From: Peter Zijlstra <peterz@infradead.org> mainline inclusion from mainline-v6.8-rc1 commit 2cd3e3772e41377f32d6eea643e0590774e9187c category: feature bugzilla: https://atomgit.com/openeuler/kernel/issues/8335 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ---------------------------------------------------------------------- BPF struct_ops uses __arch_prepare_bpf_trampoline() to write trampolines for indirect function calls. These tramplines much have matching CFI. In order to obtain the correct CFI hash for the various methods, add a matching structure that contains stub functions, the compiler will generate correct CFI which we can pilfer for the trampolines. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20231215092707.566977112@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> Conflicts: include/linux/bpf.h [Fix conflicts because of kabi.] Signed-off-by: Luo Gengkun <luogengkun2@huawei.com> --- arch/x86/include/asm/cfi.h | 6 +++ arch/x86/kernel/alternative.c | 22 +++++++++++ arch/x86/net/bpf_jit_comp.c | 66 ++++++++++++++++++++------------ include/linux/bpf.h | 13 +++++++ kernel/bpf/bpf_struct_ops.c | 16 ++++---- net/bpf/bpf_dummy_struct_ops.c | 31 ++++++++++++++- net/ipv4/bpf_tcp_ca.c | 69 ++++++++++++++++++++++++++++++++++ 7 files changed, 191 insertions(+), 32 deletions(-) diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h index 8779abd217b7..1a50b2cd4713 100644 --- a/arch/x86/include/asm/cfi.h +++ b/arch/x86/include/asm/cfi.h @@ -123,6 +123,8 @@ static inline int cfi_get_offset(void) } #define cfi_get_offset cfi_get_offset +extern u32 cfi_get_func_hash(void *func); + #else static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) { @@ -130,6 +132,10 @@ static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) } #define cfi_bpf_hash 0U #define cfi_bpf_subprog_hash 0U +static inline u32 cfi_get_func_hash(void *func) +{ + return 0; +} #endif /* CONFIG_CFI_CLANG */ #endif /* _ASM_X86_CFI_H */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 287065ad3feb..183d42302243 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -893,6 +893,28 @@ asm ( " .size cfi_bpf_subprog_hash, 4 \n" " .popsection \n" ); + +u32 cfi_get_func_hash(void *func) +{ + u32 hash; + + func -= cfi_get_offset(); + switch (cfi_mode) { + case CFI_FINEIBT: + func += 7; + break; + case CFI_KCFI: + func += 1; + break; + default: + return 0; + } + + if (get_kernel_nofault(hash, func)) + return 0; + + return hash; +} #endif #ifdef CONFIG_FINEIBT diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 35b04d0d88e5..5c020dcec31b 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -345,9 +345,8 @@ static void pop_callee_regs(u8 **pprog, bool *callee_regs_used) * in arch/x86/kernel/alternative.c */ -static void emit_fineibt(u8 **pprog, bool is_subprog) +static void emit_fineibt(u8 **pprog, u32 hash) { - u32 hash = is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash; u8 *prog = *pprog; EMIT_ENDBR(); @@ -360,9 +359,8 @@ static void emit_fineibt(u8 **pprog, bool is_subprog) *pprog = prog; } -static void emit_kcfi(u8 **pprog, bool is_subprog) +static void emit_kcfi(u8 **pprog, u32 hash) { - u32 hash = is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash; u8 *prog = *pprog; EMIT1_off32(0xb8, hash); /* movl $hash, %eax */ @@ -384,17 +382,17 @@ static void emit_kcfi(u8 **pprog, bool is_subprog) *pprog = prog; } -static void emit_cfi(u8 **pprog, bool is_subprog) +static void emit_cfi(u8 **pprog, u32 hash) { u8 *prog = *pprog; switch (cfi_mode) { case CFI_FINEIBT: - emit_fineibt(&prog, is_subprog); + emit_fineibt(&prog, hash); break; case CFI_KCFI: - emit_kcfi(&prog, is_subprog); + emit_kcfi(&prog, hash); break; default: @@ -415,7 +413,7 