mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-24 17:59:32 +00:00
![Chang S. Bae](/assets/img/avatar_default.png)
[ Upstream commit2beb4a53fc
] The kernel pushes context on to the userspace stack to prepare for the user's signal handler. When the user has supplied an alternate signal stack, via sigaltstack(2), it is easy for the kernel to verify that the stack size is sufficient for the current hardware context. Check if writing the hardware context to the alternate stack will exceed it's size. If yes, then instead of corrupting user-data and proceeding with the original signal handler, an immediate SIGSEGV signal is delivered. Refactor the stack pointer check code from on_sig_stack() and use the new helper. While the kernel allows new source code to discover and use a sufficient alternate signal stack size, this check is still necessary to protect binaries with insufficient alternate signal stack size from data corruption. Fixes:c2bc11f10a
("x86, AVX-512: Enable AVX-512 States Context Switch") Reported-by: Florian Weimer <fweimer@redhat.com> Suggested-by: Jann Horn <jannh@google.com> Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Len Brown <len.brown@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20210518200320.17239-6-chang.seok.bae@intel.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=153531 Signed-off-by: Sasha Levin <sashal@kernel.org>
888 lines
22 KiB
C
888 lines
22 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
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*
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* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
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* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
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* 2000-2002 x86-64 support by Andi Kleen
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/wait.h>
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#include <linux/tracehook.h>
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#include <linux/unistd.h>
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#include <linux/stddef.h>
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#include <linux/personality.h>
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#include <linux/uaccess.h>
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#include <linux/user-return-notifier.h>
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#include <linux/uprobes.h>
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#include <linux/context_tracking.h>
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#include <linux/syscalls.h>
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#include <asm/processor.h>
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#include <asm/ucontext.h>
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#include <asm/fpu/internal.h>
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#include <asm/fpu/signal.h>
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#include <asm/vdso.h>
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#include <asm/mce.h>
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#include <asm/sighandling.h>
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#include <asm/vm86.h>
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#ifdef CONFIG_X86_64
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#include <asm/proto.h>
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#include <asm/ia32_unistd.h>
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#endif /* CONFIG_X86_64 */
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#include <asm/syscall.h>
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#include <asm/syscalls.h>
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#include <asm/sigframe.h>
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#include <asm/signal.h>
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#define COPY(x) do { \
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get_user_ex(regs->x, &sc->x); \
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} while (0)
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#define GET_SEG(seg) ({ \
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unsigned short tmp; \
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get_user_ex(tmp, &sc->seg); \
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tmp; \
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})
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#define COPY_SEG(seg) do { \
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regs->seg = GET_SEG(seg); \
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} while (0)
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#define COPY_SEG_CPL3(seg) do { \
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regs->seg = GET_SEG(seg) | 3; \
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} while (0)
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#ifdef CONFIG_X86_64
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/*
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* If regs->ss will cause an IRET fault, change it. Otherwise leave it
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* alone. Using this generally makes no sense unless
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* user_64bit_mode(regs) would return true.
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*/
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static void force_valid_ss(struct pt_regs *regs)
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{
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u32 ar;
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asm volatile ("lar %[old_ss], %[ar]\n\t"
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"jz 1f\n\t" /* If invalid: */
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"xorl %[ar], %[ar]\n\t" /* set ar = 0 */
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"1:"
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: [ar] "=r" (ar)
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: [old_ss] "rm" ((u16)regs->ss));
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/*
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* For a valid 64-bit user context, we need DPL 3, type
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* read-write data or read-write exp-down data, and S and P
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* set. We can't use VERW because VERW doesn't check the
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* P bit.
