From patchwork Fri May 8 14:25:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 11536719 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8FC13139F for ; Fri, 8 May 2020 14:25:27 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 53F202495B for ; Fri, 8 May 2020 14:25:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hSBPJ73n"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="At594fIa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53F202495B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZG3dJKFSqaH3DN4hVYrXRQkrHeQ6BjuZKXUXvglHoVI=; b=hSBPJ73nF3dxdd QYlTMAvgTgNM+gj+3CWyxyknkt9xTE8cuWiPv/+SKBub3MADBiOAoPKrC1+Y/PgsyNlxoqDUK/dRt W4/J6WKXYej6Ou/AUOFfbd2Txdo+kR1fn8US7IBJ7UgqSsxcDsG/g163feScYrm4WZ5ev366uWH14 g/ZuUPflQ38BE4xN6HflfvIl4FvzlT1yYligUTPVY1IIr6TRmxf8JAFMa7cydtkmLG2AQxN9JoVcw SsMKeYaIqu9ExL4qlFRsYdJbqZ2y6+ObC3gvcsd4HgemnIKZscneG+XFEx/xxrNdlmCPNgoFG52FD U3si3Mk02Yu8lN5HidfA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jX3wH-0007Bm-Rw; Fri, 08 May 2020 14:25:21 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jX3wA-00072v-Da for linux-arm-kernel@lists.infradead.org; Fri, 08 May 2020 14:25:16 +0000 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D54862495A; Fri, 8 May 2020 14:25:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588947914; bh=Its7HfftSuK8NW/gnM+l30dIuDBlz589x3WcEga9g6E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=At594fIavWm4EGVfnrTCpH7voTNlEwR4JNF+95OZvS4OlS0sLk6mluLsuVmTyDRYb pp3BV8bctlNDg7rAVUkvWQt9O8CYapmf4Lmmz/nr+qbcwW5dRN3WPjx5kX2Fy2nggK Vj/e0ab7EdpAoq1RUmp7i7Dr7d5C/vL7SjQV0kJI= From: Masami Hiramatsu To: LKML Subject: [RFC PATCH v2 1/3] x86/kprobes: Support nested kprobes Date: Fri, 8 May 2020 23:25:07 +0900 Message-Id: <158894790730.14896.12415801860352216608.stgit@devnote2> X-Mailer: git-send-email 2.20.1 In-Reply-To: <158894789510.14896.13461271606820304664.stgit@devnote2> References: <158894789510.14896.13461271606820304664.stgit@devnote2> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200508_072514_531778_0F1162B3 X-CRM114-Status: GOOD ( 21.71 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Wang Nan , Song Liu , Martin KaFai Lau , Daniel Borkmann , Russell King , Network Development , Alexei Starovoitov , Arnaldo Carvalho de Melo , "David S . Miller" , Will Deacon , Steven Rostedt , Catalin Marinas , Yonghong Song , bpf , Andrii Nakryiko , Ingo Molnar , linux-arm-kernel@lists.infradead.org, Eelco Chaudron Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Make kprobes to accept 1-level nesting instead of missing it. Any kprobes hits in kprobes pre/post handler context can be nested at once. If the other kprobes hits in the nested pre/post handler context, that will be missed. This is useful if user wants to trace/debug the code which can be invoked from another kprobe handlers. We can test this feature on the kernel with CONFIG_KPROBE_EVENTS_ON_NOTRACE=y as below. # cd /sys/kernel/debug/tracing # echo p ring_buffer_lock_reserve > kprobe_events # echo p vfs_read >> kprobe_events # echo 0 > /proc/sys/debug/kprobes-optimization # to check int3 handler # echo stacktrace > events/kprobes/p_ring_buffer_lock_reserve_0/trigger # echo 1 > events/kprobes/enable # cat trace ... cat-161 [000] d..1 46602.280111: p_vfs_read_0: (vfs_read+0x0/0x150) cat-161 [000] d..2 46602.280222: p_ring_buffer_lock_reserve_0: (ring_buffer_lock_reserve+0x0/0x400) cat-161 [000] d..2 46602.280247: => kprobe_trace_func => kprobe_dispatcher => aggr_pre_handler => kprobe_int3_handler => do_int3 => int3 => ring_buffer_lock_reserve => trace_event_buffer_lock_reserve => kprobe_trace_func => kprobe_dispatcher => aggr_pre_handler => kprobe_int3_handler => do_int3 => int3 => vfs_read => kernel_read => load_elf_phdrs => load_elf_binary => search_binary_handler.part.0 => __do_execve_file.isra.0 => __x64_sys_execve => do_syscall_64 => entry_SYSCALL_64_after_hwframe This shows int3 is nested. Note that this also improve unrecoverable message to show nested probes too. Signed-off-by: Masami Hiramatsu --- Changes in v2: - Fix a build error in kprobes on ftrace. - Dump nested kprobes when hit a BUG(). --- arch/x86/include/asm/kprobes.h | 5 ++ arch/x86/kernel/kprobes/common.h | 39 ++++++++++++++- arch/x86/kernel/kprobes/core.c | 100 +++++++++++++++++--------------------- arch/x86/kernel/kprobes/ftrace.c | 6 ++ arch/x86/kernel/kprobes/opt.c | 13 +++-- kernel/kprobes.c | 1 6 files changed, 96 insertions(+), 68 deletions(-) diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h index 073eb7ad2f56..60ca23aeece8 100644 --- a/arch/x86/include/asm/kprobes.h +++ b/arch/x86/include/asm/kprobes.h @@ -83,6 +83,8 @@ static inline int arch_prepared_optinsn(struct arch_optimized_insn *optinsn) return optinsn->size; } +#define KPROBE_NEST_MAX 2 + struct prev_kprobe { struct kprobe *kp; unsigned long status; @@ -95,7 +97,8 @@ struct kprobe_ctlblk { unsigned long kprobe_status; unsigned long kprobe_old_flags; unsigned long kprobe_saved_flags; - struct prev_kprobe prev_kprobe; + struct prev_kprobe prev[KPROBE_NEST_MAX]; + int nested; }; extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); diff --git a/arch/x86/kernel/kprobes/common.h b/arch/x86/kernel/kprobes/common.h index 7d3a2e2daf01..490e871df36e 100644 --- a/arch/x86/kernel/kprobes/common.h +++ b/arch/x86/kernel/kprobes/common.h @@ -91,11 +91,46 @@ extern int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn); extern void synthesize_reljump(void *dest, void *from, void *to); extern void synthesize_relcall(void *dest, void *from, void *to); +static nokprobe_inline void +save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + int i = kcb->nested++; + + kcb->prev[i].kp = kprobe_running(); + kcb->prev[i].status = kcb->kprobe_status; + kcb->prev[i].old_flags = kcb->kprobe_old_flags; + kcb->prev[i].saved_flags = kcb->kprobe_saved_flags; +} + +static nokprobe_inline void +restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + int i = --kcb->nested; + + __this_cpu_write(current_kprobe, kcb->prev[i].kp); + kcb->kprobe_status = kcb->prev[i].status; + kcb->kprobe_old_flags = kcb->prev[i].old_flags; + kcb->kprobe_saved_flags = kcb->prev[i].saved_flags; +} + +static nokprobe_inline void pop_current_kprobe(struct kprobe_ctlblk *kcb) +{ + if (kcb->nested) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); +} + +static nokprobe_inline bool kprobe_can_nest(struct kprobe_ctlblk *kcb) +{ + return !kprobe_running() || (kcb->nested < KPROBE_NEST_MAX - 1); +} + #ifdef CONFIG_OPTPROBES -extern int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter); +extern int setup_detour_execution(struct kprobe *p, struct pt_regs *regs); extern unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr); #else /* !CONFIG_OPTPROBES */ -static inline int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter) +static inline int setup_detour_execution(struct kprobe *p, struct pt_regs *regs) { return 0; } diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 4d7022a740ab..b89eeee1649a 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -520,24 +520,6 @@ void arch_remove_kprobe(struct kprobe *p) } } -static nokprobe_inline void -save_previous_kprobe(struct kprobe_ctlblk *kcb) -{ - kcb->prev_kprobe.kp = kprobe_running(); - kcb->prev_kprobe.status = kcb->kprobe_status; - kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; - kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; -} - -static nokprobe_inline void -restore_previous_kprobe(struct kprobe_ctlblk *kcb) -{ - __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); - kcb->kprobe_status = kcb->prev_kprobe.status; - kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; - kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; -} - static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) @@ -581,26 +563,34 @@ void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) } NOKPROBE_SYMBOL(arch_prepare_kretprobe); -static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, - struct kprobe_ctlblk *kcb, int reenter) +static nokprobe_inline +int setup_booster_execution(struct kprobe *p, struct pt_regs *regs) { - if (setup_detour_execution(p, regs, reenter)) - return; - #if !defined(CONFIG_PREEMPTION) if (p->ainsn.boostable && !p->post_handler) { /* Boost up -- we can execute copied instructions directly */ + regs->ip = (unsigned long)p->ainsn.insn; + return 1; + } +#endif + return 0; +} + +static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb, int reenter) +{ + if (setup_detour_execution(p, regs) || + setup_booster_execution(p, regs)) { if (!reenter) - reset_current_kprobe(); + pop_current_kprobe(kcb); /* * Reentering boosted probe doesn't reset current_kprobe, * nor set current_kprobe, because it doesn't use single * stepping. */ - regs->ip = (unsigned long)p->ainsn.insn; return; } -#endif + if (reenter) { save_previous_kprobe(kcb); set_current_kprobe(p, regs, kcb); @@ -630,6 +620,11 @@ static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs, switch (kcb->kprobe_status) { case KPROBE_HIT_SSDONE: case KPROBE_HIT_ACTIVE: + if (kcb->nested < KPROBE_NEST_MAX - 1) { + save_previous_kprobe(kcb); + return 0; + } + fallthrough; case KPROBE_HIT_SS: kprobes_inc_nmissed_count(p); setup_singlestep(p, regs, kcb, 1); @@ -642,7 +637,11 @@ static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs, * and eventually a stack overflow. */ pr_err("Unrecoverable kprobe detected.\n"); + pr_err("Current kprobe:\n"); dump_kprobe(p); + pr_err("Nested kprobes (nested: %d):\n", kcb->nested); + while (kcb->nested) + dump_kprobe(kcb->prev[--kcb->nested].kp); BUG(); default: /* impossible cases */ @@ -678,26 +677,24 @@ int kprobe_int3_handler(struct pt_regs *regs) p = get_kprobe(addr); if (p) { - if (kprobe_running()) { - if (reenter_kprobe(p, regs, kcb)) - return 1; - } else { - set_current_kprobe(p, regs, kcb); - kcb->kprobe_status = KPROBE_HIT_ACTIVE; - - /* - * If we have no pre-handler or it returned 0, we - * continue with normal processing. If we have a - * pre-handler and it returned non-zero, that means - * user handler setup registers to exit to another - * instruction, we must skip the single stepping. - */ - if (!p->pre_handler || !p->pre_handler(p, regs)) - setup_singlestep(p, regs, kcb, 0); - else - reset_current_kprobe(); + if (kprobe_running() && reenter_kprobe(p, regs, kcb)) return 1; - } + + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, that means + * user handler setup registers to exit to another + * instruction, we must skip the single stepping. