In commit 4ed2863951 ("fs, elf: drop MAP_FIXED usage from elf_map") we
changed elf to use MAP_FIXED_NOREPLACE instead of MAP_FIXED for the
executable mappings.
Then, people reported that it broke some binaries that had overlapping
segments from the same file, and commit ad55eac74f ("elf: enforce
MAP_FIXED on overlaying elf segments") re-instated MAP_FIXED for some
overlaying elf segment cases. But only some - despite the summary line
of that commit, it only did it when it also does a temporary brk vma for
one obvious overlapping case.
Now Russell King reports another overlapping case with old 32-bit x86
binaries, which doesn't trigger that limited case. End result: we had
better just drop MAP_FIXED_NOREPLACE entirely, and go back to MAP_FIXED.
Yes, it's a sign of old binaries generated with old tool-chains, but we
do pride ourselves on not breaking existing setups.
This still leaves MAP_FIXED_NOREPLACE in place for the load_elf_interp()
and the old load_elf_library() use-cases, because nobody has reported
breakage for those. Yet.
Note that in all the cases seen so far, the overlapping elf sections
seem to be just re-mapping of the same executable with different section
attributes. We could possibly introduce a new MAP_FIXED_NOFILECHANGE
flag or similar, which acts like NOREPLACE, but allows just remapping
the same executable file using different protection flags.
It's not clear that would make a huge difference to anything, but if
people really hate that "elf remaps over previous maps" behavior, maybe
at least a more limited form of remapping would alleviate some concerns.
Alternatively, we should take a look at our elf_map() logic to see if we
end up not mapping things properly the first time.
In the meantime, this is the minimal "don't do that then" patch while
people hopefully think about it more.
Reported-by: Russell King <linux@armlinux.org.uk>
Fixes: 4ed2863951 ("fs, elf: drop MAP_FIXED usage from elf_map")
Fixes: ad55eac74f ("elf: enforce MAP_FIXED on overlaying elf segments")
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When brk was moved for binaries without an interpreter, it should have
been limited to ET_DYN only. In other words, the special case was an
ET_DYN that lacks an INTERP, not just an executable that lacks INTERP.
The bug manifested for giant static executables, where the brk would end
up in the middle of the text area on 32-bit architectures.
Reported-and-tested-by: Richard Kojedzinszky <richard@kojedz.in>
Fixes: bbdc6076d2 ("binfmt_elf: move brk out of mmap when doing direct loader exec")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Provide generic top-down mmap layout functions", v6.
This series introduces generic functions to make top-down mmap layout
easily accessible to architectures, in particular riscv which was the
initial goal of this series. The generic implementation was taken from
arm64 and used successively by arm, mips and finally riscv.
Note that in addition the series fixes 2 issues:
- stack randomization was taken into account even if not necessary.
- [1] fixed an issue with mmap base which did not take into account
randomization but did not report it to arm and mips, so by moving arm64
into a generic library, this problem is now fixed for both
architectures.
This work is an effort to factorize architecture functions to avoid code
duplication and oversights as in [1].
[1]: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1429066.html
This patch (of 14):
This preparatory commit moves this function so that further introduction
of generic topdown mmap layout is contained only in mm/util.c.
Link: http://lkml.kernel.org/r/20190730055113.23635-2-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
"passed_fileno" variable was deleted 11 years ago in 2.6.25.
Link: http://lkml.kernel.org/r/20190529201747.GA23248@avx2
Fixes: d20894a237 ("Remove a.out interpreter support in ELF loader")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have MODULE_LICENCE("GPL*") inside which was used in the initial
scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commmit eab09532d4 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE"),
made changes in the rare case when the ELF loader was directly invoked
(e.g to set a non-inheritable LD_LIBRARY_PATH, testing new versions of
the loader), by moving into the mmap region to avoid both ET_EXEC and
PIE binaries. This had the effect of also moving the brk region into
mmap, which could lead to the stack and brk being arbitrarily close to
each other. An unlucky process wouldn't get its requested stack size
and stack allocations could end up scribbling on the heap.
This is illustrated here. In the case of using the loader directly, brk
(so helpfully identified as "[heap]") is allocated with the _loader_ not
the binary. For example, with ASLR entirely disabled, you can see this
more clearly:
$ /bin/cat /proc/self/maps
555555554000-55555555c000 r-xp 00000000 ... /bin/cat
55555575b000-55555575c000 r--p 00007000 ... /bin/cat
55555575c000-55555575d000 rw-p 00008000 ... /bin/cat
55555575d000-55555577e000 rw-p 00000000 ... [heap]
...
7ffff7ff7000-7ffff7ffa000 r--p 00000000 ... [vvar]
7ffff7ffa000-7ffff7ffc000 r-xp 00000000 ... [vdso]
7ffff7ffc000-7ffff7ffd000 r--p 00027000 ... /lib/x86_64-linux-gnu/ld-2.27.so
7ffff7ffd000-7ffff7ffe000 rw-p 00028000 ... /lib/x86_64-linux-gnu/ld-2.27.so
7ffff7ffe000-7ffff7fff000 rw-p 00000000 ...
