[RFC/PATCHv3 v3 0/3] request_firmware() into pre-allocated buffers

[RFC/PATCHv3 v3 0/3] request_firmware() into pre-allocated buffers

[Stephen Boyd]

Some systems are memory constrained but they need to load very
large firmwares. The firmware subsystem allows drivers to request
this firmware be loaded from the filesystem, but this requires
that the entire firmware be loaded into kernel memory first
before it's provided to the driver. This can lead to a situation
where we map the firmware twice, once to load the firmware into
kernel memory and once to copy the firmware into the final
resting place.

This design creates needless memory pressure and delays loading
because we have to copy from kernel memory to somewhere else.
This patch sets adds support to the request firmware API to load the
firmware directly into a pre-allocated buffer, skipping the intermediate
copying step and alleviating memory pressure during firmware loading.
The drawback is that we can't use the firmware caching feature because
the memory for the firmware cache is not managed by the firmware
layer.

Patches based on v4.6-rc1.

Changes since v2:
 * Dropped DMA API changes and moved to dma coherent APIs per Catalin's
   suggestions
 * Reworked to request firmware directly into any pre-allocated buffer
 * Split off cleanup patch into patch #1 to ease review 
 * Added file reading enum for reading firmware directly into buffer

Changes since v1:
 * Rebased onto v4.6-rc1 (large conflicts due to movement of code from Mimi)
 * Added some CONFIG_HAS_DMA ifdefs around code that's using DMA ops

Stephen Boyd (2):
  firmware: Consolidate kmap/read/write logic
  firmware: Support loading into a pre-allocated buffer

Vikram Mulukutla (1):
  firmware: Provide infrastructure to make fw caching optional

 drivers/base/firmware_class.c   | 183 ++++++++++++++++++++++++++++------------
 fs/exec.c                       |  21 +++--
 include/linux/firmware.h        |   8 ++
 include/linux/fs.h              |   1 +
 security/integrity/ima/ima_fs.c |   3 +-
 5 files changed, 153 insertions(+), 63 deletions(-)

-- 
2.8.0.rc4

[RFC/PATCHv3 v3 1/3] firmware: Consolidate kmap/read/write logic

[Stephen Boyd]

We use similar structured code to read and write the kmapped
firmware pages. The only difference is read copies from the kmap
region and write copies to it. Consolidate this into one function
to reduce duplication.

Cc: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
---
 drivers/base/firmware_class.c | 57 ++++++++++++++++++++-----------------------
 1 file changed, 26 insertions(+), 31 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 773fc3099769..01d55723d82c 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -691,6 +691,29 @@ out:
 
 static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
 
+static void firmware_rw(struct firmware_buf *buf, char *buffer,
+			loff_t offset, size_t count, bool read)
+{
+	while (count) {
+		void *page_data;
+		int page_nr = offset >> PAGE_SHIFT;
+		int page_ofs = offset & (PAGE_SIZE-1);
+		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
+
+		page_data = kmap(buf->pages[page_nr]);
+
+		if (read)
+			memcpy(buffer, page_data + page_ofs, page_cnt);
+		else
+			memcpy(page_data + page_ofs, buffer, page_cnt);
+
+		kunmap(buf->pages[page_nr]);
+		buffer += page_cnt;
+		offset += page_cnt;
+		count -= page_cnt;
+	}
+}
+
 static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
 				  struct bin_attribute *bin_attr,
 				  char *buffer, loff_t offset, size_t count)
@@ -715,21 +738,8 @@ static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
 
 	ret_count = count;
 
-	while (count) {
-		void *page_data;
-		int page_nr = offset >> PAGE_SHIFT;
-		int page_ofs = offset & (PAGE_SIZE-1);
-		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
-
-		page_data = kmap(buf->pages[page_nr]);
-
-		memcpy(buffer, page_data + page_ofs, page_cnt);
+	firmware_rw(buf, buffer, offset, count, true);
 
