From 1e37392cccdea94da635e3c6d16b21865806f619 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 14 Jul 2021 11:43:54 +0200 Subject: bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip Enabling BPF_TRAMP_F_IP_ARG for trampolines that actually need it. The BPF_TRAMP_F_IP_ARG adds extra 3 instructions to trampoline code and is used only by programs with bpf_get_func_ip helper, which is added in following patch and sets call_get_func_ip bit. This patch ensures that BPF_TRAMP_F_IP_ARG flag is used only for trampolines that have programs with call_get_func_ip set. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210714094400.396467-3-jolsa@kernel.org --- kernel/bpf/trampoline.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 28a3630c48ee..b2535acfe9db 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -172,7 +172,7 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr) } static struct bpf_tramp_progs * -bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) +bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg) { const struct bpf_prog_aux *aux; struct bpf_tramp_progs *tprogs; @@ -189,8 +189,10 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) *total += tr->progs_cnt[kind]; progs = tprogs[kind].progs; - hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) + hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) { + *ip_arg |= aux->prog->call_get_func_ip; *progs++ = aux->prog; + } } return tprogs; } @@ -333,9 +335,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) struct bpf_tramp_image *im; struct bpf_tramp_progs *tprogs; u32 flags = BPF_TRAMP_F_RESTORE_REGS; + bool ip_arg = false; int err, total; - tprogs = bpf_trampoline_get_progs(tr, &total); + tprogs = bpf_trampoline_get_progs(tr, &total, &ip_arg); if (IS_ERR(tprogs)) return PTR_ERR(tprogs); @@ -357,6 +360,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; + if (ip_arg) + flags |= BPF_TRAMP_F_IP_ARG; + err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, &tr->func.model, flags, tprogs, tr->func.addr); -- cgit v1.2.3 From 9b99edcae5c80c8fb9f8e7149bae528c9e610a72 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 14 Jul 2021 11:43:55 +0200 Subject: bpf: Add bpf_get_func_ip helper for tracing programs Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs, specifically for all trampoline attach types. The trampoline's caller IP address is stored in (ctx - 8) address. so there's no reason to actually call the helper, but rather fixup the call instruction and return [ctx - 8] value directly. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org --- kernel/bpf/verifier.c | 43 +++++++++++++++++++++++++++++++++++++++++++ kernel/trace/bpf_trace.c | 15 +++++++++++++++ 2 files changed, 58 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 344ee67265cc..ceef190514e4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6161,6 +6161,27 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env, return err; } +static int check_get_func_ip(struct bpf_verifier_env *env) +{ + enum bpf_attach_type eatype = env->prog->expected_attach_type; + enum bpf_prog_type type = resolve_prog_type(env->prog); + int func_id = BPF_FUNC_get_func_ip; + + if (type == BPF_PROG_TYPE_TRACING) { + if (eatype != BPF_TRACE_FENTRY && eatype != BPF_TRACE_FEXIT && + eatype != BPF_MODIFY_RETURN) { + verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n", + func_id_name(func_id), func_id); + return -ENOTSUPP; + } + return 0; + } + + verbose(env, "func %s#%d not supported for program type %d\n", + func_id_name(func_id), func_id, type); + return -ENOTSUPP; +} + static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx_p) { @@ -6439,6 +6460,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack) env->prog->call_get_stack = true; + if (func_id == BPF_FUNC_get_func_ip) { + if (check_get_func_ip(env)) + return -ENOTSUPP; + env->prog->call_get_func_ip = true; + } + if (changes_data) clear_all_pkt_pointers(env); return 0; @@ -12632,6 +12659,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; bool expect_blinding = bpf_jit_blinding_enabled(prog); + enum bpf_prog_type prog_type = resolve_prog_type(prog); struct bpf_insn *insn = prog->insnsi; const struct bpf_func_proto *fn; const int insn_cnt = prog->len; @@ -12998,6 +13026,21 @@ patch_map_ops_generic: continue; } + /* Implement bpf_get_func_ip inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_ip) { + /* Load IP address from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); + if (!new_prog) + return -ENOMEM; + + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + patch_call_imm: fn = env->ops->get_func_proto(insn->imm, env->prog); /* all functions that have prototype and verifier allowed diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 6c77d25137e0..3e71503eeb23 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -948,6 +948,19 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = { .arg5_type = ARG_ANYTHING, }; +BPF_CALL_1(bpf_get_func_ip_tracing, void *, ctx) +{ + /* This helper call is inlined by verifier. */ + return ((u64 *)ctx)[-1]; +} + +static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = { + .func = bpf_get_func_ip_tracing, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, +}; + const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -1058,6 +1071,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_for_each_map_elem_proto; case BPF_FUNC_snprintf: return &bpf_snprintf_proto; + case BPF_FUNC_get_func_ip: + return &bpf_get_func_ip_proto_tracing; default: return bpf_base_func_proto(func_id); } -- cgit v1.2.3 From 9ffd9f3ff7193933dae171740ab70a103d460065 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 14 Jul 2021 11:43:56 +0200 Subject: bpf: Add bpf_get_func_ip helper for kprobe programs Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs, so it's now possible to call bpf_get_func_ip from both kprobe and kretprobe programs. Taking the caller's address from 'struct kprobe::addr', which is defined for both kprobe and kretprobe. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Reviewed-by: Masami Hiramatsu Link: https://lore.kernel.org/bpf/20210714094400.396467-5-jolsa@kernel.org --- kernel/bpf/verifier.c | 2 ++ kernel/trace/bpf_trace.c | 16 ++++++++++++++++ 2 files changed, 18 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ceef190514e4..97216f799ba8 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6175,6 +6175,8 @@ static int check_get_func_ip(struct bpf_verifier_env *env) return -ENOTSUPP; } return 0; + } else if (type == BPF_PROG_TYPE_KPROBE) { + return 0; } verbose(env, "func %s#%d not supported for program type %d\n", diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 3e71503eeb23..0b113716bc7a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -961,6 +961,20 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = { .arg1_type = ARG_PTR_TO_CTX, }; +BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs) +{ + struct kprobe *kp = kprobe_running(); + + return kp ? (u64) kp->addr : 0; +} + +static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = { + .func = bpf_get_func_ip_kprobe, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, +}; + const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -1092,6 +1106,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_override_return: return &bpf_override_return_proto; #endif + case BPF_FUNC_get_func_ip: + return &bpf_get_func_ip_proto_kprobe; default: return bpf_tracing_func_proto(func_id, prog); } -- cgit v1.2.3