7ffffffde000-7ffffffff000 rw-p 00000000 ... [stack]
$ /lib/x86_64-linux-gnu/ld-2.27.so /bin/cat /proc/self/maps
...
7ffff7bcc000-7ffff7bd4000 r-xp 00000000 ... /bin/cat
7ffff7bd4000-7ffff7dd3000 ---p 00008000 ... /bin/cat
7ffff7dd3000-7ffff7dd4000 r--p 00007000 ... /bin/cat
7ffff7dd4000-7ffff7dd5000 rw-p 00008000 ... /bin/cat
7ffff7dd5000-7ffff7dfc000 r-xp 00000000 ... /lib/x86_64-linux-gnu/ld-2.27.so
7ffff7fb2000-7ffff7fd6000 rw-p 00000000 ...
7ffff7ff7000-7ffff7ffa000 r--p 00000000 ... [vvar]
7ffff7ffa000-7ffff7ffc000 r-xp 00000000 ... [vdso]
7ffff7ffc000-7ffff7ffd000 r--p 00027000 ... /lib/x86_64-linux-gnu/ld-2.27.so
7ffff7ffd000-7ffff7ffe000 rw-p 00028000 ... /lib/x86_64-linux-gnu/ld-2.27.so
7ffff7ffe000-7ffff8020000 rw-p 00000000 ... [heap]
7ffffffde000-7ffffffff000 rw-p 00000000 ... [stack]
The solution is to move brk out of mmap and into ELF_ET_DYN_BASE since
nothing is there in the direct loader case (and ET_EXEC is still far
away at 0x400000). Anything that ran before should still work (i.e.
the ultimately-launched binary already had the brk very far from its
text, so this should be no different from a COMPAT_BRK standpoint). The
only risk I see here is that if someone started to suddenly depend on
the entire memory space lower than the mmap region being available when
launching binaries via a direct loader execs which seems highly
unlikely, I'd hope: this would mean a binary would _not_ work when
exec()ed normally.
(Note that this is only done under CONFIG_ARCH_HAS_ELF_RANDOMIZATION
when randomization is turned on.)
Link: http://lkml.kernel.org/r/20190422225727.GA21011@beast
Link: https://lkml.kernel.org/r/CAGXu5jJ5sj3emOT2QPxQkNQk0qbU6zEfu9=Omfhx_p0nCKPSjA@mail.gmail.com
Fixes: eab09532d4 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Ali Saidi <alisaidi@amazon.com>
Cc: Ali Saidi <alisaidi@amazon.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Get "current_pt_regs" pointer right before usage.
Space savings on x86_64:
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-180 (-180)
Function old new delta
load_elf_binary 5806 5626 -180 !!!
Looks like the compiler doesn't know that "current_pt_regs" is stable
pointer (because it doesn't know ->stack isn't) even though it knows
that "current" is stable pointer. So it saves it in the very beginning
and then tries to carry it through a lot of code.
Here is what happens here:
load_elf_binary()
...
mov rax,QWORD PTR gs:0x14c00
mov r13,QWORD PTR [rax+0x18] r13 = current->stack
call kmem_cache_alloc # first kmalloc
[980 bytes later!]
# let's spill that sucker because we need a register
# for "load_bias" calculations at
#
# if (interpreter) {
# load_bias = ELF_ET_DYN_BASE;
# if (current->flags & PF_RANDOMIZE)
# load_bias += arch_mmap_rnd();
# elf_flags |= elf_fixed;
# }
mov QWORD PTR [rsp+0x68],r13
If this is not _the_ root cause it is still eeeeh.
After the patch things become much simpler:
mov rax, QWORD PTR gs:0x14c00 # current
mov rdx, QWORD PTR [rax+0x18] # current->stack
movq [rdx+0x3fb8], 0 # fill pt_regs
...
call finalize_exec
Link: http://lkml.kernel.org/r/20190419200343.GA19788@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Tested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are two places where mapping protections are calculated: one for
executable, another one for interpreter -- take them out.
ELF read and execute permissions are interchanged with Linux PROT_READ
and PROT_EXEC, microoptimizations are welcome!
Link: http://lkml.kernel.org/r/20190417213413.GB26474@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no reason for PT_INTERP filename to linger till the end of the
whole loading process.
Link: http://lkml.kernel.org/r/20190314204953.GD18143@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Nikitas Angelinas <nikitas.angelinas@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mukesh Ojha <mojha@codeaurora.org>
[nikitas.angelinas@gmail.com: fix GPF when dereferencing invalid interpreter]
Link: http://lkml.kernel.org/r/20190330140032.GA1527@vostro
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Number of ELF program headers is 16-bit by spec, so total size
comfortably fits into "unsigned int".
