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59994fb01a
Back in 2009 we merged 501cb16d3c "Randomise PIEs", which added support for
randomizing PIE (Position Independent Executable) binaries.
That commit added randomize_et_dyn(), which correctly randomized the addresses,
but failed to honor PF_RANDOMIZE. That means it was not possible to disable PIE
randomization via the personality flag, or /proc/sys/kernel/randomize_va_space.
Since then there has been generic support for PIE randomization added to
binfmt_elf.c, selectable via ARCH_BINFMT_ELF_RANDOMIZE_PIE.
Enabling that allows us to drop randomize_et_dyn(), which means we start
honoring PF_RANDOMIZE correctly.
It also causes a fairly major change to how we layout PIE binaries.
Currently we will place the binary at 512MB-520MB for 32 bit binaries, or
512MB-1.5GB for 64 bit binaries, eg:
$ cat /proc/$$/maps
4e550000-4e580000 r-xp 00000000 08:02 129813 /bin/dash
4e580000-4e590000 rw-p 00020000 08:02 129813 /bin/dash
10014110000-10014140000 rw-p 00000000 00:00 0 [heap]
3fffaa3f0000-3fffaa5a0000 r-xp 00000000 08:02 921 /lib/powerpc64le-linux-gnu/libc-2.19.so
3fffaa5a0000-3fffaa5b0000 rw-p 001a0000 08:02 921 /lib/powerpc64le-linux-gnu/libc-2.19.so
3fffaa5c0000-3fffaa5d0000 rw-p 00000000 00:00 0
3fffaa5d0000-3fffaa5f0000 r-xp 00000000 00:00 0 [vdso]
3fffaa5f0000-3fffaa620000 r-xp 00000000 08:02 1246 /lib/powerpc64le-linux-gnu/ld-2.19.so
3fffaa620000-3fffaa630000 rw-p 00020000 08:02 1246 /lib/powerpc64le-linux-gnu/ld-2.19.so
3ffffc340000-3ffffc370000 rw-p 00000000 00:00 0 [stack]
With this commit applied we don't do any special randomisation for the binary,
and instead rely on mmap randomisation. This means the binary ends up at high
addresses, eg:
$ cat /proc/$$/maps
3fff99820000-3fff999d0000 r-xp 00000000 08:02 921 /lib/powerpc64le-linux-gnu/libc-2.19.so
3fff999d0000-3fff999e0000 rw-p 001a0000 08:02 921 /lib/powerpc64le-linux-gnu/libc-2.19.so
3fff999f0000-3fff99a00000 rw-p 00000000 00:00 0
3fff99a00000-3fff99a20000 r-xp 00000000 00:00 0 [vdso]
3fff99a20000-3fff99a50000 r-xp 00000000 08:02 1246 /lib/powerpc64le-linux-gnu/ld-2.19.so
3fff99a50000-3fff99a60000 rw-p 00020000 08:02 1246 /lib/powerpc64le-linux-gnu/ld-2.19.so
3fff99a60000-3fff99a90000 r-xp 00000000 08:02 129813 /bin/dash
3fff99a90000-3fff99aa0000 rw-p 00020000 08:02 129813 /bin/dash
3fffc3de0000-3fffc3e10000 rw-p 00000000 00:00 0 [stack]
3fffc55e0000-3fffc5610000 rw-p 00000000 00:00 0 [heap]
Although this should be OK, it's possible it might break badly written
binaries that make assumptions about the address space layout.
Signed-off-by: Vineeth Vijayan <vvijayan@mvista.com>
[mpe: Rewrite changelog]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
144 lines
4.9 KiB
C
144 lines
4.9 KiB
C
/*
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* ELF register definitions..
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_POWERPC_ELF_H
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#define _ASM_POWERPC_ELF_H
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#include <linux/sched.h> /* for task_struct */
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#include <asm/page.h>
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#include <asm/string.h>
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#include <uapi/asm/elf.h>
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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) ((x)->e_machine == ELF_ARCH)
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#define compat_elf_check_arch(x) ((x)->e_machine == EM_PPC)
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#define CORE_DUMP_USE_REGSET
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#define ELF_EXEC_PAGESIZE PAGE_SIZE
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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 0x20000000
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#define ELF_CORE_EFLAGS (is_elf2_task() ? 2 : 0)
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/*
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* Our registers are always unsigned longs, whether we're a 32 bit
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* process or 64 bit, on either a 64 bit or 32 bit kernel.