-		kunmap(buf->pages[page_nr]);
-		buffer += page_cnt;
-		offset += page_cnt;
-		count -= page_cnt;
-	}
 out:
 	mutex_unlock(&fw_lock);
 	return ret_count;
@@ -809,24 +819,9 @@ static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
 		goto out;
 
 	retval = count;
+	firmware_rw(buf, buffer, offset, count, false);
 
-	while (count) {
-		void *page_data;
-		int page_nr = offset >> PAGE_SHIFT;
-		int page_ofs = offset & (PAGE_SIZE - 1);
-		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
-
-		page_data = kmap(buf->pages[page_nr]);
-
-		memcpy(page_data + page_ofs, buffer, page_cnt);
-
-		kunmap(buf->pages[page_nr]);
-		buffer += page_cnt;
-		offset += page_cnt;
-		count -= page_cnt;
-	}
-
-	buf->size = max_t(size_t, offset, buf->size);
+	buf->size = max_t(size_t, offset + count, buf->size);
 out:
 	mutex_unlock(&fw_lock);
 	return retval;
-- 
2.8.0.rc4

[RFC/PATCHv3 v3 2/3] firmware: Provide infrastructure to make fw caching optional

[Stephen Boyd]

From: Vikram Mulukutla <markivx@codeaurora.org>

Some low memory systems with complex peripherals cannot afford to
have the relatively large firmware images taking up valuable
memory during suspend and resume. Change the internal
implementation of firmware_class to disallow caching based on a
configurable option. In the near future, variants of
request_firmware will take advantage of this feature.

Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
[stephen.boyd@linaro.org: Drop firmware_desc design and use flags]
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
---
 drivers/base/firmware_class.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 01d55723d82c..45ed20cefa10 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -112,6 +112,7 @@ static inline long firmware_loading_timeout(void)
 #define FW_OPT_FALLBACK		0
 #endif
 #define FW_OPT_NO_WARN	(1U << 3)
+#define FW_OPT_NOCACHE	(1U << 4)
 
 struct firmware_cache {
 	/* firmware_buf instance will be added into the below list */
@@ -1065,14 +1066,16 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
 	 * should be fixed in devres or driver core.
 	 */
 	/* don't cache firmware handled without uevent */
-	if (device && (opt_flags & FW_OPT_UEVENT))
+	if (device && (opt_flags & FW_OPT_UEVENT) &&
+	    !(opt_flags & FW_OPT_NOCACHE))
 		fw_add_devm_name(device, buf->fw_id);
 
 	/*
 	 * After caching firmware image is started, let it piggyback
 	 * on request firmware.
 	 */
-	if (buf->fwc->state == FW_LOADER_START_CACHE) {
+	if (!(opt_flags & FW_OPT_NOCACHE) &&
+	    buf->fwc->state == FW_LOADER_START_CACHE) {
 		if (fw_cache_piggyback_on_request(buf->fw_id))
 			kref_get(&buf->ref);
 	}
-- 
2.8.0.rc4

[RFC/PATCHv3 v3 3/3] firmware: Support loading into a pre-allocated buffer

[Stephen Boyd]

Some systems are memory constrained but they need to load very
large firmwares. The firmware subsystem allows drivers to request
this firmware be loaded from the filesystem, but this requires
that the entire firmware be loaded into kernel memory first
before it's provided to the driver. This can lead to a situation
where we map the firmware twice, once to load the firmware into
kernel memory and once to copy the firmware into the final
resting place.

This creates needless memory pressure and delays loading because
we have to copy from kernel memory to somewhere else. Let's add a
request_firmware_into_buf() API that allows drivers to request
firmware be loaded directly into a pre-allocated buffer. This
skips the intermediate step of allocating a buffer in kernel
memory to hold the firmware image while it's read from the
filesystem. It also requires that drivers know how much memory
they'll require before requesting the firmware and negates any
benefits of firmware caching because the firmware layer doesn't
manage the buffer lifetime.

