Hi,
Here is the 13th version of rethook x86 port. This is developed for a part
of fprobe series [1] for hooking function return. But since I forgot to send
it to arch maintainers, that caused conflict with IBT and SLS mitigation series.
Now I picked the x86 rethook part and send it to x86 maintainers to be
reviewed.
[1] https://lore.kernel.org/all/164735281449.1084943.12438881786173547153.stgit@devnote2/T/#u
Note that this patch is still for the bpf-next since the rethook itself
is on the bpf-next tree. But since this also uses the ANNOTATE_NOENDBR
macro which has been introduced by IBT/ENDBR patch, to build this series
you need to merge the tip/master branch with the bpf-next.
(hopefully, it is rebased soon)
The fprobe itself is for providing the function entry/exit probe
with multiple probe point. The rethook is a sub-feature to hook the
function return as same as kretprobe does. Eventually, I would like
to replace the kretprobe's trampoline with this rethook.
Thank you,
---
Masami Hiramatsu (1):
rethook: x86: Add rethook x86 implementation
arch/x86/Kconfig | 1
arch/x86/include/asm/unwind.h | 8 ++-
arch/x86/kernel/Makefile | 1
arch/x86/kernel/kprobes/common.h | 1
arch/x86/kernel/rethook.c | 121 ++++++++++++++++++++++++++++++++++++++
5 files changed, 131 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/kernel/rethook.c
--
Masami Hiramatsu (Linaro) <[email protected]>
On Wed, Mar 23, 2022 at 11:34:46AM +0900, Masami Hiramatsu wrote:
> Hi,
Hi Masami,
> Here is the 13th version of rethook x86 port. This is developed for a part
> of fprobe series [1] for hooking function return. But since I forgot to send
> it to arch maintainers, that caused conflict with IBT and SLS mitigation series.
> Now I picked the x86 rethook part and send it to x86 maintainers to be
> reviewed.
>
> [1] https://lore.kernel.org/all/164735281449.1084943.12438881786173547153.stgit@devnote2/T/#u
As mentioned elsewhere, I have similar (though not identical) concerns
to Peter for the arm64 patch, which was equally unreviewed by
maintainers, and the overall structure.
> Note that this patch is still for the bpf-next since the rethook itself
> is on the bpf-next tree. But since this also uses the ANNOTATE_NOENDBR
> macro which has been introduced by IBT/ENDBR patch, to build this series
> you need to merge the tip/master branch with the bpf-next.
> (hopefully, it is rebased soon)
I thought we were going to drop the series from the bpf-next tree so
that this could all go through review it had missed thusfar.
Is that still the plan? What's going on?
> The fprobe itself is for providing the function entry/exit probe
> with multiple probe point. The rethook is a sub-feature to hook the
> function return as same as kretprobe does. Eventually, I would like
> to replace the kretprobe's trampoline with this rethook.
Can we please start by converting each architecture to rethook?
Ideally we'd unify things such that each architecture only needs *one*
return trampoline that both ftrace and krpboes can use, which'd be
significantly easier to get right and manage.
Thanks,
Mark.
On Wed, Mar 23, 2022 at 11:55:39PM +0900, Masami Hiramatsu wrote:
> On Wed, 23 Mar 2022 14:18:40 +0000
> Mark Rutland <[email protected]> wrote:
>
> > On Wed, Mar 23, 2022 at 11:34:46AM +0900, Masami Hiramatsu wrote:
> > > Hi,
> >
> > Hi Masami,
> >
> > > Here is the 13th version of rethook x86 port. This is developed for a part
> > > of fprobe series [1] for hooking function return. But since I forgot to send
> > > it to arch maintainers, that caused conflict with IBT and SLS mitigation series.
> > > Now I picked the x86 rethook part and send it to x86 maintainers to be
> > > reviewed.
> > >
> > > [1] https://lore.kernel.org/all/164735281449.1084943.12438881786173547153.stgit@devnote2/T/#u
> >
> > As mentioned elsewhere, I have similar (though not identical) concerns
> > to Peter for the arm64 patch, which was equally unreviewed by
> > maintainers, and the overall structure.
