Bug 273517

Hi,

## Summary:
It seems that on FreeBSD 14.0-ALPHA3 for non-root users in Linux chroots, getxattr returns EPERM which causes some coreutils commands to fail (e.g. cp -a), whereas on FreeBSD 13.1 getxattr simply returned EOPNOTSUPP which lets the tools skip that step and continue successfully.

It might be the same issue as https://lists.freebsd.org/archives/freebsd-current/2023-August/004433.html "Possible issue with linux xattr support?"

## Example impact:
"apt update" failing in a fresh debootstrap due to "cp -a" failure in the apt-key script, which runs as another user "_apt". This works OK on FreeBSD 13.1. (See here https://forums.freebsd.org/threads/debian-12-bookworm-jail-encounters-gpg-error-in-freebsd-14-0.90093/#post-620794 for more details )


## Steps to reproduce:

### On fresh install FreeBSD system, where /root homedir is on UFS partition
pkg install sysutils/debootstrap
kldload linux64 fdescfs linprocfs linsysfs tmpfs
service linux onestart
cd /root
mkdir debian_build
cd debian_build
mkdir dev dev/fd dev/shm proc sys tmp
mount -t linprocfs none `pwd`/proc
mount -t devfs none `pwd`/dev
mount -t fdescfs none `pwd`/dev/fd
mount -t tmpfs none `pwd`/dev/shm
mount -t linsysfs none `pwd`/sys
mount -t tmpfs none `pwd`/tmp
chmod 1777 dev/shm tmp
debootstrap bullseye . http://deb.debian.org/debian
chroot . /bin/bash

### Inside the chroot
adduser --disabled-password --gecos "" someguy
su someguy
cd /home/someguy

### Comparing cp -a / cp --preserve=mode on both FreeBSD 13 and 14

someguy@freebsd14:~$ uname -a
FreeBSD freebsd14 14.0-ALPHA3 FreeBSD 14.0-ALPHA3 amd64 1400097 #0 stable/14-n265022-2af9390e54ed: Fri Aug 25 05:45:56 UTC 2023     root@releng1.nyi.freebsd.org:/usr/obj/usr/src/amd64.amd64/sys/GENERIC amd64

someguy@freebsd13:~$ strace cp --preserve=mode hello hello2
fgetxattr(3, "system.posix_acl_access", 0x7fffffffdcc0, 132) = -1 EOPNOTSUPP (Operation not supported)
fsetxattr(4, "system.posix_acl_access", "\2\0\0\0\1\0\6\0\377\377\377\377\4\0\4\0\377\377\377\377 \0\4\0\377\377\377\377", 28, 0) = -1 EOPNOTSUPP (Operation not supported)
+++ exited with 0 +++

someguy@freebsd14:~$ strace cp --preserve=mode hello hello2
fgetxattr(3, "system.posix_acl_access", 0x7fffffffbd30, 132) = -1 EPERM (Operation not permitted)
+++ exited with 1 +++

### ls -l fails on FreeBSD 14

someguy@freebsd14:~$ ls -l
ls: hello: Operation not permitted
ls: hello2: Operation not permitted
total 0K
-rw-r--r-- 1 someguy someguy    0 Sep  1 20:11 hello
-rw-r--r-- 1 someguy someguy    0 Sep  1 21:14 hello2

someguy@freebsd14:~$ strace ls -l 2>&1 | grep getxattr
getxattr("hello", "system.posix_acl_access", NULL, 0) = -1 EPERM (Operation not permitted)
getxattr("hello2", "system.posix_acl_access", NULL, 0) = -1 EPERM (Operation not permitted)


### apt update apt-key failure:
root@freebsd14:/# ps auxfww
root       949  0.0  0.1  13404  2964 ?        Ss   15:39   0:00 login [pam]
root       950  0.0  0.1  13368  3152 ?        S    15:39   0:01  \_ -sh
root     25160  0.0  0.2   6036  4400 ?        S    18:11   0:03      \_ /bin/bash
root     26053  0.0  0.5  14720 11140 ?        T    18:25   0:00          \_ apt -oAPT::Status-Fd=1 -oDebug::Acquire::gpgv=1 update
_apt     26056  0.0  0.7  20448 14932 ?        T    18:25   0:00          |   \_ /usr/lib/apt/methods/http
_apt     26058  0.0  0.4  13884  9832 ?        T    18:25   0:00          |   \_ /usr/lib/apt/methods/gpgv
_apt     26059  0.0  0.4  14140  9944 ?        T    18:25   0:00          |       \_ /usr/lib/apt/methods/gpgv
_apt     26060  0.0  0.0   2464  1652 ?        T    18:25   0:00          |           \_ /bin/sh /usr/bin/apt-key --quiet --readonly verify --status-fd 3 /tmp/apt.sig.OO1MDD /tmp/apt.data.FtsGdD
_apt     26061  0.0  0.0   2376  1552 ?        T    18:25   0:00          |               \_ sleep 3600

root@freebsd14:~# su _apt -s /bin/dash
$ id
uid=100(_apt) gid=65534(nogroup) groups=65534(nogroup)

_apt@freebsd14:/$ /bin/sh -x /usr/bin/apt-key --quiet --readonly verify --status-fd 1 /tmp/apt.sig.OO1MDD /tmp/apt.data.FtsGdD
# ...
+ ls -la /tmp/apt-key-gpghome.ptBlRcbxDY
ls: /tmp/apt-key-gpghome.ptBlRcbxDY: Operation not permitted
ls: /tmp/apt-key-gpghome.ptBlRcbxDY/.: Operation not permitted
ls: /tmp/apt-key-gpghome.ptBlRcbxDY/..: Operation not permitted
ls: /tmp/apt-key-gpghome.ptBlRcbxDY/pubring.gpg: Operation not permitted
total 56K
drwx------ 2 _apt root    64 Sep  1 19:41 .
drwxrwxrwt 3 root root   256 Sep  1 19:41 ..
-rw-r--r-- 1 _apt root 56156 Sep  1 19:41 pubring.gpg
+ cp -a /tmp/apt-key-gpghome.ptBlRcbxDY/pubring.gpg /tmp/apt-key-gpghome.ptBlRcbxDY/pubring.orig.gpg
cp: ‘/tmp/apt-key-gpghome.ptBlRcbxDY/pubring.gpg’: Operation not permitted