Documentation: Indent code blocks instead of using ```
Both versions are correct, but especially for one liners indenting them with four spaces instead of using ``` blocks helps readability of the source file. Change-Id: Ie2543c8c4cccefd74e966f784e651ed7dc3a9252 Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> Reviewed-on: https://review.coreboot.org/c/coreboot/+/38720 Reviewed-by: Peter Lemenkov <lemenkov@gmail.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Paul Menzel
Patrick Georgi
parent
f9bb675690
commit
cedd4525f2
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@ -63,55 +63,51 @@ directly. Therefore you need to modify the bootable CD image you just
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downloaded.
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Extract an El Torito image:
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```
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geteltorito -o ./bios.img g1uj41us.iso
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```
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geteltorito -o ./bios.img g1uj41us.iso
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Mount the partition in that image:
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```
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sudo mount -t vfat ./bios.img /mnt -o loop,offset=16384
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```
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sudo mount -t vfat ./bios.img /mnt -o loop,offset=16384
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List files, find the `AUTOEXEC.BAT` file and the `FLASH` directory:
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```
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ls /mnt
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ls /mnt/FLASH
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```
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ls /mnt
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ls /mnt/FLASH
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Inside the `FLASH` directory, there should be a directory called
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`G1ET93WW` or similar (exact name depends on your ThinkPad model and
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BIOS version). See what's inside:
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```
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ls /mnt/FLASH/G1ET93WW
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```
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ls /mnt/FLASH/G1ET93WW
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There must be a file with `.FL1` extension called `$01D2000.FL1` or
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something similar.
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Now open the `AUTOEXEC.BAT` file:
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```
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sudo vim /mnt/AUTOEXEC.BAT
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```
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sudo vim /mnt/AUTOEXEC.BAT
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You will see a list of commands:
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```
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@ECHO OFF
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PROMPT $p$g
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cd c:\flash
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command.com
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```
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@ECHO OFF
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PROMPT $p$g
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cd c:\flash
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command.com
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Replace the last line (`command.com`) with this (change path to the
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`.FL1` file according to yours):
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```
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dosflash.exe /sd /file G1ET93WW\$01D2000.FL1
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```
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dosflash.exe /sd /file G1ET93WW\$01D2000.FL1
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Save the file, then unmount the partition:
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```
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sudo unmount /mnt
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```
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sudo unmount /mnt
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Write this image to a USB drive (replace `/dev/sdX` with your USB drive
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device name):
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```
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sudo dd if=./bios.img of=/dev/sdX bs=1M
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```
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sudo dd if=./bios.img of=/dev/sdX bs=1M
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Now reboot and press F1 to enter BIOS settings. Open the **Startup** tab
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and set the startup mode to **Legacy** (or **Both**/**Legacy First**):
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@ -167,69 +163,66 @@ To be able to flash, we need SMM_BWP=0, BIOSWE=1, BLE=0, FLOCKDN=0 or
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SPI protected ranges (PRx) to have a WP bit set to 0.
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Let's see what we have. Examine HSFS register:
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```
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sudo chipsec_main -m chipsec.modules.common.spi_lock
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```
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sudo chipsec_main -m chipsec.modules.common.spi_lock
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You should see that FLOCKDN=1:
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```
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[x][ =======================================================================
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[x][ Module: SPI Flash Controller Configuration Locks
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[x][ =======================================================================
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[*] HSFS = 0xE009 << Hardware Sequencing Flash Status Register (SPIBAR + 0x4)
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[00] FDONE = 1 << Flash Cycle Done
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[01] FCERR = 0 << Flash Cycle Error
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[02] AEL = 0 << Access Error Log
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[03] BERASE = 1 << Block/Sector Erase Size
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[05] SCIP = 0 << SPI cycle in progress
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[13] FDOPSS = 1 << Flash Descriptor Override Pin-Strap Status
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[14] FDV = 1 << Flash Descriptor Valid
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[15] FLOCKDN = 1 << Flash Configuration Lock-Down
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```
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[x][ =======================================================================
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[x][ Module: SPI Flash Controller Configuration Locks
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[x][ =======================================================================
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[*] HSFS = 0xE009 << Hardware Sequencing Flash Status Register (SPIBAR + 0x4)
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[00] FDONE = 1 << Flash Cycle Done
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[01] FCERR = 0 << Flash Cycle Error
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[02] AEL = 0 << Access Error Log
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[03] BERASE = 1 << Block/Sector Erase Size
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[05] SCIP = 0 << SPI cycle in progress
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[13] FDOPSS = 1 << Flash Descriptor Override Pin-Strap Status
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[14] FDV = 1 << Flash Descriptor Valid
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[15] FLOCKDN = 1 << Flash Configuration Lock-Down
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Then check BIOS_CNTL and PR0-PR4:
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```
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sudo chipsec_main -m common.bios_wp
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```
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sudo chipsec_main -m common.bios_wp
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Good news: on old BIOS versions, SMM_BWP=0 and BLE=0.
