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Diffstat (limited to 'arch/x86/kernel/signal_32.c')
-rw-r--r--arch/x86/kernel/signal_32.c507
1 files changed, 507 insertions, 0 deletions
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
new file mode 100644
index 000000000000..c12624bc82a3
--- /dev/null
+++ b/arch/x86/kernel/signal_32.c
@@ -0,0 +1,507 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/sched/task_stack.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 <linux/syscalls.h>
+#include <asm/ucontext.h>
+#include <linux/uaccess.h>
+#include <asm/fpu/signal.h>
+#include <asm/ptrace.h>
+#include <asm/user32.h>
+#include <uapi/asm/sigcontext.h>
+#include <asm/proto.h>
+#include <asm/vdso.h>
+#include <asm/sigframe.h>
+#include <asm/sighandling.h>
+#include <asm/smap.h>
+#include <asm/gsseg.h>
+
+#ifdef CONFIG_IA32_EMULATION
+#include <asm/ia32_unistd.h>
+
+static inline void reload_segments(struct sigcontext_32 *sc)
+{
+ unsigned int cur;
+
+ savesegment(gs, cur);
+ if ((sc->gs | 0x03) != cur)
+ load_gs_index(sc->gs | 0x03);
+ savesegment(fs, cur);
+ if ((sc->fs | 0x03) != cur)
+ loadsegment(fs, sc->fs | 0x03);
+ savesegment(ds, cur);
+ if ((sc->ds | 0x03) != cur)
+ loadsegment(ds, sc->ds | 0x03);
+ savesegment(es, cur);
+ if ((sc->es | 0x03) != cur)
+ loadsegment(es, sc->es | 0x03);
+}
+
+#define sigset32_t compat_sigset_t
+#define siginfo32_t compat_siginfo_t
+#define restore_altstack32 compat_restore_altstack
+#define unsafe_save_altstack32 unsafe_compat_save_altstack
+
+#else
+
+#define sigset32_t sigset_t
+#define siginfo32_t siginfo_t
+#define __NR_ia32_sigreturn __NR_sigreturn
+#define __NR_ia32_rt_sigreturn __NR_rt_sigreturn
+#define restore_altstack32 restore_altstack
+#define unsafe_save_altstack32 unsafe_save_altstack
+#define __copy_siginfo_to_user32 copy_siginfo_to_user
+
+#endif
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+static bool ia32_restore_sigcontext(struct pt_regs *regs,
+ struct sigcontext_32 __user *usc)
+{
+ struct sigcontext_32 sc;
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current->restart_block.fn = do_no_restart_syscall;
+
+ if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
+ return false;
+
+ /* Get only the ia32 registers. */
+ regs->bx = sc.bx;
+ regs->cx = sc.cx;
+ regs->dx = sc.dx;
+ regs->si = sc.si;
+ regs->di = sc.di;
+ regs->bp = sc.bp;
+ regs->ax = sc.ax;
+ regs->sp = sc.sp;
+ regs->ip = sc.ip;
+
+ /* Get CS/SS and force CPL3 */
+ regs->cs = sc.cs | 0x03;
+ regs->ss = sc.ss | 0x03;
+
+ regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
+ /* disable syscall checks */
+ regs->orig_ax = -1;
+
+#ifdef CONFIG_IA32_EMULATION
+ /*
+ * 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_segments(&sc);
+#else
+ loadsegment(gs, sc.gs);
+ regs->fs = sc.fs;
+ regs->es = sc.es;
+ regs->ds = sc.ds;
+#endif
+
+ return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
+}
+
+SYSCALL32_DEFINE0(sigreturn)
+{
+ struct pt_regs *regs = current_pt_regs();
+ struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
+ sigset_t set;
+
+ if (!access_ok(frame, sizeof(*frame)))
+ goto badframe;
+ if (__get_user(set.sig[0], &frame->sc.oldmask)
+ || __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
+ goto badframe;
+
+ set_current_blocked(&set);
+
+ if (!ia32_restore_sigcontext(regs, &frame->sc))
+ goto badframe;
+ return regs->ax;
+
+badframe:
+ signal_fault(regs, frame, "32bit sigreturn");
+ return 0;
+}
+
+SYSCALL32_DEFINE0(rt_sigreturn)
+{
+ struct pt_regs *regs = current_pt_regs();
+ struct rt_sigframe_ia32 __user *frame;
+ sigset_t set;
+
+ frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
+
+ if (!access_ok(frame, sizeof(*frame)))
+ goto badframe;
+ if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
+ goto badframe;
+
+ set_current_blocked(&set);
+
+ if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
+ goto badframe;
+
+ if (restore_altstack32(&frame->uc.uc_stack))
+ goto badframe;
+
+ return regs->ax;
+
+badframe:
+ signal_fault(regs, frame, "32bit rt sigreturn");
+ return 0;
+}
+
+/*
+ * Set up a signal frame.
