| Message ID | 20220921204206.95480-1-hjl.tools@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86: Check corrupted return address when unwinding stack | expand |
On 9/21/22 14:42, H.J. Lu via Gcc-patches wrote: > If shadow stack is enabled, when unwinding stack, we count how many stack > frames we pop to reach the landing pad and adjust shadow stack by the same > amount. When counting the stack frame, we compare the return address on > normal stack against the return address on shadow stack. If they don't > match, return _URC_FATAL_PHASE2_ERROR for the corrupted return address on > normal stack. Don't check the return address for > > 1. Non-catchable exception where exception_class == 0. Process will be > terminated. > 2. Zero return address which marks the outermost stack frame. > 3. Signal stack frame since kernel puts a restore token on shadow stack. > > * unwind-generic.h (_Unwind_Frames_Increment): Add the EXC > argument. > * unwind.inc (_Unwind_RaiseException_Phase2): Pass EXC to > _Unwind_Frames_Increment. > (_Unwind_ForcedUnwind_Phase2): Likewise. > * config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment): > Take the EXC argument. Return _URC_FATAL_PHASE2_ERROR if the > return address on normal stack doesn't match the return address > on shadow stack. The generic bits are fine. While I'm aware of one other target that _might_ need adjustment, it's an out-of-tree target and thus clearly not your responsibility. jeff
On Wed, Sep 21, 2022 at 1:42 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > If shadow stack is enabled, when unwinding stack, we count how many stack > frames we pop to reach the landing pad and adjust shadow stack by the same > amount. When counting the stack frame, we compare the return address on > normal stack against the return address on shadow stack. If they don't > match, return _URC_FATAL_PHASE2_ERROR for the corrupted return address on > normal stack. Don't check the return address for > > 1. Non-catchable exception where exception_class == 0. Process will be > terminated. > 2. Zero return address which marks the outermost stack frame. > 3. Signal stack frame since kernel puts a restore token on shadow stack. > > * unwind-generic.h (_Unwind_Frames_Increment): Add the EXC > argument. > * unwind.inc (_Unwind_RaiseException_Phase2): Pass EXC to > _Unwind_Frames_Increment. > (_Unwind_ForcedUnwind_Phase2): Likewise. > * config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment): > Take the EXC argument. Return _URC_FATAL_PHASE2_ERROR if the > return address on normal stack doesn't match the return address > on shadow stack. > --- > libgcc/config/i386/shadow-stack-unwind.h | 51 ++++++++++++++++++++++-- > libgcc/unwind-generic.h | 2 +- > libgcc/unwind.inc | 4 +- > 3 files changed, 50 insertions(+), 7 deletions(-) > > diff --git a/libgcc/config/i386/shadow-stack-unwind.h b/libgcc/config/i386/shadow-stack-unwind.h > index 2b02682bdae..89d44165000 100644 > --- a/libgcc/config/i386/shadow-stack-unwind.h > +++ b/libgcc/config/i386/shadow-stack-unwind.h > @@ -54,10 +54,39 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > aligned. If the original shadow stack is 8 byte aligned, we just > need to pop 2 slots, one restore token, from shadow stack. Otherwise, > we need to pop 3 slots, one restore token + 4 byte padding, from > - shadow stack. */ > -#ifndef __x86_64__ > + shadow stack. > + > + When popping a stack frame, we compare the return address on normal > + stack against the return address on shadow stack. If they don't match, > + return _URC_FATAL_PHASE2_ERROR for the corrupted return address on > + normal stack. Don't check the return address for > + 1. Non-catchable exception where exception_class == 0. Process will > + be terminated. > + 2. Zero return address which marks the outermost stack frame. > + 3. Signal stack frame since kernel puts a restore token on shadow > + stack. > + */ > #undef _Unwind_Frames_Increment > -#define _Unwind_Frames_Increment(context, frames) \ > +#ifdef __x86_64__ > +#define _Unwind_Frames_Increment(exc, context, frames) \ > + { \ > + frames++; \ > + if (exc->exception_class != 0 \ > + && _Unwind_GetIP (context) != 0 \ > + && !