For a 16MB buffer, about half the time is spent performing a
memcpy from the buffer to the final resting place. I see loading
times go from 0.081171 seconds to 0.047696 seconds after applying
this patch. Plus the vmalloc pressure is reduced.

This is based on a patch from Vikram Mulukutla on
codeaurora.org[1].

[1] https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.18/commit/drivers/base/firmware_class.c?h=rel/msm-3.18&id=0a328c5f6cd999f5c591f172216835636f39bcb5
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
---
 drivers/base/firmware_class.c   | 125 +++++++++++++++++++++++++++++++---------
 fs/exec.c                       |  21 +++++--
 include/linux/firmware.h        |   8 +++
 include/linux/fs.h              |   1 +
 security/integrity/ima/ima_fs.c |   3 +-
 5 files changed, 125 insertions(+), 33 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 45ed20cefa10..6aec96a28b1a 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -46,7 +46,8 @@ MODULE_LICENSE("GPL");
 extern struct builtin_fw __start_builtin_fw[];
 extern struct builtin_fw __end_builtin_fw[];
 
-static bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
+static bool fw_get_builtin_firmware(struct firmware *fw, const char *name,
+				    void *buf, size_t size)
 {
 	struct builtin_fw *b_fw;
 
@@ -54,6 +55,9 @@ static bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
 		if (strcmp(name, b_fw->name) == 0) {
 			fw->size = b_fw->size;
 			fw->data = b_fw->data;
+
+			if (buf && fw->size <= size)
+				memcpy(buf, fw->data, fw->size);
 			return true;
 		}
 	}
@@ -74,7 +78,9 @@ static bool fw_is_builtin_firmware(const struct firmware *fw)
 
 #else /* Module case - no builtin firmware support */
 
-static inline bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
+static inline bool fw_get_builtin_firmware(struct firmware *fw,
+					   const char *name, void *buf,
+					   size_t size)
 {
 	return false;
 }
@@ -144,6 +150,7 @@ struct firmware_buf {
 	unsigned long status;
 	void *data;
 	size_t size;
+	size_t allocated_size;
 #ifdef CONFIG_FW_LOADER_USER_HELPER
 	bool is_paged_buf;
 	bool need_uevent;
@@ -179,7 +186,8 @@ static DEFINE_MUTEX(fw_lock);
 static struct firmware_cache fw_cache;
 
 static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
-					      struct firmware_cache *fwc)
+					      struct firmware_cache *fwc,
+					      void *dbuf, size_t size)
 {
 	struct firmware_buf *buf;
 
@@ -195,6 +203,8 @@ static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
 
 	kref_init(&buf->ref);
 	buf->fwc = fwc;
+	buf->data = dbuf;
+	buf->allocated_size = size;
 	init_completion(&buf->completion);
 #ifdef CONFIG_FW_LOADER_USER_HELPER
 	INIT_LIST_HEAD(&buf->pending_list);
@@ -218,7 +228,8 @@ static struct firmware_buf *__fw_lookup_buf(const char *fw_name)
 
 static int fw_lookup_and_allocate_buf(const char *fw_name,
 				      struct firmware_cache *fwc,
-				      struct firmware_buf **buf)
+				      struct firmware_buf **buf, void *dbuf,
+				      size_t size)
 {
 	struct firmware_buf *tmp;
 
@@ -230,7 +241,7 @@ static int fw_lookup_and_allocate_buf(const char *fw_name,
 		*buf = tmp;
 		return 1;
 	}
-	tmp = __allocate_fw_buf(fw_name, fwc);
+	tmp = __allocate_fw_buf(fw_name, fwc, dbuf, size);
 	if (tmp)
 		list_add(&tmp->list, &fwc->head);
 	spin_unlock(&fwc->lock);
@@ -262,6 +273,7 @@ static void __fw_free_buf(struct kref *ref)
 		vfree(buf->pages);
 	} else
 #endif
+	if (!buf->allocated_size)
 		vfree(buf->data);
 	kfree_const(buf->fw_id);
 	kfree(buf);
@@ -302,13 +314,21 @@ static void fw_finish_direct_load(struct device *device,
 	mutex_unlock(&fw_lock);
 }
 
