Permission denied, rootless with overlays (selinux disabled)

[rrichardson]

Description
Accessing files from a mounted overlay directory within a container results in EACCESS errors.
This seems very similar to #3136 but that was closed without any resolution that I was able to glean.
Also there is #1731 but I have verified that my system has the recommended configuration, as far as I can tell.

Another thing I notice, is that I chown -R the directory to the user I create within the container, but upon running ls afterwards, the files still appear to be owned by root even though chmod -R "succeeded"

On a fresh Fedora 35 installation. SELinux Disabled, /etc/containers/* is stock.
Attempting to run this command:

buildah bud -v $(pwd)/.yarn:/base/.yarn:O -v $(pwd)/node_modules:/base/node_modules:O -f docker/Dockerfile.prelude -t prelude_tmp . 

Fails when the script attempts to open a file within a mounted directory

STEP 24/27: RUN yarn
Internal Error: EACCES: permission denied, open '/base/.yarn/cache/.gitignore'
Error: EACCES: permission denied, open '/base/.yarn/cache/.gitignore'
error building at STEP "RUN yarn": error while running runtime: exit status 1

Steps to reproduce the issue:

1. With a dockerfile similar to

FROM --platform=linux/amd64 docker.io/node:16.13-alpine
RUN apk update && apk add --no-cache shadow
RUN addgroup -S ultron && adduser -S ultron -G ultron
WORKDIR /base
ADD tsconfig.json base.tsconfig.json .eslintignore .eslintrc.js package.json .
RUN chown -R ultron:ultron /base 
USER ultron
RUN ls -la ./.yarn
RUN "echo" foo > .yarn/myfile

2. And under a $HOME directory with .yarn/myfile and a similar node_modules, owned by $USER
3. Run:

buildah bud -v $(pwd)/.yarn:/base/.yarn:O -v $(pwd)/node_modules:/base/node_modules:O -f docker/Dockerfile -t tmp . 

Describe the results you received:

STEP 22/28: RUN chown -R ultron:ultron /base
STEP 23/28: USER ultron
STEP 24/28: RUN echo "foo" > .yarn/watwat
/bin/sh: can't create .yarn/watwat: Permission denied
error building at STEP "RUN echo "foo" > .yarn/watwat": error while running runtime: exit status 1

Note that it doesn't complain about chown -R ultron:ultron

Describe the results you expected:
Return of 0

Output of rpm -q buildah or apt list buildah:

λ rpm -q buildah
buildah-1.23.1-1.fc35.x86_64

Output of buildah version:

λ buildah version
Version:         1.23.1
Go Version:      go1.16.8
Image Spec:      1.0.1-dev
Runtime Spec:    1.0.2-dev
CNI Spec:        0.4.0
libcni Version:  v0.8.1
image Version:   5.16.0
Git Commit:
Built:           Tue Sep 28 11:26:37 2021
OS/Arch:         linux/amd64
BuildPlatform:   linux/amd64

Output of podman version if reporting a podman build issue:

λ podman version
Version:      3.4.2
API Version:  3.4.2
Go Version:   go1.16.8
Built:        Fri Nov 12 12:25:37 2021
OS/Arch:      linux/amd64

Output of cat /etc/*release:

λ cat /etc/*release
Fedora release 35 (Thirty Five)
NAME="Fedora Linux"
VERSION="35 (Workstation Edition)"
ID=fedora
VERSION_ID=35
VERSION_CODENAME=""
PLATFORM_ID="platform:f35"
PRETTY_NAME="Fedora Linux 35 (Workstation Edition)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:35"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f35/system-administrators-guide/"
SUPPORT_URL="https://ask.fedoraproject.org/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=35
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=35
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Workstation Edition"
VARIANT_ID=workstation
Fedora release 35 (Thirty Five)
Fedora release 35 (Thirty Five)

Output of uname -a:

λ uname -a
Linux localhost-live.lan 5.14.10-300.fc35.x86_64 #1 SMP Thu Oct 7 20:48:44 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Output of cat /etc/containers/storage.conf:

# This file is is the configuration file for all tools
# that use the containers/storage library.
# See man 5 containers-storage.conf for more information
# The "container storage" table contains all of the server options.
[storage]

# Default Storage Driver, Must be set for proper operation.
driver = "overlay"

# Temporary storage location
runroot = "/run/containers/storage"

# Primary Read/Write location of container storage
graphroot = "/var/lib/containers/storage"

# Storage path for rootless users
#
# rootless_storage_path = "$HOME/.local/share/containers/storage"

[storage.options]
# Storage options to be passed to underlying storage drivers

# AdditionalImageStores is used to pass paths to additional Read/Only image stores
# Must be comma separated list.
additionalimagestores = [
]

