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x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers 

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>
This commit is contained in:
Al Viro 2020-02-15 18:46:02 -05:00
parent 39f16c1c0f
commit 44a1d99632
1 changed files with 28 additions and 16 deletions
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44
arch/x86/ia32/ia32_signal.c
View File

@ -154,13 +154,11 @@ badframe:
#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)