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From: Masami Hiramatsu <mhiramat@redhat.com>
To: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
	lkml <linux-kernel@vger.kernel.org>
Cc: systemtap <systemtap@sources.redhat.com>,
	kvm <kvm@vger.kernel.org>, Masami Hiramatsu <mhiramat@redhat.com>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Jim Keniston <jkenisto@us.ibm.com>, Ingo Molnar <mingo@elte.hu>
Subject: [PATCH -tip v5 2/7] kprobes: checks probe address is instruction boudary on x86
Date: Fri, 08 May 2009 20:48:47 -0400	[thread overview]
Message-ID: <20090509004847.5505.37957.stgit@localhost.localdomain> (raw)
In-Reply-To: <20090509004829.5505.38720.stgit@localhost.localdomain>

Ensure safeness of inserting kprobes by checking whether the specified
address is at the first byte of a instruction on x86.
This is done by decoding probed function from its head to the probe point.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
---

 arch/x86/kernel/kprobes.c |   54 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 7b5169d..3d5e85f 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -48,12 +48,14 @@
 #include <linux/preempt.h>
 #include <linux/module.h>
 #include <linux/kdebug.h>
+#include <linux/kallsyms.h>
 
 #include <asm/cacheflush.h>
 #include <asm/desc.h>
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/alternative.h>
+#include <asm/insn.h>
 
 void jprobe_return_end(void);
 
@@ -244,6 +246,56 @@ retry:
 	}
 }
 
+/* Recover the probed instruction at addr for further analysis. */
+static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
+{
+	struct kprobe *kp;
+	kp = get_kprobe((void *)addr);
+	if (!kp)
+		return -EINVAL;
+
+	/*
+	 * Don't use p->ainsn.insn, which could be modified -- e.g.,
+	 * by fix_riprel().
+	 */
+	memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+	buf[0] = kp->opcode;
+	return 0;
+}
+
+/* Dummy buffers for kallsyms_lookup */
+static char __dummy_buf[KSYM_NAME_LEN];
+
+/* Check if paddr is at an instruction boundary */
+static int __kprobes can_probe(unsigned long paddr)
+{
+	int ret;
+	unsigned long addr, offset = 0;
+	struct insn insn;
+	kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+	/* Lookup symbol including addr */
+	if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf))
+		return 0;
+
+	/* Decode instructions */
+	addr = paddr - offset;
+	while (addr < paddr) {
+		insn_init_kernel(&insn, (void *)addr);
+		insn_get_opcode(&insn);
+		if (OPCODE1(&insn) == BREAKPOINT_INSTRUCTION) {
+			ret = recover_probed_instruction(buf, addr);
+			if (ret)
+				return 0;
+			insn_init_kernel(&insn, buf);
+		}
+		insn_get_length(&insn);
+		addr += insn.length;
+	}
+
+	return (addr == paddr);
+}
+
 /*
  * Returns non-zero if opcode modifies the interrupt flag.
  */
@@ -359,6 +411,8 @@ static void __kprobes arch_copy_kprobe(struct kprobe *p)
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
+	if (!can_probe((unsigned long)p->addr))
+		return -EILSEQ;
 	/* insn: must be on special executable page on x86. */
 	p->ainsn.insn = get_insn_slot();
 	if (!p->ainsn.insn)


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

WARNING: multiple messages have this Message-ID
From: Masami Hiramatsu <mhiramat@redhat.com>
To: Ingo Molnar<mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
	        lkml<linux-kernel@vger.kernel.org>
Cc: systemtap<systemtap@sources.redhat.com>, kvm<kvm@vger.kernel.org>,
	        Masami Hiramatsu <mhiramat@redhat.com>,
	        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	        Jim Keniston <jkenisto@us.ibm.com>,
	Ingo Molnar <mingo@elte.hu>
Subject: [PATCH -tip v5 2/7] kprobes: checks probe address is instruction 	boudary on x86
Date: Fri, 08 May 2009 20:48:47 -0400	[thread overview]
Message-ID: <20090509004847.5505.37957.stgit@localhost.localdomain> (raw)
In-Reply-To: <20090509004829.5505.38720.stgit@localhost.localdomain>

Ensure safeness of inserting kprobes by checking whether the specified
address is at the first byte of a instruction on x86.
This is done by decoding probed function from its head to the probe point.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
---

 arch/x86/kernel/kprobes.c |   54 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 7b5169d..3d5e85f 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -48,12 +48,14 @@
 #include <linux/preempt.h>
 #include <linux/module.h>
 #include <linux/kdebug.h>
+#include <linux/kallsyms.h>
 
 #include <asm/cacheflush.h>
 #include <asm/desc.h>
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/alternative.h>
+#include <asm/insn.h>
 
 void jprobe_return_end(void);
 