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Bad news: there are 4 write protected SPI ranges:
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```
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[x][ =======================================================================
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[x][ Module: BIOS Region Write Protection
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[x][ =======================================================================
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[*] BC = 0x 8 << BIOS Control (b:d.f 00:31.0 + 0xDC)
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[00] BIOSWE = 0 << BIOS Write Enable
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[01] BLE = 0 << BIOS Lock Enable
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[02] SRC = 2 << SPI Read Configuration
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[04] TSS = 0 << Top Swap Status
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[05] SMM_BWP = 0 << SMM BIOS Write Protection
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[-] BIOS region write protection is disabled!
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[x][ =======================================================================
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[x][ Module: BIOS Region Write Protection
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[x][ =======================================================================
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[*] BC = 0x 8 << BIOS Control (b:d.f 00:31.0 + 0xDC)
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[00] BIOSWE = 0 << BIOS Write Enable
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[01] BLE = 0 << BIOS Lock Enable
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[02] SRC = 2 << SPI Read Configuration
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[04] TSS = 0 << Top Swap Status
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[05] SMM_BWP = 0 << SMM BIOS Write Protection
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[-] BIOS region write protection is disabled!
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[*] BIOS Region: Base = 0x00500000, Limit = 0x00BFFFFF
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SPI Protected Ranges
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------------------------------------------------------------
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PRx (offset) | Value | Base | Limit | WP? | RP?
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------------------------------------------------------------
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PR0 (74) | 00000000 | 00000000 | 00000000 | 0 | 0
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PR1 (78) | 8BFF0B40 | 00B40000 | 00BFFFFF | 1 | 0
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PR2 (7C) | 8B100B10 | 00B10000 | 00B10FFF | 1 | 0
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PR3 (80) | 8ADE0AD0 | 00AD0000 | 00ADEFFF | 1 | 0
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PR4 (84) | 8AAF0800 | 00800000 | 00AAFFFF | 1 | 0
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```
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[*] BIOS Region: Base = 0x00500000, Limit = 0x00BFFFFF
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SPI Protected Ranges
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------------------------------------------------------------
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PRx (offset) | Value | Base | Limit | WP? | RP?
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------------------------------------------------------------
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PR0 (74) | 00000000 | 00000000 | 00000000 | 0 | 0
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PR1 (78) | 8BFF0B40 | 00B40000 | 00BFFFFF | 1 | 0
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PR2 (7C) | 8B100B10 | 00B10000 | 00B10FFF | 1 | 0
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PR3 (80) | 8ADE0AD0 | 00AD0000 | 00ADEFFF | 1 | 0
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PR4 (84) | 8AAF0800 | 00800000 | 00AAFFFF | 1 | 0
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Other way to examine SPI configuration registers is to just dump SPIBAR:
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```
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sudo chipsec_util mmio dump SPIBAR
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```
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sudo chipsec_util mmio dump SPIBAR
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You will see SPIBAR address (0xFED1F800) and registers (for example,
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00000004 is HSFS):
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```
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[mmio] MMIO register range [0x00000000FED1F800:0x00000000FED1F800+00000200]:
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+00000000: 0BFF0500
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+00000004: 0004E009
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...
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```
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[mmio] MMIO register range [0x00000000FED1F800:0x00000000FED1F800+00000200]:
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+00000000: 0BFF0500
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+00000004: 0004E009
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...
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As you can see, the only thing we need is to unset WP bit on PR0-PR4.
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But that cannot be done once FLOCKDN is set to 1.
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@ -239,23 +232,23 @@ FLOCKDN may only be cleared by a hardware reset, which includes S3
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state. On S3 resume boot path, the chipset configuration has to be
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restored and it's done by executing so-called S3 Boot Scripts. You can
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dump these scripts by executing:
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```
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sudo chipsec_util uefi s3bootscript
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```
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sudo chipsec_util uefi s3bootscript
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There are many entries. Along them, you can find instructions to write
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to HSFS (remember, we know that SPIBAR is 0xFED1F800):
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```
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Entry at offset 0x2B8F (len = 0x17, header len = 0x0):
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Data:
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02 00 17 02 00 00 00 01 00 00 00 04 f8 d1 fe 00 |
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00 00 00 09 e0 04 00 |
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Decoded:
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Opcode : S3_BOOTSCRIPT_MEM_WRITE (0x0002)
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Width : 0x02 (4 bytes)
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Address: 0xFED1F804
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Count : 0x1
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Values : 0x0004E009
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```
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Entry at offset 0x2B8F (len = 0x17, header len = 0x0):
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Data:
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02 00 17 02 00 00 00 01 00 00 00 04 f8 d1 fe 00 |
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00 00 00 09 e0 04 00 |
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Decoded:
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Opcode : S3_BOOTSCRIPT_MEM_WRITE (0x0002)
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Width : 0x02 (4 bytes)
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Address: 0xFED1F804
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Count : 0x1
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Values : 0x0004E009
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These scripts are stored in memory. The vulnerability is that we can
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overwrite this memory, change these instructions and they will be
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executed on S3 resume. Once we patch that instruction to not set FLOCKDN
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@ -268,14 +261,13 @@ in case something goes wrong, you'll be able to flash it back externally.