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*/
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ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
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if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
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ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
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regs->ss = __USER_DS;
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}
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#endif
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static int restore_sigcontext(struct pt_regs *regs,
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struct sigcontext __user *sc,
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unsigned long uc_flags)
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{
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unsigned long buf_val;
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void __user *buf;
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unsigned int tmpflags;
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unsigned int err = 0;
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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get_user_try {
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#ifdef CONFIG_X86_32
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set_user_gs(regs, GET_SEG(gs));
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COPY_SEG(fs);
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COPY_SEG(es);
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COPY_SEG(ds);
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#endif /* CONFIG_X86_32 */
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COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
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COPY(dx); COPY(cx); COPY(ip); COPY(ax);
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#ifdef CONFIG_X86_64
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COPY(r8);
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COPY(r9);
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COPY(r10);
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COPY(r11);
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COPY(r12);
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COPY(r13);
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COPY(r14);
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COPY(r15);
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#endif /* CONFIG_X86_64 */
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COPY_SEG_CPL3(cs);
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COPY_SEG_CPL3(ss);
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get_user_ex(tmpflags, &sc->flags);
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regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
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regs->orig_ax = -1; /* disable syscall checks */
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get_user_ex(buf_val, &sc->fpstate);
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buf = (void __user *)buf_val;
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} get_user_catch(err);
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#ifdef CONFIG_X86_64
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/*
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* Fix up SS if needed for the benefit of old DOSEMU and
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* CRIU.
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*/
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if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
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force_valid_ss(regs);
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#endif
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err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
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force_iret();
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return err;
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}
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int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
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struct pt_regs *regs, unsigned long mask)
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{
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int err = 0;
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put_user_try {
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#ifdef CONFIG_X86_32
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put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
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put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
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put_user_ex(regs->es, (unsigned int __user *)&sc->es);
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put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
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#endif /* CONFIG_X86_32 */
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put_user_ex(regs->di, &sc->di);
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put_user_ex(regs->si, &sc->si);
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put_user_ex(regs->bp, &sc->bp);
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put_user_ex(regs->sp, &sc->sp);
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put_user_ex(regs->bx, &sc->bx);
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put_user_ex(regs->dx, &sc->dx);
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put_user_ex(regs->cx, &sc->cx);
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put_user_ex(regs->ax, &sc->ax);
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#ifdef CONFIG_X86_64
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put_user_ex(regs->r8, &sc->r8);
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put_user_ex(regs->r9, &sc->r9);
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put_user_ex(regs->r10, &sc->r10);
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put_user_ex(regs->r11, &sc->r11);
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put_user_ex(regs->r12, &sc->r12);
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put_user_ex(regs->r13, &sc->r13);
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put_user_ex(regs->r14, &sc->r14);
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put_user_ex(regs->r15, &sc->r15);
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#endif /* CONFIG_X86_64 */
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put_user_ex(current->thread.trap_nr, &sc->trapno);
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put_user_ex(current->thread.error_code, &sc->err);
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put_user_ex(regs->ip, &sc->ip);
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#ifdef CONFIG_X86_32
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put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
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put_user_ex(regs->flags, &sc->flags);
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put_user_ex(regs->sp, &sc->sp_at_signal);
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put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
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#else /* !CONFIG_X86_32 */
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put_user_ex(regs->flags, &sc->flags);
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put_user_ex(regs->cs, &sc->cs);
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put_user_ex(0, &sc->gs);
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put_user_ex(0, &sc->fs);
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put_user_ex(regs->ss, &sc->ss);
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#endif /* CONFIG_X86_32 */
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put_user_ex(fpstate, (unsigned long __user *)&sc->fpstate);
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/* non-iBCS2 extensions.. */
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put_user_ex(mask, &sc->oldmask);
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put_user_ex(current->thread.cr2, &sc->cr2);
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} put_user_catch(err);
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return err;
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}
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/*
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* Set up a signal frame.
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*/
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/*
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* Determine which stack to use..
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*/
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static unsigned long align_sigframe(unsigned long sp)
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{
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#ifdef CONFIG_X86_32
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/*
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* Align the stack pointer according to the i386 ABI,
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* i.e. so that on function entry ((sp + 4) & 15) == 0.