# Remap-UIDs/GIDs is the mapping from UIDs/GIDs as they should appear inside of
# a container, to the UIDs/GIDs as they should appear outside of the container,
# and the length of the range of UIDs/GIDs.  Additional mapped sets can be
# listed and will be heeded by libraries, but there are limits to the number of
# mappings which the kernel will allow when you later attempt to run a
# container.
#
# remap-uids = 0:1668442479:65536
# remap-gids = 0:1668442479:65536

# Remap-User/Group is a user name which can be used to look up one or more UID/GID
# ranges in the /etc/subuid or /etc/subgid file.  Mappings are set up starting
# with an in-container ID of 0 and then a host-level ID taken from the lowest
# range that matches the specified name, and using the length of that range.
# Additional ranges are then assigned, using the ranges which specify the
# lowest host-level IDs first, to the lowest not-yet-mapped in-container ID,
# until all of the entries have been used for maps.
#
# remap-user = "containers"
# remap-group = "containers"

# Root-auto-userns-user is a user name which can be used to look up one or more UID/GID
# ranges in the /etc/subuid and /etc/subgid file.  These ranges will be partitioned
# to containers configured to create automatically a user namespace.  Containers
# configured to automatically create a user namespace can still overlap with containers
# having an explicit mapping set.
# This setting is ignored when running as rootless.
# root-auto-userns-user = "storage"
#
# Auto-userns-min-size is the minimum size for a user namespace created automatically.
# auto-userns-min-size=1024
#
# Auto-userns-max-size is the minimum size for a user namespace created automatically.
# auto-userns-max-size=65536

[storage.options.overlay]
# ignore_chown_errors can be set to allow a non privileged user running with
# a single UID within a user namespace to run containers. The user can pull
# and use any image even those with multiple uids.  Note multiple UIDs will be
# squashed down to the default uid in the container.  These images will have no
# separation between the users in the container. Only supported for the overlay
# and vfs drivers.
#ignore_chown_errors = "false"

# Inodes is used to set a maximum inodes of the container image.
# inodes = ""

# Path to an helper program to use for mounting the file system instead of mounting it
# directly.
#mount_program = "/usr/bin/fuse-overlayfs"

# mountopt specifies comma separated list of extra mount options
mountopt = "nodev,metacopy=on"

# Set to skip a PRIVATE bind mount on the storage home directory.
# skip_mount_home = "false"

# Size is used to set a maximum size of the container image.
# size = ""

# ForceMask specifies the permissions mask that is used for new files and
# directories.
#
# The values "shared" and "private" are accepted.
# Octal permission masks are also accepted.
#
#  "": No value specified.
#     All files/directories, get set with the permissions identified within the
#     image.
#  "private": it is equivalent to 0700.
#     All files/directories get set with 0700 permissions.  The owner has rwx
#     access to the files. No other users on the system can access the files.
#     This setting could be used with networked based homedirs.
#  "shared": it is equivalent to 0755.
#     The owner has rwx access to the files and everyone else can read, access
#     and execute them. This setting is useful for sharing containers storage
#     with other users.  For instance have a storage owned by root but shared
#     to rootless users as an additional store.
#     NOTE:  All files within the image are made readable and executable by any
#     user on the system. Even /etc/shadow within your image is now readable by
#     any user.
#
#   OCTAL: Users can experiment with other OCTAL Permissions.
#
#  Note: The force_mask Flag is an experimental feature, it could change in the
#  future.  When "force_mask" is set the original permission mask is stored in
#  the "user.containers.override_stat" xattr and the "mount_program" option must
#  be specified. Mount programs like "/usr/bin/fuse-overlayfs" present the
#  extended attribute permissions to processes within containers rather then the
#  "force_mask"  permissions.
#
# force_mask = ""

[storage.options.thinpool]
# Storage Options for thinpool

# autoextend_percent determines the amount by which pool needs to be
# grown. This is specified in terms of % of pool size. So a value of 20 means
# that when threshold is hit, pool will be grown by 20% of existing
# pool size.
# autoextend_percent = "20"

# autoextend_threshold determines the pool extension threshold in terms
# of percentage of pool size. For example, if threshold is 60, that means when
# pool is 60% full, threshold has been hit.
# autoextend_threshold = "80"

# basesize specifies the size to use when creating the base device, which
# limits the size of images and containers.
# basesize = "10G"

# blocksize specifies a custom blocksize to use for the thin pool.
# blocksize="64k"

# directlvm_device specifies a custom block storage device to use for the
# thin pool. Required if you setup devicemapper.
# directlvm_device = ""

# directlvm_device_force wipes device even if device already has a filesystem.
# directlvm_device_force = "True"

# fs specifies the filesystem type to use for the base device.
# fs="xfs"

# log_level sets the log level of devicemapper.
# 0: LogLevelSuppress 0 (Default)
# 2: LogLevelFatal
# 3: LogLevelErr
# 4: LogLevelWarn
# 5: LogLevelNotice
# 6: LogLevelInfo
# 7: LogLevelDebug
# log_level = "7"

