linux-kernel - Re: [PATCH RFC] brcmfmac: sanitize DMI strings v2

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Date:   Mon, 13 May 2019 11:21:49 +0200
From:   Arend Van Spriel <arend.vanspriel@...adcom.com>
To:     Hans de Goede <hdegoede@...hat.com>,
        Victor Bravo <1905@...blk.com>,
        Kalle Valo <kvalo@...eaurora.org>
Cc:     Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, linux-kernel@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: Re: [PATCH RFC] brcmfmac: sanitize DMI strings v2

On 5/7/2019 5:38 PM, Hans de Goede wrote:
> Hi,
> 
> On 06-05-19 21:30, Arend Van Spriel wrote:
>> + Luis (for real this time)
>>
>> On 5/6/2019 6:05 PM, Hans de Goede wrote:
>>> Hi,
>>>
>>> On 06-05-19 17:24, Victor Bravo wrote:
>>>> On Mon, May 06, 2019 at 03:26:28PM +0300, Kalle Valo wrote:
>>>>> Hans de Goede <hdegoede@...hat.com> writes:
>>>>>
>>>>>> If we're going to do some filtering, then I suggest we play it 
>>>>>> safe and also
>>>>>> disallow other chars which may be used as a separator somewhere, 
>>>>>> specifically
>>>>>> ':' and ','.
>>>>>>
>>>>>> Currently upstream linux-firmware has these files which rely on 
>>>>>> the DMI
>>>>>> matching:
>>>>>>
>>>>>> brcmfmac4330-sdio.Prowise-PT301.txt
>>>>>> brcmfmac43430-sdio.Hampoo-D2D3_Vi8A1.txt
>>>>>> brcmfmac43430a0-sdio.ONDA-V80 PLUS.txt
>>>>>>
>>>>>> The others are either part of the DMI override table for devices 
>>>>>> with unsuitable
>>>>>> DMI strings like "Default String"; or are device-tree based.
>>>>>>
>>>>>> So as long as we don't break those 3 (or break the ONDA one but 
>>>>>> get a symlink
>>>>>> in place) we can sanitize a bit more then just non-printable and '/'.
>>>>>>
>>>>>> Kalle, Arend, what is your opinion on this?
>>>>>>
>>>>>> Note I do not expect the ONDA V80 Plus to have a lot of Linux users,
>>>>>> but it definitely has some.
>>>>>
>>>>> To me having spaces in filenames is a bad idea, but on the other 
>>>>> hand we
>>>>> do have the "don't break existing setups" rule, so it's not so 
>>>>> simple. I
>>>>> vote for not allowing spaces, I think that's the best for the long 
>>>>> run,
>>>>> but don't know what Arend thinks.
>>
>> Hi,
>>
>> Had a day off today so I did see some of the discussion, but was not 
>> able to chime in until now.
>>
>> To be honest I always disliked spaces in filenames, but that does not 
>> necessarily make it a bad idea. What I would like to know is why 
>> built-in firmware can not deal with spaces in the firmware file names. 
>> I think Hans mentioned it in the thread and it crossed my mind as well 
>> last night. From driver perspective, being brcmfmac or any other for 
>> that matter, there is only one API to request firmware and in my 
>> opinion it should behave the same no matter where the firmware is 
>> coming from. I would prefer to fix that for built-in firmware, but we 
>> need to understand where this limitation is coming from. Hopefully 
>> Luis can elaborate on that.
> 
> Ok.

The issue is probably that make does simply split the EXTRA_FIRMWARE 
setting at each space character. I tried to use single quote so
"'brcmfmac43340-sdio.ASUSTeK COMPUTER INC.-T100HAN.txt' 
brcmfmac43340-sdio.bin". No luck. So all I could think of is patch below 
which require the user to enter a special sequence, ie. _-_ where space 
should be.

"brcmfmac43340-sdio.ASUSTeK_-_COMPUTER_-_INC.-T100HAN.txt 
brcmfmac43340-sdio.bin"

It works but I had to drop the dependency so it's all a bit hacky.

Regards,
Arend

diff --git a/firmware/Makefile b/firmware/Makefile
index 37e5ae387400..a536e5d12d5f 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -5,10 +5,11 @@
  fwdir := $(subst $(quote),,$(CONFIG_EXTRA_FIRMWARE_DIR))
  fwdir := $(addprefix $(srctree)/,$(filter-out /%,$(fwdir)))$(filter 
/%,$(fwdir))

+fw_space_escape := _-_
  obj-y  := $(addsuffix .gen.o, $(subst $(quote),,$(CONFIG_EXTRA_FIRMWARE)))

-FWNAME    = $(patsubst $(obj)/%.gen.S,%,$@)
-FWSTR     = $(subst /,_,$(subst .,_,$(subst -,_,$(FWNAME))))
+FWNAME    = $(subst $(fw_space_escape),$(space),$(patsubst 
$(obj)/%.gen.S,%,$@))
+FWSTR     = $(subst $(space),_,$(subst /,_,$(subst .,_,$(subst 
-,_,$(FWNAME)))))
  ASM_WORD  = $(if $(CONFIG_64BIT),.quad,.long)
  ASM_ALIGN = $(if $(CONFIG_64BIT),3,2)
  PROGBITS  = $(if $(CONFIG_ARM),%,@)progbits
@@ -34,7 +35,7 @@ $(obj)/%.gen.S: FORCE
  	$(call filechk,fwbin)

  # The .o files depend on the binaries directly; the .S files don't.
-$(addprefix $(obj)/, $(obj-y)): $(obj)/%.gen.o: $(fwdir)/%
+$(addprefix $(obj)/, $(obj-y)): $(obj)/%.gen.o:

  targets := $(patsubst $(obj)/%,%, \
                                  $(shell find $(obj) -name \*.gen.S 
2>/dev/null))