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The `me` region is locked, so an attempt to create a full dump will fail.
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But you can back up the `bios`:
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```
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sudo flashrom -p internal -r bios_backup.rom --ifd -i bios
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```
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sudo flashrom -p internal -r bios_backup.rom --ifd -i bios
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If you will ever need to flash it back, use `--ifd -i bios` as well:
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```
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sudo flashrom -p <YOUR_PROGRAMMER> -w bios_backup.rom --ifd -i bios
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```
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sudo flashrom -p <YOUR_PROGRAMMER> -w bios_backup.rom --ifd -i bios
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**Caution:** if you will omit `--ifd -i bios` for flashing, you will
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brick your machine, because your backup has `FF`s in place of `fd` and
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`me` regions. Flash only `bios` region!
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@ -284,83 +276,80 @@ brick your machine, because your backup has `FF`s in place of `fd` and
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The original boot script writes 0xE009 to HSFS. FLOCKDN is 15th bit, so
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let's write 0x6009 instead:
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```
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sudo chipsec_main -m tools.uefi.s3script_modify -a replace_op,mmio_wr,0xFED1F804,0x6009,0x2
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```
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sudo chipsec_main -m tools.uefi.s3script_modify -a replace_op,mmio_wr,0xFED1F804,0x6009,0x2
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You will get a lot of output and in the end you should see something
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like this:
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```
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[*] Modifying S3 boot script entry at address 0x00000000DAF49B8F..
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[mem] 0x00000000DAF49B8F
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[*] Original entry:
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2 0 17 2 0 0 0 1 0 0 0 4 f8 d1 fe 0 |
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0 0 0 9 e0 4 0 |
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[mem] buffer len = 0x17 to PA = 0x00000000DAF49B8F
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2 0 17 2 0 0 0 1 0 0 0 4 f8 d1 fe 0 |
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0 0 0 9 60 0 0 | `
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[mem] 0x00000000DAF49B8F
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[*] Modified entry:
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2 0 17 2 0 0 0 1 0 0 0 4 f8 d1 fe 0 |
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0 0 0 9 60 0 0 | `
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[*] After sleep/resume, check the value of register 0xFED1F804 is 0x6009
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[+] PASSED: The script has been modified. Go to sleep..
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```
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Now go to S3, then resume and check FLOCKDN. It should be 0:
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```
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sudo chipsec_main -m chipsec.modules.common.spi_lock
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```
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```
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...
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[x][ =======================================================================
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[x][ Module: SPI Flash Controller Configuration Locks
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[x][ =======================================================================
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[*] HSFS = 0x6008 << Hardware Sequencing Flash Status Register (SPIBAR + 0x4)
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[00] FDONE = 0 << Flash Cycle Done
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[01] FCERR = 0 << Flash Cycle Error
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[02] AEL = 0 << Access Error Log
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[03] BERASE = 1 << Block/Sector Erase Size
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[05] SCIP = 0 << SPI cycle in progress
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[13] FDOPSS = 1 << Flash Descriptor Override Pin-Strap Status
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[14] FDV = 1 << Flash Descriptor Valid
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[15] FLOCKDN = 0 << Flash Configuration Lock-Down
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[-] SPI Flash Controller configuration is not locked
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[-] FAILED: SPI Flash Controller not locked correctly.
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...
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```
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Remove WP from protected ranges:
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```
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sudo chipsec_util mmio write SPIBAR 0x74 0x4 0xAAF0800
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sudo chipsec_util mmio write SPIBAR 0x78 0x4 0xADE0AD0
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sudo chipsec_util mmio write SPIBAR 0x7C 0x4 0xB100B10
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sudo chipsec_util mmio write SPIBAR 0x80 0x4 0xBFF0B40
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```
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Verify that it worked:
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```
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sudo chipsec_main -m common.bios_wp
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```
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```
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[x][ =======================================================================
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[x][ Module: BIOS Region Write Protection
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[x][ =======================================================================
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[*] BC = 0x 9 << BIOS Control (b:d.f 00:31.0 + 0xDC)
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[00] BIOSWE = 1 << BIOS Write Enable
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[01] BLE = 0 << BIOS Lock Enable
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[02] SRC = 2 << SPI Read Configuration
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[04] TSS = 0 << Top Swap Status
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[05] SMM_BWP = 0 << SMM BIOS Write Protection
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[-] BIOS region write protection is disabled!