_Unwind_IsSignalFrame (context)) \ > + { \ > + _Unwind_Word ssp = _get_ssp (); \ > + if (ssp != 0) \ > + { \ > + ssp += 8 * frames; \ > + _Unwind_Word ra = *(_Unwind_Word *) ssp; \ > + if (ra != _Unwind_GetIP (context)) \ > + return _URC_FATAL_PHASE2_ERROR; \ > + } \ > + } \ > + } > +#else > +#define _Unwind_Frames_Increment(exc, context, frames) \ > if (_Unwind_IsSignalFrame (context)) \ > do \ > { \ > @@ -83,5 +112,19 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > } \ > while (0); \ > else \ > - frames++; > + { \ > + frames++; \ > + if (exc->exception_class != 0 \ > + && _Unwind_GetIP (context) != 0) \ > + { \ > + _Unwind_Word ssp = _get_ssp (); \ > + if (ssp != 0) \ > + { \ > + ssp += 4 * frames; \ > + _Unwind_Word ra = *(_Unwind_Word *) ssp; \ > + if (ra != _Unwind_GetIP (context)) \ > + return _URC_FATAL_PHASE2_ERROR; \ > + } \ > + } \ > + } > #endif > diff --git a/libgcc/unwind-generic.h b/libgcc/unwind-generic.h > index a87c9b3ccf6..bf721282d03 100644 > --- a/libgcc/unwind-generic.h > +++ b/libgcc/unwind-generic.h > @@ -292,6 +292,6 @@ EXCEPTION_DISPOSITION _GCC_specific_handler (PEXCEPTION_RECORD, void *, > #define _Unwind_Frames_Extra(frames) > > /* Increment frame count. */ > -#define _Unwind_Frames_Increment(context, frames) frames++ > +#define _Unwind_Frames_Increment(exc, context, frames) frames++ > > #endif /* unwind.h */ > diff --git a/libgcc/unwind.inc b/libgcc/unwind.inc > index 5efd8af1b15..a7111a7b3a8 100644 > --- a/libgcc/unwind.inc > +++ b/libgcc/unwind.inc > @@ -73,7 +73,7 @@ _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc, > gcc_assert (!match_handler); > > uw_update_context (context, &fs); > - _Unwind_Frames_Increment (context, frames); > + _Unwind_Frames_Increment (exc, context, frames); > } > > *frames_p = frames; > @@ -191,7 +191,7 @@ _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc, > /* Update cur_context to describe the same frame as fs, and discard > the previous context if necessary. */ > uw_advance_context (context, &fs); > - _Unwind_Frames_Increment (context, frames); > + _Unwind_Frames_Increment (exc, context, frames); > } > > *frames_p = frames; > -- > 2.37.3 > PING. Jeff has approved the generic changes. Thanks. -- H.J.
On Wed, Oct 5, 2022 at 5:33 AM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Wed, Sep 21, 2022 at 1:42 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > > > If shadow stack is enabled, when unwinding stack, we count how many stack > > frames we pop to reach the landing pad and adjust shadow stack by the same > > amount. When counting the stack frame, we compare the return address on > > normal stack against the return address on shadow stack. If they don't > > match, return _URC_FATAL_PHASE2_ERROR for the corrupted return address on > > normal stack. Don't check the return address for > > > > 1. Non-catchable exception where exception_class == 0. Process will be > > terminated. > > 2. Zero return address which marks the outermost stack frame. > > 3. Signal stack frame since kernel puts a restore token on shadow stack. Ok. > > > > * unwind-generic.h (_Unwind_Frames_Increment): Add the EXC > > argument. > > * unwind.inc (_Unwind_RaiseException_Phase2): Pass EXC to > > _Unwind_Frames_Increment. > > (_Unwind_ForcedUnwind_Phase2): Likewise. > > * config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment): > > Take