSION_STR);
@@ -561,12 +597,11 @@ void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map)
}

if (nodata) {
- if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
- goto error2;
-
+ fix_context_strings(context);
l = scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
"%sname=%s,uuid=%s;table_clear=no_data;",
- DM_IMA_VERSION_STR, dev_name, dev_uuid);
+ DM_IMA_VERSION_STR, context->dev_name,
+ context->dev_uuid);
}

memcpy(device_table_data + l, capacity_str, capacity_len);
@@ -580,29 +615,33 @@ void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map)
memset(&md->ima.inactive_table, 0, sizeof(md->ima.inactive_table));
}

- kfree(dev_name);
- kfree(dev_uuid);
-error2:
+error:
kfree(capacity_str);
-error1:
kfree(device_table_data);
+
+ wake_next_measure(&md->ima);
}

/*
* Measure IMA data on device rename.
*/
-void dm_ima_measure_on_device_rename(struct mapped_device *md)
+void dm_ima_measure_on_device_rename(struct mapped_device *md,
+ struct dm_ima_context *context)
{
- char *old_device_data = NULL, *new_device_data = NULL, *combined_device_data = NULL;
- char *new_dev_name = NULL, *new_dev_uuid = NULL, *capacity_str = NULL;
+ char *old_device_data = NULL, *new_device_data = NULL;
+ char *combined_device_data = NULL, *capacity_str = NULL;
bool noio = true;
int len;

- if (dm_ima_alloc_and_copy_device_data(md, &new_device_data,
- md->ima.active_table.num_targets, noio))
+ if (unlikely(!context))
return;

- if (dm_ima_alloc_and_copy_name_uuid(md, &new_dev_name, &new_dev_uuid, noio))
+ wait_to_measure(&md->ima, context->update_idx);
+
+ fix_context_strings(context);
+ if (dm_ima_alloc_and_copy_device_data(md, &new_device_data, context,
+ md->ima.active_table.num_targets,
+ noio))
goto error;

combined_device_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN * 2, noio);
@@ -619,7 +658,7 @@ void dm_ima_measure_on_device_rename(struct mapped_device *md)

len = scnprintf(combined_device_data, DM_IMA_DEVICE_BUF_LEN * 2,
"%s%snew_name=%s,new_uuid=%s;%s", DM_IMA_VERSION_STR, old_device_data,
- new_dev_name, new_dev_uuid, capacity_str);
+ context->dev_name, context->dev_uuid, capacity_str);

dm_ima_measure_data("dm_device_rename", combined_device_data, len, noio);

@@ -631,6 +670,6 @@ void dm_ima_measure_on_device_rename(struct mapped_device *md)
kfree(capacity_str);
kfree(combined_device_data);
kfree(old_device_data);
- kfree(new_dev_name);
- kfree(new_dev_uuid);
+
+ wake_next_measure(&md->ima);
}
diff --git a/drivers/md/dm-ima.h b/drivers/md/dm-ima.h
index c0548492bef0..01fa0b89a385 100644
--- a/drivers/md/dm-ima.h
+++ b/drivers/md/dm-ima.h
@@ -24,6 +24,11 @@
__dm_ima_str(DM_VERSION_MINOR) "." \
__dm_ima_str(DM_VERSION_PATCHLEVEL) ";"

+enum dm_ima_table_op {
+ DM_IMA_TABLE_SAVE,
+ DM_IMA_TABLE_RESTORE,
+};
+
#ifdef CONFIG_IMA

struct dm_ima_device_table_metadata {
@@ -45,28 +50,68 @@ struct dm_ima_device_table_metadata {
unsigned int hash_len;
};

