OS: Debian 11 5.10.0-22-amd64 #1 SMP Debian 5.10.178-3 (2023-04-22) x86_64 GNU/Linux
KDE Plasma 5.20.5
Spotify: spotify-client/stable,now 1:1.2.8.923.g4f94bf0d amd64 [installed]
我发现 Spotify 客户端发生了一件有趣的事情。为了解决客户端始终停留在全屏模式的问题，我正在编辑位于的首选项文件。~/.config/spotify/prefs
在编辑窗口首选项的值并保存后，启动 Spotify 客户端会用之前的更改覆盖这些更改。
为了尝试测试是否可以让窗口退出全屏，我将文件的所有权更改为 root，并且chmod 444.但是在启动 Spotify 客户端（作为我的非 root 用户）时，首选项文件被从 root 更改为我的用户。
root@localhost:/home/ehammer/.config/spotify# ls -l
total 12
-rw-r--r-- 1 ehammer ehammer 1265 May 13 09:39 prefs
drwx------ 4 ehammer ehammer 4096 Feb 12 2022 'User Data'
drwxrwxr-x 3 ehammer ehammer 4096 Feb 12 2022 Users
root@localhost:/home/ehammer/.config/spotify# ps -Helf | grep spotify
4 S root 39890 39357 0 80 0 - 1560 - 09:45 pts/1 00:00:00 grep spotify
root@localhost:/home/ehammer/.config/spotify# nano prefs
root@localhost:/home/ehammer/.config/spotify# ls -lisa
total 20
19794776 4 drwx------ 4 ehammer ehammer 4096 May 13 09:46 .
19791874 4 drwxr-xr-x 43 ehammer ehammer 4096 May 13 09:43 ..
19806299 4 -rw-r--r-- 1 ehammer ehammer 1233 May 13 09:46 prefs
19794777 4 drwx------ 4 ehammer ehammer 4096 Feb 12 2022 'User Data'
19795125 4 drwxrwxr-x 3 ehammer ehammer 4096 Feb 12 2022 Users
root@localhost:/home/ehammer/.config/spotify# chown root:root prefs
root@localhost:/home/ehammer/.config/spotify# chmod 444 prefs
root@localhost:/home/ehammer/.config/spotify# ls -lisa
total 20
19794776 4 drwx------ 4 ehammer ehammer 4096 May 13 09:46 .
19791874 4 drwxr-xr-x 43 ehammer ehammer 4096 May 13 09:43 ..
19806299 4 -r--r--r-- 1 root root 1233 May 13 09:46 prefs
19794777 4 drwx------ 4 ehammer ehammer 4096 Feb 12 2022 'User Data'
19795125 4 drwxrwxr-x 3 ehammer ehammer 4096 Feb 12 2022 Users
root@localhost:/home/ehammer/.config/spotify# ps -Helf | grep spotify
4 S root 40089 39357 0 80 0 - 1560 - 09:46 pts/1 00:00:00 grep spotify
0 S ehammer 39903 1580 21 80 0 - 889253 - 09:46 ? 00:00:01 /usr/share/spotify/spotify
0 S ehammer 39907 39903 0 80 0 - 99941 - 09:46 ? 00:00:00 /usr/share/spotify/spotify --type=zygote --no-zygote-sandbox --no-sandbox --log-severity=disable --user-agent-product=Chrome/111.0.5563.65 Spotify/1.2.8.923 --lang=en --user-data-dir=/home/ehammer/.config/spotify/User Data --log-file=/usr/share/spotify/debug.log
1 S ehammer 39929 39907 5 80 0 - 1054195 - 09:46 ? 00:00:00 /usr/share/spotify/spotify --type=gpu-process --no-sandbox --log-severity=disable --user-agent-product=Chrome/111.0.5563.65 Spotify/1.2.8.923 --lang=en --user-data-dir=/home/ehammer/.config/spotify/User Data --gpu-preferences=WAAAAAAAAAAgAAAIAAAAAAAAAAAAAAAAAABgAAAAAAA4AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAIAAAAAAAAAABAAAAAAAAAAgAAAAAAAAACAAAAAAAAAAIAAAAAAAAAA== --log-file=/usr/share/spotify/debug.log --shared-files --field-trial-handle=0,i,10976918143839319429,9883613349491165854,131072 --disable-features=BackForwardCache
0 S ehammer 39908 39903 0 80 0 - 99943 - 09:46 ? 00:00:00 /usr/share/spotify/spotify --type=zygote --no-sandbox --log-severity=disable --user-agent-product=Chrome/111.0.5563.65 Spotify/1.2.8.923 --lang=en --user-data-dir=/home/ehammer/.config/spotify/User Data --log-file=/usr/share/spotify/debug.log