the EXC argument. Return _URC_FATAL_PHASE2_ERROR if the > > return address on normal stack doesn't match the return address > > on shadow stack. > > --- > > libgcc/config/i386/shadow-stack-unwind.h | 51 ++++++++++++++++++++++-- > > libgcc/unwind-generic.h | 2 +- > > libgcc/unwind.inc | 4 +- > > 3 files changed, 50 insertions(+), 7 deletions(-) > > > > diff --git a/libgcc/config/i386/shadow-stack-unwind.h b/libgcc/config/i386/shadow-stack-unwind.h > > index 2b02682bdae..89d44165000 100644 > > --- a/libgcc/config/i386/shadow-stack-unwind.h > > +++ b/libgcc/config/i386/shadow-stack-unwind.h > > @@ -54,10 +54,39 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > > aligned. If the original shadow stack is 8 byte aligned, we just > > need to pop 2 slots, one restore token, from shadow stack. Otherwise, > > we need to pop 3 slots, one restore token + 4 byte padding, from > > - shadow stack. */ > > -#ifndef __x86_64__ > > + shadow stack. > > + > > + When popping a stack frame, we compare the return address on normal > > + stack against the return address on shadow stack. If they don't match, > > + return _URC_FATAL_PHASE2_ERROR for the corrupted return address on > > + normal stack. Don't check the return address for > > + 1. Non-catchable exception where exception_class == 0. Process will > > + be terminated. > > + 2. Zero return address which marks the outermost stack frame. > > + 3. Signal stack frame since kernel puts a restore token on shadow > > + stack. > > + */ > > #undef _Unwind_Frames_Increment > > -#define _Unwind_Frames_Increment(context, frames) \ > > +#ifdef __x86_64__ > > +#define _Unwind_Frames_Increment(exc, context, frames) \ > > + { \ > > + frames++; \ > > + if (exc->exception_class != 0 \ > > + && _Unwind_GetIP (context) != 0 \ > > + && !_Unwind_IsSignalFrame (context)) \ > > + { \ > > + _Unwind_Word ssp = _get_ssp (); \ > > + if (ssp != 0) \ > > + { \ > > + ssp += 8 * frames; \ > > + _Unwind_Word ra = *(_Unwind_Word *) ssp; \ > > + if (ra != _Unwind_GetIP (context)) \ > > + return _URC_FATAL_PHASE2_ERROR; \ > > + } \ > > + } \ > > + } > > +#else > > +#define _Unwind_Frames_Increment(exc, context, frames) \ > > if (_Unwind_IsSignalFrame (context)) \ > > do \ > > { \ > > @@ -83,5 +112,19 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > > } \ > > while (0); \ > > else \ > > - frames++; > > + { \ > > + frames++; \ > > + if (exc->exception_class != 0 \ > > + && _Unwind_GetIP (context) != 0) \ > > + { \ > > + _Unwind_Word ssp = _get_ssp (); \ > > + if (ssp != 0) \ > > + { \ > > + ssp += 4 * frames; \ > > + _Unwind_Word ra = *(_Unwind_Word *) ssp; \ > > + if (ra != _Unwind_GetIP (context)) \ > > + return _URC_FATAL_PHASE2_ERROR; \ > > + } \ > > + } \ > > + } > > #endif > > diff --git a/libgcc/unwind-generic.h b/libgcc/unwind-generic.h > > index a87c9b3ccf6..bf721282d03 100644 > > --- a/libgcc/unwind-generic.h > > +++ b/libgcc/unwind-generic.h > > @@ -292,6 +292,6 @@ EXCEPTION_DISPOSITION _GCC_specific_handler (PEXCEPTION_RECORD, void *, > > #define _Unwind_Frames_Extra(frames) > > > > /* Increment frame count. */ > > -#define _Unwind_Frames_Increment(context, frames) frames++ > > +#define _Unwind_Frames_Increment(exc, context, frames) frames++ > > > > #endif /* unwind.h */ > > diff --git a/libgcc/unwind.inc b/libgcc/unwind.inc > > index 5efd8af1b15..a7111a7b3a8 100644 > > --- a/libgcc/unwind.inc > > +++ b/libgcc/unwind.inc > > @@ -73,7 +73,7 @@ _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc, > > gcc_assert (!match_handler); > > > > uw_update_context (context, &fs); > > - _Unwind_Frames_Increment (context, frames); > > + _Unwind_Frames_Increment (exc, context, frames); > > } > > > > *frames_p = frames; > > @@ -191,7 +191,7 @@ _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc, > > /* Update cur_context to describe the same frame as fs, and discard > > the previous context if necessary. */ > > uw_advance_context (context, &fs); > > - _Unwind_Frames_Increment (context, frames); > > + _Unwind_Frames_Increment (exc, context, frames); > > } > > > > *frames_p = frames; > > -- > > 2.37.3 > > > > PING. Jeff has approved the generic changes. > > Thanks. > > -- > H.J. -- BR, Hongtao