+struct dm_ima_context {
+ struct dm_ima_device_table_metadata table;
+ unsigned int update_idx;
+ char dev_name[DM_NAME_LEN*2];
+ char dev_uuid[DM_UUID_LEN*2];
+};
+
/*
* This structure contains device metadata, and table hash for
* active and inactive tables for ima measurements.
*/
struct dm_ima_measurements {
+ unsigned int update_idx;
+ unsigned int measure_idx;
+ struct wait_queue_head ima_wq;
+ spinlock_t ima_lock;
struct dm_ima_device_table_metadata active_table;
struct dm_ima_device_table_metadata inactive_table;
};

-void dm_ima_measure_on_table_load(struct dm_table *table);
-void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap);
-void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all);
-void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map);
-void dm_ima_measure_on_device_rename(struct mapped_device *md);
+void dm_ima_init(struct mapped_device *md);
+void dm_ima_alloc_context(struct dm_ima_context **context, bool noio);
+void dm_ima_free_context(struct dm_ima_context *context);
+void dm_ima_context_table_op(struct mapped_device *md,
+ struct dm_ima_context *context,
+ enum dm_ima_table_op op);
+void dm_ima_measure_on_table_load(struct dm_table *table,
+ struct dm_ima_context *context);
+void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap,
+ struct dm_ima_context *context);
+void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all,
+ struct dm_ima_context *context,
+ unsigned int idx);
+void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map,
+ struct dm_ima_context *context);
+void dm_ima_measure_on_device_rename(struct mapped_device *md,
+ struct dm_ima_context *context);

#else

-static inline void dm_ima_measure_on_table_load(struct dm_table *table) {}
-static inline void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap) {}
-static inline void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all) {}
-static inline void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map) {}
-static inline void dm_ima_measure_on_device_rename(struct mapped_device *md) {}
+struct dm_ima_context;
+
+static inline void dm_ima_init(struct mapped_device *md) {}
+static inline void dm_ima_alloc_context(struct dm_ima_context **context, bool noio) {}
+static inline void dm_ima_free_context(struct dm_ima_context *context) {}
+static inline void dm_ima_context_table_op(struct mapped_device *md,
+ struct dm_ima_context *context,
+ enum dm_ima_table_op op) {}
+static inline void dm_ima_measure_on_table_load(struct dm_table *table,
+ struct dm_ima_context *context) {}
+static inline void dm_ima_measure_on_device_resume(struct mapped_device *md,
+ bool swap,
+ struct dm_ima_context *context) {}
+static inline void dm_ima_measure_on_device_remove(struct mapped_device *md,
+ bool remove_all,
+ struct dm_ima_context *context,
+ unsigned int idx) {}
+static inline void dm_ima_measure_on_table_clear(struct mapped_device *md,
+ bool new_map,
+ struct dm_ima_context *context) {}
+static inline void dm_ima_measure_on_device_rename(struct mapped_device *md,
+ struct dm_ima_context *context) {}

#endif /* CONFIG_IMA */

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 074a3c71297e..3da8b33cdc54 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -259,6 +259,80 @@ static void free_cell(struct hash_cell *hc)
}
}