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[*] BIOS Region: Base = 0x00500000, Limit = 0x00BFFFFF
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SPI Protected Ranges
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------------------------------------------------------------
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PRx (offset) | Value | Base | Limit | WP? | RP?
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------------------------------------------------------------
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PR0 (74) | 0AAF0800 | 00800000 | 00AAF000 | 0 | 0
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PR1 (78) | 0ADE0AD0 | 00AD0000 | 00ADE000 | 0 | 0
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PR2 (7C) | 0B100B10 | 00B10000 | 00B10000 | 0 | 0
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PR3 (80) | 0BFF0B40 | 00B40000 | 00BFF000 | 0 | 0
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PR4 (84) | 00000000 | 00000000 | 00000000 | 0 | 0
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```
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[*] Modifying S3 boot script entry at address 0x00000000DAF49B8F..
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[mem] 0x00000000DAF49B8F
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[*] Original entry:
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2 0 17 2 0 0 0 1 0 0 0 4 f8 d1 fe 0 |
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0 0 0 9 e0 4 0 |
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[mem] buffer len = 0x17 to PA = 0x00000000DAF49B8F
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2 0 17 2 0 0 0 1 0 0 0 4 f8 d1 fe 0 |
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0 0 0 9 60 0 0 | `
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[mem] 0x00000000DAF49B8F
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[*] Modified entry:
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2 0 17 2 0 0 0 1 0 0 0 4 f8 d1 fe 0 |
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0 0 0 9 60 0 0 | `
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[*] After sleep/resume, check the value of register 0xFED1F804 is 0x6009
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[+] PASSED: The script has been modified. Go to sleep..
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Now go to S3, then resume and check FLOCKDN. It should be 0:
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sudo chipsec_main -m chipsec.modules.common.spi_lock
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...
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[x][ =======================================================================
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[x][ Module: SPI Flash Controller Configuration Locks
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[x][ =======================================================================
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[*] HSFS = 0x6008 << Hardware Sequencing Flash Status Register (SPIBAR + 0x4)
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[00] FDONE = 0 << Flash Cycle Done
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[01] FCERR = 0 << Flash Cycle Error
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[02] AEL = 0 << Access Error Log
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[03] BERASE = 1 << Block/Sector Erase Size
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[05] SCIP = 0 << SPI cycle in progress
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[13] FDOPSS = 1 << Flash Descriptor Override Pin-Strap Status
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[14] FDV = 1 << Flash Descriptor Valid
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[15] FLOCKDN = 0 << Flash Configuration Lock-Down
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[-] SPI Flash Controller configuration is not locked
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[-] FAILED: SPI Flash Controller not locked correctly.
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...
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Remove WP from protected ranges:
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sudo chipsec_util mmio write SPIBAR 0x74 0x4 0xAAF0800
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sudo chipsec_util mmio write SPIBAR 0x78 0x4 0xADE0AD0
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sudo chipsec_util mmio write SPIBAR 0x7C 0x4 0xB100B10
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sudo chipsec_util mmio write SPIBAR 0x80 0x4 0xBFF0B40
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Verify that it worked:
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sudo chipsec_main -m common.bios_wp
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[x][ =======================================================================
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[x][ Module: BIOS Region Write Protection
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[x][ =======================================================================
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[*] BC = 0x 9 << BIOS Control (b:d.f 00:31.0 + 0xDC)
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[00] BIOSWE = 1 << BIOS Write Enable
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[01] BLE = 0 << BIOS Lock Enable
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[02] SRC = 2 << SPI Read Configuration
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[04] TSS = 0 << Top Swap Status
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[05] SMM_BWP = 0 << SMM BIOS Write Protection
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[-] BIOS region write protection is disabled!
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[*] BIOS Region: Base = 0x00500000, Limit = 0x00BFFFFF
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SPI Protected Ranges
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------------------------------------------------------------
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PRx (offset) | Value | Base | Limit | WP? | RP?
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------------------------------------------------------------
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PR0 (74) | 0AAF0800 | 00800000 | 00AAF000 | 0 | 0
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PR1 (78) | 0ADE0AD0 | 00AD0000 | 00ADE000 | 0 | 0
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PR2 (7C) | 0B100B10 | 00B10000 | 00B10000 | 0 | 0
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PR3 (80) | 0BFF0B40 | 00B40000 | 00BFF000 | 0 | 0
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PR4 (84) | 00000000 | 00000000 | 00000000 | 0 | 0
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Bingo!
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Reference in New Issue