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Date: Wed, 5 Jun 2013 17:35:26 +0800
From: Ming Lei <ming.lei@...onical.com>
To: Takashi Iwai <tiwai@...e.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 3/3] firmware loader: allow distribution to choose default
search paths
On Wed, Jun 5, 2013 at 3:10 PM, Takashi Iwai <tiwai@...e.de> wrote:
> At Wed, 5 Jun 2013 13:42:49 +0800,
> Ming Lei wrote:
>>
>> For some distributions(e.g. android), firmware images aren't put
>> under kernel built-in search paths, so introduce one Kconfig
>> option to allow distributions or users to choose its specific default
>> search paths, which are always tried before searching from kernel
>> built-in paths in direct loading.
>>
>> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>> Cc: Takashi Iwai <tiwai@...e.de>
>> Signed-off-by: Ming Lei <ming.lei@...onical.com>
>> ---
>> drivers/base/Kconfig | 12 +++++++
>> drivers/base/firmware_class.c | 76 ++++++++++++++++++++++++++++++++++++-----
>> 2 files changed, 80 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
>> index 07abd9d..5b0c909 100644
>> --- a/drivers/base/Kconfig
>> +++ b/drivers/base/Kconfig
>> @@ -156,6 +156,18 @@ config FW_LOADER_USER_HELPER
>> no longer required unless you have a special firmware file that
>> resides in a non-standard path.
>>
>> +config FW_CUSTOMIZED_PATH
>> + string "default firmware search paths for direct loading"
>> + help
>> + On some distribution(e.g. android), firmware images aren't
>> + put under kernel built-in search paths, so provide this option
>> + for distributions to choose a distribution specific firmware
>> + search path. The option allows to choose more than one path,
>> + and paths are seperated with semicolon(e.g. on android, the
>> + option might look as "/etc/firmware;/vendor/firmware").
>> +
>> + If you are unsure about this, don't choose here.
>> +
>> config DEBUG_DRIVER
>> bool "Driver Core verbose debug messages"
>> depends on DEBUG_KERNEL
>> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
>> index c743409..50b5913 100644
>> --- a/drivers/base/firmware_class.c
>> +++ b/drivers/base/firmware_class.c
>> @@ -267,6 +267,9 @@ static void fw_free_buf(struct firmware_buf *buf)
>> static char fw_path_para[256];
>> static const char * const fw_path[] = {
>> fw_path_para,
>> +#ifdef CONFIG_FW_CUSTOMIZED_PATH
>> + CONFIG_FW_CUSTOMIZED_PATH,
>> +#endif
>> "/lib/firmware/updates/" UTS_RELEASE,
>> "/lib/firmware/updates",
>> "/lib/firmware/" UTS_RELEASE,
>> @@ -314,6 +317,59 @@ static bool fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf
>> return true;
>> }
>>
>> +static bool fw_get_file_firmware(const char *path,
>> + struct firmware_buf *buf)
>> +{
>> + struct file *file;
>> + bool success;
>> +
>> + file = filp_open(path, O_RDONLY, 0);
>> + if (IS_ERR(file))
>> + return false;
>> + success = fw_read_file_contents(file, buf);
>> + fput(file);
>> +
>> + return success;
>> +}
>> +
>> +#ifdef CONFIG_FW_CUSTOMIZED_PATH
>> +/* The path in @paths is seperated by ';' */
>> +static bool fw_get_fw_file_from_paths(const char *paths, char *path,
>> + struct firmware_buf *buf)
>> +{
>> + int len, start, end;
>> + char *pos;
>> +
>> + end = -1;
>> + do {
>> + start = end + 1;
>> + pos = strchr(&paths[start], ';');
>> + if (pos) {
>> + end = (int)(pos - paths);
>> + len = end - start;
>> + } else {
>> + len = strlen(&paths[start]);
>> + }
>> +
>> + if (PATH_MAX < len + strlen(buf->fw_id))
>> + continue;
>> + strncpy(path, &paths[start], len);
>> + snprintf(&path[len], PATH_MAX - len, "/%s", buf->fw_id);
>> +
>> + if (fw_get_file_firmware(path, buf))
>> + return true;
>> + } while (pos && end < strlen(paths) - 1);
>> +
>> + return false;
>> +}
>> +#else
>> +static bool fw_get_fw_file_from_paths(const char *paths, char *path,
>> + struct firmware_buf *buf)
>> +{
>> + return false;
>> +}
>> +#endif
>> +
>> static bool fw_get_filesystem_firmware(struct device *device,
>> struct firmware_buf *buf)
>> {
>> @@ -322,19 +378,23 @@ static bool fw_get_filesystem_firmware(struct device *device,
>> char *path = __getname();
>>
>> for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
>> - struct file *file;
>>
>> /* skip the unset customized path */
>> if (!fw_path[i][0])
>> continue;
>>
>> - snprintf(path, PATH_MAX, "%s/%s", fw_path[i], buf->fw_id);
>> -
>> - file = filp_open(path, O_RDONLY, 0);
>> - if (IS_ERR(file))
>> - continue;
>> - success = fw_read_file_contents(file, buf);
>> - fput(file);
>> + /*
>> + * If CONFIG_FW_CUSTOMIZED_PATH is set, search from
>> + * these paths first
>> + */
>> + if (i == 1 && ARRAY_SIZE(fw_path) > 5) {
>> + success = fw_get_fw_file_from_paths(fw_path[1],
>> + path, buf);
>> + } else {
>> + snprintf(path, PATH_MAX, "%s/%s", fw_path[i],
>> + buf->fw_id);
>> + success = fw_get_file_firmware(path, buf);
>
> Shouldn't fw_get_fw_file_from_paths() be applied unconditionally?
> It'll be benefit for the customized path passed via module option,
> too. The only drawback is a slight code growth, but the code can be
> reduced a bit with strcspn() or such.
You mean that both the 1st two items should be covered by
fw_get_fw_file_from_paths()? If so, the function may become
a bit ugly since two strings are required to pass in, and we can't
merge one runtime string and one ro string created in compiling.
Looks we can let fw_get_fw_file_from_paths() handle all
predefined paths(CONFIG_FW_CUSTOMIZED_PATH and
kernel built-in paths), then fw_get_filesystem_firmware()
may become simple, just check fw_path_para and all
other paths by fw_get_fw_file_from_paths(). How about the
idea?
>
> BTW, I now wonder what happens if you pass a relative path.
> Did you already test it?
I tested absolute paths, and not test relative paths. Do you mean
it may cause security problem? If so, we can check and ignore them,
but it should be OK since the paths are provided by kernel builder.
>From view of function, I don't think there are much difference with
absolute paths.
Thanks,
--
Ming Lei
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