>
> Yes, those should be reviewed by arch maintainers.
>
> > > Note that this patch is still for the bpf-next since the rethook itself
> > > is on the bpf-next tree. But since this also uses the ANNOTATE_NOENDBR
> > > macro which has been introduced by IBT/ENDBR patch, to build this series
> > > you need to merge the tip/master branch with the bpf-next.
> > > (hopefully, it is rebased soon)
> >
> > I thought we were going to drop the series from the bpf-next tree so
> > that this could all go through review it had missed thusfar.
> >
> > Is that still the plan? What's going on?
>
> Now the arm64 (and other arch) port is reverted from bpf-next.
> I'll send those to you soon.
Ah; thanks for confirming!
> Since bpf-next is focusing on x86 at first, I chose this for review in
> this version. Sorry for confusion.
No problem; I think the confusion is all my own, so nothing to apologise
for! :)
> > > The fprobe itself is for providing the function entry/exit probe
> > > with multiple probe point. The rethook is a sub-feature to hook the
> > > function return as same as kretprobe does. Eventually, I would like
> > > to replace the kretprobe's trampoline with this rethook.
> >
> > Can we please start by converting each architecture to rethook?
>
> Yes. As Peter pointed, I'm planning to add a kretprobe patches to use
> rethook if available in that series. let me prepare it.
>
> > Ideally we'd unify things such that each architecture only needs *one*
> > return trampoline that both ftrace and krpboes can use, which'd be
> > significantly easier to get right and manage.
>
> Agreed :-)
Great!
Thanks,
Mark.
Add rethook for x86 implementation. Most of the code has been copied from
kretprobes on x86.
Signed-off-by: Masami Hiramatsu <[email protected]>
---
Changes in v13:
- Add no ENDBR annotation for return trampoline code.
- Replace ret with ASM_RET for Straight-Line-Speculation mitigation.
Changes in v11:
- Mark arch_rethook_fixup_return() as NOKPROBE_SYMBOL.
- Add a function prototype of arch_rethook_trampoline_callback
to suppress warning.
Changes in v10:
- Add a dummy @mcount to arch_rethook_prepare().
Changes in v5:
- Fix a build error if !CONFIG_KRETPROBES and !CONFIG_RETHOOK.
Changes in v4:
- fix stack backtrace as same as kretprobe does.
---
arch/x86/Kconfig | 1
arch/x86/include/asm/unwind.h | 8 ++-
arch/x86/kernel/Makefile | 1
arch/x86/kernel/kprobes/common.h | 1
arch/x86/kernel/rethook.c | 121 ++++++++++++++++++++++++++++++++++++++
5 files changed, 131 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/kernel/rethook.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9b356da6f46b..1270b65a5546 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -221,6 +221,7 @@ config X86
select HAVE_KPROBES_ON_FTRACE
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
+ select HAVE_RETHOOK
select HAVE_KVM
select HAVE_LIVEPATCH if X86_64
select HAVE_MIXED_BREAKPOINTS_REGS
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 2a1f8734416d..192df5b2094d 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -5,6 +5,7 @@
#include <linux/sched.h>
#include <linux/ftrace.h>
#include <linux/kprobes.h>
+#include <linux/rethook.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
@@ -16,7 +17,7 @@ struct unwind_state {
unsigned long stack_mask;
struct task_struct *task;
int graph_idx;
-#ifdef CONFIG_KRETPROBES
+#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
struct llist_node *kr_cur;
#endif
bool error;
@@ -107,6 +108,11 @@ static inline
unsigned long unwind_recover_kretprobe(struct unwind_state *state,
unsigned long addr, unsigned long *addr_p)
{
+#ifdef CONFIG_RETHOOK
+ if (is_rethook_trampoline(addr))
+ return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
+ &state->kr_cur);
+#endif
#ifdef CONFIG_KRETPROBES
return is_kretprobe_trampoline(addr) ?
kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 6aef9ee28a39..792a893a5cc5 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
obj-$(CONFIG_X86_TSC) += trace_clock.o
obj-$(CONFIG_TRACING) += trace.o
+obj-$(CONFIG_RETHOOK) += rethook.o
obj-$(CONFIG_CRASH_CORE) += crash_core_$(BITS).o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec_$(BITS).o
obj-$(CONFIG_KEXEC_CORE) += relocate_kernel_$(BITS).o crash.o
diff --git a/arch/x86/kernel/kprobes/common.h b/arch/x86/kernel/kprobes/common.h
index 7d3a2e2daf01..c993521d4933 100644
--- a/arch/x86/kernel/kprobes/common.h
+++ b/arch/x86/kernel/kprobes/common.h
@@ -6,6 +6,7 @@
#include <asm/asm.h>
#include <asm/frame.h>
+#include <asm/insn.h>
#ifdef CONFIG_X86_64
diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c
new file mode 100644
index 000000000000..3e916361c33b
--- /dev/null
+++ b/arch/x86/kernel/rethook.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * x86 implementation of rethook. Mostly copied from arch/x86/kernel/kprobes/core.c.
+ */
+#include <linux/bug.h>
+#include <linux/rethook.h>
+#include <linux/kprobes.h>
+#include <linux/objtool.h>
+
+#include "kprobes/common.h"
+
+__visible void arch_rethook_trampoline_callback(struct pt_regs *regs);
+
+/*
+ * When a target function returns, this code saves registers and calls
+ * arch_rethook_trampoline_callback(), which calls the rethook handler.
+ */
+asm(
+ ".text\n"
+ ".global arch_rethook_trampoline\n"
+ ".type arch_rethook_trampoline, @function\n"
+ "arch_rethook_trampoline:\n"
+#ifdef CONFIG_X86_64
+ ANNOTATE_NOENDBR /* This is only jumped from ret instruction */
+ /* Push a fake return address to tell the unwinder it's a kretprobe. */
+ " pushq $arch_rethook_trampoline\n"
+ UNWIND_HINT_FUNC
+ /* Save the 'sp - 8', this will be fixed later. */
+ " pushq %rsp\n"
+ " pushfq\n"
+ SAVE_REGS_STRING
+ " movq %rsp, %rdi\n"
+ " call arch_rethook_trampoline_callback\n"
+ RESTORE_REGS_STRING
+ /* In the callback function, 'regs->flags' is copied to 'regs->sp'. */
+ " addq $8, %rsp\n"
+ " popfq\n"
+#else
+ /* Push a fake return address to tell the unwinder it's a kretprobe. */
+ " pushl $arch_rethook_trampoline\n"
+ UNWIND_HINT_FUNC
+ /* Save the 'sp - 4', this will be fixed later. */
+ " pushl %esp\n"
+ " pushfl\n"
+ SAVE_REGS_STRING
+ " movl %esp, %eax\n"
+ " call arch_rethook_trampoline_callback\n"
+ RESTORE_REGS_STRING
+ /* In the callback function, 'regs->flags' is copied to 'regs->sp'. */
+ " addl $4, %esp\n"
+ " popfl\n"
+#endif
+ ASM_RET
+ ".size arch_rethook_trampoline, .-arch_rethook_trampoline\n"
+);
+NOKPROBE_SYMBOL(arch_rethook_trampoline);
+
+/*
+ * Called from arch_rethook_trampoline
+ */
+__used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs)
+{
+ unsigned long *frame_pointer;
+
+ /* fixup registers */
+ regs->cs = __KERNEL_CS;
+#ifdef CONFIG_X86_32
+ regs->gs = 0;
+#endif
+ regs->ip = (unsigned long)&arch_rethook_trampoline;
+ regs->orig_ax = ~0UL;
+ regs->sp += sizeof(long);
+ frame_pointer = ®s->sp + 1;
+
+ /*
+ * The return address at 'frame_pointer' is recovered by the
+ * arch_rethook_fixup_return() which called from this
+ * rethook_trampoline_handler().
