* [PATCH -tip 4/6 V4] x86: kprobes checks safeness of insertion address.
@ 2009-04-02 17:24 Masami Hiramatsu
2009-04-03 5:18 ` Ananth N Mavinakayanahalli
0 siblings, 1 reply; 6+ messages in thread
From: Masami Hiramatsu @ 2009-04-02 17:24 UTC (permalink / raw)
To: Ingo Molnar, Ananth N Mavinakayanahalli, Jim Keniston
Cc: LKML, systemtap-ml, kvm, Andi Kleen, Andrew Morton,
Arnaldo Carvalho de Melo, Steven Rostedt, Frederic Weisbecker
Ensure safeness of inserting kprobes by checking whether the specified
address is at the first byte of a instruction. 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 | 51 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 51 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 7b5169d..39c79cc 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 +246,53 @@ retry:
}
}
+/* Recover original instruction */
+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 will be modified by fix_riprel */
+ memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+ buf[0] = kp->opcode;
+ return 0;
+}
+
+/* Dummy buffers for lookup_symbol_attrs */
+static char __dummy_buf[KSYM_NAME_LEN];
+
+/* Check whether the address can be probed */
+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 +408,8 @@ 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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH -tip 4/6 V4] x86: kprobes checks safeness of insertion address.
2009-04-02 17:24 [PATCH -tip 4/6 V4] x86: kprobes checks safeness of insertion address Masami Hiramatsu
@ 2009-04-03 5:18 ` Ananth N Mavinakayanahalli
2009-04-03 16:02 ` [PATCH -tip 4/6 V4.1] " Masami Hiramatsu
0 siblings, 1 reply; 6+ messages in thread
From: Ananth N Mavinakayanahalli @ 2009-04-03 5:18 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Ingo Molnar, Jim Keniston, LKML, systemtap-ml, kvm, Andi Kleen,
Andrew Morton, Arnaldo Carvalho de Melo, Steven Rostedt,
Frederic Weisbecker
On Thu, Apr 02, 2009 at 01:24:57PM -0400, Masami Hiramatsu wrote:
> +/* Recover original instruction */
> +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 will be modified by fix_riprel */
> + memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
> + buf[0] = kp->opcode;
> + return 0;
> +}
> +
> +/* Dummy buffers for lookup_symbol_attrs */
> +static char __dummy_buf[KSYM_NAME_LEN];
> +
> +/* Check whether the address can be probed */
> +static int __kprobes can_probe(unsigned long paddr)
A better description would've been "Check if paddr is at an instruction
boundary". Otherwise looks good.
Ananth
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH -tip 4/6 V4.1] x86: kprobes checks safeness of insertion address.
2009-04-03 5:18 ` Ananth N Mavinakayanahalli
@ 2009-04-03 16:02 ` Masami Hiramatsu
2009-04-03 17:28 ` Jim Keniston
0 siblings, 1 reply; 6+ messages in thread
From: Masami Hiramatsu @ 2009-04-03 16:02 UTC (permalink / raw)
To: ananth
Cc: Ingo Molnar, Jim Keniston, LKML, systemtap-ml, kvm, Andi Kleen,
Andrew Morton, Arnaldo Carvalho de Melo, Steven Rostedt,
Frederic Weisbecker
Ensure safeness of inserting kprobes by checking whether the specified
address is at the first byte of a instruction. This is done by decoding
probed function from its head to the probe point.
changes from v4:
- change a comment according to Ananth's suggestion.
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 | 51 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 51 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 7b5169d..e4f36e7 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 +246,53 @@ retry:
}
}
+/* Recover original instruction */
+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 will be modified by fix_riprel */
+ memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+ buf[0] = kp->opcode;
+ return 0;
+}
+
+/* Dummy buffers for lookup_symbol_attrs */
+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 +408,8 @@ 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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH -tip 4/6 V4.1] x86: kprobes checks safeness of insertion address.
2009-04-03 16:02 ` [PATCH -tip 4/6 V4.1] " Masami Hiramatsu
@ 2009-04-03 17:28 ` Jim Keniston
2009-04-03 19:20 ` Masami Hiramatsu
0 siblings, 1 reply; 6+ messages in thread
From: Jim Keniston @ 2009-04-03 17:28 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: ananth, Ingo Molnar, LKML, systemtap-ml, kvm, Andi Kleen,
Andrew Morton, Arnaldo Carvalho de Melo, Steven Rostedt,
Frederic Weisbecker
On Fri, 2009-04-03 at 12:02 -0400, Masami Hiramatsu wrote:
> Ensure safeness of inserting kprobes by checking whether the specified
> address is at the first byte of a instruction. This is done by decoding
> probed function from its head to the probe point.
