[OE-core][dunfell 14/28] wic: Fix permissions when using exclude or include path

Steve Sakoman
2020-12-03T15:09:16Z

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

When parameters include_path or exclude_path are passed to the rootfs
plugin, it will copy the partition content into a folder and make all
the modifications there.

This is done using copyhardlinktree(), which does not take into
consideration the content of the pseudo folder, which contains the
information about the right permissions and ownership of the folders.

This results in a rootfs owned by the user that is running the wic
command (usually UID 1000), which makes some rootfs unbootable.

This bug can be easily triggerd with the following .wks

part / --source rootfs --fstype=ext4 --exclude-path=home

And this sequence:

$ wic create test-permissions -e core-image-minimal -o test/
$ sudo mount test/test-permissions-202004080823-sda.direct.p1 /mnt
$ ls -la /mnt/etc/shadow

To fix this we copy the content of the pseudo folders to the new folder
and modify the pseudo database using the "pseudo -B" command.

If the rootfs is not a rootfs generated by bitbake a warning is shown
making the user aware that the permissions on the target might not match
what he expects.

WARNING: /tmp/test/../pseudo folder does not exist. Usernames and permissions will be invalid

Cc: Paul Barker <pbarker@konsulko.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo@ribalda.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit fd739c15cdba221d9d497d3402b7d929c0be2ca4)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
---
scripts/lib/wic/partition.py | 7 +++--
scripts/lib/wic/plugins/source/rootfs.py | 37 ++++++++++++++++++++++--
2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/scripts/lib/wic/partition.py b/scripts/lib/wic/partition.py
index 3490b4e75d..6e87770f3a 100644
--- a/scripts/lib/wic/partition.py
+++ b/scripts/lib/wic/partition.py
@@ -191,7 +191,7 @@ class Partition():
(self.mountpoint, self.size, self.fixed_size))

def prepare_rootfs(self, cr_workdir, oe_builddir, rootfs_dir,
- native_sysroot, real_rootfs = True):
+ native_sysroot, real_rootfs = True, pseudo_dir = None):
"""
Prepare content for a rootfs partition i.e. create a partition
and fill it from a /rootfs dir.
@@ -199,8 +199,9 @@ class Partition():
Currently handles ext2/3/4, btrfs, vfat and squashfs.
"""
p_prefix = os.environ.get("PSEUDO_PREFIX", "%s/usr" % native_sysroot)
- p_localstatedir = os.environ.get("PSEUDO_LOCALSTATEDIR",
- "%s/../pseudo" % rootfs_dir)
+ if (pseudo_dir == None):
+ pseudo_dir = "%s/../pseudo" % rootfs_dir
+ p_localstatedir = os.environ.get("PSEUDO_LOCALSTATEDIR", pseudo_dir)
p_passwd = os.environ.get("PSEUDO_PASSWD", rootfs_dir)
p_nosymlinkexp = os.environ.get("PSEUDO_NOSYMLINKEXP", "1")
pseudo = "export PSEUDO_PREFIX=%s;" % p_prefix
diff --git a/scripts/lib/wic/plugins/source/rootfs.py b/scripts/lib/wic/plugins/source/rootfs.py
index 705aeb5563..8b2a067385 100644
--- a/scripts/lib/wic/plugins/source/rootfs.py
+++ b/scripts/lib/wic/plugins/source/rootfs.py
@@ -20,7 +20,7 @@ from oe.path import copyhardlinktree

from wic import WicError
from wic.pluginbase import SourcePlugin
-from wic.misc import get_bitbake_var
+from wic.misc import get_bitbake_var, exec_native_cmd

logger = logging.getLogger('wic')

@@ -44,6 +44,15 @@ class RootfsPlugin(SourcePlugin):

return os.path.realpath(image_rootfs_dir)

+ @staticmethod
+ def __get_pseudo(native_sysroot, rootfs, pseudo_dir):
+ pseudo = "export PSEUDO_PREFIX=%s/usr;" % native_sysroot
+ pseudo += "export PSEUDO_LOCALSTATEDIR=%s;" % pseudo_dir
+ pseudo += "export PSEUDO_PASSWD=%s;" % rootfs
+ pseudo += "export PSEUDO_NOSYMLINKEXP=1;"
+ pseudo += "%s " % get_bitbake_var("FAKEROOTCMD")
+ return pseudo
+
@classmethod
def do_prepare_partition(cls, part, source_params, cr, cr_workdir,
oe_builddir, bootimg_dir, kernel_dir,
@@ -68,8 +77,14 @@ class RootfsPlugin(SourcePlugin):
"it is not a valid path, exiting" % part.rootfs_dir)

part.rootfs_dir = cls.__get_rootfs_dir(rootfs_dir)
+ pseudo_dir = os.path.join(part.rootfs_dir, "../pseudo")
+ if not os.path.lexists(pseudo_dir):
+ logger.warn("%s folder does not exist. "
+ "Usernames and permissions will be invalid " % pseudo_dir)
+ pseudo_dir = None

new_rootfs = None
+ new_pseudo = None
# Handle excluded paths.
if part.exclude_path or part.include_path:
# We need a new rootfs directory we can delete files from. Copy to
@@ -78,9 +93,24 @@ class RootfsPlugin(SourcePlugin):

if os.path.lexists(new_rootfs):
shutil.rmtree(os.path.join(new_rootfs))
-
copyhardlinktree(part.rootfs_dir, new_rootfs)

+ # Convert the pseudo directory to its new location
+ if (pseudo_dir):
+ new_pseudo = os.path.realpath(
+ os.path.join(cr_workdir, "pseudo%d" % part.lineno))
+ if os.path.lexists(new_pseudo):
+ shutil.rmtree(new_pseudo)
+ os.mkdir(new_pseudo)
+ shutil.copy(os.path.join(pseudo_dir, "files.db"),
+ os.path.join(new_pseudo, "files.db"))
+
+ pseudo_cmd = "%s -B -m %s -M %s" % (cls.__get_pseudo(native_sysroot,
+ new_rootfs,
+ new_pseudo),
+ part.rootfs_dir, new_rootfs)
+ exec_native_cmd(pseudo_cmd, native_sysroot)
+
for path in part.include_path or []:
copyhardlinktree(path, new_rootfs)

@@ -112,4 +142,5 @@ class RootfsPlugin(SourcePlugin):
shutil.rmtree(full_path)

part.prepare_rootfs(cr_workdir, oe_builddir,
- new_rootfs or part.rootfs_dir, native_sysroot)
+ new_rootfs or part.rootfs_dir, native_sysroot,
+ pseudo_dir = new_pseudo or pseudo_dir)
--
2.17.1