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*/
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sp = ((sp + 4) & -16ul) - 4;
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#else /* !CONFIG_X86_32 */
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sp = round_down(sp, 16) - 8;
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#endif
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return sp;
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}
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static void __user *
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get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
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void __user **fpstate)
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{
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/* Default to using normal stack */
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bool nested_altstack = on_sig_stack(regs->sp);
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bool entering_altstack = false;
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unsigned long math_size = 0;
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unsigned long sp = regs->sp;
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unsigned long buf_fx = 0;
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int ret;
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/* redzone */
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if (IS_ENABLED(CONFIG_X86_64))
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sp -= 128;
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/* This is the X/Open sanctioned signal stack switching. */
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if (ka->sa.sa_flags & SA_ONSTACK) {
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/*
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* This checks nested_altstack via sas_ss_flags(). Sensible
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* programs use SS_AUTODISARM, which disables that check, and
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* programs that don't use SS_AUTODISARM get compatible.
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*/
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if (sas_ss_flags(sp) == 0) {
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sp = current->sas_ss_sp + current->sas_ss_size;
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entering_altstack = true;
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}
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} else if (IS_ENABLED(CONFIG_X86_32) &&
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!nested_altstack &&
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regs->ss != __USER_DS &&
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!(ka->sa.sa_flags & SA_RESTORER) &&
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ka->sa.sa_restorer) {
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/* This is the legacy signal stack switching. */
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sp = (unsigned long) ka->sa.sa_restorer;
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entering_altstack = true;
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}
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sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
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&buf_fx, &math_size);
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*fpstate = (void __user *)sp;
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sp = align_sigframe(sp - frame_size);
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/*
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* If we are on the alternate signal stack and would overflow it, don't.
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* Return an always-bogus address instead so we will die with SIGSEGV.
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*/
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if (unlikely((nested_altstack || entering_altstack) &&
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!__on_sig_stack(sp))) {
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if (show_unhandled_signals && printk_ratelimit())
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pr_info("%s[%d] overflowed sigaltstack\n",
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current->comm, task_pid_nr(current));
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return (void __user *)-1L;
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}
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/* save i387 and extended state */
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ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
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if (ret < 0)
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return (void __user *)-1L;
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return (void __user *)sp;
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}
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#ifdef CONFIG_X86_32
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static const struct {
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u16 poplmovl;
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u32 val;
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u16 int80;
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} __attribute__((packed)) retcode = {
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0xb858, /* popl %eax; movl $..., %eax */
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__NR_sigreturn,
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0x80cd, /* int $0x80 */
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};
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static const struct {
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u8 movl;
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u32 val;
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u16 int80;
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u8 pad;
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} __attribute__((packed)) rt_retcode = {
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0xb8, /* movl $..., %eax */
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__NR_rt_sigreturn,
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0x80cd, /* int $0x80 */
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0
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};
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static int
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__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
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struct pt_regs *regs)
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{
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struct sigframe __user *frame;
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void __user *restorer;
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int err = 0;
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void __user *fpstate = NULL;
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frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
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if (!access_ok(frame, sizeof(*frame)))
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return -EFAULT;
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if (__put_user(sig, &frame->sig))
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return -EFAULT;
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if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
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return -EFAULT;
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if (_NSIG_WORDS > 1) {
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if (__copy_to_user(&frame->extramask, &set->sig[1],
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sizeof(frame->extramask)))
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return -EFAULT;
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}
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if (current->mm->context.vdso)
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restorer = current->mm->context.vdso +
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vdso_image_32.sym___kernel_sigreturn;
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else
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restorer = &frame->retcode;
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if (ksig->ka.sa.sa_flags & SA_RESTORER)
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restorer = ksig->ka.sa.sa_restorer;
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/* Set up to return from userspace. */
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err |= __put_user(restorer, &frame->pretcode);
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/*
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* This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
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*
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* WE DO NOT USE IT ANY MORE! It's only left here for historical
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* reasons and because gdb uses it as a signature to notice
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* signal handler stack frames.