diff --git a/libgcc/config/i386/shadow-stack-unwind.h b/libgcc/config/i386/shadow-stack-unwind.h index 2b02682bdae..89d44165000 100644 --- a/libgcc/config/i386/shadow-stack-unwind.h +++ b/libgcc/config/i386/shadow-stack-unwind.h @@ -54,10 +54,39 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see aligned. If the original shadow stack is 8 byte aligned, we just need to pop 2 slots, one restore token, from shadow stack. Otherwise, we need to pop 3 slots, one restore token + 4 byte padding, from - shadow stack. */ -#ifndef __x86_64__ + shadow stack. + + When popping a stack frame, we compare the return address on normal + stack against the return address on shadow stack. If they don't match, + return _URC_FATAL_PHASE2_ERROR for the corrupted return address on + normal stack. Don't check the return address for + 1. Non-catchable exception where exception_class == 0. Process will + be terminated. + 2. Zero return address which marks the outermost stack frame. + 3. Signal stack frame since kernel puts a restore token on shadow + stack. + */ #undef _Unwind_Frames_Increment -#define _Unwind_Frames_Increment(context, frames) \ +#ifdef __x86_64__ +#define _Unwind_Frames_Increment(exc, context, frames) \ + { \ + frames++; \ + if (exc->exception_class != 0 \ + && _Unwind_GetIP (context) != 0 \ + && !_Unwind_IsSignalFrame (context)) \ + { \ + _Unwind_Word ssp = _get_ssp (); \ + if (ssp != 0) \ + { \ + ssp += 8 * frames; \ + _Unwind_Word ra = *(_Unwind_Word *) ssp; \ + if (ra != _Unwind_GetIP (context)) \ + return _URC_FATAL_PHASE2_ERROR; \ + } \ + } \ + } +#else +#define _Unwind_Frames_Increment(exc, context, frames) \ if (_Unwind_IsSignalFrame (context)) \ do \ { \ @@ -83,5 +112,19 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see } \ while (0); \ else \ - frames++; + { \ + frames++; \ + if (exc->exception_class != 0 \ + && _Unwind_GetIP (context) != 0) \ + { \ + _Unwind_Word ssp = _get_ssp (); \ + if (ssp != 0) \ + { \ + ssp += 4 * frames; \ + _Unwind_Word ra = *(_Unwind_Word *) ssp; \ + if (ra != _Unwind_GetIP (context)) \ + return _URC_FATAL_PHASE2_ERROR; \ + } \ + } \ + } #endif diff --git a/libgcc/unwind-generic.h b/libgcc/unwind-generic.h index a87c9b3ccf6..bf721282d03 100644 --- a/libgcc/unwind-generic.h +++ b/libgcc/unwind-generic.h @@ -292,6 +292,6 @@ EXCEPTION_DISPOSITION _GCC_specific_handler (PEXCEPTION_RECORD, void *, #define _Unwind_Frames_Extra(frames) /* Increment frame count. */ -#define _Unwind_Frames_Increment(context, frames) frames++ +#define _Unwind_Frames_Increment(exc, context, frames) frames++ #endif /* unwind.h */ diff --git a/libgcc/unwind.inc b/libgcc/unwind.inc index 5efd8af1b15..a7111a7b3a8 100644 --- a/libgcc/unwind.inc +++ b/libgcc/unwind.inc @@ -73,7 +73,7 @@ _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc, gcc_assert (!match_handler); uw_update_context (context, &fs); - _Unwind_Frames_Increment (context, frames); + _Unwind_Frames_Increment (exc, context, frames); } *frames_p = frames; @@ -191,7 +191,7 @@ _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc, /* Update cur_context to describe the same frame as fs, and discard the previous context if necessary. */ uw_advance_context (context, &fs); - _Unwind_Frames_Increment (context, frames); + _Unwind_Frames_Increment (exc, context, frames); } *frames_p = frames;