The patch titled
jprobes: make jprobes a little safer for users
has been added to the -mm tree. Its filename is
jprobes-make-jprobes-a-little-safer-for-users.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: jprobes: make jprobes a little safer for users
From: Michael Ellerman <michael@xxxxxxxxxxxxxx>
I realise jprobes are a razor-blades-included type of interface, but that
doesn't mean we can't try and make them safer to use. This guy I know once
wrote code like this:
struct jprobe jp = { .kp.symbol_name = "foo", .entry = "jprobe_foo" };
And then his kernel exploded. Oops.
This patch adds an arch hook, arch_deref_entry_point() (I don't like it
either) which takes the void * in a struct jprobe, and gives back the text
address that it represents.
We can then use that in register_jprobe() to check that the entry point we're
passed is actually in the kernel text, rather than just some random value.
Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx>
Cc: Prasanna S Panchamukhi <prasanna@xxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/ia64/kernel/kprobes.c | 7 ++++++-
arch/powerpc/kernel/kprobes.c | 11 ++++++++---
kernel/kprobes.c | 9 +++++++++
3 files changed, 23 insertions(+), 4 deletions(-)
diff -puN arch/ia64/kernel/kprobes.c~jprobes-make-jprobes-a-little-safer-for-users arch/ia64/kernel/kprobes.c
--- a/arch/ia64/kernel/kprobes.c~jprobes-make-jprobes-a-little-safer-for-users
+++ a/arch/ia64/kernel/kprobes.c
@@ -936,10 +936,15 @@ static void ia64_get_bsp_cfm(struct unw_
return;
}
+unsigned long arch_deref_entry_point(void *entry)
+{
+ return ((struct fnptr *)entry)->ip;
+}
+
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
- unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
+ unsigned long addr = arch_deref_entry_point(jp->entry);
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
struct param_bsp_cfm pa;
int bytes;
diff -puN arch/powerpc/kernel/kprobes.c~jprobes-make-jprobes-a-little-safer-for-users arch/powerpc/kernel/kprobes.c
--- a/arch/powerpc/kernel/kprobes.c~jprobes-make-jprobes-a-little-safer-for-users
+++ a/arch/powerpc/kernel/kprobes.c
@@ -492,6 +492,13 @@ int __kprobes kprobe_exceptions_notify(s
return ret;
}
+#ifdef CONFIG_PPC64
+unsigned long arch_deref_entry_point(void *entry)
+{
+ return (unsigned long)(((func_descr_t *)entry)->entry);
+}
+#endif
+
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
@@ -500,11 +507,9 @@ int __kprobes setjmp_pre_handler(struct
memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
/* setup return addr to the jprobe handler routine */
+ regs->nip = arch_deref_entry_point(jp->entry);
#ifdef CONFIG_PPC64
- regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
-#else
- regs->nip = (unsigned long)jp->entry;
#endif
return 1;
diff -puN kernel/kprobes.c~jprobes-make-jprobes-a-little-safer-for-users kernel/kprobes.c
--- a/kernel/kprobes.c~jprobes-make-jprobes-a-little-safer-for-users
+++ a/kernel/kprobes.c
@@ -675,9 +675,18 @@ static struct notifier_block kprobe_exce
.priority = 0x7fffffff /* we need to be notified first */
};
+unsigned long __weak arch_deref_entry_point(void *entry)
+{
+ return (unsigned long)entry;
+}
int __kprobes register_jprobe(struct jprobe *jp)
{
+ unsigned long addr = arch_deref_entry_point(jp->entry);
+
+ if (!kernel_text_address(addr))
+ return -EINVAL;
+
/* Todo: Verify probepoint is a function entry point */
jp->kp.pre_handler = setjmp_pre_handler;
jp->kp.break_handler = longjmp_break_handler;
_
Patches currently in -mm which might be from michael@xxxxxxxxxxxxxx are
jprobes-make-struct-jprobeentry-a-void.patch
jprobes-remove-jprobe_entry.patch
jprobes-make-jprobes-a-little-safer-for-users.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