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*/
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err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
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if (err)
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return -EFAULT;
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/* Set up registers for signal handler */
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regs->sp = (unsigned long)frame;
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regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
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regs->ax = (unsigned long)sig;
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regs->dx = 0;
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regs->cx = 0;
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regs->ds = __USER_DS;
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regs->es = __USER_DS;
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regs->ss = __USER_DS;
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regs->cs = __USER_CS;
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return 0;
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}
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static int __setup_rt_frame(int sig, struct ksignal *ksig,
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sigset_t *set, struct pt_regs *regs)
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{
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struct rt_sigframe __user *frame;
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void __user *restorer;
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int err = 0;
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void __user *fpstate = NULL;
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frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
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if (!access_ok(frame, sizeof(*frame)))
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return -EFAULT;
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put_user_try {
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put_user_ex(sig, &frame->sig);
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put_user_ex(&frame->info, &frame->pinfo);
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put_user_ex(&frame->uc, &frame->puc);
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/* Create the ucontext. */
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if (static_cpu_has(X86_FEATURE_XSAVE))
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put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
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else
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put_user_ex(0, &frame->uc.uc_flags);
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put_user_ex(0, &frame->uc.uc_link);
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save_altstack_ex(&frame->uc.uc_stack, regs->sp);
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/* Set up to return from userspace. */
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restorer = current->mm->context.vdso +
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vdso_image_32.sym___kernel_rt_sigreturn;
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if (ksig->ka.sa.sa_flags & SA_RESTORER)
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restorer = ksig->ka.sa.sa_restorer;
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put_user_ex(restorer, &frame->pretcode);
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/*
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* This is movl $__NR_rt_sigreturn, %ax ; int $0x80
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*
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* WE DO NOT USE IT ANY MORE! It's only left here for historical
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* reasons and because gdb uses it as a signature to notice
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* signal handler stack frames.
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*/
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put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
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} put_user_catch(err);
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err |= copy_siginfo_to_user(&frame->info, &ksig->info);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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return -EFAULT;
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/* Set up registers for signal handler */
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regs->sp = (unsigned long)frame;
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regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
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regs->ax = (unsigned long)sig;
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regs->dx = (unsigned long)&frame->info;
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regs->cx = (unsigned long)&frame->uc;
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regs->ds = __USER_DS;
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regs->es = __USER_DS;
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regs->ss = __USER_DS;
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regs->cs = __USER_CS;
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return 0;
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}
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#else /* !CONFIG_X86_32 */
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static unsigned long frame_uc_flags(struct pt_regs *regs)
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{
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unsigned long flags;
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if (boot_cpu_has(X86_FEATURE_XSAVE))
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flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
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else
|
|
flags = UC_SIGCONTEXT_SS;
|
|
|
|
if (likely(user_64bit_mode(regs)))
|
|
flags |= UC_STRICT_RESTORE_SS;
|
|
|
|
return flags;
|
|
}
|
|
|
|
static int __setup_rt_frame(int sig, struct ksignal *ksig,
|
|
sigset_t *set, struct pt_regs *regs)
|
|
{
|
|
struct rt_sigframe __user *frame;
|
|
void __user *fp = NULL;
|
|
unsigned long uc_flags;
|
|
int err = 0;
|
|
|
|
frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
|
|
|
|
if (!access_ok(frame, sizeof(*frame)))
|
|
return -EFAULT;
|
|
|
|
if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
|
|
if (copy_siginfo_to_user(&frame->info, &ksig->info))
|
|
return -EFAULT;
|
|
}
|
|
|
|
uc_flags = frame_uc_flags(regs);
|
|
|
|
put_user_try {
|
|
/* Create the ucontext. */
|
|
put_user_ex(uc_flags, &frame->uc.uc_flags);
|
|
put_user_ex(0, &frame->uc.uc_link);
|
|
save_altstack_ex(&frame->uc.uc_stack, regs->sp);
|
|
|
|
/* Set up to return from userspace. If provided, use a stub
|
|
already in userspace. */
|
|
/* x86-64 should always use SA_RESTORER. */
|
|
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
|
|
put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
|
|
} else {
|
|
/* could use a vstub here */
|
|
err |= -EFAULT;
|
|
}
|
|
} put_user_catch(err);
|
|
|
|
err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, 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->di = sig;
|
|
/* In case the signal handler was declared without prototypes */
|
|
regs->ax = 0;
|
|
|
|
/* This also works for non SA_SIGINFO handlers because they expect the
|
|
next argument after the signal number on the stack. */
|
|
regs->si = (unsigned long)&frame->info;
|
|
regs->dx = (unsigned long)&frame->uc;
|
|
regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
|
|
|
|
regs->sp = (unsigned long)frame;
|
|
|
|
/*
|
|
* Set up the CS and SS registers to run signal handlers in
|
|
* 64-bit mode, even if the handler happens to be interrupting
|
|
* 32-bit or 16-bit code.
