lkml.org 
[lkml]   [2020]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC][PATCH v2 13/22] x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers
Date
From: Al Viro <viro@zeniv.linux.org.uk>

What's left is just a sequence of stores to userland addresses, with all
error handling, etc. done out of line. Calling that from user_access block
is safe, but rather than teaching objtool to recognize it as such we can
just make it always_inline - it is small enough and has few enough callers,
for the space savings not to be an issue.

Rename the sucker to __unsafe_setup_sigcontext32() and provide
unsafe_put_sigcontext32() with usual kind of semantics.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/x86/ia32/ia32_signal.c | 44 ++++++++++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index a96995aa23da..799ca5b31b87 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -154,13 +154,11 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn)

#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })

-static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
- void __user *fpstate,
- struct pt_regs *regs, unsigned int mask)
+static __always_inline int
+__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
+ void __user *fpstate,
+ struct pt_regs *regs, unsigned int mask)
{
- if (!user_access_begin(sc, sizeof(struct sigcontext_32)))
- return -EFAULT;
-
unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
@@ -187,13 +185,18 @@ static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
/* non-iBCS2 extensions.. */
unsafe_put_user(mask, &sc->oldmask, Efault);
unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
- user_access_end();
return 0;
+
Efault:
- user_access_end();
return -EFAULT;
}

+#define unsafe_put_sigcontext32(sc, fp, regs, set, label) \
+do { \
+ if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0])) \
+ goto label; \
+} while(0)
+
/*
* Determine which stack to use..
*/
@@ -234,7 +237,7 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
struct sigframe_ia32 __user *frame;
void __user *restorer;
int err = 0;
- void __user *fpstate = NULL;
+ void __user *fp = NULL;

/* copy_to_user optimizes that into a single 8 byte store */
static const struct {
@@ -247,7 +250,7 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
0x80cd, /* int $0x80 */
};

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

if (!access_ok(frame, sizeof(*frame)))
return -EFAULT;
@@ -255,9 +258,12 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
if (__put_user(sig, &frame->sig))
return -EFAULT;

- if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
+ if (!user_access_begin(&frame->sc, sizeof(struct sigcontext_32)))
return -EFAULT;

+ unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
+ user_access_end();
+
if (__put_user(set->sig[1], &frame->extramask[0]))
return -EFAULT;

@@ -301,6 +307,9 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
regs->ss = __USER32_DS;

return 0;
+Efault:
+ user_access_end();
+ return -EFAULT;
}

int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
@@ -309,7 +318,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
struct rt_sigframe_ia32 __user *frame;
void __user *restorer;
int err = 0;
- void __user *fpstate = NULL;
+ void __user *fp = NULL;

/* __copy_to_user optimizes that into a single 8 byte store */
static const struct {
@@ -324,7 +333,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
0,
};

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

if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -355,9 +364,12 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
user_access_end();

- err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
- err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
- regs, set->sig[0]);
+ if (__copy_siginfo_to_user32(&frame->info, &ksig->info, false))
+ return -EFAULT;
+ if (!user_access_begin(&frame->uc.uc_mcontext, sizeof(struct sigcontext_32)))
+ return -EFAULT;
+ unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
+ user_access_end();
err |= __put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask);

if (err)
--
2.11.0
\
 
 \ /
  Last update: 2020-03-27 03:33    [W:0.089 / U:0.460 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site