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1daeaa3151
Both the execve() and sigreturn() family of syscalls have the
ability to change registers in ways that may not be compatabile
with the syscall path they were called from.
In particular, SYSRET and SYSEXIT can't handle non-default %cs and %ss,
and some bits in eflags.
These syscalls have stubs that are hardcoded to jump to the IRET path,
and not return to the original syscall path.
The following commit:
76f5df43ca ("Always allocate a complete "struct pt_regs" on the kernel stack")
recently changed this for some 32-bit compat syscalls, but introduced a bug where
execve from a 32-bit program to a 64-bit program would fail because it still returned
via SYSRETL. This caused Wine to fail when built for both 32-bit and 64-bit.
This patch sets TIF_NOTIFY_RESUME for execve() and sigreturn() so
that the IRET path is always taken on exit to userspace.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1426978461-32089-1-git-send-email-brgerst@gmail.com
[ Improved the changelog and comments. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
266 lines
7.1 KiB
C
266 lines
7.1 KiB
C
#ifndef _ASM_X86_PTRACE_H
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#define _ASM_X86_PTRACE_H
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#include <asm/segment.h>
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#include <asm/page_types.h>
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#include <uapi/asm/ptrace.h>
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#ifndef __ASSEMBLY__
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#ifdef __i386__
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struct pt_regs {
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unsigned long bx;
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unsigned long cx;
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unsigned long dx;
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unsigned long si;
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unsigned long di;
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unsigned long bp;
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unsigned long ax;
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unsigned long ds;
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unsigned long es;
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unsigned long fs;
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unsigned long gs;
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unsigned long orig_ax;
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unsigned long ip;
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unsigned long cs;
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unsigned long flags;
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unsigned long sp;
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unsigned long ss;
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};
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#else /* __i386__ */
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struct pt_regs {
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/*
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* C ABI says these regs are callee-preserved. They aren't saved on kernel entry
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* unless syscall needs a complete, fully filled "struct pt_regs".
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*/
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unsigned long r15;
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unsigned long r14;
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unsigned long r13;
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unsigned long r12;
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unsigned long bp;
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unsigned long bx;
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/* These regs are callee-clobbered. Always saved on kernel entry. */
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unsigned long r11;
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unsigned long r10;
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unsigned long r9;
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unsigned long r8;
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unsigned long ax;
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unsigned long cx;
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unsigned long dx;
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unsigned long si;
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unsigned long di;
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/*
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* On syscall entry, this is syscall#. On CPU exception, this is error code.
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* On hw interrupt, it's IRQ number:
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*/
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unsigned long orig_ax;
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/* Return frame for iretq */
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unsigned long ip;
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unsigned long cs;
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unsigned long flags;
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unsigned long sp;
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unsigned long ss;
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/* top of stack page */
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};
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#endif /* !__i386__ */
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#ifdef CONFIG_PARAVIRT
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#include <asm/paravirt_types.h>
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#endif
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struct cpuinfo_x86;
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struct task_struct;
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extern unsigned long profile_pc(struct pt_regs *regs);
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#define profile_pc profile_pc
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extern unsigned long
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convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
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extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
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int error_code, int si_code);
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extern unsigned long syscall_trace_enter_phase1(struct pt_regs *, u32 arch);
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extern long syscall_trace_enter_phase2(struct pt_regs *, u32 arch,
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unsigned long phase1_result);
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extern long syscall_trace_enter(struct pt_regs *);
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extern void syscall_trace_leave(struct pt_regs *);
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static inline unsigned long regs_return_value(struct pt_regs *regs)
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{
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return regs->ax;
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}
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/*
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* user_mode_vm(regs) determines whether a register set came from user mode.
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* This is true if V8086 mode was enabled OR if the register set was from
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* protected mode with RPL-3 CS value. This tricky test checks that with
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* one comparison. Many places in the kernel can bypass this full check
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* if they have already ruled out V8086 mode, so user_mode(regs) can be used.