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*
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* This macro relies on elf_regs[i] having the right type to truncate to,
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* either u32 or u64. It defines the body of the elf_core_copy_regs
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* function, either the native one with elf_gregset_t elf_regs or
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* the 32-bit one with elf_gregset_t32 elf_regs.
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*/
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#define PPC_ELF_CORE_COPY_REGS(elf_regs, regs) \
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int i, nregs = min(sizeof(*regs) / sizeof(unsigned long), \
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(size_t)ELF_NGREG); \
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for (i = 0; i < nregs; i++) \
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elf_regs[i] = ((unsigned long *) regs)[i]; \
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memset(&elf_regs[i], 0, (ELF_NGREG - i) * sizeof(elf_regs[0]))
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/* Common routine for both 32-bit and 64-bit native processes */
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static inline void ppc_elf_core_copy_regs(elf_gregset_t elf_regs,
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struct pt_regs *regs)
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{
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PPC_ELF_CORE_COPY_REGS(elf_regs, regs);
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}
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#define ELF_CORE_COPY_REGS(gregs, regs) ppc_elf_core_copy_regs(gregs, regs);
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typedef elf_vrregset_t elf_fpxregset_t;
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/* ELF_HWCAP 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 userspace,
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but it's not easy, and we've already done it here. */
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# define ELF_HWCAP (cur_cpu_spec->cpu_user_features)
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# define ELF_HWCAP2 (cur_cpu_spec->cpu_user_features2)
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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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#define ELF_PLATFORM (cur_cpu_spec->platform)
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/* While ELF_PLATFORM indicates the ISA supported by the platform, it
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* may not accurately reflect the underlying behavior of the hardware
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* (as in the case of running in Power5+ compatibility mode on a
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* Power6 machine). ELF_BASE_PLATFORM allows ld.so to load libraries
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* that are tuned for the real hardware.
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*/
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#define ELF_BASE_PLATFORM (powerpc_base_platform)
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#ifdef __powerpc64__
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# define ELF_PLAT_INIT(_r, load_addr) do { \
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_r->gpr[2] = load_addr; \
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} while (0)
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#endif /* __powerpc64__ */
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#ifdef __powerpc64__
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# define SET_PERSONALITY(ex) \
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do { \
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if (((ex).e_flags & 0x3) == 2) \
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set_thread_flag(TIF_ELF2ABI); \
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else \
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clear_thread_flag(TIF_ELF2ABI); \
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if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
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set_thread_flag(TIF_32BIT); \
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else \
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clear_thread_flag(TIF_32BIT); \
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if (personality(current->personality) != PER_LINUX32) \
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set_personality(PER_LINUX | \
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(current->personality & (~PER_MASK))); \
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} 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. This
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* is only required to work around bugs in old 32bit toolchains. Since
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* the 64bit ABI has never had these issues dont enable the workaround
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* even if we have an executable stack.
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*/
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# define elf_read_implies_exec(ex, exec_stk) (is_32bit_task() ? \
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(exec_stk == EXSTACK_DEFAULT) : 0)
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#else
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# define elf_read_implies_exec(ex, exec_stk) (exec_stk == EXSTACK_DEFAULT)
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#endif /* __powerpc64__ */
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extern int dcache_bsize;
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extern int icache_bsize;
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extern int ucache_bsize;
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/* vDSO has arch_setup_additional_pages */
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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 uses_interp);
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#define VDSO_AUX_ENT(a,b) NEW_AUX_ENT(a,b)
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/* 1GB for 64bit, 8MB for 32bit */
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#define STACK_RND_MASK (is_32bit_task() ? \
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(0x7ff >> (PAGE_SHIFT - 12)) : \
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(0x3ffff >> (PAGE_SHIFT - 12)))
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extern unsigned long arch_randomize_brk(struct mm_struct *mm);
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#define arch_randomize_brk arch_randomize_brk
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#ifdef CONFIG_SPU_BASE
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/* Notes used in ET_CORE. Note name is "SPU/<fd>/<filename>". */
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#define NT_SPU 1
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#define ARCH_HAVE_EXTRA_ELF_NOTES
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#endif /* CONFIG_SPU_BASE */
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#endif /* _ASM_POWERPC_ELF_H */
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