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6fdc6dd902
linux/arch/x86/include/asm/elf.h
Thomas Gleixner 6fdc6dd902 x86/vdso: Plug race between mapping and ELF header setup 
The vsyscall32 sysctl can racy against a concurrent fork when it switches
from disabled to enabled:

    arch_setup_additional_pages()
	if (vdso32_enabled)
           --> No mapping
                                        sysctl.vsysscall32()
                                          --> vdso32_enabled = true
    create_elf_tables()
      ARCH_DLINFO_IA32
        if (vdso32_enabled) {
           --> Add VDSO entry with NULL pointer

Make ARCH_DLINFO_IA32 check whether the VDSO mapping has been set up for
the newly forked process or not.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170410151723.602367196@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-10 18:31:41 +02:00

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#ifndef _ASM_X86_ELF_H
#define _ASM_X86_ELF_H
/*
* ELF register definitions..
*/
#include <linux/thread_info.h>
#include <asm/ptrace.h>
#include <asm/user.h>
#include <asm/auxvec.h>
typedef unsigned long elf_greg_t;
#define ELF_NGREG (sizeof(struct user_regs_struct) / sizeof(elf_greg_t))
typedef elf_greg_t elf_gregset_t[ELF_NGREG];
typedef struct user_i387_struct elf_fpregset_t;
#ifdef __i386__
typedef struct user_fxsr_struct elf_fpxregset_t;
#define R_386_NONE 0
#define R_386_32 1
#define R_386_PC32 2
#define R_386_GOT32 3
#define R_386_PLT32 4
#define R_386_COPY 5
#define R_386_GLOB_DAT 6
#define R_386_JMP_SLOT 7
#define R_386_RELATIVE 8
#define R_386_GOTOFF 9
#define R_386_GOTPC 10
#define R_386_NUM 11
/*
* These are used to set parameters in the core dumps.
*/
#define ELF_CLASS ELFCLASS32
#define ELF_DATA ELFDATA2LSB
#define ELF_ARCH EM_386
#else
/* x86-64 relocation types */
#define R_X86_64_NONE 0 /* No reloc */
#define R_X86_64_64 1 /* Direct 64 bit */
#define R_X86_64_PC32 2 /* PC relative 32 bit signed */
#define R_X86_64_GOT32 3 /* 32 bit GOT entry */
#define R_X86_64_PLT32 4 /* 32 bit PLT address */
#define R_X86_64_COPY 5 /* Copy symbol at runtime */
#define R_X86_64_GLOB_DAT 6 /* Create GOT entry */
#define R_X86_64_JUMP_SLOT 7 /* Create PLT entry */
#define R_X86_64_RELATIVE 8 /* Adjust by program base */
#define R_X86_64_GOTPCREL 9 /* 32 bit signed pc relative
offset to GOT */
#define R_X86_64_32 10 /* Direct 32 bit zero extended */
#define R_X86_64_32S 11 /* Direct 32 bit sign extended */
#define R_X86_64_16 12 /* Direct 16 bit zero extended */
#define R_X86_64_PC16 13 /* 16 bit sign extended pc relative */
#define R_X86_64_8 14 /* Direct 8 bit sign extended */
#define R_X86_64_PC8 15 /* 8 bit sign extended pc relative */
#define R_X86_64_NUM 16
/*
* These are used to set parameters in the core dumps.
*/
#define ELF_CLASS ELFCLASS64
#define ELF_DATA ELFDATA2LSB
#define ELF_ARCH EM_X86_64
#endif
#include <asm/vdso.h>
#ifdef CONFIG_X86_64
extern unsigned int vdso64_enabled;
#endif
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
extern unsigned int vdso32_enabled;
#endif
/*
* This is used to ensure we don't load something for the wrong architecture.
*/
#define elf_check_arch_ia32(x) \
(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486))
#include <asm/processor.h>
#ifdef CONFIG_X86_32
#include <asm/desc.h>
#define elf_check_arch(x) elf_check_arch_ia32(x)
/* SVR4/i386 ABI (pages 3-31, 3-32) says that when the program starts %edx
contains a pointer to a function which might be registered using `atexit'.
This provides a mean for the dynamic linker to call DT_FINI functions for
shared libraries that have been loaded before the code runs.
A value of 0 tells we have no such handler.
We might as well make sure everything else is cleared too (except for %esp),
just to make things more deterministic.
