[ Upstream commit e7f7785449a1f459a4a3ca92f82f56fb054dd2b9 ]

In 2016 Linus moved install_exec_creds immediately after
setup_new_exec, in binfmt_elf as a cleanup and as part of closing a
potential information leak.

Perform the same cleanup for the other binary formats.

Different binary formats doing the same things the same way makes exec
easier to reason about and easier to maintain.

Greg Ungerer reports:
> I tested the the whole series on non-MMU m68k and non-MMU arm
> (exercising binfmt_flat) and it all tested out with no problems,
> so for the binfmt_flat changes:
Tested-by: Greg Ungerer <gerg@linux-m68k.org>

Ref: 9f834ec18def ("binfmt_elf: switch to new creds when switching to new mm")
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Stable-dep-of: e7f703ff2507 ("binfmt: Fix error return code in load_elf_fdpic_binary()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

commit 6045ab5fea4c849153ebeb0acb532da5f29d69c4 upstream.

bFLT binaries are usually created using elf2flt.

The linker script used by elf2flt has defined the .data section like the
following for the last 19 years:

.data : {
	_sdata = . ;
	__data_start = . ;
	data_start = . ;
	*(.got.plt)
	*(.got)
	FILL(0) ;
	. = ALIGN(0x20) ;
	LONG(-1)
	. = ALIGN(0x20) ;
	...
}

It places the .got.plt input section before the .got input section.
The same is true for the default linker script (ld --verbose) on most
architectures except x86/x86-64.

The binfmt_flat loader should relocate all GOT entries until it encounters
a -1 (the LONG(-1) in the linker script).

The problem is that the .got.plt input section starts with a GOTPLT header
(which has size 16 bytes on elf64-riscv and 8 bytes on elf32-riscv), where
the first word is set to -1. See the binutils implementation for riscv [1].

This causes the binfmt_flat loader to stop relocating GOT entries
prematurely and thus causes the application to crash when running.

Fix this by skipping the whole GOTPLT header, since the whole GOTPLT header
is reserved for the dynamic linker.

The GOTPLT header will only be skipped for bFLT binaries with flag
FLAT_FLAG_GOTPIC set. This flag is unconditionally set by elf2flt if the
supplied ELF binary has the symbol _GLOBAL_OFFSET_TABLE_ defined.
ELF binaries without a .got input section should thus remain unaffected.

Tested on RISC-V Canaan Kendryte K210 and RISC-V QEMU nommu_virt_defconfig.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elfnn-riscv.c;hb=binutils-2_38#l3275

Cc: <stable@vger.kernel.org>
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Link: https://lore.kernel.org/r/20220414091018.896737-1-niklas.cassel@wdc.com
Fixed-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202204182333.OIUOotK8-lkp@intel.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 2217b982624680d19a80ebb4600d05c8586c4f96 upstream.

binfmt_flat loader uses the gap between text and data to store data
segment pointers for the libraries. Even in the absence of shared
libraries it stores at least one pointer to the executable's own data
segment. Text and data can go back to back in the flat binary image and
without offsetting data segment last few instructions in the text
segment may get corrupted by the data segment pointer.

Fix it by reverting commit a2357223c50a ("binfmt_flat: don't offset the
data start").

Cc: stable@vger.kernel.org
Fixes: a2357223c50a ("binfmt_flat: don't offset the data start")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fixes gcc '-Wunused-but-set-variable' warning:

  fs/binfmt_flat.c: In function load_flat_file:
  fs/binfmt_flat.c:419:16: warning: variable inode set but not used [-Wunused-but-set-variable]

It's never used and can be removed.

Link: http://lkml.kernel.org/r/20190525125341.9844-1-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull m68nommu updates from Greg Ungerer:
 "A series of cleanups for the FLAT format binary loader, binfmt_flat,
  from Christoph.

  The end goal is to support no-MMU on RISC-V, and the last patch
  enables that"

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
  riscv: add binfmt_flat support
  binfmt_flat: don't offset the data start
  binfmt_flat: move the MAX_SHARED_LIBS definition to binfmt_flat.c
  binfmt_flat: remove the persistent argument from flat_get_addr_from_rp
  binfmt_flat: provide an asm-generic/flat.h
  binfmt_flat: make support for old format binaries optional
  binfmt_flat: add a ARCH_HAS_BINFMT_FLAT option
  binfmt_flat: add endianess annotations
  binfmt_flat: use fixed size type for the on-disk format
  binfmt_flat: consolidate two version of flat_v2_reloc_t
  binfmt_flat: remove the unused OLD_FLAT_FLAG_RAM definition
  binfmt_flat: remove the uapi <linux/flat.h> header
  binfmt_flat: replace flat_argvp_envp_on_stack with a Kconfig variable
  binfmt_flat: remove flat_old_ram_flag
  binfmt_flat: provide a default version of flat_get_relocate_addr
  binfmt_flat: remove flat_set_persistent
  binfmt_flat: remove flat_reloc_valid

load_flat_shared_library() is broken: It only calls load_flat_file() if
prepare_binprm() returns zero, but prepare_binprm() returns the number of
bytes read - so this only happens if the file is empty.

Instead, call into load_flat_file() if the number of bytes read is
non-negative. (Even if the number of bytes is zero - in that case,
load_flat_file() will see nullbytes and return a nice -ENOEXEC.)

In addition, remove the code related to bprm creds and stop using
prepare_binprm() - this code is loading a library, not a main executable,
and it only actually uses the members "buf", "file" and "filename" of the
linux_binprm struct. Instead, call kernel_read() directly.

Link: http://lkml.kernel.org/r/20190524201817.16509-1-jannh@google.com
Fixes: 287980e49ffc ("remove lots of IS_ERR_VALUE abuses")
Signed-off-by: Jann Horn <jannh@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Ever since the initial commit of the binfmt_flat shared library
support back in the bitkeeper days we've offset the actual in-memory
.data start by one field per possible shared library, or 1 in case
shared library support isn't enabled.  I can't find anything in the
loader that actually makes use of it, nor was it present before
shared library support it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

MAX_SHARED_LIBS is an implementation detail of the kernel loader,
and should be kept away from the file format definition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

The argument is never used.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

No need to carry the extra code around, given that systems using flat
binaries are generally very resource constrained.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>