diff options
| author | Daniel Micay <danielmicay@gmail.com> | 2022-10-29 03:53:57 -0400 |
|---|---|---|
| committer | Daniel Micay <danielmicay@gmail.com> | 2022-10-29 03:53:57 -0400 |
| commit | 45ff49c34d6e2ec7fa77af05c158548f86ee6b49 (patch) | |
| tree | e4bf51ceb14dbceb969fb60f40c9ee6ab845c8a2 /static/features.html | |
| parent | 53c6cdf17ade82686e9be24d79d9f76f5c0611ec (diff) | |
document minor restored kernel hardening features
Diffstat (limited to 'static/features.html')
| -rw-r--r-- | static/features.html | 59 |
1 files changed, 34 insertions, 25 deletions
diff --git a/static/features.html b/static/features.html index 1ce4646d..3ae248a3 100644 --- a/static/features.html +++ b/static/features.html @@ -310,31 +310,40 @@ <li> Hardened kernel <ul> - <li>4-level page tables are enabled on arm64 to provide a much larger - address space (48-bit instead of 39-bit) with significantly higher - entropy Address Space Layout Randomization (33-bit instead of - 24-bit).</li> - <li>Random canaries with a leading zero are added to the kernel heap - (slub) to block C string overflows, absorb small overflows and detect - linear overflows or other heap corruption when the canary value is - checked (on free, copies to/from userspace, etc.).</li> - <li>Memory is wiped (zeroed) as soon as it's released in both the - low-level kernel page allocator and higher level kernel heap allocator - (slub). This substantially reduces the lifetime of sensitive data in - memory, mitigates use-after-free vulnerabilities and makes most - uninitialized data usage vulnerabilities harmless. Without our - changes, memory that's released retains data indefinitely until the - memory is handed out for other uses and gets partially or fully - overwritten by new data.</li> - <li>Kernel stack allocations are zeroed to make most uninitialized - data usage vulnerabilities harmless.</li> - <li>Assorted attack surface reduction through disabling features or - setting up infrastructure to dynamically enable/disable them only as - needed (perf, ptrace).</li> - <li>Assorted upstream hardening features are enabled, including many - which we played a part in developing and landing upstream as part of - our linux-hardened project (which we intend to revive as a more active - project again).</li> + <li>4-level page tables are enabled on arm64 to provide a much + larger address space (48-bit instead of 39-bit) with + significantly higher entropy Address Space Layout + Randomization (33-bit instead of 24-bit).</li> + <li>Random canaries with a leading zero are added to the + kernel heap (slub) to block C string overflows, absorb small + overflows and detect linear overflows or other heap corruption + when the canary value is checked (on free, copies to/from + userspace, etc.).</li> + <li>Memory is wiped (zeroed) as soon as it's released in both + the low-level kernel page allocator and higher level kernel + heap allocator (slub). This substantially reduces the lifetime + of sensitive data in memory, mitigates use-after-free + vulnerabilities and makes most uninitialized data usage + vulnerabilities harmless. Without our changes, memory that's + released retains data indefinitely until the memory is handed + out for other uses and gets partially or fully overwritten by + new data.</li> + <li>Kernel stack allocations are zeroed to make most + uninitialized data usage vulnerabilities harmless.</li> + <li>Assorted attack surface reduction through disabling + features or setting up infrastructure to dynamically + enable/disable them only as needed (perf, ptrace).</li> + <li>Assorted upstream hardening features are enabled, + including many which we played a part in developing and + landing upstream as part of our linux-hardened project (which + we intend to revive as a more active project again).</li> + <li>Forced kernel module signing with per-build keys and + lockdown mode set to forced confidentiality mode help to + enforce a low-level boundary between the kernel and userspace + even if mistakes are made in SELinux policy or there's a deep + userspace compromise.</li> + <li>Additional consistency / integrity checks are enabled for + frequently targeted kernel data structures.</li> </ul> </li> <li>Android Runtime Just-In-Time (JIT) compilation/profiling is fully |