6ea65ff79c
The segment register slots in struct pt_regs are padded to 32 bits. Some of these are stored with instructions like "pushl %es", which leaves the high 16 bits as they were. So the high bits of these fields in struct pt_regs contain kernel stack garbage. These bits are ignored by everything and never leak to user space, except in core dumps. The user struct pt_regs is always at the base of the thread's kernel stack and so it seems unlikely the information that leaks from here is ever worthwhile so as to be a security concern, but I'm not sure about that. It has been this way for ages; userland consumers of core dumps all mask off these high bits themselves. So it is not urgent. This change masks off the padding bits of the segment register slots in core dumps. ptrace already masks off these high bits, so this makes the values in core dumps consistent with what ptrace would report just before the process died. As I read the processor manuals, the cs and ss values will always be padded with zero bits rather than stack garbage. But unlike "pushl %es", this is not simple to test with a userland program. So I added the two instructions rather than wonder if they are really never necessary. I think that x86_64 does not have this problem (for either 32-bit or 64-bit processes). It only uses "mov" instructions from segment registers, which zero-extend. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
173 lines
5.1 KiB
C
173 lines
5.1 KiB
C
#ifndef __ASMi386_ELF_H
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#define __ASMi386_ELF_H
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/*
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* ELF register definitions..
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*/
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#include <asm/ptrace.h>
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#include <asm/user.h>
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#include <asm/auxvec.h>
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#include <linux/utsname.h>
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#define R_386_NONE 0
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#define R_386_32 1
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#define R_386_PC32 2
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#define R_386_GOT32 3
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#define R_386_PLT32 4
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#define R_386_COPY 5
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#define R_386_GLOB_DAT 6
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#define R_386_JMP_SLOT 7
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#define R_386_RELATIVE 8
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#define R_386_GOTOFF 9
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#define R_386_GOTPC 10
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#define R_386_NUM 11
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typedef unsigned long elf_greg_t;
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#define ELF_NGREG (sizeof (struct user_regs_struct) / sizeof(elf_greg_t))
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typedef elf_greg_t elf_gregset_t[ELF_NGREG];
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typedef struct user_i387_struct elf_fpregset_t;
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typedef struct user_fxsr_struct elf_fpxregset_t;
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/*
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* This is used to ensure we don't load something for the wrong architecture.
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*/
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#define elf_check_arch(x) \
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(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486))
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/*
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* These are used to set parameters in the core dumps.
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*/
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#define ELF_CLASS ELFCLASS32
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#define ELF_DATA ELFDATA2LSB
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#define ELF_ARCH EM_386
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#ifdef __KERNEL__
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#include <asm/processor.h>
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#include <asm/system.h> /* for savesegment */
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#include <asm/desc.h>
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/* SVR4/i386 ABI (pages 3-31, 3-32) says that when the program starts %edx
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contains a pointer to a function which might be registered using `atexit'.
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This provides a mean for the dynamic linker to call DT_FINI functions for
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shared libraries that have been loaded before the code runs.
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A value of 0 tells we have no such handler.
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We might as well make sure everything else is cleared too (except for %esp),
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just to make things more deterministic.