Space savings: 7 bytes!
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-7 (-7)
Function old new delta
load_elf_phdrs 137 130 -7
Link: http://lkml.kernel.org/r/20190204202715.GA27482@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus recently observed that if we did not worry about the padding
member in struct siginfo it is only about 48 bytes, and 48 bytes is
much nicer than 128 bytes for allocating on the stack and copying
around in the kernel.
The obvious thing of only adding the padding when userspace is
including siginfo.h won't work as there are sigframe definitions in
the kernel that embed struct siginfo.
So split siginfo in two; kernel_siginfo and siginfo. Keeping the
traditional name for the userspace definition. While the version that
is used internally to the kernel and ultimately will not be padded to
128 bytes is called kernel_siginfo.
The definition of struct kernel_siginfo I have put in include/signal_types.h
A set of buildtime checks has been added to verify the two structures have
the same field offsets.
To make it easy to verify the change kernel_siginfo retains the same
size as siginfo. The reduction in size comes in a following change.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
An overview of the general architecture changes:
- Massive DMA ops refactoring from Christoph Hellwig (huzzah for
deleting crufty code!).
- We introduce NT_MIPS_DSP & NT_MIPS_FP_MODE ELF notes & corresponding
regsets to expose DSP ASE & floating point mode state respectively,
both for live debugging & core dumps.
- We better optimize our code by hard-coding cpu_has_* macros at
compile time where their values are known due to the ISA revision
that the kernel build is targeting.
- The EJTAG exception handler now better handles SMP systems, where it
was previously possible for CPUs to clobber a register value saved
by another CPU.
- Our implementation of memset() gained a couple of fixes for MIPSr6
systems to return correct values in some cases where stores fault.
- We now implement ioremap_wc() using the uncached-accelerated cache
coherency attribute where supported, which is detected during boot,
and fall back to plain uncached access where necessary. The
MIPS-specific (and unused in tree) ioremap_uncached_accelerated() &
ioremap_cacheable_cow() are removed.
- The prctl(PR_SET_FP_MODE, ...) syscall is better supported for SMP
systems by reworking the way we ensure remote CPUs that may be
running threads within the affected process switch mode.
- Systems using the MIPS Coherence Manager will now set the
MIPS_IC_SNOOPS_REMOTE flag to avoid some unnecessary cache
maintenance overhead when flushing the icache.
- A few fixes were made for building with clang/LLVM, which
now sucessfully builds kernels for many of our platforms.
- Miscellaneous cleanups all over.
And some platform-specific changes:
- ar7 gained stubs for a few clock API functions to fix build failures
for some drivers.
- ath79 gained support for a few new SoCs, a few fixes & better
gpio-keys support.
- Ci20 now exposes its SPI bus using the spi-gpio driver.
- The generic platform can now auto-detect a suitable value for
PHYS_OFFSET based upon the memory map described by the device tree,
allowing us to avoid wasting memory on page book-keeping for systems
where RAM starts at a non-zero physical address.
- Ingenic systems using the jz4740 platform code now link their
vmlinuz higher to allow for kernels of a realistic size.
- Loongson32 now builds the kernel targeting MIPSr1 rather than MIPSr2
to avoid CPU errata.
- Loongson64 gains a couple of fixes, a workaround for a write
buffering issue & support for the Loongson 3A R3.1 CPU.
- Malta now uses the piix4-poweroff driver to handle powering down.
- Microsemi Ocelot gained support for its SPI bus & NOR flash, its
second MDIO bus and can now be supported by a FIT/.itb image.
- Octeon saw a bunch of header cleanups which remove a lot of
duplicate or unused code.
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Merge tag 'mips_4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux
Pull MIPS updates from Paul Burton:
"Here are the main MIPS changes for 4.19.
An overview of the general architecture changes:
- Massive DMA ops refactoring from Christoph Hellwig (huzzah for
deleting crufty code!).
- We introduce NT_MIPS_DSP & NT_MIPS_FP_MODE ELF notes &
corresponding regsets to expose DSP ASE & floating point mode state
respectively, both for live debugging & core dumps.
- We better optimize our code by hard-coding cpu_has_* macros at
compile time where their values are known due to the ISA revision
that the kernel build is targeting.
- The EJTAG exception handler now better handles SMP systems, where
it was previously possible for CPUs to clobber a register value
saved by another CPU.
- Our implementation of memset() gained a couple of fixes for MIPSr6
systems to return correct values in some cases where stores fault.
- We now implement ioremap_wc() using the uncached-accelerated cache
coherency attribute where supported, which is detected during boot,
and fall back to plain uncached access where necessary. The
MIPS-specific (and unused in tree) ioremap_uncached_accelerated() &
ioremap_cacheable_cow() are removed.
- The prctl(PR_SET_FP_MODE, ...) syscall is better supported for SMP
systems by reworking the way we ensure remote CPUs that may be
running threads within the affected process switch mode.
