[tip: x86/misc] x86/signal: Merge get_sigframe()

From: tip-bot2 for Brian Gerst
Date: Wed Oct 19 2022 - 08:15:03 EST

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The following commit has been merged into the x86/misc branch of tip:

Commit-ID: 9c36e592b3f899c90b9d0d46ae29fcc065051b96
Gitweb: https://git.kernel.org/tip/9c36e592b3f899c90b9d0d46ae29fcc065051b96
Author: Brian Gerst <brgerst@xxxxxxxxx>
AuthorDate: Mon, 06 Jun 2022 16:37:59 -04:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 19 Oct 2022 09:58:49 +02:00

x86/signal: Merge get_sigframe()

Adapt the native get_sigframe() function so that the compat signal code
can use it.

Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220606203802.158958-6-brgerst@xxxxxxxxx
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/ia32/ia32_signal.c | 34 +------------
arch/x86/include/asm/sighandling.h | 4 +-
arch/x86/kernel/signal.c | 80 +++++++++++++----------------
3 files changed, 42 insertions(+), 76 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index a78885e..e28421f 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -196,40 +196,6 @@ do { \
goto label; \
} while(0)

-/*
- * Determine which stack to use..
- */
-static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
- size_t frame_size,
- void __user **fpstate)
-{
- unsigned long sp, fx_aligned, math_size;
-
- /* Default to using normal stack */
- sp = regs->sp;
-
- /* This is the X/Open sanctioned signal stack switching. */
- if (ksig->ka.sa.sa_flags & SA_ONSTACK)
- sp = sigsp(sp, ksig);
- /* This is the legacy signal stack switching. */
- else if (regs->ss != __USER_DS &&
- !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
- ksig->ka.sa.sa_restorer)
- sp = (unsigned long) ksig->ka.sa.sa_restorer;
-
- sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
- *fpstate = (struct _fpstate_32 __user *) sp;
- if (!copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
- math_size))
- return (void __user *) -1L;
-
- sp -= frame_size;
- /* Align the stack pointer according to the i386 ABI,
- * i.e. so that on function entry ((sp + 4) & 15) == 0. */
- sp = ((sp + 4) & -16ul) - 4;
- return (void __user *) sp;
-}
-
int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
{
compat_sigset_t *set = (compat_sigset_t *) sigmask_to_save();
diff --git a/arch/x86/include/asm/sighandling.h b/arch/x86/include/asm/sighandling.h
index 65e6672..c9e9784 100644
--- a/arch/x86/include/asm/sighandling.h
+++ b/arch/x86/include/asm/sighandling.h
@@ -15,4 +15,8 @@

void signal_fault(struct pt_regs *regs, void __user *frame, char *where);

+void __user *
+get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
+ void __user **fpstate);
+
#endif /* _ASM_X86_SIGHANDLING_H */
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 489a085..890ca05 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -48,6 +48,23 @@
#include <asm/sigframe.h>
#include <asm/signal.h>

+static inline int is_ia32_compat_frame(struct ksignal *ksig)
+{
+ return IS_ENABLED(CONFIG_IA32_EMULATION) &&
+ ksig->ka.sa.sa_flags & SA_IA32_ABI;
+}
+
+static inline int is_ia32_frame(struct ksignal *ksig)
+{
+ return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
+}
+
+static inline int is_x32_frame(struct ksignal *ksig)
+{
+ return IS_ENABLED(CONFIG_X86_X32_ABI) &&
+ ksig->ka.sa.sa_flags & SA_X32_ABI;
+}
+
#ifdef CONFIG_X86_64
/*
* If regs->ss will cause an IRET fault, change it. Otherwise leave it
@@ -223,24 +240,12 @@ do { \
/*
* Determine which stack to use..
*/
-static unsigned long align_sigframe(unsigned long sp)
-{
-#ifdef CONFIG_X86_32
- /*
- * Align the stack pointer according to the i386 ABI,
- * i.e. so that on function entry ((sp + 4) & 15) == 0.
- */
- sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4;
-#else /* !CONFIG_X86_32 */
- sp = round_down(sp, FRAME_ALIGNMENT) - 8;
-#endif
- return sp;
-}
-
-static void __user *
-get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
+void __user *
+get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
void __user **fpstate)
{
+ struct k_sigaction *ka = &ksig->ka;
+ int ia32_frame = is_ia32_frame(ksig);
/* Default to using normal stack */
bool nested_altstack = on_sig_stack(regs->sp);
bool entering_altstack = false;
@@ -249,7 +254,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
unsigned long buf_fx = 0;

/* redzone */
- if (IS_ENABLED(CONFIG_X86_64))
+ if (!ia32_frame)
sp -= 128;

/* This is the X/Open sanctioned signal stack switching. */
@@ -263,7 +268,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
sp = current->sas_ss_sp + current->sas_ss_size;
entering_altstack = true;
}
- } else if (IS_ENABLED(CONFIG_X86_32) &&
+ } else if (ia32_frame &&
!nested_altstack &&
regs->ss != __USER_DS &&
!(ka->sa.sa_flags & SA_RESTORER) &&
@@ -273,11 +278,19 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
entering_altstack = true;
}

- sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
- &buf_fx, &math_size);
+ sp = fpu__alloc_mathframe(sp, ia32_frame, &buf_fx, &math_size);
*fpstate = (void __user *)sp;

- sp = align_sigframe(sp - frame_size);
+ sp -= frame_size;
+
+ if (ia32_frame)
+ /*
+ * Align the stack pointer according to the i386 ABI,
+ * i.e. so that on function entry ((sp + 4) & 15) == 0.
+ */
+ sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4;
+ else
+ sp = round_down(sp, FRAME_ALIGNMENT) - 8;

/*
* If we are on the alternate signal stack and would overflow it, don't.
@@ -331,7 +344,7 @@ __setup_frame(struct ksignal *ksig, struct pt_regs *regs)
void __user *restorer;
void __user *fp = NULL;

- frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
+ frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);

if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -386,7 +399,7 @@ static int __setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
void __user *restorer;
void __user *fp = NULL;

- frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
+ frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);

if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -469,7 +482,7 @@ static int __setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
return -EFAULT;

- frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
+ frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe), &fp);
uc_flags = frame_uc_flags(regs);

if (!user_access_begin(frame, sizeof(*frame)))
@@ -572,7 +585,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
return -EFAULT;

- frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
+ frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);

uc_flags = frame_uc_flags(regs);

@@ -742,23 +755,6 @@ unsigned long get_sigframe_size(void)
return max_frame_size;
}

-static inline int is_ia32_compat_frame(struct ksignal *ksig)
-{
- return IS_ENABLED(CONFIG_IA32_EMULATION) &&
- ksig->ka.sa.sa_flags & SA_IA32_ABI;
-}
-
-static inline int is_ia32_frame(struct ksignal *ksig)
-{
- return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
-}
-
-static inline int is_x32_frame(struct ksignal *ksig)
-{
- return IS_ENABLED(CONFIG_X86_X32_ABI) &&
- ksig->ka.sa.sa_flags & SA_X32_ABI;
-}
-
static int
setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
{

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