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>, DLE <dle-develop@lists.sourceforge.net>, "Masami Hiramatsu" <mhiramat@redhat.com>, "Ananth N Mavinakayanahalli" <ananth@in.ibm.com>, "Avi Kivity" <avi@redhat.com>, "Andi Kleen" <ak@linux.intel.com>, "Christoph Hellwig" <hch@infradead.org>, "Frank Ch. Eigler" <fche@redhat.com>, "Frederic Weisbecker" <fweisbec@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>, "Ingo Molnar" <mingo@elte.hu>, "Jason Baron" <jbaron@redhat.com>, "Jim Keniston" <jkenisto@us.ibm.com>, "K.Prasad" <prasad@linux.vnet.ibm.com>, "Lai Jiangshan" <laijs@cn.fujitsu.com>, "Li Zefan" <lizf@cn.fujitsu.com>, PrzemysławPawełczyk <przemyslaw@pawelczyk.it>, "Roland McGrath" <roland@redhat.com>, "Sam Ravnborg" <sam@ravnborg.org>, "Srikar Dronamraju" <srikar@linux.vnet.ibm.com>, "Steven Rostedt" <rostedt@goodmis.org>, "Tom Zanussi" <tzanussi@gmail.com>, "Vegard Nossum" <vegard.nossum@gmail.com> Subject: [PATCH -tip v14 03/12] kprobes: checks probe address is instruction boudary on x86 Date: Thu, 13 Aug 2009 16:34:28 -0400 [thread overview] Message-ID: <20090813203428.31965.21939.stgit@localhost.localdomain> (raw) In-Reply-To: <20090813203403.31965.20973.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> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Avi Kivity <avi@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Frank Ch. Eigler <fche@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jason Baron <jbaron@redhat.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it> Cc: Roland McGrath <roland@redhat.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tom Zanussi <tzanussi@gmail.com> Cc: Vegard Nossum <vegard.nossum@gmail.com> --- arch/x86/kernel/kprobes.c | 69 +++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 69 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index b5b1848..80d493f 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -48,6 +48,7 @@ #include <linux/preempt.h> #include <linux/module.h> #include <linux/kdebug.h> +#include <linux/kallsyms.h> #include <asm/cacheflush.h> #include <asm/desc.h> @@ -55,6 +56,7 @@ #include <asm/uaccess.h> #include <asm/alternative.h> #include <asm/debugreg.h> +#include <asm/insn.h> void jprobe_return_end(void); @@ -245,6 +247,71 @@ 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; + + /* + * Basically, kp->ainsn.insn has an original instruction. + * However, RIP-relative instruction can not do single-stepping + * at different place, fix_riprel() tweaks the displacement of + * that instruction. In that case, we can't recover the instruction + * from the kp->ainsn.insn. + * + * On the other hand, kp->opcode has a copy of the first byte of + * the probed instruction, which is overwritten by int3. And + * the instruction at kp->addr is not modified by kprobes except + * for the first byte, we can recover the original instruction + * from it and kp->opcode. + */ + 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]; + + if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf)) + return 0; + + /* Decode instructions */ + addr = paddr - offset; + while (addr < paddr) { + kernel_insn_init(&insn, (void *)addr); + insn_get_opcode(&insn); + + /* Check if the instruction has been modified. */ + if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { + ret = recover_probed_instruction(buf, addr); + if (ret) + /* + * Another debugging subsystem might insert + * this breakpoint. In that case, we can't + * recover it. + */ + return 0; + kernel_insn_init(&insn, buf); + } + insn_get_length(&insn); + addr += insn.length; + } + + return (addr == paddr); +} + /* * Returns non-zero if opcode modifies the interrupt flag. */ @@ -360,6 +427,8 @@ 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 (diff)