@@ -244,6 +246,56 @@ retry:
 	}
 }
 
+/* Recover the probed instruction at addr for further analysis. */
+static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
+{
+	struct kprobe *kp;
+	kp = get_kprobe((void *)addr);
+	if (!kp)
+		return -EINVAL;
+
+	/*
+	 * Don't use p->ainsn.insn, which could be modified -- e.g.,
+	 * by fix_riprel().
+	 */
+	memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+	buf[0] = kp->opcode;
+	return 0;
+}
+
+/* Dummy buffers for kallsyms_lookup */
+static char __dummy_buf[KSYM_NAME_LEN];
+
+/* Check if paddr is at an instruction boundary */
+static int __kprobes can_probe(unsigned long paddr)
+{
+	int ret;
+	unsigned long addr, offset = 0;
+	struct insn insn;
+	kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+	/* Lookup symbol including addr */
+	if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf))
+		return 0;
+
+	/* Decode instructions */
+	addr = paddr - offset;
+	while (addr < paddr) {
+		insn_init_kernel(&insn, (void *)addr);
+		insn_get_opcode(&insn);
+		if (OPCODE1(&insn) == BREAKPOINT_INSTRUCTION) {
+			ret = recover_probed_instruction(buf, addr);
+			if (ret)
+				return 0;
+			insn_init_kernel(&insn, buf);
+		}
+		insn_get_length(&insn);
+		addr += insn.length;
+	}
+
+	return (addr == paddr);
+}
+
 /*
  * Returns non-zero if opcode modifies the interrupt flag.
  */
@@ -359,6 +411,8 @@ static void __kprobes arch_copy_kprobe(struct kprobe *p)
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
+	if (!can_probe((unsigned long)p->addr))
+		return -EILSEQ;
 	/* insn: must be on special executable page on x86. */
 	p->ainsn.insn = get_insn_slot();
 	if (!p->ainsn.insn)


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

  parent reply	other threads:[~2009-05-09  0:46 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-09  0:48 [PATCH -tip v5 0/7] tracing: kprobe-based event tracer and x86 instruction decoder Masami Hiramatsu
2009-05-09  0:48 ` [PATCH -tip v5 1/7] x86: instruction decorder API Masami Hiramatsu
2009-05-11  9:27   ` Christoph Hellwig
2009-05-11 14:36     ` Masami Hiramatsu
2009-05-13  8:23   ` Gleb Natapov
2009-05-13  9:35     ` Przemysław Pawełczyk
2009-05-13  9:43       ` Gleb Natapov
2009-05-13 14:35         ` Masami Hiramatsu
2009-05-13 15:20           ` Gleb Natapov
2009-05-09  0:48 ` Masami Hiramatsu [this message]
2009-05-11 14:20   ` [PATCH -tip v5 2/7] kprobes: checks probe address is instruction boudary on x86 Steven Rostedt
2009-05-11 15:01     ` Masami Hiramatsu
2009-05-11 15:14       ` Masami Hiramatsu
2009-05-11 15:22       ` Steven Rostedt
2009-05-11 18:21         ` Masami Hiramatsu
2009-05-09  0:48 ` [PATCH -tip v5 3/7] kprobes: cleanup fix_riprel() using insn decoder " Masami Hiramatsu
2009-05-09  0:48 ` [PATCH -tip v5 4/7] tracing: add kprobe-based event tracer Masami Hiramatsu
2009-05-09 16:36   ` Frédéric Weisbecker
2009-05-09 17:33     ` Masami Hiramatsu
2009-05-11 21:26       ` Frederic Weisbecker
2009-05-11  9:32   ` Christoph Hellwig
2009-05-11 10:53     ` Ingo Molnar
2009-05-11 15:28     ` Frank Ch. Eigler
2009-05-09  0:49 ` [PATCH -tip v5 5/7] x86: fix kernel_trap_sp() Masami Hiramatsu
2009-05-11  9:28   ` Christoph Hellwig
2009-05-11 13:48     ` Masami Hiramatsu
2009-05-09  0:49 ` [PATCH -tip v5 6/7] x86: add pt_regs register and stack access APIs Masami Hiramatsu
2009-05-09  0:49 ` [PATCH -tip v5 7/7] tracing: add arguments support on kprobe-based event tracer Masami Hiramatsu
2009-05-11 14:35   ` Steven Rostedt
2009-05-09  4:43 ` [PATCH -tip v5 0/7] tracing: kprobe-based event tracer and x86 instruction decoder Ingo Molnar
2009-05-11 14:40   ` Masami Hiramatsu
2009-05-11 14:56     ` Steven Rostedt
2009-05-11 20:05       ` Masami Hiramatsu
2009-05-11 21:47         ` Ingo Molnar
2009-05-12 22:03   ` Masami Hiramatsu
2009-05-13 13:21     ` Ingo Molnar

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