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6b2484e13a
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200627072935.62652-1-grandmaster@al2klimov.de
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
129 lines
4.9 KiB
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129 lines
4.9 KiB
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=========================================
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Dell Remote BIOS Update driver (dell_rbu)
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=========================================
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Purpose
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=======
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Document demonstrating the use of the Dell Remote BIOS Update driver
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for updating BIOS images on Dell servers and desktops.
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Scope
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=====
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This document discusses the functionality of the rbu driver only.
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It does not cover the support needed from applications to enable the BIOS to
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update itself with the image downloaded in to the memory.
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Overview
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========
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This driver works with Dell OpenManage or Dell Update Packages for updating
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the BIOS on Dell servers (starting from servers sold since 1999), desktops
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and notebooks (starting from those sold in 2005).
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Please go to http://support.dell.com register and you can find info on
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OpenManage and Dell Update packages (DUP).
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Libsmbios can also be used to update BIOS on Dell systems go to
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https://linux.dell.com/libsmbios/ for details.
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Dell_RBU driver supports BIOS update using the monolithic image and packetized
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image methods. In case of monolithic the driver allocates a contiguous chunk
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of physical pages having the BIOS image. In case of packetized the app
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using the driver breaks the image in to packets of fixed sizes and the driver
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would place each packet in contiguous physical memory. The driver also
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maintains a link list of packets for reading them back.
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If the dell_rbu driver is unloaded all the allocated memory is freed.
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The rbu driver needs to have an application (as mentioned above) which will
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inform the BIOS to enable the update in the next system reboot.
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The user should not unload the rbu driver after downloading the BIOS image
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or updating.
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The driver load creates the following directories under the /sys file system::
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/sys/class/firmware/dell_rbu/loading
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/sys/class/firmware/dell_rbu/data
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/sys/devices/platform/dell_rbu/image_type
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/sys/devices/platform/dell_rbu/data
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/sys/devices/platform/dell_rbu/packet_size
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The driver supports two types of update mechanism; monolithic and packetized.
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These update mechanism depends upon the BIOS currently running on the system.
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Most of the Dell systems support a monolithic update where the BIOS image is
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copied to a single contiguous block of physical memory.
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In case of packet mechanism the single memory can be broken in smaller chunks
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of contiguous memory and the BIOS image is scattered in these packets.
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By default the driver uses monolithic memory for the update type. This can be
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changed to packets during the driver load time by specifying the load
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parameter image_type=packet. This can also be changed later as below::
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echo packet > /sys/devices/platform/dell_rbu/image_type
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In packet update mode the packet size has to be given before any packets can
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be downloaded. It is done as below::
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echo XXXX > /sys/devices/platform/dell_rbu/packet_size
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In the packet update mechanism, the user needs to create a new file having
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packets of data arranged back to back. It can be done as follows:
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The user creates packets header, gets the chunk of the BIOS image and
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places it next to the packetheader; now, the packetheader + BIOS image chunk
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added together should match the specified packet_size. This makes one
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packet, the user needs to create more such packets out of the entire BIOS
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image file and then arrange all these packets back to back in to one single
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file.
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This file is then copied to /sys/class/firmware/dell_rbu/data.
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Once this file gets to the driver, the driver extracts packet_size data from
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the file and spreads it across the physical memory in contiguous packet_sized
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space.
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This method makes sure that all the packets get to the driver in a single operation.
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In monolithic update the user simply get the BIOS image (.hdr file) and copies
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to the data file as is without any change to the BIOS image itself.
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Do the steps below to download the BIOS image.
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1) echo 1 > /sys/class/firmware/dell_rbu/loading
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2) cp bios_image.hdr /sys/class/firmware/dell_rbu/data
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3) echo 0 > /sys/class/firmware/dell_rbu/loading
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The /sys/class/firmware/dell_rbu/ entries will remain till the following is
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done.
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::
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echo -1 > /sys/class/firmware/dell_rbu/loading
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Until this step is completed the driver cannot be unloaded.
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Also echoing either mono, packet or init in to image_type will free up the
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memory allocated by the driver.
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If a user by accident executes steps 1 and 3 above without executing step 2;
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it will make the /sys/class/firmware/dell_rbu/ entries disappear.
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The entries can be recreated by doing the following::
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echo init > /sys/devices/platform/dell_rbu/image_type
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.. note:: echoing init in image_type does not change its original value.
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Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to
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read back the image downloaded.
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.. note::
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After updating the BIOS image a user mode application needs to execute
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code which sends the BIOS update request to the BIOS. So on the next reboot
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the BIOS knows about the new image downloaded and it updates itself.
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Also don't unload the rbu driver if the image has to be updated.
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