- Systems using the MIPS Coherence Manager will now set the
MIPS_IC_SNOOPS_REMOTE flag to avoid some unnecessary cache
maintenance overhead when flushing the icache.
- A few fixes were made for building with clang/LLVM, which now
sucessfully builds kernels for many of our platforms.
- Miscellaneous cleanups all over.
And some platform-specific changes:
- ar7 gained stubs for a few clock API functions to fix build
failures for some drivers.
- ath79 gained support for a few new SoCs, a few fixes & better
gpio-keys support.
- Ci20 now exposes its SPI bus using the spi-gpio driver.
- The generic platform can now auto-detect a suitable value for
PHYS_OFFSET based upon the memory map described by the device tree,
allowing us to avoid wasting memory on page book-keeping for
systems where RAM starts at a non-zero physical address.
- Ingenic systems using the jz4740 platform code now link their
vmlinuz higher to allow for kernels of a realistic size.
- Loongson32 now builds the kernel targeting MIPSr1 rather than
MIPSr2 to avoid CPU errata.
- Loongson64 gains a couple of fixes, a workaround for a write
buffering issue & support for the Loongson 3A R3.1 CPU.
- Malta now uses the piix4-poweroff driver to handle powering down.
- Microsemi Ocelot gained support for its SPI bus & NOR flash, its
second MDIO bus and can now be supported by a FIT/.itb image.
- Octeon saw a bunch of header cleanups which remove a lot of
duplicate or unused code"
* tag 'mips_4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (123 commits)
MIPS: Remove remnants of UASM_ISA
MIPS: netlogic: xlr: Remove erroneous check in nlm_fmn_send()
MIPS: VDSO: Force link endianness
MIPS: Always specify -EB or -EL when using clang
MIPS: Use dins to simplify __write_64bit_c0_split()
MIPS: Use read-write output operand in __write_64bit_c0_split()
MIPS: Avoid using array as parameter to write_c0_kpgd()
MIPS: vdso: Allow clang's --target flag in VDSO cflags
MIPS: genvdso: Remove GOT checks
MIPS: Remove obsolete MIPS checks for DST node "chosen@0"
MIPS: generic: Remove input symbols from defconfig
MIPS: Delete unused code in linux32.c
MIPS: Remove unused sys_32_mmap2
MIPS: Remove nabi_no_regargs
mips: dts: mscc: enable spi and NOR flash support on ocelot PCB123
mips: dts: mscc: Add spi on Ocelot
MIPS: Loongson: Merge load addresses
MIPS: Loongson: Set Loongson32 to MIPS32R1
MIPS: mscc: ocelot: add interrupt controller properties to GPIO controller
MIPS: generic: Select MIPS_AUTO_PFN_OFFSET
...
The regset API documented in <linux/regset.h> defines -ENODEV as the
result of the `->active' handler to be used where the feature requested
is not available on the hardware found. However code handling core file
note generation in `fill_thread_core_info' interpretes any non-zero
result from the `->active' handler as the regset requested being active.
Consequently processing continues (and hopefully gracefully fails later
on) rather than being abandoned right away for the regset requested.
Fix the problem then by making the code proceed only if a positive
result is returned from the `->active' handler.
Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 4206d3aa19 ("elf core dump: notes user_regset")
Patchwork: https://patchwork.linux-mips.org/patch/19332/
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
The current code does not make sure to page align bss before calling
vm_brk(), and this can lead to a VM_BUG_ON() in __mm_populate() due to
the requested lenght not being correctly aligned.
Let us make sure to align it properly.
Kees: only applicable to CONFIG_USELIB kernels: 32-bit and configured
for libc5.
Link: http://lkml.kernel.org/r/20180705145539.9627-1-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reported-by: syzbot+5dcb560fe12aa5091c06@syzkaller.appspotmail.com
Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 4ed2863951 ("fs, elf: drop MAP_FIXED usage from elf_map") is
printing spurious messages under memory pressure due to map_addr == -ENOMEM.
9794 (a.out): Uhuuh, elf segment at 00007f2e34738000(fffffffffffffff4) requested but the memory is mapped already
14104 (a.out): Uhuuh, elf segment at 00007f34fd76c000(fffffffffffffff4) requested but the memory is mapped already
16843 (a.out): Uhuuh, elf segment at 00007f930ecc7000(fffffffffffffff4) requested but the memory is mapped already
Complain only if -EEXIST, and use %px for printing the address.