+#ifdef CONFIG_IMA
+
+/*
+ * Called while holding to _hash_lock, to guarantee the ordering of the
+ * following dm_ima_measure_on_* functions, which should be called
+ * right after dropping the _hash_lock
+ */
+static unsigned int dm_ima_init_context(struct hash_cell *hc,
+ struct dm_ima_context *context,
+ bool need_idx)
+{
+ lockdep_assert_held(&_hash_lock);
+
+ if (unlikely(!context))
+ return need_idx ? hc->md->ima.update_idx++ : 0;
+
+ context->update_idx = hc->md->ima.update_idx++;
+ strcpy(context->dev_name, hc->name);
+ strcpy(context->dev_uuid, hc->uuid ? : "");
+
+ return context->update_idx;
+}
+
+/*
+ * Called by do_resume() to guarantee correct ordering, since do_resume()
+ * does not grab the _hash_lock when the table is not getting swapped or
+ * when actually swapping the active table
+ */
+static bool dm_ima_need_measure(struct mapped_device *md,
+ struct dm_table *table,
+ struct dm_ima_context *context)
+{
+ int srcu_idx;
+ struct hash_cell *hc;
+ bool need_measure = false;
+
+ if (unlikely(!context))
+ return false;
+
+ down_write(&_hash_lock);
+ /* Check if the device has been removed */
+ hc = dm_get_mdptr(md);
+ if (hc) {
+ /*
+ * If we have a table, we need to make sure that it's the
+ * active table. Otherwise we raced with another process
+ * setting the active table and it will do the measurement
+ */
+ if (!table || dm_get_live_table(md, &srcu_idx) == table) {
+ dm_ima_init_context(hc, context, false);
+ need_measure = true;
+ }
+ if (table)
+ dm_put_live_table(md, srcu_idx);
+ }
+ up_write(&_hash_lock);
+
+ return need_measure;
+}
+#else
+static inline unsigned int dm_ima_init_context(struct hash_cell *hc,
+ struct dm_ima_context *context,
+ bool neex_idx)
+{
+ return 0;
+}
+static inline bool dm_ima_need_measure(struct mapped_device *md,
+ struct dm_table *table,
+ struct dm_ima_context *context)
+{
+ return false;
+}
+#endif
+
/*
* The kdev_t and uuid of a device can never change once it is
* initially inserted.
@@ -344,7 +418,10 @@ static int dm_hash_remove_all(unsigned flags)
struct hash_cell *hc;
struct mapped_device *md;
struct dm_table *t;
+ struct dm_ima_context *ima_context = NULL;
+ unsigned int ima_idx;

+ dm_ima_alloc_context(&ima_context, true);
retry:
dev_skipped = 0;

@@ -353,6 +430,7 @@ static int dm_hash_remove_all(unsigned flags)
for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
if (flags & DM_REMOVE_INTERRUPTIBLE && fatal_signal_pending(current)) {
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
return -EINTR;
}

@@ -367,6 +445,7 @@ static int dm_hash_remove_all(unsigned flags)
continue;
}

+ ima_idx = dm_ima_init_context(hc, ima_context, true);
t = __hash_remove(hc);

up_write(&_hash_lock);
@@ -375,7 +454,7 @@ static int dm_hash_remove_all(unsigned flags)
dm_sync_table(md);
dm_table_destroy(t);
}
- dm_ima_measure_on_device_remove(md, true);
+ dm_ima_measure_on_device_remove(md, true, ima_context, ima_idx);
dm_put(md);
if (likely(flags & DM_REMOVE_KEEP_OPEN_DEVICES))
dm_destroy(md);
@@ -396,6 +475,7 @@ static int dm_hash_remove_all(unsigned flags)
if (dev_skipped && !(flags & DM_REMOVE_ONLY_DEFERRED))
DMWARN("remove_all left %d open device(s)", dev_skipped);

+ dm_ima_free_context(ima_context);
return 0;
}

@@ -443,6 +523,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
struct mapped_device *md;
unsigned int change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
int srcu_idx;
+ struct dm_ima_context *ima_context = NULL;

/*
* duplicate new.
@@ -451,6 +532,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
if (!new_data)
return ERR_PTR(-ENOMEM);

+ dm_ima_alloc_context(&ima_context, true);
down_write(&_hash_lock);

/*
@@ -467,6 +549,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
param->name, new);
dm_put(hc->md);
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
kfree(new_data);
return ERR_PTR(-EBUSY);
}
@@ -479,6 +562,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
DMERR("Unable to rename non-existent device, %s to %s%s",
param->name, change_uuid ? "uuid " : "", new);
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
kfree(new_data);
return ERR_PTR(-ENXIO);
}
@@ -492,6 +576,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
param->name, new, hc->uuid);
dm_put(hc->md);
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
kfree(new_data);
return ERR_PTR(-EINVAL);
}
@@ -514,9 +599,11 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,

md = hc->md;