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*/
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#define ELF_PLAT_INIT(_r, load_addr) do { \
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_r->ebx = 0; _r->ecx = 0; _r->edx = 0; \
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_r->esi = 0; _r->edi = 0; _r->ebp = 0; \
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_r->eax = 0; \
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} while (0)
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#define USE_ELF_CORE_DUMP
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#define ELF_EXEC_PAGESIZE 4096
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/* This is the location that an ET_DYN program is loaded if exec'ed. Typical
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use of this is to invoke "./ld.so someprog" to test out a new version of
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the loader. We need to make sure that it is out of the way of the program
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that it will "exec", and that there is sufficient room for the brk. */
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#define ELF_ET_DYN_BASE (TASK_SIZE / 3 * 2)
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/* regs is struct pt_regs, pr_reg is elf_gregset_t (which is
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now struct_user_regs, they are different) */
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#define ELF_CORE_COPY_REGS(pr_reg, regs) \
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pr_reg[0] = regs->ebx; \
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pr_reg[1] = regs->ecx; \
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pr_reg[2] = regs->edx; \
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pr_reg[3] = regs->esi; \
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pr_reg[4] = regs->edi; \
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pr_reg[5] = regs->ebp; \
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pr_reg[6] = regs->eax; \
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pr_reg[7] = regs->xds & 0xffff; \
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pr_reg[8] = regs->xes & 0xffff; \
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pr_reg[9] = regs->xfs & 0xffff; \
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savesegment(gs,pr_reg[10]); \
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pr_reg[11] = regs->orig_eax; \
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pr_reg[12] = regs->eip; \
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pr_reg[13] = regs->xcs & 0xffff; \
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pr_reg[14] = regs->eflags; \
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pr_reg[15] = regs->esp; \
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pr_reg[16] = regs->xss & 0xffff;
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/* This yields a mask that user programs can use to figure out what
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instruction set this CPU supports. This could be done in user space,
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but it's not easy, and we've already done it here. */
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#define ELF_HWCAP (boot_cpu_data.x86_capability[0])
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/* This yields a string that ld.so will use to load implementation
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specific libraries for optimization. This is more specific in
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intent than poking at uname or /proc/cpuinfo.
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For the moment, we have only optimizations for the Intel generations,
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but that could change... */
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#define ELF_PLATFORM (utsname()->machine)
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#define SET_PERSONALITY(ex, ibcs2) do { } while (0)
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/*
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* An executable for which elf_read_implies_exec() returns TRUE will
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* have the READ_IMPLIES_EXEC personality flag set automatically.
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*/
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#define elf_read_implies_exec(ex, executable_stack) (executable_stack != EXSTACK_DISABLE_X)
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struct task_struct;
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extern int dump_task_regs (struct task_struct *, elf_gregset_t *);
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extern int dump_task_fpu (struct task_struct *, elf_fpregset_t *);
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extern int dump_task_extended_fpu (struct task_struct *, struct user_fxsr_struct *);
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#define ELF_CORE_COPY_TASK_REGS(tsk, elf_regs) dump_task_regs(tsk, elf_regs)
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#define ELF_CORE_COPY_FPREGS(tsk, elf_fpregs) dump_task_fpu(tsk, elf_fpregs)
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#define ELF_CORE_COPY_XFPREGS(tsk, elf_xfpregs) dump_task_extended_fpu(tsk, elf_xfpregs)
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#define VDSO_HIGH_BASE (__fix_to_virt(FIX_VDSO))
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#define VDSO_BASE ((unsigned long)current->mm->context.vdso)
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#ifdef CONFIG_COMPAT_VDSO
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# define VDSO_COMPAT_BASE VDSO_HIGH_BASE
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# define VDSO_PRELINK VDSO_HIGH_BASE
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#else
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# define VDSO_COMPAT_BASE VDSO_BASE
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# define VDSO_PRELINK 0
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#endif
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#define VDSO_SYM(x) \
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(VDSO_COMPAT_BASE + (unsigned long)(x) - VDSO_PRELINK)
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#define VDSO_HIGH_EHDR ((const struct elfhdr *) VDSO_HIGH_BASE)
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#define VDSO_EHDR ((const struct elfhdr *) VDSO_COMPAT_BASE)
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extern void __kernel_vsyscall;
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#define VDSO_ENTRY VDSO_SYM(&__kernel_vsyscall)
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#ifndef CONFIG_COMPAT_VDSO
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#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
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struct linux_binprm;
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extern int arch_setup_additional_pages(struct linux_binprm *bprm,
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int executable_stack);
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#endif
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extern unsigned int vdso_enabled;
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#define ARCH_DLINFO \
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do if (vdso_enabled) { \
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NEW_AUX_ENT(AT_SYSINFO, VDSO_ENTRY); \
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NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_COMPAT_BASE); \
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} while (0)
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#endif
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#endif
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