linux/arch/x86/ia32/ia32_signal.c
Andy Lutomirski 6f121e548f x86, vdso: Reimplement vdso.so preparation in build-time C
Currently, vdso.so files are prepared and analyzed by a combination
of objcopy, nm, some linker script tricks, and some simple ELF
parsers in the kernel.  Replace all of that with plain C code that
runs at build time.

All five vdso images now generate .c files that are compiled and
linked in to the kernel image.

This should cause only one userspace-visible change: the loaded vDSO
images are stripped more heavily than they used to be.  Everything
outside the loadable segment is dropped.  In particular, this causes
the section table and section name strings to be missing.  This
should be fine: real dynamic loaders don't load or inspect these
tables anyway.  The result is roughly equivalent to eu-strip's
--strip-sections option.

The purpose of this change is to enable the vvar and hpet mappings
to be moved to the page following the vDSO load segment.  Currently,
it is possible for the section table to extend into the page after
the load segment, so, if we map it, it risks overlapping the vvar or
hpet page.  This happens whenever the load segment is just under a
multiple of PAGE_SIZE.

The only real subtlety here is that the old code had a C file with
inline assembler that did 'call VDSO32_vsyscall' and a linker script
that defined 'VDSO32_vsyscall = __kernel_vsyscall'.  This most
likely worked by accident: the linker script entry defines a symbol
associated with an address as opposed to an alias for the real
dynamic symbol __kernel_vsyscall.  That caused ld to relocate the
reference at link time instead of leaving an interposable dynamic
relocation.  Since the VDSO32_vsyscall hack is no longer needed, I
now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it
work.  vdso2c will generate an error and abort the build if the
resulting image contains any dynamic relocations, so we won't
silently generate bad vdso images.

(Dynamic relocations are a problem because nothing will even attempt
to relocate the vdso.)