- dm_ima_measure_on_device_rename(md);
+ dm_ima_init_context(hc, ima_context, false);

up_write(&_hash_lock);
+ dm_ima_measure_on_device_rename(md, ima_context);
+ dm_ima_free_context(ima_context);
kfree(old_name);

return md;
@@ -995,13 +1082,17 @@ static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_si
struct mapped_device *md;
int r;
struct dm_table *t;
+ struct dm_ima_context *ima_context = NULL;
+ unsigned int ima_idx;

+ dm_ima_alloc_context(&ima_context, true);
down_write(&_hash_lock);
hc = __find_device_hash_cell(param);

if (!hc) {
DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
return -ENXIO;
}

@@ -1015,14 +1106,17 @@ static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_si
if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
up_write(&_hash_lock);
dm_put(md);
+ dm_ima_free_context(ima_context);
return 0;
}
DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
up_write(&_hash_lock);
dm_put(md);
+ dm_ima_free_context(ima_context);
return r;
}

+ ima_idx = dm_ima_init_context(hc, ima_context, true);
t = __hash_remove(hc);
up_write(&_hash_lock);

@@ -1033,7 +1127,8 @@ static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_si

param->flags &= ~DM_DEFERRED_REMOVE;

- dm_ima_measure_on_device_remove(md, false);
+ dm_ima_measure_on_device_remove(md, false, ima_context, ima_idx);
+ dm_ima_free_context(ima_context);

if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr, false))
param->flags |= DM_UEVENT_GENERATED_FLAG;
@@ -1169,13 +1264,16 @@ static int do_resume(struct dm_ioctl *param)
struct mapped_device *md;
struct dm_table *new_map, *old_map = NULL;
bool need_resize_uevent = false;
+ struct dm_ima_context *ima_context = NULL;

+ dm_ima_alloc_context(&ima_context, true);
down_write(&_hash_lock);

hc = __find_device_hash_cell(param);
if (!hc) {
DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
return -ENXIO;
}

@@ -1184,13 +1282,15 @@ static int do_resume(struct dm_ioctl *param)
new_map = hc->new_map;
hc->new_map = NULL;
param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
-
+ if (new_map)
+ dm_ima_init_context(hc, ima_context, false);
up_write(&_hash_lock);

/* Do we need to load a new map ? */
if (new_map) {
sector_t old_size, new_size;

+ dm_ima_context_table_op(md, ima_context, DM_IMA_TABLE_SAVE);
/* Suspend if it isn't already suspended */
if (param->flags & DM_SKIP_LOCKFS_FLAG)
suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
@@ -1204,6 +1304,8 @@ static int do_resume(struct dm_ioctl *param)
if (hc && !hc->new_map) {
hc->new_map = new_map;
new_map = NULL;
+ dm_ima_init_context(hc, ima_context,
+ false);
} else {
r = -ENXIO;
}
@@ -1211,7 +1313,9 @@ static int do_resume(struct dm_ioctl *param)
if (new_map) {
dm_sync_table(md);
dm_table_destroy(new_map);
- }
+ } else
+ dm_ima_context_table_op(md, ima_context, DM_IMA_TABLE_RESTORE);
+ dm_ima_free_context(ima_context);
dm_put(md);
return r;
}
@@ -1222,9 +1326,12 @@ static int do_resume(struct dm_ioctl *param)
if (IS_ERR(old_map)) {
dm_sync_table(md);
dm_table_destroy(new_map);
+ dm_ima_free_context(ima_context);
dm_put(md);
return PTR_ERR(old_map);
}
+ if (dm_ima_need_measure(md, new_map, ima_context))
+ dm_ima_measure_on_device_resume(md, true, ima_context);
new_size = dm_get_size(md);
if (old_size && new_size && old_size != new_size)
need_resize_uevent = true;
@@ -1238,7 +1345,10 @@ static int do_resume(struct dm_ioctl *param)
if (dm_suspended_md(md)) {
r = dm_resume(md);
if (!r) {
- dm_ima_measure_on_device_resume(md, new_map ? true : false);
+ if (!new_map && dm_ima_need_measure(md, NULL,
+ ima_context))
+ dm_ima_measure_on_device_resume(md, false,
+ ima_context);

if (!dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr, need_resize_uevent))
param->flags |= DM_UEVENT_GENERATED_FLAG;
@@ -1255,6 +1365,7 @@ static int do_resume(struct dm_ioctl *param)
if (!r)
__dev_status(md, param);