+ */
+
+#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })
+
+static __always_inline int
+__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
+ void __user *fpstate,
+ struct pt_regs *regs, unsigned int mask)
+{
+ unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
+#ifdef CONFIG_IA32_EMULATION
+ 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);
+ unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
+#else
+ unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
+ unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
+ unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
+#endif
+
+ unsafe_put_user(regs->di, &sc->di, Efault);
+ unsafe_put_user(regs->si, &sc->si, Efault);
+ unsafe_put_user(regs->bp, &sc->bp, Efault);
+ unsafe_put_user(regs->sp, &sc->sp, Efault);
+ unsafe_put_user(regs->bx, &sc->bx, Efault);
+ unsafe_put_user(regs->dx, &sc->dx, Efault);
+ unsafe_put_user(regs->cx, &sc->cx, Efault);
+ unsafe_put_user(regs->ax, &sc->ax, Efault);
+ unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
+ unsafe_put_user(current->thread.error_code, &sc->err, Efault);
+ unsafe_put_user(regs->ip, &sc->ip, Efault);
+ unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
+ unsafe_put_user(regs->flags, &sc->flags, Efault);
+ unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
+ unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
+
+ unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
+
+ /* non-iBCS2 extensions.. */
+ unsafe_put_user(mask, &sc->oldmask, Efault);
+ unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
+ return 0;
+
+Efault:
+ 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)
+
+int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+ sigset32_t *set = (sigset32_t *) sigmask_to_save();
+ struct sigframe_ia32 __user *frame;
+ void __user *restorer;
+ void __user *fp = 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), &fp);
+
+ 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 +
+ vdso_image_32.sym___kernel_sigreturn;
+ else
+ restorer = &frame->retcode;
+ }
+
+ if (!user_access_begin(frame, sizeof(*frame)))
+ return -EFAULT;
+
+ unsafe_put_user(ksig->sig, &frame->sig, Efault);
+ unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
+ unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
+ unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
+ /*
+ * These are actually not used anymore, but left because some
+ * gdb versions depend on them as a marker.
+ */
+ unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
+ user_access_end();
+
+ /* 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 = ksig->sig;
+ regs->dx = 0;
+ regs->cx = 0;
+
+#ifdef CONFIG_IA32_EMULATION
+ loadsegment(ds, __USER_DS);
+ loadsegment(es, __USER_DS);
+#else
+ regs->ds = __USER_DS;
+ regs->es = __USER_DS;
+#endif
+
+ regs->cs = __USER32_CS;
+ regs->ss = __USER_DS;
+
+ return 0;
+Efault:
+ user_access_end();
+ return -EFAULT;
+}
+
+int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+ sigset32_t *set = (sigset32_t *) sigmask_to_save();
+ struct rt_sigframe_ia32 __user *frame;
+ void __user *restorer;
+ void __user *fp = NULL;
+
+ /* unsafe_put_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), &fp);
+
+ if (!user_access_begin(frame, sizeof(*frame)))
+ return -EFAULT;
+
+ unsafe_put_user(ksig->sig, &frame->sig, Efault);
+ unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
+ unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
+
+ /* Create the ucontext. */
+ if (static_cpu_has(X86_FEATURE_XSAVE))
+ unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
+ else
+ unsafe_put_user(0, &frame->uc.uc_flags, Efault);
+ unsafe_put_user(0, &frame->uc.uc_link, Efault);
+ unsafe_save_altstack32(&frame->uc.uc_stack, regs->sp, Efault);
+
+ if (ksig->ka.sa.sa_flags & SA_RESTORER)
+ restorer = ksig->ka.sa.sa_restorer;
+ else
+ restorer = current->mm->context.vdso +
+ vdso_image_32.sym___kernel_rt_sigreturn;
+ unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
+
+ /*
+ * Not actually used anymore, but left because some gdb
+ * versions need it.
+ */
+ unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
+ unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
+ unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
+ user_access_end();
+
+ if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
+ 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 = ksig->sig;
+ regs->dx = (unsigned long) &frame->info;
+ regs->cx = (unsigned long) &frame->uc;
+
+#ifdef CONFIG_IA32_EMULATION
+ loadsegment(ds, __USER_DS);
+ loadsegment(es, __USER_DS);
+#else
+ regs->ds = __USER_DS;
+ regs->es = __USER_DS;
+#endif
+
+ regs->cs = __USER32_CS;
+ regs->ss = __USER_DS;
+
+ return 0;
+Efault:
+ user_access_end();
+ return -EFAULT;
+}
+
+/*
+ * The siginfo_t structure and handing code is very easy
+ * to break in several ways. It must always be updated when new
+ * updates are made to the main siginfo_t, and
+ * copy_siginfo_to_user32() must be updated when the
+ * (arch-independent) copy_siginfo_to_user() is updated.