+ */
+ rethook_trampoline_handler(regs, (unsigned long)frame_pointer);
+
+ /*
+ * Copy FLAGS to 'pt_regs::sp' so that arch_rethook_trapmoline()
+ * can do RET right after POPF.
+ */
+ regs->sp = regs->flags;
+}
+NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
+
+/*
+ * arch_rethook_trampoline() skips updating frame pointer. The frame pointer
+ * saved in arch_rethook_trampoline_callback() points to the real caller
+ * function's frame pointer. Thus the arch_rethook_trampoline() doesn't have
+ * a standard stack frame with CONFIG_FRAME_POINTER=y.
+ * Let's mark it non-standard function. Anyway, FP unwinder can correctly
+ * unwind without the hint.
+ */
+STACK_FRAME_NON_STANDARD_FP(arch_rethook_trampoline);
+
+/* This is called from rethook_trampoline_handler(). */
+void arch_rethook_fixup_return(struct pt_regs *regs,
+ unsigned long correct_ret_addr)
+{
+ unsigned long *frame_pointer = ®s->sp + 1;
+
+ /* Replace fake return address with real one. */
+ *frame_pointer = correct_ret_addr;
+}
+NOKPROBE_SYMBOL(arch_rethook_fixup_return);
+
+void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs, bool mcount)
+{
+ unsigned long *stack = (unsigned long *)regs->sp;
+
+ rh->ret_addr = stack[0];
+ rh->frame = regs->sp;
+
+ /* Replace the return addr with trampoline addr */
+ stack[0] = (unsigned long) arch_rethook_trampoline;
+}
+NOKPROBE_SYMBOL(arch_rethook_prepare);
On Wed, 23 Mar 2022 14:18:40 +0000
Mark Rutland <[email protected]> wrote:
> On Wed, Mar 23, 2022 at 11:34:46AM +0900, Masami Hiramatsu wrote:
> > Hi,
>
> Hi Masami,
>
> > Here is the 13th version of rethook x86 port. This is developed for a part
> > of fprobe series [1] for hooking function return. But since I forgot to send
> > it to arch maintainers, that caused conflict with IBT and SLS mitigation series.
> > Now I picked the x86 rethook part and send it to x86 maintainers to be
> > reviewed.
> >
> > [1] https://lore.kernel.org/all/164735281449.1084943.12438881786173547153.stgit@devnote2/T/#u
>
> As mentioned elsewhere, I have similar (though not identical) concerns
> to Peter for the arm64 patch, which was equally unreviewed by
> maintainers, and the overall structure.
Yes, those should be reviewed by arch maintainers.
>
> > Note that this patch is still for the bpf-next since the rethook itself
> > is on the bpf-next tree. But since this also uses the ANNOTATE_NOENDBR
> > macro which has been introduced by IBT/ENDBR patch, to build this series
> > you need to merge the tip/master branch with the bpf-next.
> > (hopefully, it is rebased soon)
>
> I thought we were going to drop the series from the bpf-next tree so
> that this could all go through review it had missed thusfar.
>
> Is that still the plan? What's going on?
Now the arm64 (and other arch) port is reverted from bpf-next.
I'll send those to you soon.
Since bpf-next is focusing on x86 at first, I chose this for review in
this version. Sorry for confusion.
>
> > The fprobe itself is for providing the function entry/exit probe
> > with multiple probe point. The rethook is a sub-feature to hook the
> > function return as same as kretprobe does. Eventually, I would like
> > to replace the kretprobe's trampoline with this rethook.
>
> Can we please start by converting each architecture to rethook?
Yes. As Peter pointed, I'm planning to add a kretprobe patches to use
rethook if available in that series. let me prepare it.
>
> Ideally we'd unify things such that each architecture only needs *one*
> return trampoline that both ftrace and krpboes can use, which'd be
> significantly easier to get right and manage.
