vdso: don't forget to adjust vma_area_list->nr

A proxy vdso is removed from the vma_area_list list,
so vma_area_list->nr must be decremented.

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
iov: Add iov_grow_page() helper

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
iov: Add iov_init() helper

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
iov: Add iovec2pagemap() helper

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
iov: Add page_server_iov to iov and back helpers

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
restore: Make sure the last_pid is writen with zero offset

Otherwise I see on 3.16-rc1 and higher

| [  100.851730] futex wrote to ns_last_pid when file position was not 0!
| This will not be supported in the future. To silence this
| warning, set kernel.sysctl_writes_strict = -1

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: add new dumpable01 test to check that dumpable flag is preserved

This confirms that the fix in commit d5bb7e9748fd to preserve the dumpable flag
after migration is working as expected.

In this test case, the dumpable flag is expected to always be set to 1, as
test_init will use prctl to reset it to 1 after using setuid and setgid.

Tested:
- # test/zdtm.sh static/dumpable01
  Test: zdtm/live/static/dumpable01, Result: PASS
- # test/zdtm.sh ns/static/dumpable01
  Test: zdtm/live/static/dumpable01, Result: PASS
- Confirmed that the test fails after reverting commit d5bb7e9748fd.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Revert "pie: A quick workaround for PR_SET_DUMPABLE == 2 restore error."

This reverts commit 8870aa1e4f86da5fad087a31fe93bacd95144e09.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
restore: preserve dumpable flag when it is set to 2

Commit d5bb7e9748fd started to preserve the dumpable flag across migration by
using prctl to get the value on dump and set it back on restore.

On some situations, the dumpable flag can be set to 2.  This happens when it is
not reset (with prctl) after using setuid() or after using execv() on a binary
that has executable but not read permissions, when the fs.suid_dumpable sysctl
is also set to 2.  However, it is not possible to set it to 2 using prctl,
which would make criu restore fail.

Fix this by checking for the value before passing it to prctl.  In case the
value of the dumpable flag was 2 at the source, check whether it is already 2
at the destination, which is likely to happen if the fs.suid_dumpable sysctl is
also set to 2 where restore is running.  In that case, preserve the value,
otherwise reset it to 0 which is the most secure fallback.

Fixes: d5bb7e9748fda52a8653edd2804a4b15c4e4a1e1

Tested:
- Using dumpable02 zdtm test after setting fs.suid_dumpable to 2.
  # sysctl -w fs.suid_dumpable=2
  # test/zdtm.sh ns/static/dumpable02
  4: DEBUG: before dump: dumpable=2
  4: DEBUG: after restore: dumpable=2
  4: PASS
  Test: zdtm/live/static/dumpable02, Result: PASS

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: add new dumpable02 test to check that dumpable flag set to 0 or 2 works

This confirms that the fix to handle dumpable flag set to 2 still works after
restore.

To force dumpable flag set to 0 or 2 (whatever the fs.suid_dumpable is set to),
chmod the test binary to 0111 (executable, but not readable) and execv() it
while running as non-root.  The kernel will unset the dumpable flag to prevent
a core dump or ptrace to giving the user access to the pages of the binary
(which are supposedly not readable by that user.)

Tested:
- # test/zdtm.sh static/dumpable02
  Test: zdtm/live/static/dumpable02, Result: PASS
- # test/zdtm.sh ns/static/dumpable02
  Test: zdtm/live/static/dumpable02, Result: PASS
- Used -DDEBUG to confirm the value of the dumpable flag was 0 or 2 to match
  the fs.suid_dumpable sysctl in the tests (both in and out of namespaces.)
- Confirmed that the test fails if the commit that fixes handling of dumpable
  flag with value 2 is reverted and the fs.suid_dumpable sysctl is set to 2.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: add missing entries to test/zdtm/.gitignore

This adds new tests "cgroup00" and "clean_mntns" to the .gitignore file.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
git: add /dev to test/.gitignore

The /dev directory is also created by zdtm when running ns/ enabled tests.
Add it to the list, together with entries such as /bin and /lib.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vdso: image -- Add VMA_AREA_VVAR flag

Will need it to handle vvar zones in a special way.

Because VMA_UNSUPP never goes into the image file
lets reuse bit 12 for VVAR.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vdso: dump -- Don't dump contents of vvar zone

vvar zone is mapped by a kernel and must not ever
been dumped into image, the data present there is
valid on running kernel only.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vdso: util -- Show 'vvar' abreviature when meet VMA_AREA_VVAR

This is for debug purpose mostly.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vdso: parasite -- Prepare new vdso mark structure.

Because of new vvar area we need to carry the
address of vvar proxy inside the mark. Thus
add members needed and update routines.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vdso: x86 -- Add handling of vvar zones

New kernel 3.16 will have old vDSO zone splitted into the two vmas:
one for vdso code itself and second that named vvar for data been
referenced from vdso code.

Because I can't do 'dump' and 'restore' parts of the code separately
(otherwise test would fail) the commit is pretty big one and hard to
read so here is detailed explanation what's going on.

 1) When start dumping we detect vvar zone by reading /proc/pid/smap
    and looking up for "[vvar]" token. Note the vvar zone is mapped
    by a kernel with PF/IO flags so we should not fail here.

    Also it's assumed that at least for now kernel won't be changed
    much and [vvar] zone always follows the [vdso] zone, otherwise
    criu will print error.

 2) In previous commits we disabled dumping vvar area contents so
    the restorer code never try to read vvar data but still we need
    to map vvar zone thus vma entry remains in image.

 3) As with previous vdso format we might have 2 cases

    a) Dump and restore is happening on same kernel
    b) Dump and restore are done on different kernels

    To detect which case we have we parse vdso data from image
    and find symbols offsets then compare their values with runtime
    symbols provided us by a kernel. If they match and (!!!) the
    size of vvar zone is the same -- we simply remap both zones
    from runtime kernel into the positions dumpee had at checkpoint
    time. This is that named "inplace" remap (a).

    If this happens the vdso_proxify() routine drops VMA_AREA_REGULAR
    from vvar area provided by a caller code and restorer won't try
    to handle this vma. It looks somehow strange and probably should
    be reworked but for now I left it as is to minimize the patch.

    In case of (b) we need to generate a proxy. We do that in same
    way as we were before just include vvar zone into proxy and save
    vvar proxy address inside vdso mark injected into vdso area. Thus
    on subsequent checkpoint we can detect proxy vvar zone and rip
    it off the list of vmas to handle.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vdso: x86 -- Make sure the mark version matches

Otherwise we're meeting somehow corrupted mark and
must abort dumping.

Reported-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test/ext-links: fix path to the ip tool

run.sh: line 17: xip: command not found

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: add a target to execute non-zdtm tests

make -C test other

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>