diff options
| author | Pawan Gupta <pawan.kumar.gupta@linux.intel.com> | 2024-06-21 21:17:21 -0700 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2025-05-09 13:22:04 -0700 |
| commit | 8754e67ad4ac692c67ff1f99c0d07156f04ae40c (patch) | |
| tree | e5b008534b11b3cdf6ddb72cbf1310ee33f85889 /arch/x86/net/bpf_jit_comp.c | |
| parent | 159013a7ca18c271ff64192deb62a689b622d860 (diff) | |
x86/its: Add support for ITS-safe indirect thunk
Due to ITS, indirect branches in the lower half of a cacheline may be
vulnerable to branch target injection attack.
Introduce ITS-safe thunks to patch indirect branches in the lower half of
cacheline with the thunk. Also thunk any eBPF generated indirect branches
in emit_indirect_jump().
Below category of indirect branches are not mitigated:
- Indirect branches in the .init section are not mitigated because they are
discarded after boot.
- Indirect branches that are explicitly marked retpoline-safe.
Note that retpoline also mitigates the indirect branches against ITS. This
is because the retpoline sequence fills an RSB entry before RET, and it
does not suffer from RSB-underflow part of the ITS.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 9e5fe2ba858f..01e8119db5db 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -661,7 +661,10 @@ static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip) { u8 *prog = *pprog; - if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) { + if (cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS)) { + OPTIMIZER_HIDE_VAR(reg); + emit_jump(&prog, &__x86_indirect_its_thunk_array[reg], ip); + } else if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) { EMIT_LFENCE(); EMIT2(0xFF, 0xE0 + reg); } else if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) { |