Merge remote-tracking branch 'raja/limit_bdev_writes' into arraybolt3/trixie

Author: ArrayBolt3

README.md

@@ -248,6 +248,9 @@ Kernel space:
 - Optional - On compatible AMD CPUs enable Secure Memory Encryption (SME) to protect against
   cold boot attacks and Secure Encrypted Virtualization (SEV) for further guest memory isolation.
 
+- Prevent runaway privileged processes from writing to block devices that are mounted by
+  filesystems to protect against filesystem corruption and kernel crashes.
+
 Direct memory access:
 
 - Enable strict IOMMU translation to protect against some DMA attacks via the use

etc/default/grub.d/40_kernel_hardening.cfg#security-misc-shared

@@ -259,6 +259,18 @@ GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX erst_disable"
 #GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX mem_encrypt=on"
 #GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX kvm_amd.sev=1"
 
+## Prevent processes from writing to block devices that are mounted by filesystems.
+## Enhances system stability and security by protecting against runaway privileged processes.
+## Allowing processes to write to the buffer cache can cause filesystem corruption and kernel crashes.
+## Does not prevent data modifications using direct SCSI commands or lower-level storage stack access.
+## May lead to breakages in certain limited scenarios.
+##
+## https://github.com/torvalds/linux/commit/ed5cc702d311c14b653323d76062b0294effa66e
+## https://lore.kernel.org/lkml/20240105-vfs-super-4092d802972c@brauner/
+## https://github.com/a13xp0p0v/kernel-hardening-checker/issues/186
+##
+GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX bdev_allow_write_mounted=0"
+
 ## 2. Direct Memory Access:
 ##
 ## https://madaidans-insecurities.github.io/guides/linux-hardening.html#dma-attacks