| Message ID | 20220402073942.3782529-1-xukuohai@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 042152c27c3bc3e20882f75c289ced32331f4010 |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,v2] bpf, arm64: Sign return address for jited code | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Clearly marked for bpf-next |
| netdev/fixes_present | success | Fixes tag not required for -next series |
| netdev/subject_prefix | success | Link |
| netdev/cover_letter | success | Single patches do not need cover letters |
| netdev/patch_count | success | Link |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/cc_maintainers | success | CCed 14 of 14 maintainers |
| netdev/build_clang | success | Errors and warnings before: 0 this patch: 0 |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/verify_fixes | success | No Fixes tag |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 40 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
| bpf/vmtest-bpf-next-PR | success | PR summary |
Hello: This patch was applied to bpf/bpf-next.git (master) by Daniel Borkmann <daniel@iogearbox.net>: On Sat, 2 Apr 2022 03:39:42 -0400 you wrote: > Sign return address for jited code when the kernel is built with pointer > authentication enabled. > > 1. Sign LR with paciasp instruction before LR is pushed to stack. Since > paciasp acts like landing pads for function entry, no need to insert > bti instruction before paciasp. > > [...] Here is the summary with links: - [bpf-next,v2] bpf, arm64: Sign return address for jited code https://git.kernel.org/bpf/bpf-next/c/042152c27c3b You are awesome, thank you!
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 3920213244f0..194c95ccc1cf 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -263,6 +263,9 @@ /* HINTs */ #define A64_HINT(x) aarch64_insn_gen_hint(x) +#define A64_PACIASP A64_HINT(AARCH64_INSN_HINT_PACIASP) +#define A64_AUTIASP A64_HINT(AARCH64_INSN_HINT_AUTIASP) + /* BTI */ #define A64_BTI_C A64_HINT(AARCH64_INSN_HINT_BTIC) #define A64_BTI_J A64_HINT(AARCH64_INSN_HINT_BTIJ) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 093fa9ea1083..8ab4035dea27 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -236,7 +236,8 @@ static bool is_lsi_offset(int offset, int scale) } /* Tail call offset to jump into */ -#if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) +#if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) || \ + IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL) #define PROLOGUE_OFFSET 9 #else #define PROLOGUE_OFFSET 8 @@ -278,8 +279,11 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) * */ + /* Sign lr */ + if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) + emit(A64_PACIASP, ctx); /* BTI landing pad */ - if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) + else if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) emit(A64_BTI_C, ctx); /* Save FP and LR registers to stay align with ARM64 AAPCS */ @@ -580,6 +584,10 @@ static void build_epilogue(struct jit_ctx *ctx) /* Set return value */ emit(A64_MOV(1, A64_R(0), r0), ctx); + /* Authenticate lr */ + if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) + emit(A64_AUTIASP, ctx); + emit(A64_RET(A64_LR), ctx); }
Sign return address for jited code when the kernel is built with pointer authentication enabled. 1. Sign LR with paciasp instruction before LR is pushed to stack. Since paciasp acts like landing pads for function entry, no need to insert bti instruction before paciasp. 2. Authenticate LR with autiasp instruction after LR is poped from stack. For bpf tail call, the stack frame constructed by the caller is reused by the callee. That is, the stack frame is constructed by the caller and destructed by the callee. Thus LR is signed and pushed to the stack in the caller's prologue, and poped from the stack and authenticated in the callee's epilogue. For bpf2bpf call, the caller and callee construct their own stack frames, and sign and authenticate their own LRs. Signed-off-by: Xu Kuohai <xukuohai@huawei.com> --- v1->v2: - Add bpf tail call and bpf2bpf call description to commit message - Rebased to bpf-next arch/arm64/net/bpf_jit.h | 3 +++ arch/arm64/net/bpf_jit_comp.c | 12 ++++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-)