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf, { u8 *prog = *pprog; - emit_cfi(&prog, is_subprog); + emit_cfi(&prog, is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash); /* BPF trampoline can be made to work without these nops, * but let's waste 5 bytes for now and optimize later */ @@ -2536,10 +2534,19 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im u8 *prog; bool save_ret; + /* + * F_INDIRECT is only compatible with F_RET_FENTRY_RET, it is + * explicitly incompatible with F_CALL_ORIG | F_SKIP_FRAME | F_IP_ARG + * because @func_addr. + */ + WARN_ON_ONCE((flags & BPF_TRAMP_F_INDIRECT) && + (flags & ~(BPF_TRAMP_F_INDIRECT | BPF_TRAMP_F_RET_FENTRY_RET))); + /* extra registers for struct arguments */ - for (i = 0; i < m->nr_args; i++) + for (i = 0; i < m->nr_args; i++) { if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) nr_regs += (m->arg_size[i] + 7) / 8 - 1; + } /* x86-64 supports up to MAX_BPF_FUNC_ARGS arguments. 1-6 * are passed through regs, the remains are through stack. @@ -2622,20 +2629,27 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im prog = rw_image; - EMIT_ENDBR(); - /* - * This is the direct-call trampoline, as such it needs accounting - * for the __fentry__ call. - */ - x86_call_depth_emit_accounting(&prog, NULL); + if (flags & BPF_TRAMP_F_INDIRECT) { + /* + * Indirect call for bpf_struct_ops + */ + emit_cfi(&prog, cfi_get_func_hash(func_addr)); + } else { + /* + * Direct-call fentry stub, as such it needs accounting for the + * __fentry__ call. + */ + x86_call_depth_emit_accounting(&prog, NULL); + } EMIT1(0x55); /* push rbp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ - if (!is_imm8(stack_size)) + if (!is_imm8(stack_size)) { /* sub rsp, stack_size */ EMIT3_off32(0x48, 0x81, 0xEC, stack_size); - else + } else { /* sub rsp, stack_size */ EMIT4(0x48, 0x83, 0xEC, stack_size); + } if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) EMIT1(0x50); /* push rax */ /* mov QWORD PTR [rbp - rbx_off], rbx */ @@ -2669,10 +2683,11 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im } } - if (fentry->nr_links) + if (fentry->nr_links) { if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET, image, rw_image)) return -EINVAL; + } if (fmod_ret->nr_links) { branches = kcalloc(fmod_ret->nr_links, sizeof(u8 *), @@ -2691,11 +2706,12 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im restore_regs(m, &prog, regs_off); save_args(m, &prog, arg_stack_off, true); - if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) + if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) { /* Before calling the original function, restore the * tail_call_cnt from stack to rax. */ RESTORE_TAIL_CALL_CNT(stack_size); + } if (flags & BPF_TRAMP_F_ORIG_STACK) { emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, 8); @@ -2724,17 +2740,19 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im /* Update the branches saved in invoke_bpf_mod_ret with the * aligned address of do_fexit. */ - for (i = 0; i < fmod_ret->nr_links; i++) + for (i = 0; i < fmod_ret->nr_links; i++) { emit_cond_near_jump(&branches[i], image + (prog - (u8 *)rw_image), image + (branches[i] - (u8 *)rw_image), X86_JNE); + } } - if (fexit->nr_links) + if (fexit->nr_links) { if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off, false, image, rw_image)) { ret = -EINVAL; goto cleanup; } + } if (flags & BPF_TRAMP_F_RESTORE_REGS) restore_regs(m, &prog, regs_off); @@ -2751,11 +2769,12 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im ret = -EINVAL; goto cleanup; } - } else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) + } else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) { /* Before running the original function, restore