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>, DLE <dle-develop@lists.sourceforge.net>, "Masami Hiramatsu" <mhiramat@redhat.com>, "Ananth N Mavinakayanahalli" <ananth@in.ibm.com>, "Avi Kivity" <avi@redhat.com>, "Andi Kleen" <ak@linux.intel.com>, "Christoph Hellwig" <hch@infradead.org>, "Frank Ch. Eigler" <fche@redhat.com>, "Frederic Weisbecker" <fweisbec@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>, "Ingo Molnar" <mingo@elte.hu>, "Jason Baron" <jbaron@redhat.com>, "Jim Keniston" <jkenisto@us.ibm.com>, "K.Prasad" <prasad@linux.vnet.ibm.com>, "Lai Jiangshan" <laijs@cn.fujitsu.com>, "Li Zefan" <lizf@cn.fujitsu.com>, PrzemysławPawełczyk <przemyslaw@pawelczyk.it>, "Roland McGrath" <roland@redhat.com>, "Sam Ravnborg" <sam@ravnborg.org> Subject: [PATCH -tip v14 03/12] kprobes: checks probe address is instruction boudary on x86 Date: Thu, 13 Aug 2009 16:34:28 -0400 [thread overview] Message-ID: <20090813203428.31965.21939.stgit@localhost.localdomain> (raw) In-Reply-To: <20090813203403.31965.20973.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> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Avi Kivity <avi@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Frank Ch. Eigler <fche@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jason Baron <jbaron@redhat.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it> Cc: Roland McGrath <roland@redhat.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tom Zanussi <tzanussi@gmail.com> Cc: Vegard Nossum <vegard.nossum@gmail.com> --- arch/x86/kernel/kprobes.c | 69 +++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 69 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index b5b1848..80d493f 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -48,6 +48,7 @@ #include <linux/preempt.h> #include <linux/module.h> #include <linux/kdebug.h> +#include <linux/kallsyms.h> #include <asm/cacheflush.h> #include <asm/desc.h> @@ -55,6 +56,7 @@ #include <asm/uaccess.h> #include <asm/alternative.h> #include <asm/debugreg.h> +#include <asm/insn.h> void jprobe_return_end(void); @@ -245,6 +247,71 @@ 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; + + /* + * Basically, kp->ainsn.insn has an original instruction. + * However, RIP-relative instruction can not do single-stepping + * at different place, fix_riprel() tweaks the displacement of + * that instruction. In that case, we can't recover the instruction + * from the kp->ainsn.insn. + * + * On the other hand, kp->opcode has a copy of the first byte of + * the probed instruction, which is overwritten by int3. And + * the instruction at kp->addr is not modified by kprobes except + * for the first byte, we can recover the original instruction + * from it and kp->opcode. + */ + 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]; + + if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf)) + return 0; + + /* Decode instructions */ + addr = paddr - offset; + while (addr < paddr) { + kernel_insn_init(&insn, (void *)addr); + insn_get_opcode(&insn); + + /* Check if the instruction has been modified. */ + if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { + ret = recover_probed_instruction(buf, addr); + if (ret) + /* + * Another debugging subsystem might insert + * this breakpoint. In that case, we can't + * recover it. + */ + return 0; + kernel_insn_init(&insn, buf); + } + insn_get_length(&insn); + addr += insn.length; + } + + return (addr == paddr); +} + /* * Returns non-zero if opcode modifies the interrupt flag. */ @@ -360,6 +427,8 @@ 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
