Unprivileged Rootless Buildah on Kubernete

[jaredpricedev]

Description
I see this issue (#4049) is several years old and I was wondering if there has been any update with newer version of Buildah.

I have tried all the steps listed in that issue but I am still receiving an error with newuidmap. I am running a gitlab runner on RKE2. The image the runner is using is the Containerfile found here --> https://github.com/containers/image_build/blob/main/buildah/Containerfile

/etc/subgid (in container)

build:1:999
build:1001:64535

/etc/subuid (in container)

build:1:999
build:1001:64535

Steps to reproduce the issue:
1.
2.
3.

Describe the results you received:

WARN[0000] running newgidmap: exit status 1: newgidmap: write to gid_map failed: Operation not permitted
WARN[0000] Falling back to single mapping
WARN[0000] Error running newuidmap: exit status 1: newuidmap: write to uid_map failed: Operation not permitted
WARN[0000] Falling back to single mapping
...
...
Error: creating build container: copying system image from manifest list: writing blob: adding layer with blob "sha256:54e56e6f85721741ee7bf0336de8ad3bf138a56769a6d0097b600a0e361be58d"/""/"sha256:235cb1df51fddfcab96f2126fe2e4a93327f46dd33c6c2b9dbb0d5c0a95c0d23": unpacking failed (error: exit status 1; output: potentially insufficient UIDs or GIDs available in user namespace (requested 0:12 for /var/spool/mail): Check /etc/subuid and /etc/subgid if configured locally and run "podman system migrate": lchown /var/spool/mail: invalid argument)

Describe the results you expected:

Output of rpm -q buildah or apt list buildah:

buildah-1.37.1-1.fc40.x86_64

Output of buildah version:

Version:         1.37.1
Go Version:      go1.22.6
Image Spec:      1.1.0
Runtime Spec:    1.2.0
CNI Spec:        1.1.0
libcni Version:
image Version:   5.33.1
Git Commit:
Built:           Thu Aug 15 19:59:01 2024
OS/Arch:         linux/amd64
BuildPlatform:   linux/amd64

Output of podman version if reporting a podman build issue:

(paste your output here)

Output of cat /etc/*release:

Fedora release 40 (Forty)
NAME="Fedora Linux"
VERSION="40 (Container Image)"
ID=fedora
VERSION_ID=40
VERSION_CODENAME=""
PLATFORM_ID="platform:f40"
PRETTY_NAME="Fedora Linux 40 (Container Image)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:40"
DEFAULT_HOSTNAME="fedora"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f40/system-administrators-guide/"
SUPPORT_URL="https://ask.fedoraproject.org/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=40
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=40
SUPPORT_END=2025-05-13
VARIANT="Container Image"
VARIANT_ID=container
Fedora release 40 (Forty)
Fedora release 40 (Forty)

Output of uname -a:

Linux runner 4.18.0-553.8.1.el8_10.x86_64 #1 SMP Fri Jun 14 03:19:37 EDT 2024 x86_64 GNU/Linux

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

# This file is the configuration file for all tools
# that use the containers/storage library. The storage.conf file
# overrides all other storage.conf files. Container engines using the
# container/storage library do not inherit fields from other storage.conf
# files.
#
#  Note: The storage.conf file overrides other storage.conf files based on this precedence:
#      /usr/containers/storage.conf
#      /etc/containers/storage.conf
#      $HOME/.config/containers/storage.conf
#      $XDG_CONFIG_HOME/containers/storage.conf (If XDG_CONFIG_HOME is set)
# 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
# When changing the graphroot location on an SELINUX system, you must
# ensure  the labeling matches the default locations labels with the
# following commands:
# semanage fcontext -a -e /var/lib/containers/storage /NEWSTORAGEPATH
# restorecon -R -v /NEWSTORAGEPATH
graphroot = "/var/lib/containers/storage"

# Optional alternate location of image store if a location separate from the
# container store is required. If set, it must be different than graphroot.
# imagestore = ""


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

# Transient store mode makes all container metadata be saved in temporary storage
# (i.e. runroot above). This is faster, but doesn't persist across reboots.
# Additional garbage collection must also be performed at boot-time, so this
# option should remain disabled in most configurations.
# transient_store = true

[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 = [
"/var/lib/shared",
"/usr/lib/containers/storage",
]

# Allows specification of how storage is populated when pulling images. This
# option can speed the pulling process of images compressed with format
# zstd:chunked. Containers/storage looks for files within images that are being
# pulled from a container registry that were previously pulled to the host.  It
# can copy or create a hard link to the existing file when it finds them,
# eliminating the need to pull them from the container registry. These options
# can deduplicate pulling of content, disk storage of content and can allow the
# kernel to use less memory when running containers.

# containers/storage supports four keys
#   * enable_partial_images="true" | "false"
#     Tells containers/storage to look for files previously pulled in storage
#     rather then always pulling them from the container registry.
#   * use_hard_links = "false" | "true"
#     Tells containers/storage to use hard links rather then create new files in
#     the image, if an identical file already existed in storage.
#   * ostree_repos = ""
#     Tells containers/storage where an ostree repository exists that might have
#     previously pulled content which can be used when attempting to avoid
#     pulling content from the container registry
#   * convert_images = "false" | "true"
#     If set to true, containers/storage will convert images to a
#     format compatible with partial pulls in order to take advantage
#     of local deduplication and hard linking.  It is an expensive
#     operation so it is not enabled by default.
pull_options = {enable_partial_images = "true", use_hard_links = "false", ostree_repos=""}

# 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. This setting overrides the
# Remap-UIDs/GIDs setting.
#
# 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 maximum 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,fsync=0"

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

# Set to use composefs to mount data layers with overlay.
# use_composefs = "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 than the
#  "force_mask"  permissions.
#
# force_mask = ""

[codethief]

Hi @jaredpricedev , what does capsh --print say? Do you have CAP_SETUID and CAP_SETGID?

What do cat /proc/self/uid_map and cat /proc/self/gid_map say? Are there enough UIDs/GIDs available?

I'm not familiar with RKE2 but it seems to use SELinux. Could that play a role here?

[rhatdan]

Right the big thing is within the container that you are running buildah cat /proc/self/uid_map, this looks like you have very few UIDs to play with.