Link: http://lkml.kernel.org/r/201804182307.FAC17665.SFMOFJVFtHOLOQ@I-love.SAKURA.ne.jp
Fixes: 4ed2863951 ("fs, elf: drop MAP_FIXED usage from elf_map") is
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Anshuman has reported that with "fs, elf: drop MAP_FIXED usage from
elf_map" applied, some ELF binaries in his environment fail to start
with
[ 23.423642] 9148 (sed): Uhuuh, elf segment at 0000000010030000 requested but the memory is mapped already
[ 23.423706] requested [10030000, 10040000] mapped [10030000, 10040000] 100073 anon
The reason is that the above binary has overlapping elf segments:
LOAD 0x0000000000000000 0x0000000010000000 0x0000000010000000
0x0000000000013a8c 0x0000000000013a8c R E 10000
LOAD 0x000000000001fd40 0x000000001002fd40 0x000000001002fd40
0x00000000000002c0 0x00000000000005e8 RW 10000
LOAD 0x0000000000020328 0x0000000010030328 0x0000000010030328
0x0000000000000384 0x00000000000094a0 RW 10000
That binary has two RW LOAD segments, the first crosses a page border
into the second
0x1002fd40 (LOAD2-vaddr) + 0x5e8 (LOAD2-memlen) == 0x10030328 (LOAD3-vaddr)
Handle this situation by enforcing MAP_FIXED when we establish a
temporary brk VMA to handle overlapping segments. All other mappings
will still use MAP_FIXED_NOREPLACE.
Link: http://lkml.kernel.org/r/20180213100440.GM3443@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both load_elf_interp and load_elf_binary rely on elf_map to map segments
on a controlled address and they use MAP_FIXED to enforce that. This is
however dangerous thing prone to silent data corruption which can be
even exploitable.
Let's take CVE-2017-1000253 as an example. At the time (before commit
eab09532d400: "binfmt_elf: use ELF_ET_DYN_BASE only for PIE")
ELF_ET_DYN_BASE was at TASK_SIZE / 3 * 2 which is not that far away from
the stack top on 32b (legacy) memory layout (only 1GB away). Therefore
we could end up mapping over the existing stack with some luck.
The issue has been fixed since then (a87938b2e246: "fs/binfmt_elf.c: fix
bug in loading of PIE binaries"), ELF_ET_DYN_BASE moved moved much
further from the stack (eab09532d4 and later by c715b72c1ba4: "mm:
revert x86_64 and arm64 ELF_ET_DYN_BASE base changes") and excessive
stack consumption early during execve fully stopped by da029c11e6
("exec: Limit arg stack to at most 75% of _STK_LIM"). So we should be
safe and any attack should be impractical. On the other hand this is
just too subtle assumption so it can break quite easily and hard to
spot.
I believe that the MAP_FIXED usage in load_elf_binary (et. al) is still
fundamentally dangerous. Moreover it shouldn't be even needed. We are
at the early process stage and so there shouldn't be unrelated mappings
(except for stack and loader) existing so mmap for a given address should
succeed even without MAP_FIXED. Something is terribly wrong if this is
not the case and we should rather fail than silently corrupt the
underlying mapping.
Address this issue by changing MAP_FIXED to the newly added
MAP_FIXED_NOREPLACE. This will mean that mmap will fail if there is an
existing mapping clashing with the requested one without clobbering it.
[mhocko@suse.com: fix build]
[akpm@linux-foundation.org: coding-style fixes]
[avagin@openvz.org: don't use the same value for MAP_FIXED_NOREPLACE and MAP_SYNC]
Link: http://lkml.kernel.org/r/20171218184916.24445-1-avagin@openvz.org
Link: http://lkml.kernel.org/r/20171213092550.2774-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide a final callback into fs/exec.c before start_thread() takes
over, to handle any last-minute changes, like the coming restoration of
the stack limit.
Link: http://lkml.kernel.org/r/1518638796-20819-3-git-send-email-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Greg KH <greg@kroah.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If vm.max_map_count bumped above 2^26 (67+ mil) and system has enough RAM
to allocate all the VMAs (~12.8 GB on Fedora 27 with 200-byte VMAs), then
it should be possible to overflow 32-bit "size", pass paranoia check,
allocate very little vmalloc space and oops while writing into vmalloc
guard page...
But I didn't test this, only coredump of regular process.