|
|
*
|
|
* SS is subtle. In 64-bit mode, we don't need any particular
|
|
* SS descriptor, but we do need SS to be valid. It's possible
|
|
* that the old SS is entirely bogus -- this can happen if the
|
|
* signal we're trying to deliver is #GP or #SS caused by a bad
|
|
* SS value. We also have a compatbility issue here: DOSEMU
|
|
* relies on the contents of the SS register indicating the
|
|
* SS value at the time of the signal, even though that code in
|
|
* DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
|
|
* avoids relying on sigreturn to restore SS; instead it uses
|
|
* a trampoline.) So we do our best: if the old SS was valid,
|
|
* we keep it. Otherwise we replace it.
|
|
*/
|
|
regs->cs = __USER_CS;
|
|
|
|
if (unlikely(regs->ss != __USER_DS))
|
|
force_valid_ss(regs);
|
|
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_X86_32 */
|
|
|
|
static int x32_setup_rt_frame(struct ksignal *ksig,
|
|
compat_sigset_t *set,
|
|
struct pt_regs *regs)
|
|
{
|
|
#ifdef CONFIG_X86_X32_ABI
|
|
struct rt_sigframe_x32 __user *frame;
|
|
unsigned long uc_flags;
|
|
void __user *restorer;
|
|
int err = 0;
|
|
void __user *fpstate = NULL;
|
|
|
|
frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
|
|
|
|
if (!access_ok(frame, sizeof(*frame)))
|
|
return -EFAULT;
|
|
|
|
if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
|
|
if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true))
|
|
return -EFAULT;
|
|
}
|
|
|
|
uc_flags = frame_uc_flags(regs);
|
|
|
|
put_user_try {
|
|
/* Create the ucontext. */
|
|
put_user_ex(uc_flags, &frame->uc.uc_flags);
|
|
put_user_ex(0, &frame->uc.uc_link);
|
|
compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
|
|
put_user_ex(0, &frame->uc.uc__pad0);
|
|
|
|
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
|
|
restorer = ksig->ka.sa.sa_restorer;
|
|
} else {
|
|
/* could use a vstub here */
|
|
restorer = NULL;
|
|
err |= -EFAULT;
|
|
}
|
|
put_user_ex(restorer, (unsigned long __user *)&frame->pretcode);
|
|
} put_user_catch(err);
|
|
|
|
err |= 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;
|
|
|
|
/* We use the x32 calling convention here... */
|
|
regs->di = ksig->sig;
|
|
regs->si = (unsigned long) &frame->info;
|
|
regs->dx = (unsigned long) &frame->uc;
|
|
|
|
loadsegment(ds, __USER_DS);
|
|
loadsegment(es, __USER_DS);
|
|
|
|
regs->cs = __USER_CS;
|
|
regs->ss = __USER_DS;
|
|
#endif /* CONFIG_X86_X32_ABI */
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Do a signal return; undo the signal stack.