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*/
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static inline int user_mode(struct pt_regs *regs)
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{
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#ifdef CONFIG_X86_32
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return (regs->cs & SEGMENT_RPL_MASK) == USER_RPL;
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#else
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return !!(regs->cs & 3);
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#endif
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}
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static inline int user_mode_vm(struct pt_regs *regs)
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{
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#ifdef CONFIG_X86_32
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return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >=
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USER_RPL;
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#else
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return user_mode(regs);
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#endif
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}
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static inline int v8086_mode(struct pt_regs *regs)
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{
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#ifdef CONFIG_X86_32
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return (regs->flags & X86_VM_MASK);
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#else
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return 0; /* No V86 mode support in long mode */
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#endif
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}
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#ifdef CONFIG_X86_64
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static inline bool user_64bit_mode(struct pt_regs *regs)
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{
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#ifndef CONFIG_PARAVIRT
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/*
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* On non-paravirt systems, this is the only long mode CPL 3
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* selector. We do not allow long mode selectors in the LDT.
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*/
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return regs->cs == __USER_CS;
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#else
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/* Headers are too twisted for this to go in paravirt.h. */
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return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
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#endif
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}
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#define current_user_stack_pointer() current_pt_regs()->sp
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#define compat_user_stack_pointer() current_pt_regs()->sp
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#endif
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#ifdef CONFIG_X86_32
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extern unsigned long kernel_stack_pointer(struct pt_regs *regs);
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#else
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static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
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{
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return regs->sp;
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}
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#endif
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#define GET_IP(regs) ((regs)->ip)
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#define GET_FP(regs) ((regs)->bp)
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#define GET_USP(regs) ((regs)->sp)
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#include <asm-generic/ptrace.h>
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/* Query offset/name of register from its name/offset */
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extern int regs_query_register_offset(const char *name);
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extern const char *regs_query_register_name(unsigned int offset);
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#define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
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/**
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* regs_get_register() - get register value from its offset
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* @regs: pt_regs from which register value is gotten.
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* @offset: offset number of the register.
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*
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* regs_get_register returns the value of a register. The @offset is the
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* offset of the register in struct pt_regs address which specified by @regs.
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* If @offset is bigger than MAX_REG_OFFSET, this returns 0.
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*/
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static inline unsigned long regs_get_register(struct pt_regs *regs,
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unsigned int offset)
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{
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if (unlikely(offset > MAX_REG_OFFSET))
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return 0;
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#ifdef CONFIG_X86_32
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/*
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* Traps from the kernel do not save sp and ss.
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* Use the helper function to retrieve sp.
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*/
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if (offset == offsetof(struct pt_regs, sp) &&
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regs->cs == __KERNEL_CS)
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return kernel_stack_pointer(regs);
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#endif
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return *(unsigned long *)((unsigned long)regs + offset);
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}
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/**
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* regs_within_kernel_stack() - check the address in the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @addr: address which is checked.
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*
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* regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
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* If @addr is within the kernel stack, it returns true. If not, returns false.
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*/
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static inline int regs_within_kernel_stack(struct pt_regs *regs,
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unsigned long addr)
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{
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return ((addr & ~(THREAD_SIZE - 1)) ==
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(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
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}
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/**
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* regs_get_kernel_stack_nth() - get Nth entry of the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @n: stack entry number.
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*
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* regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
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* is specified by @regs. If the @n th entry is NOT in the kernel stack,
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* this returns 0.
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*/
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static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
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unsigned int n)
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{
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unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
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addr += n;
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if (regs_within_kernel_stack(regs, (unsigned long)addr))
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return *addr;
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else
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return 0;
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}
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#define arch_has_single_step() (1)
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#ifdef CONFIG_X86_DEBUGCTLMSR
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#define arch_has_block_step() (1)
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#else
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#define arch_has_block_step() (boot_cpu_data.x86 >= 6)
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#endif
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#define ARCH_HAS_USER_SINGLE_STEP_INFO
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/*
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* When hitting ptrace_stop(), we cannot return using SYSRET because
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* that does not restore the full CPU state, only a minimal set. The
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* ptracer can change arbitrary register values, which is usually okay
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* because the usual ptrace stops run off the signal delivery path which
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* forces IRET; however, ptrace_event() stops happen in arbitrary places
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* in the kernel and don't force IRET path.
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*
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* So force IRET path after a ptrace stop.
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*/
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#define arch_ptrace_stop_needed(code, info) \
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({ \
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force_iret(); \
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false; \
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})
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struct user_desc;
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extern int do_get_thread_area(struct task_struct *p, int idx,
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struct user_desc __user *info);
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extern int do_set_thread_area(struct task_struct *p, int idx,
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struct user_desc __user *info, int can_allocate);
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_PTRACE_H */
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