*/
#define ELF_PLAT_INIT(_r, load_addr) \
do { \
_r->bx = 0; _r->cx = 0; _r->dx = 0; \
_r->si = 0; _r->di = 0; _r->bp = 0; \
_r->ax = 0; \
} while (0)
/*
* regs is struct pt_regs, pr_reg is elf_gregset_t (which is
* now struct_user_regs, they are different)
*/
#define ELF_CORE_COPY_REGS_COMMON(pr_reg, regs) \
do { \
pr_reg[0] = regs->bx; \
pr_reg[1] = regs->cx; \
pr_reg[2] = regs->dx; \
pr_reg[3] = regs->si; \
pr_reg[4] = regs->di; \
pr_reg[5] = regs->bp; \
pr_reg[6] = regs->ax; \
pr_reg[7] = regs->ds & 0xffff; \
pr_reg[8] = regs->es & 0xffff; \
pr_reg[9] = regs->fs & 0xffff; \
pr_reg[11] = regs->orig_ax; \
pr_reg[12] = regs->ip; \
pr_reg[13] = regs->cs & 0xffff; \
pr_reg[14] = regs->flags; \
pr_reg[15] = regs->sp; \
pr_reg[16] = regs->ss & 0xffff; \
} while (0);
#define ELF_CORE_COPY_REGS(pr_reg, regs) \
do { \
ELF_CORE_COPY_REGS_COMMON(pr_reg, regs);\
pr_reg[10] = get_user_gs(regs); \
} while (0);
#define ELF_CORE_COPY_KERNEL_REGS(pr_reg, regs) \
do { \
ELF_CORE_COPY_REGS_COMMON(pr_reg, regs);\
savesegment(gs, pr_reg[10]); \
} while (0);
#define ELF_PLATFORM (utsname()->machine)
#define set_personality_64bit() do { } while (0)
#else /* CONFIG_X86_32 */
/*
* This is used to ensure we don't load something for the wrong architecture.
*/
#define elf_check_arch(x) \
((x)->e_machine == EM_X86_64)
#define compat_elf_check_arch(x) \
(elf_check_arch_ia32(x) || \
(IS_ENABLED(CONFIG_X86_X32_ABI) && (x)->e_machine == EM_X86_64))
#if __USER32_DS != __USER_DS
# error "The following code assumes __USER32_DS == __USER_DS"
#endif
static inline void elf_common_init(struct thread_struct *t,
struct pt_regs *regs, const u16 ds)
{
/* ax gets execve's return value. */
/*regs->ax = */ regs->bx = regs->cx = regs->dx = 0;
regs->si = regs->di = regs->bp = 0;
regs->r8 = regs->r9 = regs->r10 = regs->r11 = 0;
regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
t->fsbase = t->gsbase = 0;
t->fsindex = t->gsindex = 0;
t->ds = t->es = ds;
}
#define ELF_PLAT_INIT(_r, load_addr) \
elf_common_init(&current->thread, _r, 0)
#define COMPAT_ELF_PLAT_INIT(regs, load_addr) \
elf_common_init(&current->thread, regs, __USER_DS)
void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp);
#define compat_start_thread compat_start_thread
void set_personality_ia32(bool);
#define COMPAT_SET_PERSONALITY(ex) \
set_personality_ia32((ex).e_machine == EM_X86_64)
#define COMPAT_ELF_PLATFORM ("i686")
/*
* regs is struct pt_regs, pr_reg is elf_gregset_t (which is
* now struct_user_regs, they are different). Assumes current is the process
* getting dumped.
*/
#define ELF_CORE_COPY_REGS(pr_reg, regs) \
do { \
unsigned v; \
(pr_reg)[0] = (regs)->r15; \
(pr_reg)[1] = (regs)->r14; \
(pr_reg)[2] = (regs)->r13; \
(pr_reg)[3] = (regs)->r12; \
(pr_reg)[4] = (regs)->bp; \
(pr_reg)[5] = (regs)->bx; \
(pr_reg)[6] = (regs)->r11; \
(pr_reg)[7] = (regs)->r10; \
(pr_reg)[8] = (regs)->r9; \
(pr_reg)[9] = (regs)->r8; \
(pr_reg)[10] = (regs)->ax; \
(pr_reg)[11] = (regs)->cx; \
(pr_reg)[12] = (regs)->dx; \
(pr_reg)[13] = (regs)->si; \
(pr_reg)[14] = (regs)->di; \
(pr_reg)[15] = (regs)->orig_ax; \
(pr_reg)[16] = (regs)->ip; \
(pr_reg)[17] = (regs)->cs; \
(pr_reg)[18] = (regs)->flags; \
(pr_reg)[19] = (regs)->sp; \
(pr_reg)[20] = (regs)->ss; \
(pr_reg)[21] = current->thread.fsbase; \
(pr_reg)[22] = current->thread.gsbase; \
asm("movl %%ds,%0" : "=r" (v)); (pr_reg)[23] = v; \
asm("movl %%es,%0" : "=r" (v)); (pr_reg)[24] = v; \
asm("movl %%fs,%0" : "=r" (v)); (pr_reg)[25] = v; \
asm("movl %%gs,%0" : "=r" (v)); (pr_reg)[26] = v; \
} while (0);
/* I'm not sure if we can use '-' here */
#define ELF_PLATFORM ("x86_64")
