e6e5494cb2
Move the i386 VDSO down into a vma and thus randomize it. Besides the security implications, this feature also helps debuggers, which can COW a vma-backed VDSO just like a normal DSO and can thus do single-stepping and other debugging features. It's good for hypervisors (Xen, VMWare) too, which typically live in the same high-mapped address space as the VDSO, hence whenever the VDSO is used, they get lots of guest pagefaults and have to fix such guest accesses up - which slows things down instead of speeding things up (the primary purpose of the VDSO). There's a new CONFIG_COMPAT_VDSO (default=y) option, which provides support for older glibcs that still rely on a prelinked high-mapped VDSO. Newer distributions (using glibc 2.3.3 or later) can turn this option off. Turning it off is also recommended for security reasons: attackers cannot use the predictable high-mapped VDSO page as syscall trampoline anymore. There is a new vdso=[0|1] boot option as well, and a runtime /proc/sys/vm/vdso_enabled sysctl switch, that allows the VDSO to be turned on/off. (This version of the VDSO-randomization patch also has working ELF coredumping, the previous patch crashed in the coredumping code.) This code is a combined work of the exec-shield VDSO randomization code and Gerd Hoffmann's hypervisor-centric VDSO patch. Rusty Russell started this patch and i completed it. [akpm@osdl.org: cleanups] [akpm@osdl.org: compile fix] [akpm@osdl.org: compile fix 2] [akpm@osdl.org: compile fix 3] [akpm@osdl.org: revernt MAXMEM change] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Cc: Gerd Hoffmann <kraxel@suse.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Zachary Amsden <zach@vmware.com> Cc: Andi Kleen <ak@muc.de> Cc: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
217 lines
6.9 KiB
C
217 lines
6.9 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/processor.h>
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#include <asm/system.h> /* for savesegment */
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#include <asm/auxvec.h>
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#include <asm/desc.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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/* 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; \
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pr_reg[8] = regs->xes; \
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savesegment(fs,pr_reg[9]); \
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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; \
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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;
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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 (system_utsname.machine)
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#ifdef __KERNEL__
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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_COMPAT_SYM(x) \
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(VDSO_COMPAT_BASE + (unsigned long)(x) - VDSO_PRELINK)
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#define VDSO_SYM(x) \
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(VDSO_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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#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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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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/*
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* These macros parameterize elf_core_dump in fs/binfmt_elf.c to write out
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* extra segments containing the vsyscall DSO contents. Dumping its
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* contents makes post-mortem fully interpretable later without matching up
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* the same kernel and hardware config to see what PC values meant.
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* Dumping its extra ELF program headers includes all the other information
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* a debugger needs to easily find how the vsyscall DSO was being used.
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*/
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#define ELF_CORE_EXTRA_PHDRS (VDSO_HIGH_EHDR->e_phnum)
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#define ELF_CORE_WRITE_EXTRA_PHDRS \
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do { \
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const struct elf_phdr *const vsyscall_phdrs = \
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(const struct elf_phdr *) (VDSO_HIGH_BASE \
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+ VDSO_HIGH_EHDR->e_phoff); \
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int i; \
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Elf32_Off ofs = 0; \
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for (i = 0; i < VDSO_HIGH_EHDR->e_phnum; ++i) { \
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struct elf_phdr phdr = vsyscall_phdrs[i]; \
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if (phdr.p_type == PT_LOAD) { \
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BUG_ON(ofs != 0); \
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ofs = phdr.p_offset = offset; \
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phdr.p_memsz = PAGE_ALIGN(phdr.p_memsz); \
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phdr.p_filesz = phdr.p_memsz; \
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offset += phdr.p_filesz; \
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} \
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else \
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phdr.p_offset += ofs; \
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phdr.p_paddr = 0; /* match other core phdrs */ \
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DUMP_WRITE(&phdr, sizeof(phdr)); \
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} \
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} while (0)
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#define ELF_CORE_WRITE_EXTRA_DATA \
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do { \
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const struct elf_phdr *const vsyscall_phdrs = \
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(const struct elf_phdr *) (VDSO_HIGH_BASE \
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+ VDSO_HIGH_EHDR->e_phoff); \
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int i; \
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for (i = 0; i < VDSO_HIGH_EHDR->e_phnum; ++i) { \
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if (vsyscall_phdrs[i].p_type == PT_LOAD) \
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DUMP_WRITE((void *) vsyscall_phdrs[i].p_vaddr, \
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PAGE_ALIGN(vsyscall_phdrs[i].p_memsz)); \
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} \
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} while (0)
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#endif
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#endif
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