the * tail_call_cnt from stack to rax. */ RESTORE_TAIL_CALL_CNT(stack_size); + } /* restore return value of orig_call or fentry prog back into RAX */ if (save_ret) @@ -2763,9 +2782,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, -rbx_off); EMIT1(0xC9); /* leave */ - if (flags & BPF_TRAMP_F_SKIP_FRAME) + if (flags & BPF_TRAMP_F_SKIP_FRAME) { /* skip our return address and return to parent */ EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */ + } emit_return(&prog, image + (prog - (u8 *)rw_image)); /* Make sure the trampoline generation logic doesn't overflow */ if (WARN_ON_ONCE(prog > (u8 *)rw_image_end - BPF_INSN_SAFETY)) { diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2839780ba1b5..3bb9b329340f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1113,6 +1113,17 @@ struct btf_func_model { */ #define BPF_TRAMP_F_TAIL_CALL_CTX BIT(7) +/* + * Indicate the trampoline should be suitable to receive indirect calls; + * without this indirectly calling the generated code can result in #UD/#CP, + * depending on the CFI options. + * + * Used by bpf_struct_ops. + * + * Incompatible with FENTRY usage, overloads @func_addr argument. + */ +#define BPF_TRAMP_F_INDIRECT BIT(8) + /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 * bytes on x86. */ @@ -1787,6 +1798,7 @@ struct bpf_struct_ops { struct btf_func_model func_models[BPF_STRUCT_OPS_MAX_NR_MEMBERS]; u32 type_id; u32 value_id; + void *cfi_stubs; KABI_RESERVE(1) KABI_RESERVE(2) @@ -1805,6 +1817,7 @@ int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key, int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, struct bpf_tramp_link *link, const struct btf_func_model *model, + void *stub_func, void *image, void *image_end); static inline bool bpf_try_module_get(const void *data, struct module *owner) { diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 4d53c53fc5aa..02068bd0e4d9 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -352,17 +352,16 @@ const struct bpf_link_ops bpf_struct_ops_link_lops = { int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, struct bpf_tramp_link *link, const struct btf_func_model *model, - void *image, void *image_end) + void *stub_func, void *image, void *image_end) { - u32 flags; + u32 flags = BPF_TRAMP_F_INDIRECT; int size; tlinks[BPF_TRAMP_FENTRY].links[0] = link; tlinks[BPF_TRAMP_FENTRY].nr_links = 1; - /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops, - * and it must be used alone. - */ - flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0; + + if (model->ret_size > 0) + flags |= BPF_TRAMP_F_RET_FENTRY_RET; size = arch_bpf_trampoline_size(model, flags, tlinks, NULL); if (size < 0) @@ -370,7 +369,7 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, if (size > (unsigned long)image_end - (unsigned long)image) return -E2BIG; return arch_prepare_bpf_trampoline(NULL, image, image_end, - model, flags, tlinks, NULL); + model, flags, tlinks, stub_func); } static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, @@ -504,11 +503,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, err = bpf_struct_ops_prepare_trampoline(tlinks, link, &st_ops->func_models[i], + *(void **)(st_ops->cfi_stubs + moff), image, image_end); if (err < 0) goto reset_unlock; - *(void **)(kdata + moff) = image; + *(void **)(kdata + moff) = image + cfi_get_offset(); image += err; /* put prog_id to udata */ diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c index 2748f9d77b18..8906f7bdf4a9 100644 --- a/net/bpf/bpf_dummy_struct_ops.c +++ b/net/bpf/bpf_dummy_struct_ops.c @@ -12,6 +12,11 @@ extern struct bpf_struct_ops bpf_bpf_dummy_ops; /* A common type for test_N with return value in bpf_dummy_ops */ typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...); +static int dummy_ops_test_ret_function(struct bpf_dummy_ops_state *state, ...) +{ + return 0; +} + struct bpf_dummy_ops_test_args { u64 args[MAX_BPF_FUNC_ARGS]; struct bpf_dummy_ops_state state; @@ -62,7 +67,7 @@ static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args) static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args) { - dummy_ops_test_ret_fn test = (void *)image; + dummy_ops_test_ret_fn test = (void *)image + cfi_get_offset(); struct bpf_dummy_ops_state *state = NULL; /* state needs to be NULL if args[0] is 0 */ @@ -119,6 +124,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, op_idx = prog->expected_attach_type; err = bpf_struct_ops_prepare_trampoline(tlinks, link, &st_ops->func_models[op_idx], + &dummy_ops_test_ret_function, image, image + PAGE_SIZE); if (err < 0) goto out; @@ -219,6 +225,28 @@ static void bpf_dummy_unreg(void *kdata) { } +static int bpf_dummy_test_1(struct bpf_dummy_ops_state *cb) +{ + return 0; +} + +static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2, + char a3, unsigned long a4) +{ + return 0; +} + +static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb) +{ + return 0; +} + +static struct bpf_dummy_ops __bpf_bpf_dummy_ops = { + .test_1 = bpf_dummy_test_1, + .test_2 = bpf_dummy_test_2, + .test_sleepable = bpf_dummy_test_sleepable, +}; + struct bpf_struct_ops bpf_bpf_dummy_ops = { .verifier_ops = &bpf_dummy_verifier_ops, .init = bpf_dummy_init, @@ -227,4 +255,5 @@ struct bpf_struct_ops bpf_bpf_dummy_ops = { .reg = bpf_dummy_reg, .unreg = bpf_dummy_unreg, .name = "bpf_dummy_ops", + .cfi_stubs = &__bpf_bpf_dummy_ops, }; diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 39dcccf0f174..ae8b15e6896f 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -271,6 +271,74 @@ static int bpf_tcp_ca_validate(void *kdata) return tcp_validate_congestion_control(kdata); } +static u32 bpf_tcp_ca_ssthresh(struct sock *sk) +{ + return 0; +} + +static void bpf_tcp_ca_cong_avoid(struct sock *sk, u32 ack, u32 acked) +{ +} + +static void bpf_tcp_ca_set_state(struct sock *sk, u8 new_state) +{ +} + +static void bpf_tcp_ca_cwnd_event(struct sock *sk, enum tcp_ca_event ev) +{ +} + +static void bpf_tcp_ca_in_ack_event(struct sock *sk, u32 flags) +{ +} + +static void bpf_tcp_ca_pkts_acked(struct sock *sk, const struct ack_sample *sample) +{ +} + +static u32 bpf_tcp_ca_min_tso_segs(struct sock *sk) +{ + return 0; +} + +static void bpf_tcp_ca_cong_control(struct sock *sk, const struct rate_sample *rs) +{ +} + +static u32 bpf_tcp_ca_undo_cwnd(struct sock *sk) +{ + return 0; +} + +static u32 bpf_tcp_ca_sndbuf_expand(struct sock *sk) +{ + return 0; +} + +static void __bpf_tcp_ca_init(struct sock *sk) +{ +} + +static void __bpf_tcp_ca_release(struct sock *sk) +{ +} + +static struct tcp_congestion_ops __bpf_ops_tcp_congestion_ops = { + .ssthresh = bpf_tcp_ca_ssthresh, + .cong_avoid = bpf_tcp_ca_cong_avoid, + .set_state = bpf_tcp_ca_set_state, + .cwnd_event = bpf_tcp_ca_cwnd_event, + .in_ack_event = bpf_tcp_ca_in_ack_event, + .pkts_acked = bpf_tcp_ca_pkts_acked, + .min_tso_segs = bpf_tcp_ca_min_tso_segs, + .cong_control = bpf_tcp_ca_cong_control, + .undo_cwnd = bpf_tcp_ca_undo_cwnd, + .sndbuf_expand = bpf_tcp_ca_sndbuf_expand, + + .init = __bpf_tcp_ca_init, + .release = __bpf_tcp_ca_release, +}; + struct bpf_struct_ops bpf_tcp_congestion_ops = { .verifier_ops = &bpf_tcp_ca_verifier_ops, .reg = bpf_tcp_ca_reg, @@ -281,6 +349,7 @@ struct bpf_struct_ops bpf_tcp_congestion_ops = { .init = bpf_tcp_ca_init, .validate = bpf_tcp_ca_validate, .name = "tcp_congestion_ops", + .cfi_stubs = &__bpf_ops_tcp_congestion_ops, }; static int __init bpf_tcp_ca_kfunc_init(void) -- 2.34.1