Link: http://lkml.kernel.org/r/20180112203427.GA9109@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull ARM updates from Russell King:
- add support for ELF fdpic binaries on both MMU and noMMU platforms
- linker script cleanups
- support for compressed .data section for XIP images
- discard memblock arrays when possible
- various cleanups
- atomic DMA pool updates
- better diagnostics of missing/corrupt device tree
- export information to allow userspace kexec tool to place images more
inteligently, so that the device tree isn't overwritten by the
booting kernel
- make early_printk more efficient on semihosted systems
- noMMU cleanups
- SA1111 PCMCIA update in preparation for further cleanups
* 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (38 commits)
ARM: 8719/1: NOMMU: work around maybe-uninitialized warning
ARM: 8717/2: debug printch/printascii: translate '\n' to "\r\n" not "\n\r"
ARM: 8713/1: NOMMU: Support MPU in XIP configuration
ARM: 8712/1: NOMMU: Use more MPU regions to cover memory
ARM: 8711/1: V7M: Add support for MPU to M-class
ARM: 8710/1: Kconfig: Kill CONFIG_VECTORS_BASE
ARM: 8709/1: NOMMU: Disallow MPU for XIP
ARM: 8708/1: NOMMU: Rework MPU to be mostly done in C
ARM: 8707/1: NOMMU: Update MPU accessors to use cp15 helpers
ARM: 8706/1: NOMMU: Move out MPU setup in separate module
ARM: 8702/1: head-common.S: Clear lr before jumping to start_kernel()
ARM: 8705/1: early_printk: use printascii() rather than printch()
ARM: 8703/1: debug.S: move hexbuf to a writable section
ARM: add additional table to compressed kernel
ARM: decompressor: fix BSS size calculation
pcmcia: sa1111: remove special sa1111 mmio accessors
pcmcia: sa1111: use sa1111_get_irq() to obtain IRQ resources
ARM: better diagnostics with missing/corrupt dtb
ARM: 8699/1: dma-mapping: Remove init_dma_coherent_pool_size()
ARM: 8698/1: dma-mapping: Mark atomic_pool as __ro_after_init
..
Currently the regset API doesn't allow for the possibility that
regsets (or at least, the amount of meaningful data in a regset)
may change in size.
In particular, this results in useless padding being added to
coredumps if a regset's current size is smaller than its
theoretical maximum size.
This patch adds a get_size() function to struct user_regset.
Individual regset implementations can implement this function to
return the current size of the regset data. A regset_size()
function is added to provide callers with an abstract interface for
determining the size of a regset without needing to know whether
the regset is dynamically sized or not.
The only affected user of this interface is the ELF coredump code:
This patch ports ELF coredump to dump regsets with their actual
size in the coredump. This has no effect except for new regsets
that are dynamically sized and provide a get_size() implementation.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This series provides the needed changes to suport the ELF_FDPIC binary
format on ARM. Both MMU and non-MMU systems are supported. This format
has many advantages over the BFLT format used on MMU-less systems, such
as being real ELF that can be parsed by standard tools, can support
shared dynamic libs, etc.
Pull more set_fs removal from Al Viro:
"Christoph's 'use kernel_read and friends rather than open-coding
set_fs()' series"
* 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: unexport vfs_readv and vfs_writev
fs: unexport vfs_read and vfs_write
fs: unexport __vfs_read/__vfs_write
lustre: switch to kernel_write
gadget/f_mass_storage: stop messing with the address limit
mconsole: switch to kernel_read
btrfs: switch write_buf to kernel_write
net/9p: switch p9_fd_read to kernel_write
mm/nommu: switch do_mmap_private to kernel_read
serial2002: switch serial2002_tty_write to kernel_{read/write}
fs: make the buf argument to __kernel_write a void pointer
fs: fix kernel_write prototype
fs: fix kernel_read prototype
fs: move kernel_read to fs/read_write.c
fs: move kernel_write to fs/read_write.c
autofs4: switch autofs4_write to __kernel_write
ashmem: switch to ->read_iter
On platforms where both ELF and ELF-FDPIC variants are available, the
regular ELF loader will happily identify FDPIC binaries as proper ELF
and load them without the necessary FDPIC fixups, resulting in an
immediate user space crash. Let's prevent binflt_elf from loading those
binaries so binfmt_elf_fdpic has a chance to pick them up. For those
architectures that don't define elf_check_fdpic(), a default version
returning false is provided.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Mickael GUENE <mickael.guene@st.com>
Tested-by: Vincent Abriou <vincent.abriou@st.com>
Tested-by: Andras Szemzo <szemzo.andras@gmail.com>
running set*id processes. To do this, the bprm_secureexec LSM hook is
collapsed into the bprm_set_creds hook so the secureexec-ness of an exec
can be determined early enough to make decisions about rlimits and the
resulting memory layouts. Other logic acting on the secureexec-ness of an
exec is similarly consolidated. Capabilities needed some special handling,
but the refactoring removed other special handling, so that was a wash.
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Merge tag 'secureexec-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull secureexec update from Kees Cook:
"This series has the ultimate goal of providing a sane stack rlimit
when running set*id processes.
To do this, the bprm_secureexec LSM hook is collapsed into the
bprm_set_creds hook so the secureexec-ness of an exec can be
determined early enough to make decisions about rlimits and the
resulting memory layouts. Other logic acting on the secureexec-ness of
an exec is similarly consolidated. Capabilities needed some special
handling, but the refactoring removed other special handling, so that
was a wash"
* tag 'secureexec-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
exec: Consolidate pdeath_signal clearing
exec: Use sane stack rlimit under secureexec
exec: Consolidate dumpability logic
smack: Remove redundant pdeath_signal clearing
exec: Use secureexec for clearing pdeath_signal
exec: Use secureexec for setting dumpability
LSM: drop bprm_secureexec hook
commoncap: Move cap_elevated calculation into bprm_set_creds
commoncap: Refactor to remove bprm_secureexec hook
smack: Refactor to remove bprm_secureexec hook
selinux: Refactor to remove bprm_secureexec hook
apparmor: Refactor to remove bprm_secureexec hook
binfmt: Introduce secureexec flag
exec: Correct comments about "point of no return"
exec: Rename bprm->cred_prepared to called_set_creds
Use proper ssize_t and size_t types for the return value and count
argument, move the offset last and make it an in/out argument like
all other read/write helpers, and make the buf argument a void pointer
to get rid of lots of casts in the callers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and
randomize_stack_top() are not required.
PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not
set, no need to re-check after that.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: stable@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20170815154011.GB1076@redhat.com
The bprm_secureexec hook can be moved earlier. Right now, it is called
during create_elf_tables(), via load_binary(), via search_binary_handler(),
via exec_binprm(). Nearly all (see exception below) state used by
bprm_secureexec is created during the bprm_set_creds hook, called from
prepare_binprm().
For all LSMs (except commoncaps described next), only the first execution
of bprm_set_creds takes any effect (they all check bprm->called_set_creds
which prepare_binprm() sets after the first call to the bprm_set_creds
hook). However, all these LSMs also only do anything with bprm_secureexec
when they detected a secure state during their first run of bprm_set_creds.
Therefore, it is functionally identical to move the detection into
bprm_set_creds, since the results from secureexec here only need to be
based on the first call to the LSM's bprm_set_creds hook.
The single exception is that the commoncaps secureexec hook also examines
euid/uid and egid/gid differences which are controlled by bprm_fill_uid(),
via prepare_binprm(), which can be called multiple times (e.g.
binfmt_script, binfmt_misc), and may clear the euid/egid for the final
load (i.e. the script interpreter). However, while commoncaps specifically
ignores bprm->cred_prepared, and runs its bprm_set_creds hook each time
prepare_binprm() may get called, it needs to base the secureexec decision
on the final call to bprm_set_creds. As a result, it will need special
handling.
To begin this refactoring, this adds the secureexec flag to the bprm
struct, and calls the secureexec hook during setup_new_exec(). This is
safe since all the cred work is finished (and past the point of no return).
This explicit call will be removed in later patches once the hook has been
removed.
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
When building the argv/envp pointers, the envp is needlessly
pre-incremented instead of just continuing after the argv pointers are
finished. In some (likely impossible) race where the strings could be
changed from userspace between copy_strings() and here, it might be
possible to confuse the envp position. Instead, just use sp like
everything else.
Link: http://lkml.kernel.org/r/20170622173838.GA43308@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Qualys Security Advisory <qsa@qualys.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The ELF_ET_DYN_BASE position was originally intended to keep loaders
away from ET_EXEC binaries. (For example, running "/lib/ld-linux.so.2
/bin/cat" might cause the subsequent load of /bin/cat into where the
loader had been loaded.)
With the advent of PIE (ET_DYN binaries with an INTERP Program Header),
ELF_ET_DYN_BASE continued to be used since the kernel was only looking
at ET_DYN. However, since ELF_ET_DYN_BASE is traditionally set at the
top 1/3rd of the TASK_SIZE, a substantial portion of the address space
is unused.
For 32-bit tasks when RLIMIT_STACK is set to RLIM_INFINITY, programs are
loaded above the mmap region. This means they can be made to collide
(CVE-2017-1000370) or nearly collide (CVE-2017-1000371) with
pathological stack regions.
Lowering ELF_ET_DYN_BASE solves both by moving programs below the mmap
region in all cases, and will now additionally avoid programs falling
back to the mmap region by enforcing MAP_FIXED for program loads (i.e.
if it would have collided with the stack, now it will fail to load
instead of falling back to the mmap region).
To allow for a lower ELF_ET_DYN_BASE, loaders (ET_DYN without INTERP)
are loaded into the mmap region, leaving space available for either an
ET_EXEC binary with a fixed location or PIE being loaded into mmap by
the loader. Only PIE programs are loaded offset from ELF_ET_DYN_BASE,
which means architectures can now safely lower their values without risk
of loaders colliding with their subsequently loaded programs.
For 64-bit, ELF_ET_DYN_BASE is best set to 4GB to allow runtimes to use
the entire 32-bit address space for 32-bit pointers.
Thanks to PaX Team, Daniel Micay, and Rik van Riel for inspiration and
suggestions on how to implement this solution.
Fixes: d1fd836dcf ("mm: split ET_DYN ASLR from mmap ASLR")
Link: http://lkml.kernel.org/r/20170621173201.GA114489@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Qualys Security Advisory <qsa@qualys.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a trivial, mostly empty <linux/sched/cputime.h> header
to prepare for the moving of cputime functionality out of sched.h.