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-05-05 13:18:51 -07:00

501 lines
13 KiB
C

/*
* linux/arch/x86_64/ia32/ia32_signal.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
* 2000-12-* x86-64 compatibility mode signal handling by Andi Kleen
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compat.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/ptrace.h>
#include <asm/ia32_unistd.h>
#include <asm/user32.h>
#include <asm/sigcontext32.h>
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/sigframe.h>
#include <asm/sighandling.h>
#include <asm/sys_ia32.h>
#include <asm/smap.h>
int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
{
int err = 0;
bool ia32 = test_thread_flag(TIF_IA32);
if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
return -EFAULT;
put_user_try {
/* If you change siginfo_t structure, please make sure that
this code is fixed accordingly.
It should never copy any pad contained in the structure
to avoid security leaks, but must copy the generic
3 ints plus the relevant union member. */
put_user_ex(from->si_signo, &to->si_signo);
put_user_ex(from->si_errno, &to->si_errno);
put_user_ex((short)from->si_code, &to->si_code);
if (from->si_code < 0) {
put_user_ex(from->si_pid, &to->si_pid);
put_user_ex(from->si_uid, &to->si_uid);
put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr);
} else {
/*
* First 32bits of unions are always present:
* si_pid === si_band === si_tid === si_addr(LS half)
*/
put_user_ex(from->_sifields._pad[0],
&to->_sifields._pad[0]);
switch (from->si_code >> 16) {
case __SI_FAULT >> 16:
break;
case __SI_SYS >> 16:
put_user_ex(from->si_syscall, &to->si_syscall);
put_user_ex(from->si_arch, &to->si_arch);
break;
case __SI_CHLD >> 16:
if (ia32) {
put_user_ex(from->si_utime, &to->si_utime);
put_user_ex(from->si_stime, &to->si_stime);
} else {
put_user_ex(from->si_utime, &to->_sifields._sigchld_x32._utime);
put_user_ex(from->si_stime, &to->_sifields._sigchld_x32._stime);
}
put_user_ex(from->si_status, &to->si_status);
/* FALL THROUGH */
default:
case __SI_KILL >> 16:
put_user_ex(from->si_uid, &to->si_uid);
break;
case __SI_POLL >> 16:
put_user_ex(from->si_fd, &to->si_fd);
break;
case __SI_TIMER >> 16:
put_user_ex(from->si_overrun, &to->si_overrun);
put_user_ex(ptr_to_compat(from->si_ptr),
&to->si_ptr);
break;
/* This is not generated by the kernel as of now. */
case __SI_RT >> 16:
case __SI_MESGQ >> 16:
put_user_ex(from->si_uid, &to->si_uid);
put_user_ex(from->si_int, &to->si_int);
break;
}
}
} put_user_catch(err);
return err;
}
int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
int err = 0;
u32 ptr32;
if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t)))
return -EFAULT;
get_user_try {
get_user_ex(to->si_signo, &from->si_signo);
get_user_ex(to->si_errno, &from->si_errno);
get_user_ex(to->si_code, &from->si_code);
get_user_ex(to->si_pid, &from->si_pid);
get_user_ex(to->si_uid, &from->si_uid);
get_user_ex(ptr32, &from->si_ptr);
to->si_ptr = compat_ptr(ptr32);
} get_user_catch(err);
return err;
}
/*
* Do a signal return; undo the signal stack.
*/
#define loadsegment_gs(v) load_gs_index(v)
#define loadsegment_fs(v) loadsegment(fs, v)
#define loadsegment_ds(v) loadsegment(ds, v)
#define loadsegment_es(v) loadsegment(es, v)
#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })
#define set_user_seg(seg, v) loadsegment_##seg(v)
#define COPY(x) { \
get_user_ex(regs->x, &sc->x); \
}
#define GET_SEG(seg) ({ \
unsigned short tmp; \
get_user_ex(tmp, &sc->seg); \
tmp; \
})
#define COPY_SEG_CPL3(seg) do { \
regs->seg = GET_SEG(seg) | 3; \
} while (0)
#define RELOAD_SEG(seg) { \
unsigned int pre = GET_SEG(seg); \
unsigned int cur = get_user_seg(seg); \
pre |= 3; \
if (pre != cur) \
set_user_seg(seg, pre); \
}
static int ia32_restore_sigcontext(struct pt_regs *regs,
struct sigcontext_ia32 __user *sc,
unsigned int *pax)
{
unsigned int tmpflags, err = 0;
void __user *buf;
u32 tmp;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
get_user_try {
/*
* Reload fs and gs if they have changed in the signal
* handler. This does not handle long fs/gs base changes in
* the handler, but does not clobber them at least in the
* normal case.
*/
RELOAD_SEG(gs);
RELOAD_SEG(fs);
RELOAD_SEG(ds);
RELOAD_SEG(es);
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
COPY(dx); COPY(cx); COPY(ip);
/* Don't touch extended registers */
COPY_SEG_CPL3(cs);
COPY_SEG_CPL3(ss);
get_user_ex(tmpflags, &sc->flags);
regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
/* disable syscall checks */
regs->orig_ax = -1;
get_user_ex(tmp, &sc->fpstate);
buf = compat_ptr(tmp);
get_user_ex(*pax, &sc->ax);
} get_user_catch(err);
err |= restore_xstate_sig(buf, 1);
return err;
}
asmlinkage long sys32_sigreturn(void)
{
struct pt_regs *regs = current_pt_regs();
struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
sigset_t set;
unsigned int ax;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_COMPAT_NSIG_WORDS > 1
&& __copy_from_user((((char *) &set.sig) + 4),
&frame->extramask,
sizeof(frame->extramask))))
goto badframe;
set_current_blocked(&set);
if (ia32_restore_sigcontext(regs, &frame->sc, &ax))
goto badframe;
return ax;
badframe:
signal_fault(regs, frame, "32bit sigreturn");
return 0;
}
asmlinkage long sys32_rt_sigreturn(void)
{
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe_ia32 __user *frame;
sigset_t set;
unsigned int ax;
frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto badframe;
set_current_blocked(&set);
if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
goto badframe;
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;
return ax;
badframe:
signal_fault(regs, frame, "32bit rt sigreturn");
return 0;
}
/*
* Set up a signal frame.
*/
static int ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc,
void __user *fpstate,
struct pt_regs *regs, unsigned int mask)
{
int err = 0;
put_user_try {
put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
put_user_ex(regs->di, &sc->di);
put_user_ex(regs->si, &sc->si);
put_user_ex(regs->bp, &sc->bp);
put_user_ex(regs->sp, &sc->sp);
put_user_ex(regs->bx, &sc->bx);
put_user_ex(regs->dx, &sc->dx);
put_user_ex(regs->cx, &sc->cx);
put_user_ex(regs->ax, &sc->ax);
put_user_ex(current->thread.trap_nr, &sc->trapno);
put_user_ex(current->thread.error_code, &sc->err);
put_user_ex(regs->ip, &sc->ip);
put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
put_user_ex(regs->flags, &sc->flags);
put_user_ex(regs->sp, &sc->sp_at_signal);
put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
/* non-iBCS2 extensions.. */
put_user_ex(mask, &sc->oldmask);
put_user_ex(current->thread.cr2, &sc->cr2);
} put_user_catch(err);
return err;
}
/*
* 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;
/* 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 & 0xffff) != __USER32_DS &&
!(ksig->ka.sa.sa_flags & SA_RESTORER) &&
ksig->ka.sa.sa_restorer)
sp = (unsigned long) ksig->ka.sa.sa_restorer;
if (used_math()) {
unsigned long fx_aligned, math_size;
sp = alloc_mathframe(sp, 1, &fx_aligned, &math_size);
*fpstate = (struct _fpstate_ia32 __user *) sp;
if (save_xstate_sig(*fpstate, (void __user *)fx_aligned,
math_size) < 0)
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(int sig, struct ksignal *ksig,
compat_sigset_t *set, struct pt_regs *regs)
{
struct sigframe_ia32 __user *frame;
void __user *restorer;
int err = 0;
void __user *fpstate = NULL;
/* copy_to_user optimizes that into a single 8 byte store */
static const struct {
u16 poplmovl;
u32 val;
u16 int80;
} __attribute__((packed)) code = {
0xb858, /* popl %eax ; movl $...,%eax */
__NR_ia32_sigreturn,
0x80cd, /* int $0x80 */
};
frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
if (__put_user(sig, &frame->sig))
return -EFAULT;
if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
return -EFAULT;
if (_COMPAT_NSIG_WORDS > 1) {
if (__copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask)))
return -EFAULT;
}
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
restorer = ksig->ka.sa.sa_restorer;
} else {
/* Return stub is in 32bit vsyscall page */
if (current->mm->context.vdso)
restorer = current->mm->context.vdso +
selected_vdso32->sym___kernel_sigreturn;
else
restorer = &frame->retcode;
}
put_user_try {
put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
/*
* These are actually not used anymore, but left because some
* gdb versions depend on them as a marker.
*/
put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
} put_user_catch(err);
if (err)
return -EFAULT;
/* Set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
/* Make -mregparm=3 work */
regs->ax = sig;
regs->dx = 0;
regs->cx = 0;
loadsegment(ds, __USER32_DS);
loadsegment(es, __USER32_DS);
regs->cs = __USER32_CS;
regs->ss = __USER32_DS;
return 0;
}
int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
compat_sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe_ia32 __user *frame;
void __user *restorer;
int err = 0;
void __user *fpstate = NULL;
/* __copy_to_user optimizes that into a single 8 byte store */
static const struct {
u8 movl;
u32 val;
u16 int80;
u8 pad;
} __attribute__((packed)) code = {
0xb8,
__NR_ia32_rt_sigreturn,
0x80cd,
0,
};
frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
put_user_try {
put_user_ex(sig, &frame->sig);
put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
/* Create the ucontext. */
if (cpu_has_xsave)
put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
else
put_user_ex(0, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
if (ksig->ka.sa.sa_flags & SA_RESTORER)
restorer = ksig->ka.sa.sa_restorer;
else
restorer = current->mm->context.vdso +
selected_vdso32->sym___kernel_rt_sigreturn;
put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
/*
* Not actually used anymore, but left because some gdb
* versions need it.
*/
put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
} put_user_catch(err);
err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
/* Set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
/* Make -mregparm=3 work */
regs->ax = sig;
regs->dx = (unsigned long) &frame->info;
regs->cx = (unsigned long) &frame->uc;
loadsegment(ds, __USER32_DS);
loadsegment(es, __USER32_DS);
regs->cs = __USER32_CS;
regs->ss = __USER32_DS;
return 0;
}