linux.git/arch/x86/entry/syscalls, branch v5.5

syscalls/x86: Use the correct function type for sys_ni_syscall

2019-10-11T10:49:18+00:00

Use the correct function type for sys_ni_syscall() in system
call tables to fix indirect call mismatches with Control-Flow
Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen 
Acked-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: H . Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20191008224049.115427-5-samitolvanen@google.com
Signed-off-by: Ingo Molnar

syscalls/x86: Use COMPAT_SYSCALL_DEFINE0 for IA32 (rt_)sigreturn

2019-10-11T10:49:18+00:00

Use COMPAT_SYSCALL_DEFINE0 to define (rt_)sigreturn() syscalls to
replace sys32_sigreturn() and sys32_rt_sigreturn(). This fixes indirect
call mismatches with Control-Flow Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen 
Acked-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: H . Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20191008224049.115427-4-samitolvanen@google.com
Signed-off-by: Ingo Molnar

x86/syscalls: Split the x32 syscalls into their own table

2019-07-22T08:31:23+00:00

For unfortunate historical reasons, the x32 syscalls and the x86_64
syscalls are not all numbered the same.  As an example, ioctl() is nr 16 on
x86_64 but 514 on x32.

This has potentially nasty consequences, since it means that there are two
valid RAX values to do ioctl(2) and two invalid RAX values.  The valid
values are 16 (i.e. ioctl(2) using the x86_64 ABI) and (514 | 0x40000000)
(i.e. ioctl(2) using the x32 ABI).

The invalid values are 514 and (16 | 0x40000000).  514 will enter the
"COMPAT_SYSCALL_DEFINE3(ioctl, ...)" entry point with in_compat_syscall()
and in_x32_syscall() returning false, whereas (16 | 0x40000000) will enter
the native entry point with in_compat_syscall() and in_x32_syscall()
returning true.  Both are bogus, and both will exercise code paths in the
kernel and in any running seccomp filters that really ought to be
unreachable.

Splitting out the x32 syscalls into their own tables, allows both bogus
invocations to return -ENOSYS.  I've checked glibc, musl, and Bionic, and
all of them appear to call syscalls with their correct numbers, so this
change should have no effect on them.

There is an added benefit going forward: new syscalls that need special
handling on x32 can share the same number on x32 and x86_64.  This means
that the special syscall range 512-547 can be treated as a legacy wart
instead of something that may need to be extended in the future.

Also add a selftest to verify the new behavior.

Signed-off-by: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/208024256b764312598f014ebfb0a42472c19354.1562185330.git.luto@kernel.org

x86/syscalls: Disallow compat entries for all types of 64-bit syscalls

2019-07-22T08:31:22+00:00

A "compat" entry in the syscall tables means to use a different entry on
32-bit and 64-bit builds.

This only makes sense for syscalls that exist in the first place in 32-bit
builds, so disallow it for anything other than i386.

Signed-off-by: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/4b7565954c5a06530ac01d98cb1592538fd8ae51.1562185330.git.luto@kernel.org

x86/syscalls: Use the compat versions of rt_sigsuspend() and rt_sigprocmask()

2019-07-22T08:31:22+00:00

I'm working on some code that detects at build time if there's a
COMPAT_SYSCALL_DEFINE() that is not referenced in the x86 syscall tables.
It catches three offenders: rt_sigsuspend(), rt_sigprocmask(), and
sendfile64().

For rt_sigsuspend() and rt_sigprocmask(), the only potential difference
between the native and compat versions is that the compat version converts
the sigset_t, but, on little endian architectures, the conversion is a
no-op.  This is why they both currently work on x86.

To make the code more consistent, and to make the upcoming patches work,
rewire x86 to use the compat vesions.

sendfile64() is more complicated, and will be addressed separately.

Signed-off-by: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/51643ac3157b5921eae0e172a8a0b1d953e68ebb.1562185330.git.luto@kernel.org

Merge tag 'clone3-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2019-07-11T17:09:44+00:00

Pull clone3 system call from Christian Brauner:
 "This adds the clone3 syscall which is an extensible successor to clone
  after we snagged the last flag with CLONE_PIDFD during the 5.2 merge
  window for clone(). It cleanly supports all of the flags from clone()
  and thus all legacy workloads.

  There are few user visible differences between clone3 and clone.
  First, CLONE_DETACHED will cause EINVAL with clone3 so we can reuse
  this flag. Second, the CSIGNAL flag is deprecated and will cause
  EINVAL to be reported. It is superseeded by a dedicated "exit_signal"
  argument in struct clone_args thus freeing up even more flags. And
  third, clone3 gives CLONE_PIDFD a dedicated return argument in struct
  clone_args instead of abusing CLONE_PARENT_SETTID's parent_tidptr
  argument.

  The clone3 uapi is designed to be easy to handle on 32- and 64 bit:

    /* uapi */
    struct clone_args {
            __aligned_u64 flags;
            __aligned_u64 pidfd;
            __aligned_u64 child_tid;
            __aligned_u64 parent_tid;
            __aligned_u64 exit_signal;
            __aligned_u64 stack;
            __aligned_u64 stack_size;
            __aligned_u64 tls;
    };

  and a separate kernel struct is used that uses proper kernel typing:

    /* kernel internal */
    struct kernel_clone_args {
            u64 flags;
            int __user *pidfd;
            int __user *child_tid;
            int __user *parent_tid;
            int exit_signal;
            unsigned long stack;
            unsigned long stack_size;
            unsigned long tls;
    };

  The system call comes with a size argument which enables the kernel to
  detect what version of clone_args userspace is passing in. clone3
  validates that any additional bytes a given kernel does not know about
  are set to zero and that the size never exceeds a page.

  A nice feature is that this patchset allowed us to cleanup and
  simplify various core kernel codepaths in kernel/fork.c by making the
  internal _do_fork() function take struct kernel_clone_args even for
  legacy clone().

  This patch also unblocks the time namespace patchset which wants to
  introduce a new CLONE_TIMENS flag.

  Note, that clone3 has only been wired up for x86{_32,64}, arm{64}, and
  xtensa. These were the architectures that did not require special
  massaging.

  Other architectures treat fork-like system calls individually and
  after some back and forth neither Arnd nor I felt confident that we
  dared to add clone3 unconditionally to all architectures. We agreed to
  leave this up to individual architecture maintainers. This is why
  there's an additional patch that introduces __ARCH_WANT_SYS_CLONE3
  which any architecture can set once it has implemented support for
  clone3. The patch also adds a cond_syscall(clone3) for architectures
  such as nios2 or h8300 that generate their syscall table by simply
  including asm-generic/unistd.h. The hope is to get rid of
  __ARCH_WANT_SYS_CLONE3 and cond_syscall() rather soon"

* tag 'clone3-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  arch: handle arches who do not yet define clone3
  arch: wire-up clone3() syscall
  fork: add clone3

arch: wire-up pidfd_open()

2019-06-28T10:17:55+00:00

This wires up the pidfd_open() syscall into all arches at once.

Signed-off-by: Christian Brauner 
Reviewed-by: David Howells 
Reviewed-by: Oleg Nesterov 
Acked-by: Arnd Bergmann 
Cc: "Eric W. Biederman" 
Cc: Kees Cook 
Cc: Joel Fernandes (Google) 
Cc: Thomas Gleixner 
Cc: Jann Horn 
Cc: Andy Lutomirsky 
Cc: Andrew Morton 
Cc: Aleksa Sarai 
Cc: Linus Torvalds 
Cc: Al Viro 
Cc: linux-api@vger.kernel.org
Cc: linux-alpha@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org

arch: wire-up clone3() syscall

2019-06-09T07:29:46+00:00

Wire up the clone3() call on all arches that don't require hand-rolled
assembly.

Some of the arches look like they need special assembly massaging and it is
probably smarter if the appropriate arch maintainers would do the actual
wiring. Arches that are wired-up are:
- x86{_32,64}
- arm{64}
- xtensa

Signed-off-by: Christian Brauner 
Acked-by: Arnd Bergmann 
Cc: Kees Cook 
Cc: David Howells 
Cc: Andrew Morton 
Cc: Oleg Nesterov 
Cc: Adrian Reber 
Cc: Linus Torvalds 
Cc: Al Viro 
Cc: Florian Weimer 
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org

uapi, x86: Fix the syscall numbering of the mount API syscalls [ver #2]

2019-05-16T16:23:45+00:00

Fix the syscall numbering of the mount API syscalls so that the numbers
match between i386 and x86_64 and that they're in the common numbering
scheme space.

Fixes: a07b20004793 ("vfs: syscall: Add open_tree(2) to reference or clone a mount")
Fixes: 2db154b3ea8e ("vfs: syscall: Add move_mount(2) to move mounts around")
Fixes: 24dcb3d90a1f ("vfs: syscall: Add fsopen() to prepare for superblock creation")
Fixes: ecdab150fddb ("vfs: syscall: Add fsconfig() for configuring and managing a context")
Fixes: 93766fbd2696 ("vfs: syscall: Add fsmount() to create a mount for a superblock")
Fixes: cf3cba4a429b ("vfs: syscall: Add fspick() to select a superblock for reconfiguration")
Reported-by: Arnd Bergmann 
Signed-off-by: David Howells 
Reviewed-by: Arnd Bergmann 
Signed-off-by: Al Viro

vfs: syscall: Add fspick() to select a superblock for reconfiguration

2019-03-20T22:49:06+00:00

Provide an fspick() system call that can be used to pick an existing
mountpoint into an fs_context which can thereafter be used to reconfigure a
superblock (equivalent of the superblock side of -o remount).

This looks like:

	int fd = fspick(AT_FDCWD, "/mnt",
			FSPICK_CLOEXEC | FSPICK_NO_AUTOMOUNT);
	fsconfig(fd, FSCONFIG_SET_FLAG, "intr", NULL, 0);
	fsconfig(fd, FSCONFIG_SET_FLAG, "noac", NULL, 0);
	fsconfig(fd, FSCONFIG_CMD_RECONFIGURE, NULL, NULL, 0);

At the point of fspick being called, the file descriptor referring to the
filesystem context is in exactly the same state as the one that was created
by fsopen() after fsmount() has been successfully called.

Signed-off-by: David Howells 
cc: linux-api@vger.kernel.org
Signed-off-by: Al Viro