extern void set_personality_64bit(void);
extern unsigned int sysctl_vsyscall32;
extern int force_personality32;
#endif /* !CONFIG_X86_32 */
#define CORE_DUMP_USE_REGSET
#define ELF_EXEC_PAGESIZE 4096
/* This is the location that an ET_DYN program is loaded if exec'ed. Typical
use of this is to invoke "./ld.so someprog" to test out a new version of
the loader. We need to make sure that it is out of the way of the program
that it will "exec", and that there is sufficient room for the brk. */
#define ELF_ET_DYN_BASE (TASK_SIZE / 3 * 2)
/* This yields a mask that user programs can use to figure out what
instruction set this CPU supports. This could be done in user space,
but it's not easy, and we've already done it here. */
#define ELF_HWCAP (boot_cpu_data.x86_capability[CPUID_1_EDX])
extern u32 elf_hwcap2;
/*
* HWCAP2 supplies mask with kernel enabled CPU features, so that
* the application can discover that it can safely use them.
* The bits are defined in uapi/asm/hwcap2.h.
*/
#define ELF_HWCAP2 (elf_hwcap2)
/* This yields a string that ld.so will use to load implementation
specific libraries for optimization. This is more specific in
intent than poking at uname or /proc/cpuinfo.
For the moment, we have only optimizations for the Intel generations,
but that could change... */
#define SET_PERSONALITY(ex) set_personality_64bit()
/*
* An executable for which elf_read_implies_exec() returns TRUE will
* have the READ_IMPLIES_EXEC personality flag set automatically.
*/
#define elf_read_implies_exec(ex, executable_stack) \
(executable_stack != EXSTACK_DISABLE_X)
struct task_struct;
#define ARCH_DLINFO_IA32 \
do { \
if (VDSO_CURRENT_BASE) { \
NEW_AUX_ENT(AT_SYSINFO, VDSO_ENTRY); \
NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_CURRENT_BASE); \
} \
} while (0)
#ifdef CONFIG_X86_32
#define STACK_RND_MASK (0x7ff)
#define ARCH_DLINFO ARCH_DLINFO_IA32
/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
#else /* CONFIG_X86_32 */
/* 1GB for 64bit, 8MB for 32bit */
#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff)
#define ARCH_DLINFO \
do { \
if (vdso64_enabled) \
NEW_AUX_ENT(AT_SYSINFO_EHDR, \
(unsigned long __force)current->mm->context.vdso); \
} while (0)
/* As a historical oddity, the x32 and x86_64 vDSOs are controlled together. */
#define ARCH_DLINFO_X32 \
do { \
if (vdso64_enabled) \
NEW_AUX_ENT(AT_SYSINFO_EHDR, \
(unsigned long __force)current->mm->context.vdso); \
} while (0)
#define AT_SYSINFO 32
#define COMPAT_ARCH_DLINFO \
if (test_thread_flag(TIF_X32)) \
ARCH_DLINFO_X32; \
else \
ARCH_DLINFO_IA32
#define COMPAT_ELF_ET_DYN_BASE (TASK_UNMAPPED_BASE + 0x1000000)
#endif /* !CONFIG_X86_32 */
#define VDSO_CURRENT_BASE ((unsigned long)current->mm->context.vdso)
#define VDSO_ENTRY \
((unsigned long)current->mm->context.vdso + \
vdso_image_32.sym___kernel_vsyscall)
struct linux_binprm;
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp);
extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp);
#define compat_arch_setup_additional_pages compat_arch_setup_additional_pages
/*
* True on X86_32 or when emulating IA32 on X86_64
*/
static inline int mmap_is_ia32(void)
{
return IS_ENABLED(CONFIG_X86_32) ||
(IS_ENABLED(CONFIG_COMPAT) &&
test_thread_flag(TIF_ADDR32));
}
/* Do not change the values. See get_align_mask() */
enum align_flags {
ALIGN_VA_32 = BIT(0),
ALIGN_VA_64 = BIT(1),
};
struct va_alignment {
int flags;
unsigned long mask;
unsigned long bits;
} ____cacheline_aligned;
extern struct va_alignment va_align;
extern unsigned long align_vdso_addr(unsigned long);
#endif /* _ASM_X86_ELF_H */
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