next prev parent reply other threads:[~2009-08-13 20:35 UTC|newest] Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-08-13 20:34 [PATCH -tip v14 00/12] tracing: kprobe-based event tracer and x86 instruction decoder Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:34 ` [PATCH -tip v14 01/12] x86: instruction decoder API Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-19 23:42 ` Frederic Weisbecker 2009-08-20 0:21 ` Frederic Weisbecker 2009-08-20 15:03 ` Masami Hiramatsu 2009-08-20 15:03 ` Masami Hiramatsu 2009-08-20 15:25 ` Frederic Weisbecker 2009-08-20 16:16 ` Masami Hiramatsu 2009-08-20 16:16 ` Masami Hiramatsu 2009-08-20 18:07 ` Frederic Weisbecker 2009-08-20 19:01 ` Masami Hiramatsu 2009-08-20 19:01 ` Masami Hiramatsu 2009-08-20 20:14 ` Frederic Weisbecker 2009-08-20 14:42 ` Masami Hiramatsu 2009-08-20 14:42 ` Masami Hiramatsu 2009-08-20 14:46 ` Frederic Weisbecker 2009-08-13 20:34 ` [PATCH -tip v14 02/12] x86: x86 instruction decoder build-time selftest Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu [this message] 2009-08-13 20:34 ` [PATCH -tip v14 03/12] kprobes: checks probe address is instruction boudary on x86 Masami Hiramatsu 2009-08-18 23:03 ` Frederic Weisbecker 2009-08-18 23:17 ` Masami Hiramatsu 2009-08-18 23:17 ` Masami Hiramatsu 2009-08-18 23:43 ` Frederic Weisbecker 2009-08-19 0:19 ` Masami Hiramatsu 2009-08-19 0:19 ` Masami Hiramatsu 2009-08-19 0:46 ` Frederic Weisbecker 2009-08-13 20:34 ` [PATCH -tip v14 04/12] kprobes: cleanup fix_riprel() using insn decoder " Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:34 ` [PATCH -tip v14 05/12] x86: add pt_regs register and stack access APIs Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:34 ` [PATCH -tip v14 06/12] tracing: ftrace dynamic ftrace_event_call support Masami Hiramatsu 2009-08-13 20:34 ` Masami Hiramatsu 2009-08-13 20:35 ` [PATCH -tip v14 07/12] tracing: Introduce TRACE_FIELD_ZERO() macro Masami Hiramatsu 2009-08-13 20:35 ` Masami Hiramatsu 2009-08-19 1:09 ` Frederic Weisbecker 2009-08-19 2:20 ` Masami Hiramatsu 2009-08-19 2:20 ` Masami Hiramatsu 2009-08-19 13:58 ` Frederic Weisbecker 2009-08-13 20:35 ` [PATCH -tip v14 08/12] tracing: add kprobe-based event tracer Masami Hiramatsu 2009-08-13 20:35 ` Masami Hiramatsu 2009-08-19 1:23 ` Frederic Weisbecker 2009-08-13 20:35 ` [PATCH -tip v14 09/12] tracing: Kprobe-tracer supports more than 6 arguments Masami Hiramatsu 2009-08-13 20:35 ` Masami Hiramatsu 2009-08-13 20:35 ` [PATCH -tip v14 10/12] tracing: Generate names for each kprobe event automatically Masami Hiramatsu 2009-08-13 20:35 ` Masami Hiramatsu 2009-08-13 20:35 ` [PATCH -tip v14 11/12] tracing: Kprobe tracer assigns new event ids for each event Masami Hiramatsu 2009-08-13 20:35 ` Masami Hiramatsu 2009-08-13 20:35 ` [PATCH -tip v14 12/12] tracing: Add kprobes event profiling interface Masami Hiramatsu 2009-08-13 20:35 ` Masami Hiramatsu 2009-08-13 20:57 ` [TOOL] kprobestest : Kprobe stress test tool Masami Hiramatsu 2009-08-13 20:57 ` Masami Hiramatsu 2009-08-20 18:43 ` Frederic Weisbecker 2009-08-20 19:45 ` Masami Hiramatsu 2009-08-20 19:45 ` Masami Hiramatsu 2009-08-21 0:01 ` Frederic Weisbecker 2009-08-21 1:00 ` Masami Hiramatsu 2009-08-21 1:00 ` Masami Hiramatsu 2009-08-21 19:43 ` [PATCH tracing/kprobes 1/4] x86: Fix x86 instruction decoder selftest to check only .text Masami Hiramatsu 2009-08-21 19:43 ` Masami Hiramatsu 2009-08-23 19:34 ` Frederic Weisbecker 2009-08-21 19:43 ` [PATCH tracing/kprobes 2/4] x86: Check awk features before generating inat-tables.c Masami Hiramatsu 2009-08-21 19:43 ` Masami Hiramatsu 2009-08-21 19:43 ` [PATCH tracing/kprobes 3/4] tracing/kprobes: Fix format typo in trace_kprobes Masami Hiramatsu 2009-08-21 19:43 ` Masami Hiramatsu 2009-08-21 19:43 ` [PATCH tracing/kprobes 4/4] tracing/kprobes: Change trace_arg to probe_arg Masami Hiramatsu 2009-08-21 19:43 ` Masami Hiramatsu 2009-08-13 20:59 ` [TOOL] c2kpe: C expression to kprobe event format converter Masami Hiramatsu 2009-08-13 20:59 ` Masami Hiramatsu 2009-08-13 21:05 ` Christoph Hellwig 2009-08-13 21:05 ` Christoph Hellwig 2009-08-30 19:50 ` Frederic Weisbecker 2009-08-31 4:14 ` Masami Hiramatsu 2009-08-31 4:14 ` Masami Hiramatsu 2009-08-31 22:14 ` Frederic Weisbecker
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