Update all code that relies on these facilities.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/coredump.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/coredump.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On 32-bit powerpc the ELF PLT sections of binaries (built with
--bss-plt, or with a toolchain which defaults to it) look like this:
[17] .sbss NOBITS 0002aff8 01aff8 000014 00 WA 0 0 4
[18] .plt NOBITS 0002b00c 01aff8 000084 00 WAX 0 0 4
[19] .bss NOBITS 0002b090 01aff8 0000a4 00 WA 0 0 4
Which results in an ELF load header:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x019c70 0x00029c70 0x00029c70 0x01388 0x014c4 RWE 0x10000
This is all correct, the load region containing the PLT is marked as
executable. Note that the PLT starts at 0002b00c but the file mapping
ends at 0002aff8, so the PLT falls in the 0 fill section described by
the load header, and after a page boundary.
Unfortunately the generic ELF loader ignores the X bit in the load
headers when it creates the 0 filled non-file backed mappings. It
assumes all of these mappings are RW BSS sections, which is not the case
for PPC.
gcc/ld has an option (--secure-plt) to not do this, this is said to
incur a small performance penalty.
Currently, to support 32-bit binaries with PLT in BSS kernel maps
*entire brk area* with executable rights for all binaries, even
--secure-plt ones.
Stop doing that.
Teach the ELF loader to check the X bit in the relevant load header and
create 0 filled anonymous mappings that are executable if the load
header requests that.
Test program showing the difference in /proc/$PID/maps:
int main() {
char buf[16*1024];
char *p = malloc(123); /* make "[heap]" mapping appear */
int fd = open("/proc/self/maps", O_RDONLY);
int len = read(fd, buf, sizeof(buf));
write(1, buf, len);
printf("%p\n", p);
return 0;
}
Compiled using: gcc -mbss-plt -m32 -Os test.c -otest
Unpatched ppc64 kernel:
00100000-00120000 r-xp 00000000 00:00 0 [vdso]
0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094 /usr/lib/libc-2.17.so
10000000-10010000 r-xp 00000000 fd:00 100674505 /home/user/test
10010000-10020000 r--p 00000000 fd:00 100674505 /home/user/test
10020000-10030000 rw-p 00010000 fd:00 100674505 /home/user/test
10690000-106c0000 rwxp 00000000 00:00 0 [heap]
f7f70000-f7fa0000 r-xp 00000000 fd:00 67898089 /usr/lib/ld-2.17.so
f7fa0000-f7fb0000 r--p 00020000 fd:00 67898089 /usr/lib/ld-2.17.so
f7fb0000-f7fc0000 rw-p 00030000 fd:00 67898089 /usr/lib/ld-2.17.so
ffa90000-ffac0000 rw-p 00000000 00:00 0 [stack]
0x10690008
Patched ppc64 kernel:
00100000-00120000 r-xp 00000000 00:00 0 [vdso]
0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094 /usr/lib/libc-2.17.so
10000000-10010000 r-xp 00000000 fd:00 100674505 /home/user/test
10010000-10020000 r--p 00000000 fd:00 100674505 /home/user/test
10020000-10030000 rw-p 00010000 fd:00 100674505 /home/user/test
10180000-101b0000 rw-p 00000000 00:00 0 [heap]
^^^^ this has changed
f7c60000-f7c90000 r-xp 00000000 fd:00 67898089 /usr/lib/ld-2.17.so
f7c90000-f7ca0000 r--p 00020000 fd:00 67898089 /usr/lib/ld-2.17.so
f7ca0000-f7cb0000 rw-p 00030000 fd:00 67898089 /usr/lib/ld-2.17.so
ff860000-ff890000 rw-p 00000000 00:00 0 [stack]
0x10180008
The patch was originally posted in 2012 by Jason Gunthorpe
and apparently ignored:
https://lkml.org/lkml/2012/9/30/138
Lightly run-tested.
Link: http://lkml.kernel.org/r/20161215131950.23054-1-dvlasenk@redhat.com
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the new nsec based cputime accessors as part of the whole cputime
conversion from cputime_t to nsecs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-12-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that most cputime readers use the transition API which return the
task cputime in old style cputime_t, we can safely store the cputime in
nsecs. This will eventually make cputime statistics less opaque and more
granular. Back and forth convertions between cputime_t and nsecs in order
to deal with cputime_t random granularity won't be needed anymore.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-8-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This API returns a task's cputime in cputime_t in order to ease the
conversion of cputime internals to use nsecs units instead. Blindly
converting all cputime readers to use this API now will later let us
convert more smoothly and step by step all these places to use the
new nsec based cputime.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-7-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the last section of a core file ends with an unmapped or zero page,
the size of the file does not correspond with the last dump_skip() call.
gdb complains that the file is truncated and can be confusing to users.
After all of the vma sections are written, make sure that the file size
is no smaller than the current file position.
This problem can be demonstrated with gdb's bigcore testcase on the
sparc architecture.
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds