为什么 Podman 会使用不同的 UID 报告"Not enough IDs available in namespace"？

Question

事实：

1. 无根豆荚人非常适合 uid1480
2. Rootless podman for uid2088失败
3. CentOS 7
4. 内核3.10.0-1062.1.2.el7.x86_64
5. 波德曼版本1.4.4
6. 几乎整个环境已在两者之间删除
7. /tmp的文件系统xfs
8. 两个用户的capsh输出相同，但对于 uid/用户名
9. 两个 UID 在/etc/sub{u,g}id文件中具有相同的条目
10. $HOME/.config/containers/storage.conf是默认值，除 uid 外，两者之间相同。storage.conf如下，以供参考。

我编写了以下 shell 脚本来演示两者在操作环境中的相似程度：

#!/bin/sh
for i in 1480 2088; do
sudo chroot --userspec "$i":10 / env -i /bin/sh <<EOF
echo -------------- $i ----------------
/usr/sbin/capsh --print
grep "$i" /etc/subuid /etc/subgid
mkdir /tmp/"$i"
HOME=/tmp/"$i"
export HOME
podman --root=/tmp/"$i" info > /tmp/podman."$i"
podman run --rm --root=/tmp/"$i" docker.io/library/busybox printf "tCOMPLETEn"
echo -----------END $i END-------------
EOF
sudo rm -rf /tmp/"$i"
done

下面是脚本的输出：

$ sh /tmp/podman-fail.sh
[sudo] password for functional:
-------------- 1480 ----------------
Current: =
Bounding set =cap_chown,cap_dac_override,cap_dac_read_search,cap_fowner,cap_fsetid,cap_kill,cap_setgid,cap_setuid,cap_setpcap,cap_linux_immutable,cap_net_bind_service,cap_net_broadcast,cap_net_admin,cap_net_raw,cap_ipc_lock,cap_ipc_owner,cap_sys_module,cap_sys_rawio,cap_sys_chroot,cap_sys_ptrace,cap_sys_pacct,cap_sys_admin,cap_sys_boot,cap_sys_nice,cap_sys_resource,cap_sys_time,cap_sys_tty_config,cap_mknod,cap_lease,cap_audit_write,cap_audit_control,cap_setfcap,cap_mac_override,cap_mac_admin,cap_syslog,35,36
Securebits: 00/0x0/1'b0
secure-noroot: no (unlocked)
secure-no-suid-fixup: no (unlocked)
secure-keep-caps: no (unlocked)
uid=1480(functional)
gid=10(wheel)
groups=0(root)
/etc/subuid:1480:100000:65536
/etc/subgid:1480:100000:65536
Trying to pull docker.io/library/busybox...Getting image source signatures
Copying blob 7c9d20b9b6cd done
Copying config 19485c79a9 done
Writing manifest to image destination
Storing signatures
ERRO[0003] could not find slirp4netns, the network namespace won't be configured: exec: "slirp4netns": executable file not found in $PATH
COMPLETE
-----------END 1480 END-------------
-------------- 2088 ----------------
Current: =
Bounding set =cap_chown,cap_dac_override,cap_dac_read_search,cap_fowner,cap_fsetid,cap_kill,cap_setgid,cap_setuid,cap_setpcap,cap_linux_immutable,cap_net_bind_service,cap_net_broadcast,cap_net_admin,cap_net_raw,cap_ipc_lock,cap_ipc_owner,cap_sys_module,cap_sys_rawio,cap_sys_chroot,cap_sys_ptrace,cap_sys_pacct,cap_sys_admin,cap_sys_boot,cap_sys_nice,cap_sys_resource,cap_sys_time,cap_sys_tty_config,cap_mknod,cap_lease,cap_audit_write,cap_audit_control,cap_setfcap,cap_mac_override,cap_mac_admin,cap_syslog,35,36
Securebits: 00/0x0/1'b0
secure-noroot: no (unlocked)
secure-no-suid-fixup: no (unlocked)
secure-keep-caps: no (unlocked)
uid=2088(broken)
gid=10(wheel)
groups=0(root)
/etc/subuid:2088:100000:65536
/etc/subgid:2088:100000:65536
Trying to pull docker.io/library/busybox...Getting image source signatures
Copying blob 7c9d20b9b6cd done
Copying config 19485c79a9 done
Writing manifest to image destination
Storing signatures
ERRO[0003] Error while applying layer: ApplyLayer exit status 1 stdout:  stderr: there might not be enough IDs available in the namespace (requested 65534:65534 for /home): lchown /home: invalid argument
ERRO[0003] Error pulling image ref //busybox:latest: Error committing the finished image: error adding layer with blob "sha256:7c9d20b9b6cda1c58bc4f9d6c401386786f584437abbe87e58910f8a9a15386b": ApplyLayer exit status 1 stdout:  stderr: there might not be enough IDs available in the namespace (requested 65534:65534 for /home): lchown /home: invalid argument
Failed
Error: unable to pull docker.io/library/busybox: unable to pull image: Error committing the finished image: error adding layer with blob "sha256:7c9d20b9b6cda1c58bc4f9d6c401386786f584437abbe87e58910f8a9a15386b": ApplyLayer exit status 1 stdout:  stderr: there might not be enough IDs available in the namespace (requested 65534:65534 for /home): lchown /home: invalid argument