-static int fw_get_filesystem_firmware(struct device *device,
-				       struct firmware_buf *buf)
+static int
+fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
 {
 	loff_t size;
 	int i, len;
 	int rc = -ENOENT;
 	char *path;
+	enum kernel_read_file_id id = READING_FIRMWARE;
+	size_t msize = INT_MAX;
+
+	/* Already populated data member means we're loading into a buffer */
+	if (buf->data) {
+		id = READING_FIRMWARE_INTO_BUF;
+		msize = buf->allocated_size;
+	}
 
 	path = __getname();
 	if (!path)
@@ -327,8 +347,8 @@ static int fw_get_filesystem_firmware(struct device *device,
 		}
 
 		buf->size = 0;
-		rc = kernel_read_file_from_path(path, &buf->data, &size,
-						INT_MAX, READING_FIRMWARE);
+		rc = kernel_read_file_from_path(path, &buf->data, &size, msize,
+						id);
 		if (rc) {
 			if (rc == -ENOENT)
 				dev_dbg(device, "loading %s failed with error %d\n",
@@ -692,6 +712,15 @@ out:
 
 static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
 
+static void firmware_rw_buf(struct firmware_buf *buf, char *buffer,
+			   loff_t offset, size_t count, bool read)
+{
+	if (read)
+		memcpy(buffer, buf->data + offset, count);
+	else
+		memcpy(buf->data + offset, buffer, count);
+}
+
 static void firmware_rw(struct firmware_buf *buf, char *buffer,
 			loff_t offset, size_t count, bool read)
 {
@@ -739,7 +768,10 @@ static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
 
 	ret_count = count;
 
-	firmware_rw(buf, buffer, offset, count, true);
+	if (buf->data)
+		firmware_rw_buf(buf, buffer, offset, count, true);
+	else
+		firmware_rw(buf, buffer, offset, count, true);
 
 out:
 	mutex_unlock(&fw_lock);
@@ -815,12 +847,21 @@ static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
 		goto out;
 	}
 
-	retval = fw_realloc_buffer(fw_priv, offset + count);
-	if (retval)
-		goto out;
+	if (buf->data) {
+		if (offset + count > buf->allocated_size) {
+			retval = -ENOMEM;
+			goto out;
+		}
+		firmware_rw_buf(buf, buffer, offset, count, false);
+		retval = count;
+	} else {
+		retval = fw_realloc_buffer(fw_priv, offset + count);
+		if (retval)
+			goto out;
 
-	retval = count;
-	firmware_rw(buf, buffer, offset, count, false);
+		retval = count;
+		firmware_rw(buf, buffer, offset, count, false);
+	}
 
 	buf->size = max_t(size_t, offset + count, buf->size);
 out:
@@ -890,7 +931,8 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
 	struct firmware_buf *buf = fw_priv->buf;
 
 	/* fall back on userspace loading */
-	buf->is_paged_buf = true;
+	if (!buf->data)
+		buf->is_paged_buf = true;
 
 	dev_set_uevent_suppress(f_dev, true);
 
@@ -925,7 +967,7 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
 
 	if (is_fw_load_aborted(buf))
 		retval = -EAGAIN;
-	else if (!buf->data)
+	else if (buf->is_paged_buf && !buf->data)
 		retval = -ENOMEM;
 
 	device_del(f_dev);
@@ -1008,7 +1050,7 @@ static int sync_cached_firmware_buf(struct firmware_buf *buf)
  */
 static int
 _request_firmware_prepare(struct firmware **firmware_p, const char *name,
-			  struct device *device)
+			  struct device *device, void *dbuf, size_t size)
 {
 	struct firmware *firmware;
 	struct firmware_buf *buf;
@@ -1021,12 +1063,12 @@ _request_firmware_prepare(struct firmware **firmware_p, const char *name,
 		return -ENOMEM;
 	}
 
-	if (fw_get_builtin_firmware(firmware, name)) {
+	if (fw_get_builtin_firmware(firmware, name, dbuf, size)) {
 		dev_dbg(device, "using built-in %s\n", name);
 		return 0; /* assigned */
 	}
 
-	ret = fw_lookup_and_allocate_buf(name, &fw_cache, &buf);
+	ret = fw_lookup_and_allocate_buf(name, &fw_cache, &buf, dbuf, size);
 
 	/*
 	 * bind with 'buf' now to avoid warning in failure path
@@ -1089,7 +1131,8 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
 /* called from request_firmware() and request_firmware_work_func() */
 static int
 _request_firmware(const struct firmware **firmware_p, const char *name,
-		  struct device *device, unsigned int opt_flags)
+		  struct device *device, void *buf, size_t size,
+		  unsigned int opt_flags)
 {
 	struct firmware *fw = NULL;
 	long timeout;
@@ -1103,7 +1146,7 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
 		goto out;
 	}
 
-	ret = _request_firmware_prepare(&fw, name, device);
+	ret = _request_firmware_prepare(&fw, name, device, buf, size);
 	if (ret <= 0) /* error or already assigned */
 		goto out;
 
@@ -1182,7 +1225,7 @@ request_firmware(const struct firmware **firmware_p, const char *name,
 
 	/* Need to pin this module until return */
 	__module_get(THIS_MODULE);
-	ret = _request_firmware(firmware_p, name, device,
+	ret = _request_firmware(firmware_p, name, device, NULL, 0,
 				FW_OPT_UEVENT | FW_OPT_FALLBACK);
 	module_put(THIS_MODULE);
 	return ret;
@@ -1206,7 +1249,7 @@ int request_firmware_direct(const struct firmware **firmware_p,
 	int ret;
 
 	__module_get(THIS_MODULE);
-	ret = _request_firmware(firmware_p, name, device,
+	ret = _request_firmware(firmware_p, name, device, NULL, 0,
 				FW_OPT_UEVENT | FW_OPT_NO_WARN);
 	module_put(THIS_MODULE);
 	return ret;
@@ -1214,6 +1257,36 @@ int request_firmware_direct(const struct firmware **firmware_p,
 EXPORT_SYMBOL_GPL(request_firmware_direct);
 
 /**
+ * request_firmware_into_buf - load firmware into a previously allocated buffer
+ * @firmware_p: pointer to firmware image
+ * @name: name of firmware file
+ * @device: device for which firmware is being loaded and DMA region allocated
+ * @buf: address of buffer to load firmware into
+ * @size: size of buffer
+ *
+ * This function works pretty much like request_firmware(), but it doesn't
+ * allocate a buffer to hold the firmware data. Instead, the firmware
+ * is loaded directly into the buffer pointed to by @buf and the @firmware_p
+ * data member is pointed at @buf.
+ *
+ * This function doesn't cache firmware either.
+ */
+int
+request_firmware_into_buf(const struct firmware **firmware_p, const char *name,
+			  struct device *device, void *buf, size_t size)
+{
+	int ret;
+
+	__module_get(THIS_MODULE);
+	ret = _request_firmware(firmware_p, name, device, buf, size,
+				FW_OPT_UEVENT | FW_OPT_FALLBACK |
+				FW_OPT_NOCACHE);
+	module_put(THIS_MODULE);
+	return ret;
+}
+EXPORT_SYMBOL(request_firmware_into_buf);
+
+/**
  * release_firmware: - release the resource associated with a firmware image
  * @fw: firmware resource to release
  **/
@@ -1245,7 +1318,7 @@ static void request_firmware_work_func(struct work_struct *work)
 
 	fw_work = container_of(work, struct firmware_work, work);
 
