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Kernel: Add a 'disable_kaslr' kernel command line parameter

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This parameter can be used to disable the KASLR mechanism.
This commit is contained in:
Idan Horowitz 2022-03-25 00:02:52 +02:00 • committed by Linus Groh
parent 54a12d34eb
commit f9c6f37bac
2 changed files with 9 additions and 4 deletions
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2
Base/usr/share/man/man7/boot_parameters.md
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@ -89,6 +89,8 @@ List of options:
* **`vmmouse`** - This parameter expects a binary value of **`on`** or **`off`**. If enabled and
running on a VMWare Hypervisor, the kernel will enable absolute mouse mode.
* **`disable_kaslr`** - If present on the command line, the KASLR security mitigation will be disabled.
## See also
* [`SystemServer`(7)](help://man/7/SystemServer).

7
Kernel/Prekernel/init.cpp
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@ -96,10 +96,13 @@ extern "C" [[noreturn]] void init()
FlatPtr default_kernel_load_base = 0x2000200000;
#endif
// KASLR
FlatPtr kernel_load_base = default_kernel_load_base;
if (__builtin_strstr(kernel_cmdline, "disable_kaslr") == nullptr) {
FlatPtr maximum_offset = (FlatPtr)KERNEL_PD_SIZE - MAX_KERNEL_SIZE - 2 * MiB; // The first 2 MiB are used for mapping the pre-kernel
FlatPtr kernel_load_base = default_kernel_load_base + (generate_secure_seed() % maximum_offset);
kernel_load_base += (generate_secure_seed() % maximum_offset);
kernel_load_base &= ~(2 * MiB - 1);
}
FlatPtr kernel_load_end = 0;
for (size_t i = 0; i < kernel_elf_header.e_phnum; i++) {