|
|
*/
|
|
#ifdef CONFIG_X86_32
|
|
SYSCALL_DEFINE0(sigreturn)
|
|
{
|
|
struct pt_regs *regs = current_pt_regs();
|
|
struct sigframe __user *frame;
|
|
sigset_t set;
|
|
|
|
frame = (struct sigframe __user *)(regs->sp - 8);
|
|
|
|
if (!access_ok(frame, sizeof(*frame)))
|
|
goto badframe;
|
|
if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
|
|
&& __copy_from_user(&set.sig[1], &frame->extramask,
|
|
sizeof(frame->extramask))))
|
|
goto badframe;
|
|
|
|
set_current_blocked(&set);
|
|
|
|
/*
|
|
* x86_32 has no uc_flags bits relevant to restore_sigcontext.
|
|
* Save a few cycles by skipping the __get_user.
|
|
*/
|
|
if (restore_sigcontext(regs, &frame->sc, 0))
|
|
goto badframe;
|
|
return regs->ax;
|
|
|
|
badframe:
|
|
signal_fault(regs, frame, "sigreturn");
|
|
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_X86_32 */
|
|
|
|
SYSCALL_DEFINE0(rt_sigreturn)
|
|
{
|
|
struct pt_regs *regs = current_pt_regs();
|
|
struct rt_sigframe __user *frame;
|
|
sigset_t set;
|
|
unsigned long uc_flags;
|
|
|
|
frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
|
|
if (!access_ok(frame, sizeof(*frame)))
|
|
goto badframe;
|
|
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
|
|
goto badframe;
|
|
if (__get_user(uc_flags, &frame->uc.uc_flags))
|
|
goto badframe;
|
|
|
|
set_current_blocked(&set);
|
|
|
|
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
|
|
goto badframe;
|
|
|
|
if (restore_altstack(&frame->uc.uc_stack))
|
|
goto badframe;
|
|
|
|
return regs->ax;
|
|
|
|
badframe:
|
|
signal_fault(regs, frame, "rt_sigreturn");
|
|
return 0;
|
|
}
|
|
|
|
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)
|
|
{
|
|
int usig = ksig->sig;
|
|
sigset_t *set = sigmask_to_save();
|
|
compat_sigset_t *cset = (compat_sigset_t *) set;
|
|
|
|
/* Perform fixup for the pre-signal frame. */
|
|
rseq_signal_deliver(ksig, regs);
|
|
|
|
/* Set up the stack frame */
|
|
if (is_ia32_frame(ksig)) {
|
|
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
|
|
return ia32_setup_rt_frame(usig, ksig, cset, regs);
|
|
else
|
|
return ia32_setup_frame(usig, ksig, cset, regs);
|
|
} else if (is_x32_frame(ksig)) {
|
|
return x32_setup_rt_frame(ksig, cset, regs);
|
|
} else {
|
|
return __setup_rt_frame(ksig->sig, ksig, set, regs);
|
|
}
|
|
}
|
|
|
|
static void
|
|
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
|
|
{
|
|
bool stepping, failed;
|
|
struct fpu *fpu = ¤t->thread.fpu;
|
|
|
|
if (v8086_mode(regs))
|
|
save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
|
|
|
|
/* Are we from a system call? */
|
|
if (syscall_get_nr(current, regs) >= 0) {
|
|
/* If so, check system call restarting.. */
|
|
switch (syscall_get_error(current, regs)) {
|
|
case -ERESTART_RESTARTBLOCK:
|
|
case -ERESTARTNOHAND:
|
|
regs->ax = -EINTR;
|
|
break;
|
|
|
|
case -ERESTARTSYS:
|
|
if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
|
|
regs->ax = -EINTR;
|
|
break;
|
|
}
|
|
/* fallthrough */
|
|
case -ERESTARTNOINTR:
|
|
regs->ax = regs->orig_ax;
|
|
regs->ip -= 2;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
|
|
* so that register information in the sigcontext is correct and
|
|
* then notify the tracer before entering the signal handler.
|
|
*/
|
|
stepping = test_thread_flag(TIF_SINGLESTEP);
|
|
if (stepping)
|
|
user_disable_single_step(current);
|
|
|
|
failed = (setup_rt_frame(ksig, regs) < 0);
|
|
if (!failed) {
|
|
/*
|
|
* Clear the direction flag as per the ABI for function entry.