-	_request_firmware(&fw, fw_work->name, fw_work->device,
+	_request_firmware(&fw, fw_work->name, fw_work->device, NULL, 0,
 			  fw_work->opt_flags);
 	fw_work->cont(fw, fw_work->context);
 	put_device(fw_work->device); /* taken in request_firmware_nowait() */
@@ -1378,7 +1451,7 @@ static int uncache_firmware(const char *fw_name)
 
 	pr_debug("%s: %s\n", __func__, fw_name);
 
-	if (fw_get_builtin_firmware(&fw, fw_name))
+	if (fw_get_builtin_firmware(&fw, fw_name, NULL, 0))
 		return 0;
 
 	buf = fw_lookup_buf(fw_name);
diff --git a/fs/exec.c b/fs/exec.c
index c4010b8207a1..19894c36aea7 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -836,8 +836,8 @@ int kernel_read(struct file *file, loff_t offset,
 
 EXPORT_SYMBOL(kernel_read);
 
-int kernel_read_file(struct file *file, void **buf, loff_t *size,
-		     loff_t max_size, enum kernel_read_file_id id)
+static int _kernel_read_file(struct file *file, void **buf, loff_t *size,
+			     loff_t max_size, enum kernel_read_file_id id)
 {
 	loff_t i_size, pos;
 	ssize_t bytes = 0;
@@ -856,7 +856,8 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 	if (i_size <= 0)
 		return -EINVAL;
 
-	*buf = vmalloc(i_size);
+	if (id != READING_FIRMWARE_INTO_BUF)
+		*buf = vmalloc(i_size);
 	if (!*buf)
 		return -ENOMEM;
 
@@ -885,11 +886,19 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 
 out:
 	if (ret < 0) {
-		vfree(*buf);
-		*buf = NULL;
+		if (id != READING_FIRMWARE_INTO_BUF) {
+			vfree(*buf);
+			*buf = NULL;
+		}
 	}
 	return ret;
 }
+
+int kernel_read_file(struct file *file, void **buf, loff_t *size,
+		     loff_t max_size, enum kernel_read_file_id id)
+{
+	return _kernel_read_file(file, buf, size, max_size, id);
+}
 EXPORT_SYMBOL_GPL(kernel_read_file);
 
 int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
@@ -905,7 +914,7 @@ int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 
-	ret = kernel_read_file(file, buf, size, max_size, id);
+	ret = _kernel_read_file(file, buf, size, max_size, id);
 	fput(file);
 	return ret;
 }
diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index 5c41c5e75b5c..bdc24ee92823 100644
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -47,6 +47,8 @@ int request_firmware_nowait(
 	void (*cont)(const struct firmware *fw, void *context));
 int request_firmware_direct(const struct firmware **fw, const char *name,
 			    struct device *device);
+int request_firmware_into_buf(const struct firmware **firmware_p,
+	const char *name, struct device *device, void *buf, size_t size);
 
 void release_firmware(const struct firmware *fw);
 #else
@@ -75,5 +77,11 @@ static inline int request_firmware_direct(const struct firmware **fw,
 	return -EINVAL;
 }
 
+static inline int request_firmware_into_buf(const struct firmware **firmware_p,
+	const char *name, struct device *device, void *buf, size_t size);
+{
+	return -EINVAL;
+}
+
 #endif
 #endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 14a97194b34b..4fb8596b3dd4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2582,6 +2582,7 @@ extern int do_pipe_flags(int *, int);
 
 enum kernel_read_file_id {
 	READING_FIRMWARE = 1,
+	READING_FIRMWARE_INTO_BUF,
 	READING_MODULE,
 	READING_KEXEC_IMAGE,
 	READING_KEXEC_INITRAMFS,
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 60d011aaec38..b922d6ca2fb0 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -272,7 +272,8 @@ static ssize_t ima_read_policy(char *path)
 	datap = path;
 	strsep(&datap, "\n");
 
-	rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
+	rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY,
+					NULL);
 	if (rc < 0) {
 		pr_err("Unable to open file: %s (%d)", path, rc);
 		return rc;
-- 
2.8.0.rc4

Re: [RFC/PATCHv3 v3 3/3] firmware: Support loading into a pre-allocated buffer

[Mimi Zohar]