>
> changes from v4:
> - change a comment according to Ananth's suggestion.
>
> 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 | 51 +++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 51 insertions(+), 0 deletions(-)
>
>
> diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
...
>
> +/* Recover original instruction */
/* Recover the probed instruction at addr for further analysis. */
See below.
> +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 will be modified by fix_riprel */
fix_riprel doesn't affect the instruction's length, which is what
concerns this patch. But we want this function to be useful for
unforeseen uses as well, so I like the code you have. Just consider the
suggested comment changes.
/*
* 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;
> +}
Jim Keniston
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH -tip 4/6 V4.1] x86: kprobes checks safeness of insertion address.
2009-04-03 17:28 ` Jim Keniston
@ 2009-04-03 19:20 ` Masami Hiramatsu
2009-04-03 21:21 ` [PATCH -tip 4/6 V4.2] " Masami Hiramatsu
0 siblings, 1 reply; 6+ messages in thread
From: Masami Hiramatsu @ 2009-04-03 19:20 UTC (permalink / raw)
To: Jim Keniston
Cc: ananth, Ingo Molnar, LKML, systemtap-ml, kvm, Andi Kleen,
Andrew Morton, Arnaldo Carvalho de Melo, Steven Rostedt,
Frederic Weisbecker
Jim Keniston wrote:
> On Fri, 2009-04-03 at 12:02 -0400, Masami Hiramatsu wrote:
>> Ensure safeness of inserting kprobes by checking whether the specified
>> address is at the first byte of a instruction. This is done by decoding
>> probed function from its head to the probe point.
>>
>> changes from v4:
>> - change a comment according to Ananth's suggestion.
>>
>> 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 | 51 +++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 51 insertions(+), 0 deletions(-)
>>
>>
>> diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
> ...
>> +/* Recover original instruction */
>
> /* Recover the probed instruction at addr for further analysis. */
> See below.
Sure.
>
>> +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 will be modified by fix_riprel */
>
> fix_riprel doesn't affect the instruction's length, which is what
> concerns this patch. But we want this function to be useful for
> unforeseen uses as well, so I like the code you have. Just consider the
> suggested comment changes.
>
> /*
> * Don't use p->ainsn.insn, which could be modified -- e.g.,
> * by fix_riprel().
> */
Thanks, I'll update comments then!
>
>> + memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
>> + buf[0] = kp->opcode;
>> + return 0;
>> +}
>
> Jim Keniston
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH -tip 4/6 V4.2] x86: kprobes checks safeness of insertion address.
2009-04-03 19:20 ` Masami Hiramatsu
@ 2009-04-03 21:21 ` Masami Hiramatsu
0 siblings, 0 replies; 6+ messages in thread
From: Masami Hiramatsu @ 2009-04-03 21:21 UTC (permalink / raw)
To: Jim Keniston
Cc: ananth, Ingo Molnar, LKML, systemtap-ml, kvm, Andi Kleen,
Andrew Morton, Arnaldo Carvalho de Melo, Steven Rostedt,
Frederic Weisbecker
x86: kprobes checks safeness of insertion address.
From: Masami Hiramatsu <mhiramat@redhat.com>
Ensure safeness of inserting kprobes by checking whether the specified
address is at the first byte of a instruction. This is done by decoding
probed function from its head to the probe point.
changes from v4.1:
- update comments according to Jim's suggestion.
- s/lookup_symbol_attrs/kallsyms_lookup/ in a comment.
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2009-04-03 21:22 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2009-04-02 17:24 [PATCH -tip 4/6 V4] x86: kprobes checks safeness of insertion address Masami Hiramatsu
2009-04-03 5:18 ` Ananth N Mavinakayanahalli
2009-04-03 16:02 ` [PATCH -tip 4/6 V4.1] " Masami Hiramatsu
2009-04-03 17:28 ` Jim Keniston
2009-04-03 19:20 ` Masami Hiramatsu
2009-04-03 21:21 ` [PATCH -tip 4/6 V4.2] " Masami Hiramatsu
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