|
|
*
|
|
* Clear RF when entering the signal handler, because
|
|
* it might disable possible debug exception from the
|
|
* signal handler.
|
|
*
|
|
* Clear TF for the case when it wasn't set by debugger to
|
|
* avoid the recursive send_sigtrap() in SIGTRAP handler.
|
|
*/
|
|
regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
|
|
/*
|
|
* Ensure the signal handler starts with the new fpu state.
|
|
*/
|
|
fpu__clear(fpu);
|
|
}
|
|
signal_setup_done(failed, ksig, stepping);
|
|
}
|
|
|
|
static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
|
|
{
|
|
#ifdef CONFIG_IA32_EMULATION
|
|
if (current_thread_info()->status & TS_COMPAT_RESTART)
|
|
return __NR_ia32_restart_syscall;
|
|
#endif
|
|
#ifdef CONFIG_X86_X32_ABI
|
|
return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
|
|
#else
|
|
return __NR_restart_syscall;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Note that 'init' is a special process: it doesn't get signals it doesn't
|
|
* want to handle. Thus you cannot kill init even with a SIGKILL even by
|
|
* mistake.
|
|
*/
|
|
void do_signal(struct pt_regs *regs)
|
|
{
|
|
struct ksignal ksig;
|
|
|
|
if (get_signal(&ksig)) {
|
|
/* Whee! Actually deliver the signal. */
|
|
handle_signal(&ksig, regs);
|
|
return;
|
|
}
|
|
|
|
/* Did we come from a system call? */
|
|
if (syscall_get_nr(current, regs) >= 0) {
|
|
/* Restart the system call - no handlers present */
|
|
switch (syscall_get_error(current, regs)) {
|
|
case -ERESTARTNOHAND:
|
|
case -ERESTARTSYS:
|
|
case -ERESTARTNOINTR:
|
|
regs->ax = regs->orig_ax;
|
|
regs->ip -= 2;
|
|
break;
|
|
|
|
case -ERESTART_RESTARTBLOCK:
|
|
regs->ax = get_nr_restart_syscall(regs);
|
|
regs->ip -= 2;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If there's no signal to deliver, we just put the saved sigmask
|
|
* back.
|
|
*/
|
|
restore_saved_sigmask();
|
|
}
|
|
|
|
void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
|
|
{
|
|
struct task_struct *me = current;
|
|
|
|
if (show_unhandled_signals && printk_ratelimit()) {
|
|
printk("%s"
|
|
"%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
|
|
task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
|
|
me->comm, me->pid, where, frame,
|
|
regs->ip, regs->sp, regs->orig_ax);
|
|
print_vma_addr(KERN_CONT " in ", regs->ip);
|
|
pr_cont("\n");
|
|
}
|
|
|
|
force_sig(SIGSEGV);
|
|
}
|
|
|
|
#ifdef CONFIG_X86_X32_ABI
|
|
asmlinkage long sys32_x32_rt_sigreturn(void)
|
|
{
|
|
struct pt_regs *regs = current_pt_regs();
|
|
struct rt_sigframe_x32 __user *frame;
|
|
sigset_t set;
|
|
unsigned long uc_flags;
|
|
|
|
frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
|
|
|
|
if (!access_ok(frame, sizeof(*frame)))
|
|
goto badframe;
|
|
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
|
|
goto badframe;
|
|
if (__get_user(uc_flags, &frame->uc.uc_flags))
|
|
goto badframe;
|
|
|
|
set_current_blocked(&set);
|
|
|
|
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
|
|
goto badframe;
|
|
|
|
if (compat_restore_altstack(&frame->uc.uc_stack))
|
|
goto badframe;
|
|
|
|
return regs->ax;
|
|
|
|
badframe:
|
|
signal_fault(regs, frame, "x32 rt_sigreturn");
|
|
return 0;
|
|
}
|
|
#endif
|