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) + setup_singlestep(p, regs, kcb, 0); + else + pop_current_kprobe(kcb); + return 1; } else if (*addr != INT3_INSN_OPCODE) { /* * The breakpoint instruction was removed right @@ -994,13 +991,7 @@ int kprobe_debug_handler(struct pt_regs *regs) cur->post_handler(cur, regs, 0); } - /* Restore back the original saved kprobes variables and continue. */ - if (kcb->kprobe_status == KPROBE_REENTER) { - restore_previous_kprobe(kcb); - goto out; - } - reset_current_kprobe(); -out: + pop_current_kprobe(kcb); /* * if somebody else is singlestepping across a probe point, flags * will have TF set, in which case, continue the remaining processing @@ -1043,10 +1034,7 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) */ regs->flags |= kcb->kprobe_old_flags; - if (kcb->kprobe_status == KPROBE_REENTER) - restore_previous_kprobe(kcb); - else - reset_current_kprobe(); + pop_current_kprobe(kcb); } else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE || kcb->kprobe_status == KPROBE_HIT_SSDONE) { /* diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c index 681a4b36e9bb..09274a647e37 100644 --- a/arch/x86/kernel/kprobes/ftrace.c +++ b/arch/x86/kernel/kprobes/ftrace.c @@ -25,13 +25,15 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, return; kcb = get_kprobe_ctlblk(); - if (kprobe_running()) { + if (!kprobe_can_nest(kcb)) { kprobes_inc_nmissed_count(p); } else { unsigned long orig_ip = regs->ip; /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */ regs->ip = ip + sizeof(kprobe_opcode_t); + if (kprobe_running()) + save_previous_kprobe(kcb); __this_cpu_write(current_kprobe, p); kcb->kprobe_status = KPROBE_HIT_ACTIVE; if (!p->pre_handler || !p->pre_handler(p, regs)) { @@ -50,7 +52,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, * If pre_handler returns !0, it changes regs->ip. We have to * skip emulating post_handler. */ - __this_cpu_write(current_kprobe, NULL); + pop_current_kprobe(kcb); } } NOKPROBE_SYMBOL(kprobe_ftrace_handler); diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index ea13f6888284..ec7cfd4906e3 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -168,15 +168,16 @@ STACK_FRAME_NON_STANDARD(optprobe_template_func); static void optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) { + struct kprobe_ctlblk *kcb; /* This is possible if op is under delayed unoptimizing */ if (kprobe_disabled(&op->kp)) return; preempt_disable(); - if (kprobe_running()) { + kcb = get_kprobe_ctlblk(); + if (!kprobe_can_nest(kcb)) { kprobes_inc_nmissed_count(&op->kp); } else { - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); /* Save skipped registers */ regs->cs = __KERNEL_CS; #ifdef CONFIG_X86_32 @@ -186,10 +187,12 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) regs->ip = (unsigned long)op->kp.addr + INT3_INSN_SIZE; regs->orig_ax = ~0UL; + if (kprobe_running()) + save_previous_kprobe(kcb); __this_cpu_write(current_kprobe, &op->kp); kcb->kprobe_status = KPROBE_HIT_ACTIVE; opt_pre_handler(&op->kp, regs); - __this_cpu_write(current_kprobe, NULL); + pop_current_kprobe(kcb); } preempt_enable(); } @@ -500,7 +503,7 @@ extern void arch_unoptimize_kprobes(struct list_head *oplist, } } -int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter) +int setup_detour_execution(struct kprobe *p, struct pt_regs *regs) { struct optimized_kprobe *op; @@ -509,8 +512,6 @@ int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter) op = container_of(p, struct optimized_kprobe, kp); /* Detour through copied instructions */ regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX; - if (!reenter) - reset_current_kprobe(); return 1; } return 0; diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 2625c241ac00..7b9d3e394295 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2137,7 +2137,6 @@ EXPORT_SYMBOL_GPL(enable_kprobe); /* Caller must NOT call this in usual path. This is only for critical case */ void dump_kprobe(struct kprobe *kp) { - pr_err("Dumping kprobe:\n"); pr_err("Name: %s\nOffset: %x\nAddress: %pS\n", kp->symbol_name, kp->offset, kp->addr); }