Hi Stephen,

On Tue, 2016-05-10 at 15:26 -0700, Stephen Boyd wrote:

> -static int fw_get_filesystem_firmware(struct device *device,
> -				       struct firmware_buf *buf)
> +static int
> +fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
>  {
>  	loff_t size;
>  	int i, len;
>  	int rc = -ENOENT;
>  	char *path;
> +	enum kernel_read_file_id id = READING_FIRMWARE;
> +	size_t msize = INT_MAX;
> +
> +	/* Already populated data member means we're loading into a buffer */
> +	if (buf->data) {
> +		id = READING_FIRMWARE_INTO_BUF;

In both cases we're reading the firmware into a buffer.  In this case,
it is pre-allocated.  Other than it being pre-allocated, is there
anything special about this buffer?  There has to be a more appropriate
string identifier.

> +		msize = buf->allocated_size;
> +	}
> 
>  	path = __getname();
>  	if (!path)

> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -836,8 +836,8 @@ int kernel_read(struct file *file, loff_t offset,
> 
>  EXPORT_SYMBOL(kernel_read);
> 
> -int kernel_read_file(struct file *file, void **buf, loff_t *size,
> -		     loff_t max_size, enum kernel_read_file_id id)
> +static int _kernel_read_file(struct file *file, void **buf, loff_t *size,
> +			     loff_t max_size, enum kernel_read_file_id id)
>  {
>  	loff_t i_size, pos;
>  	ssize_t bytes = 0;
> @@ -856,7 +856,8 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
>  	if (i_size <= 0)
>  		return -EINVAL;
> 
> -	*buf = vmalloc(i_size);
> +	if (id != READING_FIRMWARE_INTO_BUF)
> +		*buf = vmalloc(i_size);
>  	if (!*buf)
>  		return -ENOMEM;
> 
> @@ -885,11 +886,19 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
> 
>  out:
>  	if (ret < 0) {
> -		vfree(*buf);
> -		*buf = NULL;
> +		if (id != READING_FIRMWARE_INTO_BUF) {
> +			vfree(*buf);
> +			*buf = NULL;
> +		}
>  	}
>  	return ret;
>  }
> +
> +int kernel_read_file(struct file *file, void **buf, loff_t *size,
> +		     loff_t max_size, enum kernel_read_file_id id)
> +{
> +	return _kernel_read_file(file, buf, size, max_size, id);
> +}
>  EXPORT_SYMBOL_GPL(kernel_read_file);

This seems to be exactly the same as the original version.

> 
>  int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
> @@ -905,7 +914,7 @@ int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
>  	if (IS_ERR(file))
>  		return PTR_ERR(file);
> 
> -	ret = kernel_read_file(file, buf, size, max_size, id);
> +	ret = _kernel_read_file(file, buf, size, max_size, id);
>  	fput(file);
>  	return ret;
>  }
> diff --git a/include/linux/firmware.h b/include/linux/firmware.h
> index 5c41c5e75b5c..bdc24ee92823 100644
> --- a/include/linux/firmware.h
> +++ b/include/linux/firmware.h
> @@ -47,6 +47,8 @@ int request_firmware_nowait(
>  	void (*cont)(const struct firmware *fw, void *context));
>  int request_firmware_direct(const struct firmware **fw, const char *name,
>  			    struct device *device);
> +int request_firmware_into_buf(const struct firmware **firmware_p,
> +	const char *name, struct device *device, void *buf, size_t size);
> 
>  void release_firmware(const struct firmware *fw);
>  #else
> @@ -75,5 +77,11 @@ static inline int request_firmware_direct(const struct firmware **fw,
>  	return -EINVAL;
>  }
> 
> +static inline int request_firmware_into_buf(const struct firmware **firmware_p,
> +	const char *name, struct device *device, void *buf, size_t size);
> +{
> +	return -EINVAL;
> +}
> +
>  #endif
>  #endif
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 14a97194b34b..4fb8596b3dd4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2582,6 +2582,7 @@ extern int do_pipe_flags(int *, int);
> 
>  enum kernel_read_file_id {
>  	READING_FIRMWARE = 1,
> +	READING_FIRMWARE_INTO_BUF,
>  	READING_MODULE,
>  	READING_KEXEC_IMAGE,
>  	READING_KEXEC_INITRAMFS,

Commit "1284ab5 fs: define a string representation of the
kernel_read_file_id enumeration", which is queued to be upstreamed,
changes this a bit.

> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
> index 60d011aaec38..b922d6ca2fb0 100644
> --- a/security/integrity/ima/ima_fs.c
> +++ b/security/integrity/ima/ima_fs.c
> @@ -272,7 +272,8 @@ static ssize_t ima_read_policy(char *path)
>  	datap = path;
>  	strsep(&datap, "\n");
> 
> -	rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
> +	rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY,
> +					NULL);

It doesn't look like kernel_read_file_from_path() changed.

Mimi

>  	if (rc < 0) {
>  		pr_err("Unable to open file: %s (%d)", path, rc);
>  		return rc;

Re: [RFC/PATCHv3 v3 3/3] firmware: Support loading into a pre-allocated buffer

[Mimi Zohar]

On Wed, 2016-05-11 at 13:22 -0700, Stephen Boyd wrote:
> Quoting Mimi Zohar (2016-05-11 05:41:52)
> > Hi Stephen,
> > 
> > On Tue, 2016-05-10 at 15:26 -0700, Stephen Boyd wrote:
> > 
> > > -static int fw_get_filesystem_firmware(struct device *device,
> > > -                                    struct firmware_buf *buf)
> > > +static int
> > > +fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
> > >  {
> > >       loff_t size;
> > >       int i, len;
> > >       int rc = -ENOENT;
> > >       char *path;
> > > +     enum kernel_read_file_id id = READING_FIRMWARE;
> > > +     size_t msize = INT_MAX;
> > > +
> > > +     /* Already populated data member means we're loading into a buffer */
> > > +     if (buf->data) {
> > > +             id = READING_FIRMWARE_INTO_BUF;
> > 
> > In both cases we're reading the firmware into a buffer.  In this case,
> > it is pre-allocated.  Other than it being pre-allocated, is there
> > anything special about this buffer? 
> 
> No. I'm not sure what you're asking/implying.
> 
> > There has to be a more appropriate
> > string identifier.
> 
> Ok. Any suggestions? The point of the new id is so that we know if we
> need to allocate the buffer or not in kernel_read_file().

If you're still using DMA, then perhaps "READING_FIRMWARE_DMA".   If the
only difference is that the buffer is pre-allocated, then maybe
"READING_FIRMWARE_PREALLOC_BUFFER". 

>  Alternatively
> we could indicate that by a NULL *buf pointer, but it seems that half
> the time that's not initialized to NULL so it didn't seem safe to rely
> on that fact or update the callsites appropriately.

Assuming that the pre-allocated buffer is smaller than the firmware
size, then a new name definitely needs to be specified, so that the
firmware signature can be verified on the security_kernel_read_file()
hook, as opposed to the security_kernel_post_read_file() hook.  The
patch would look something like:

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 68b26c3..c799459 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -359,6 +359,10 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 #endif
                return 0;       /* We rely on module signature checking */
        }
+
+       if (file && read_id == READING_FIRMWARE_INTO_BUF)
+               return process_measurement(file, NULL, 0, MAY_READ,
+                                          FIRMWARE_CHECK, 0);
        return 0;
 }

@@ -404,6 +408,9 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
                return 0;
        }

+       if (file && read_id == READING_FIRMWARE_INTO_BUF)
+               return 0;
+
        func = read_idmap[read_id] ?: FILE_CHECK;
        return process_measurement(file, buf, size, MAY_READ, func, 0);
 }

Once we've decided on a more appropriate identifier string, I'll post
the patch.

Mimi