[RFC PATCH 0/6] remove in-kernel syscall invocations (part 3 == compat cruft)

Dominik Brodowski
2018-03-18T16:10:50Z

Here is a third series of patches which reduce the number of syscall
invocations from within the kernel. Once this long-term goal is achieved,
the syscall entry path can be streamlined.

This series focuses on a few compat syscall definitions in arch/ which
have no other in-kernel users. In particular, it introduces generic compat
syscalls for a handful of mm- and fs-related functions. Their calling
convention depends on whether the architecture sets
__ARCH_WANT_LE_COMPAT_SYS (little-endian calling convention)
and/or __ARCH_WANT_COMPAT_SYS_WITH_PADDING.

As I am not used to non-x86 architectures, please bear with me in case I
broke something or missed some peculiarities. In particular, I was
surprised that a couple of compat syscall definitions used "u64" or
"unsigned long" as parameter definitions -- though the code makes it clear
that they expected an "u32" or an "unsigned int" instead. CVE-2009-0029
seems to be handled already by the compat_sys_*() compat_SyS_*() /
C_SYSC_*() indirection provided for by include/linux/compat.h. Or do I
miss something here?

I did not bother addressing metag and tile, as they are going away.
Parisc and sh (sys_sh32.c in particular) provide similar wrappers for
"native" (non-compat) use, so they are left as-is as well.

Patches 5 and 6 in this series are x86-only.

Thanks,
Dominik

Dominik Brodowski (6):
fs: provide a generic compat_sys_fallocate() implementation
fs: provide a generic compat_sys_truncate64() implementation
fs: provide generic compat_sys_p{read,write}64() implementations
mm: provide generic compat_sys_readahead() implementation
x86: use _do_fork() in compat_sys_x86_clone()
x86: remove compat_sys_x86_waitpid()

arch/mips/include/asm/unistd.h | 8 ++++
arch/mips/kernel/linux32.c | 35 ---------------
arch/mips/kernel/scall64-o32.S | 10 ++---
arch/powerpc/include/asm/unistd.h | 5 +++
arch/powerpc/kernel/sys_ppc32.c | 30 -------------
arch/s390/include/asm/unistd.h | 4 ++
arch/s390/kernel/compat_linux.c | 33 --------------
arch/s390/kernel/compat_linux.h | 5 ---
arch/s390/kernel/syscalls/syscall.tbl | 10 ++---
arch/sparc/include/asm/unistd.h | 4 ++
arch/sparc/kernel/sys_sparc32.c | 41 -----------------
arch/sparc/kernel/systbls.h | 19 --------
arch/sparc/kernel/systbls_64.S | 4 +-
arch/x86/entry/syscalls/syscall_32.tbl | 12 ++---
arch/x86/ia32/sys_ia32.c | 46 +------------------
arch/x86/include/asm/sys_ia32.h | 14 ------
arch/x86/include/asm/unistd.h | 5 +++
fs/open.c | 52 +++++++++++++++++++++-
fs/read_write.c | 74 +++++++++++++++++++++++++++++--
include/linux/compat.h | 42 ++++++++++++++++++
mm/readahead.c | 81 ++++++++++++++++++++++++----------
21 files changed, 266 insertions(+), 268 deletions(-)

--
2.16.2