+ *
+ * It is also easy to put a new member in the siginfo_t
+ * which has implicit alignment which can move internal structure
+ * alignment around breaking the ABI. This can happen if you,
+ * for instance, put a plain 64-bit value in there.
+ */
+
+/*
+* If adding a new si_code, there is probably new data in
+* the siginfo. Make sure folks bumping the si_code
+* limits also have to look at this code. Make sure any
+* new fields are handled in copy_siginfo_to_user32()!
+*/
+static_assert(NSIGILL == 11);
+static_assert(NSIGFPE == 15);
+static_assert(NSIGSEGV == 10);
+static_assert(NSIGBUS == 5);
+static_assert(NSIGTRAP == 6);
+static_assert(NSIGCHLD == 6);
+static_assert(NSIGSYS == 2);
+
+/* This is part of the ABI and can never change in size: */
+static_assert(sizeof(siginfo32_t) == 128);
+
+/* This is a part of the ABI and can never change in alignment */
+static_assert(__alignof__(siginfo32_t) == 4);
+
+/*
+* The offsets of all the (unioned) si_fields are fixed
+* in the ABI, of course. Make sure none of them ever
+* move and are always at the beginning:
+*/
+static_assert(offsetof(siginfo32_t, _sifields) == 3 * sizeof(int));
+
+static_assert(offsetof(siginfo32_t, si_signo) == 0);
+static_assert(offsetof(siginfo32_t, si_errno) == 4);
+static_assert(offsetof(siginfo32_t, si_code) == 8);
+
+/*
+* Ensure that the size of each si_field never changes.
+* If it does, it is a sign that the
+* copy_siginfo_to_user32() code below needs to updated
+* along with the size in the CHECK_SI_SIZE().
+*
+* We repeat this check for both the generic and compat
+* siginfos.
+*
+* Note: it is OK for these to grow as long as the whole
+* structure stays within the padding size (checked
+* above).
+*/
+
+#define CHECK_SI_OFFSET(name) \
+ static_assert(offsetof(siginfo32_t, _sifields) == \
+ offsetof(siginfo32_t, _sifields.name))
+
+#define CHECK_SI_SIZE(name, size) \
+ static_assert(sizeof_field(siginfo32_t, _sifields.name) == size)
+
+CHECK_SI_OFFSET(_kill);
+CHECK_SI_SIZE (_kill, 2*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_pid) == 0xC);
+static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
+
+CHECK_SI_OFFSET(_timer);
+#ifdef CONFIG_COMPAT
+/* compat_siginfo_t doesn't have si_sys_private */
+CHECK_SI_SIZE (_timer, 3*sizeof(int));
+#else
+CHECK_SI_SIZE (_timer, 4*sizeof(int));
+#endif
+static_assert(offsetof(siginfo32_t, si_tid) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_overrun) == 0x10);
+static_assert(offsetof(siginfo32_t, si_value) == 0x14);
+
+CHECK_SI_OFFSET(_rt);
+CHECK_SI_SIZE (_rt, 3*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_pid) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
+static_assert(offsetof(siginfo32_t, si_value) == 0x14);
+
+CHECK_SI_OFFSET(_sigchld);
+CHECK_SI_SIZE (_sigchld, 5*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_pid) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
+static_assert(offsetof(siginfo32_t, si_status) == 0x14);
+static_assert(offsetof(siginfo32_t, si_utime) == 0x18);
+static_assert(offsetof(siginfo32_t, si_stime) == 0x1C);
+
+CHECK_SI_OFFSET(_sigfault);
+CHECK_SI_SIZE (_sigfault, 4*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_addr) == 0x0C);
+
+static_assert(offsetof(siginfo32_t, si_trapno) == 0x10);
+
+static_assert(offsetof(siginfo32_t, si_addr_lsb) == 0x10);
+
+static_assert(offsetof(siginfo32_t, si_lower) == 0x14);
+static_assert(offsetof(siginfo32_t, si_upper) == 0x18);
+
+static_assert(offsetof(siginfo32_t, si_pkey) == 0x14);
+
+static_assert(offsetof(siginfo32_t, si_perf_data) == 0x10);
+static_assert(offsetof(siginfo32_t, si_perf_type) == 0x14);
+static_assert(offsetof(siginfo32_t, si_perf_flags) == 0x18);
+
+CHECK_SI_OFFSET(_sigpoll);
+CHECK_SI_SIZE (_sigpoll, 2*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_band) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_fd) == 0x10);
+
+CHECK_SI_OFFSET(_sigsys);
+CHECK_SI_SIZE (_sigsys, 3*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_call_addr) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_syscall) == 0x10);
+static_assert(offsetof(siginfo32_t, si_arch) == 0x14);
+
+/* any new si_fields should be added here */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.