Agreed :-)
Thank you,
>
> Thanks,
> Mark.
--
Masami Hiramatsu <[email protected]>
On Thu, Mar 24, 2022 at 7:21 PM Masami Hiramatsu <[email protected]> wrote:
>
> On Thu, 24 Mar 2022 19:03:43 -0700
> Alexei Starovoitov <[email protected]> wrote:
>
> > On Wed, Mar 23, 2022 at 4:41 AM Masami Hiramatsu <[email protected]> wrote:
> > >
> > > On Wed, 23 Mar 2022 09:05:26 +0100
> > > Peter Zijlstra <[email protected]> wrote:
> > >
> > > > On Wed, Mar 23, 2022 at 11:34:59AM +0900, Masami Hiramatsu wrote:
> > > > > Add rethook for x86 implementation. Most of the code has been copied from
> > > > > kretprobes on x86.
> > > >
> > > > Right; as said, I'm really unhappy with growing a carbon copy of this
> > > > stuff instead of sharing. Can we *please* keep it a single instance?
> > >
> > > OK, then let me update the kprobe side too.
> > >
> > > > Them being basically indentical, it should be trivial to have
> > > > CONFIG_KPROBE_ON_RETHOOK (or somesuch) and just share this.
> > >
> > > Yes, ideally it should use CONFIG_HAVE_RETHOOK since the rethook arch port
> > > must be a copy of the kretprobe implementation. But for safety, I think
> > > having CONFIG_KPROBE_ON_RETHOOK is a good idea until replacing all kretprobe
> > > implementations.
> >
> > Masami,
> >
> > you're respinning this patch to combine
> > arch_rethook_trampoline and __kretprobe_trampoline
> > right?
>
> Yes, let me send the first patch set (for x86 at first).
great
> BTW, can you review these 2 patches? These are only for the fprobes,
> so it can be picked to bpf-next.
>
> https://lore.kernel.org/all/164802091567.1732982.1242854551611267542.stgit@devnote2/T/#u
Yes. They look good. Will push them soon.
Hi,
The title is not updated. It should be;
rethook: x86: Add rethook x86 porting (drived from "fprobe: Introduce fprobe function entry/exit probe" series)
Thank you,
On Wed, 23 Mar 2022 11:34:46 +0900
Masami Hiramatsu <[email protected]> wrote:
> Hi,
>
> Here is the 13th version of rethook x86 port. This is developed for a part
> of fprobe series [1] for hooking function return. But since I forgot to send
> it to arch maintainers, that caused conflict with IBT and SLS mitigation series.
> Now I picked the x86 rethook part and send it to x86 maintainers to be
> reviewed.
>
> [1] https://lore.kernel.org/all/164735281449.1084943.12438881786173547153.stgit@devnote2/T/#u
>
> Note that this patch is still for the bpf-next since the rethook itself
> is on the bpf-next tree. But since this also uses the ANNOTATE_NOENDBR
> macro which has been introduced by IBT/ENDBR patch, to build this series
> you need to merge the tip/master branch with the bpf-next.
> (hopefully, it is rebased soon)
>
> The fprobe itself is for providing the function entry/exit probe
> with multiple probe point. The rethook is a sub-feature to hook the
> function return as same as kretprobe does. Eventually, I would like
> to replace the kretprobe's trampoline with this rethook.
>
> Thank you,
>
> ---
>
> Masami Hiramatsu (1):
> rethook: x86: Add rethook x86 implementation
>
>
> arch/x86/Kconfig | 1
> arch/x86/include/asm/unwind.h | 8 ++-
> arch/x86/kernel/Makefile | 1
> arch/x86/kernel/kprobes/common.h | 1
> arch/x86/kernel/rethook.c | 121 ++++++++++++++++++++++++++++++++++++++
> 5 files changed, 131 insertions(+), 1 deletion(-)
> create mode 100644 arch/x86/kernel/rethook.c
>
> --
> Masami Hiramatsu (Linaro) <[email protected]>
--
Masami Hiramatsu <[email protected]>