+ dm_ima_free_context(ima_context);
dm_put(md);
return r;
}
@@ -1532,11 +1643,12 @@ static bool is_valid_type(enum dm_queue_mode cur, enum dm_queue_mode new)

static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_size)
{
- int r;
+ int r, srcu_idx;
struct hash_cell *hc;
struct dm_table *t, *old_map = NULL;
struct mapped_device *md;
struct target_type *immutable_target_type;
+ struct dm_ima_context *ima_context = NULL;

md = find_device(param);
if (!md)
@@ -1552,8 +1664,6 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
if (r)
goto err_unlock_md_type;

- dm_ima_measure_on_table_load(t);
-
immutable_target_type = dm_get_immutable_target_type(md);
if (immutable_target_type &&
(immutable_target_type != dm_table_get_immutable_target_type(t)) &&
@@ -1580,12 +1690,14 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si

dm_unlock_md_type(md);

+ dm_ima_alloc_context(&ima_context, false);
/* stage inactive table */
down_write(&_hash_lock);
hc = dm_get_mdptr(md);
if (!hc) {
DMERR("device has been removed from the dev hash table.");
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
r = -ENXIO;
goto err_destroy_table;
}
@@ -1593,8 +1705,15 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
if (hc->new_map)
old_map = hc->new_map;
hc->new_map = t;
+ dm_ima_init_context(hc, ima_context, false);
+ /* Make sure new_map doesn't get freed before we measure it*/
+ dm_get_live_table(md, &srcu_idx);
up_write(&_hash_lock);

+ dm_ima_measure_on_table_load(t, ima_context);
+ dm_ima_free_context(ima_context);
+ dm_put_live_table(md, srcu_idx);
+
param->flags |= DM_INACTIVE_PRESENT_FLAG;
__dev_status(md, param);

@@ -1623,13 +1742,16 @@ static int table_clear(struct file *filp, struct dm_ioctl *param, size_t param_s
struct mapped_device *md;
struct dm_table *old_map = NULL;
bool has_new_map = false;
+ struct dm_ima_context *ima_context = NULL;

+ dm_ima_alloc_context(&ima_context, true);
down_write(&_hash_lock);

hc = __find_device_hash_cell(param);
if (!hc) {
DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
up_write(&_hash_lock);
+ dm_ima_free_context(ima_context);
return -ENXIO;
}

@@ -1639,8 +1761,11 @@ static int table_clear(struct file *filp, struct dm_ioctl *param, size_t param_s
has_new_map = true;
}

+ dm_ima_init_context(hc, ima_context, false);
md = hc->md;
up_write(&_hash_lock);
+ dm_ima_measure_on_table_clear(md, has_new_map, ima_context);
+ dm_ima_free_context(ima_context);

param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
__dev_status(md, param);
@@ -1649,7 +1774,6 @@ static int table_clear(struct file *filp, struct dm_ioctl *param, size_t param_s
dm_sync_table(md);
dm_table_destroy(old_map);
}
- dm_ima_measure_on_table_clear(md, has_new_map);
dm_put(md);

return 0;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8b60c9804f5b..87011c41ef7b 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2546,6 +2546,8 @@ int dm_create(int minor, struct mapped_device **result)
if (!md)
return -ENXIO;

+ dm_ima_init(md);
+
*result = md;
return 0;
}
--
2.53.0