# min_free_space specifies the min free space percent in a thin pool require for
# new device creation to succeed. Valid values are from 0% - 99%.
# Value 0% disables
# min_free_space = "10%"

# mkfsarg specifies extra mkfs arguments to be used when creating the base
# device.
# mkfsarg = ""

# metadata_size is used to set the `pvcreate --metadatasize` options when
# creating thin devices. Default is 128k
# metadata_size = ""

# Size is used to set a maximum size of the container image.
# size = ""

# use_deferred_removal marks devicemapper block device for deferred removal.
# If the thinpool is in use when the driver attempts to remove it, the driver
# tells the kernel to remove it as soon as possible. Note this does not free
# up the disk space, use deferred deletion to fully remove the thinpool.
# use_deferred_removal = "True"

# use_deferred_deletion marks thinpool device for deferred deletion.
# If the device is busy when the driver attempts to delete it, the driver
# will attempt to delete device every 30 seconds until successful.
# If the program using the driver exits, the driver will continue attempting
# to cleanup the next time the driver is used. Deferred deletion permanently
# deletes the device and all data stored in device will be lost.
# use_deferred_deletion = "True"

# xfs_nospace_max_retries specifies the maximum number of retries XFS should
# attempt to complete IO when ENOSPC (no space) error is returned by
# underlying storage device.
# xfs_nospace_max_retries = "0"

[rrichardson]

λ cat /etc/subuid
rick:100000:65536
λ cat /etc/subgid
rick:100000:65536

[rrichardson]

I just attempted to run the above buildah command with sudo, and achieved the same results.
also tried --cap-add=all and various --security-opt settings..
also, if its relevant:

buildah info
{
    "host": {
        "CgroupVersion": "v2",
        "Distribution": {
            "distribution": "fedora",
            "version": "35"
        },
        "MemFree": 56602050560,
        "MemTotal": 67338829824,
        "OCIRuntime": "crun",
        "SwapFree": 8589930496,
        "SwapTotal": 8589930496,
        "arch": "amd64",
        "cpus": 24,
        "hostname": "localhost-live.lan",
        "kernel": "5.14.10-300.fc35.x86_64",
        "os": "linux",
        "rootless": true,
        "uptime": "1h 0m 35.22s (Approximately 0.04 days)"
    },
    "store": {
        "ContainerStore": {
            "number": 11
        },
        "GraphDriverName": "overlay",
        "GraphOptions": [
            "overlay.mount_program=/usr/bin/fuse-overlayfs",
            "overlay.mount_program=/usr/bin/fuse-overlayfs"
        ],
        "GraphRoot": "/home/rick/.local/share/containers/storage",
        "GraphStatus": {
            "Backing Filesystem": "btrfs",
            "Native Overlay Diff": "false",
            "Supports d_type": "true",
            "Using metacopy": "false"
        },
        "ImageStore": {
            "number": 26
        },
        "RunRoot": "/run/user/1000/containers"
    }
}

[rhatdan]

@flouthoc PTAL

[flouthoc]

@rrichardson
I was able to reproduce this. I think you need to use U with :O like :O,U. The :U suffix tells Buildah to use the correct host UID and GID based on the UID and GID within the container, to change the owner and group of the source volume.

Final command which made it work for me.
$buildah build -v $(pwd)/hello:/base/.yarn:O,U -t test .

My Containerfile

FROM --platform=linux/amd64 docker.io/node:16.13-alpine
RUN apk update && apk add --no-cache shadow
RUN addgroup -S ultron && adduser -S ultron -G ultron
RUN chown -R ultron:ultron /base/.yarn
RUN ls -la
WORKDIR /base
USER ultron
RUN ls -la ./.yarn
RUN "echo" foo > .yarn/myfile

[rrichardson]

@flouthoc - Oh this is excellent. I now see that option in the --volume portion of the bud man page.
I have verified that I can run it with ,U and it works.

Thanks!

[rrichardson]

@rhatdan - If it is possible to convert this to a discussion item, it seems like it'd be a great bit for a FAQ of sorts.

[flouthoc]

I don't see any option to convert this into discussion or probably I don't know. @rhatdan Do you know how could we convert this into discussion. Anyways @rrichardson I think github issues are very SEO friendly 😄

[TomSweeneyRedHat]

@rrichardson @flouthoc I've transferred this issue to a discussion. Aditya, at least on my GItHub page for the issues, there's a "Convert to Discussion" link in the right sidebar of the issue's page. Clicking on that moved this here.

[rrichardson]

I am aware of such a link, however, it was not available to me in this repository. Perhaps it is a permissions issue. :)