下面是1480uid 的storage.conf。除了s/1480/2088/之外，它是相同的：

[storage]
driver = "vfs"
runroot = "/run/user/1480"
graphroot = "/tmp/1480/.local/share/containers/storage"
[storage.options]
size = ""
remap-uids = ""
remap-gids = ""
remap-user = ""
remap-group = ""
ostree_repo = ""
skip_mount_home = ""
mount_program = ""
mountopt = ""
[storage.options.thinpool]
autoextend_percent = ""
autoextend_threshold = ""
basesize = ""
blocksize = ""
directlvm_device = ""
directlvm_device_force = ""
fs = ""
log_level = ""
min_free_space = ""
mkfsarg = ""
mountopt = ""
use_deferred_deletion = ""
use_deferred_removal = ""
xfs_nospace_max_retries = ""

您可以看到用户的两个podman info输出之间基本上没有区别：

$ diff -u /tmp/podman.1480 /tmp/podman.2088
--- /tmp/podman.1480    2019-10-17 22:41:21.991573733 -0400
+++ /tmp/podman.2088    2019-10-17 22:41:26.182584536 -0400
@@ -7,7 +7,7 @@
Distribution:
distribution: '"centos"'
version: "7"
-  MemFree: 45654056960
+  MemFree: 45652697088
MemTotal: 67306323968
OCIRuntime:
package: containerd.io-1.2.6-3.3.el7.x86_64
@@ -24,7 +24,7 @@
kernel: 3.10.0-1062.1.2.el7.x86_64
os: linux
rootless: true
-  uptime: 30h 17m 50.23s (Approximately 1.25 days)
+  uptime: 30h 17m 54.42s (Approximately 1.25 days)
registries:
blocked: null
insecure: null
@@ -35,14 +35,14 @@
- quay.io
- registry.centos.org
store:
-  ConfigFile: /tmp/1480/.config/containers/storage.conf
+  ConfigFile: /tmp/2088/.config/containers/storage.conf
ContainerStore:
number: 0
GraphDriverName: vfs
GraphOptions: null
-  GraphRoot: /tmp/1480
+  GraphRoot: /tmp/2088
GraphStatus: {}
ImageStore:
number: 0
-  RunRoot: /run/user/1480
-  VolumePath: /tmp/1480/volumes
+  RunRoot: /run/user/2088
+  VolumePath: /tmp/2088/volumes

我拒绝相信 podman 的源代码中有if (2088 == uid) { abort(); }或类似的废话。我错过了什么？

Answer 1

podman system migrate为您修复there might not be enough IDs available in the namespace吗？

它为我和其他人做到了： https://github.com/containers/libpod/issues/3421

Answer 2

AFAICT、子 UID 和 GID 范围不应在用户之间重叠。 作为参考，以下是useradd手册页对此事的看法：

SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT
(number)
If /etc/subuid exists, the commands useradd and newusers
(unless the user already have subordinate group IDs)
allocate SUB_GID_COUNT unused group IDs from the range
SUB_GID_MIN to SUB_GID_MAX for each new user.
The default values for SUB_GID_MIN, SUB_GID_MAX,
SUB_GID_COUNT are respectively 100000, 600100000 and 65536.
SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT
(number)
If /etc/subuid exists, the commands useradd and newusers
(unless the user already have subordinate user IDs) allocate
SUB_UID_COUNT unused user IDs from the range SUB_UID_MIN to
SUB_UID_MAX for each new user.
The default values for SUB_UID_MIN, SUB_UID_MAX,
SUB_UID_COUNT are respectively 100000, 600100000 and 65536.

关键字是未使用的。

Answer 3

CentOS 7.6 默认不支持无根构建 - 请参阅 https://github.com/containers/buildah/pull/1166 和 https://www.redhat.com/en/blog/preview-running-containers-without-root-rhel-76