1 S ehammer 39987 39908 0 80 0 - 155341 - 09:46 ? 00:00:00 /usr/share/spotify/spotify --type=utility --utility-sub-type=storage.mojom.StorageService --lang=en-US --service-sandbox-type=utility --no-sandbox --proxy-server=direct:// --log-severity=disable --user-agent-product=Chrome/111.0.5563.65 Spotify/1.2.8.923 --lang=en --user-data-dir=/home/ehammer/.config/spotify/User Data --log-file=/usr/share/spotify/debug.log --shared-files=v8_context_snapshot_data:100 --field-trial-handle=0,i,10976918143839319429,9883613349491165854,131072 --disable-features=BackForwardCache
1 S ehammer 40065 39908 44 80 0 - 13148967 - 09:46 ? 00:00:02 /usr/share/spotify/spotify --type=renderer --log-severity=disable --user-agent-product=Chrome/111.0.5563.65 Spotify/1.2.8.923 --disable-spell-checking --user-data-dir=/home/ehammer/.config/spotify/User Data --first-renderer-process --no-sandbox --log-file=/usr/share/spotify/debug.log --lang=en-US --num-raster-threads=4 --enable-main-frame-before-activation --renderer-client-id=5 --time-ticks-at-unix-epoch=-1683982549076978 --launch-time-ticks=3057595647 --shared-files=v8_context_snapshot_data:100 --field-trial-handle=0,i,10976918143839319429,9883613349491165854,131072 --disable-features=BackForwardCache
0 S ehammer 39995 39903 3 80 0 - 260094 - 09:46 ? 00:00:00 /usr/share/spotify/spotify --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --no-sandbox --proxy-server=direct:// --log-severity=disable --user-agent-product=Chrome/111.0.5563.65 Spotify/1.2.8.923 --lang=en --user-data-dir=/home/ehammer/.config/spotify/User Data --log-file=/usr/share/spotify/debug.log --shared-files=v8_context_snapshot_data:100 --field-trial-handle=0,i,10976918143839319429,9883613349491165854,131072 --disable-features=BackForwardCache
root@localhost:/home/ehammer/.config/spotify# ls -lisa
total 20
19794776 4 drwx------ 4 ehammer ehammer 4096 May 13 09:46 .
19791874 4 drwxr-xr-x 43 ehammer ehammer 4096 May 13 09:43 ..
19812078 4 -rw-r--r-- 1 ehammer ehammer 1233 May 13 09:46 prefs
19794777 4 drwx------ 4 ehammer ehammer 4096 Feb 12 2022 'User Data'
19795125 4 drwxrwxr-x 3 ehammer ehammer 4096 Feb 12 2022 Users
ps 输出中的调试日志不存在，但有一些日志条目：
May 13 09:47:01 localhost systemd[1377]: app-spotify-4ebf47d306f04211acbf7b15afdef435.scope: Consumed 4.087s CPU time.
May 13 09:47:01 localhost systemd[1377]: app-spotify-4ebf47d306f04211acbf7b15afdef435.scope: Succeeded.
May 13 09:46:46 localhost dbus-daemon[1397]: [session uid=1000 pid=1397] Activating service name='org.kde.kwalletd5' requested by ':1.103' (uid=1000 pid=39903 comm="/usr/share/spotify/spotify ")
May 13 09:46:46 localhost dbus-daemon[1397]: [session uid=1000 pid=1397] Activating service name='org.kde.kwalletd5' requested by ':1.103' (uid=1000 pid=39903 comm="/usr/share/spotify/spotify ")
May 13 09:46:46 localhost systemd[1377]: Started Spotify - Music Player.
systemd 或 dbus 是否允许它执行超级用户操作？我的非 root 用户确实具有 sudo 访问权限，但只能使用密码。 kwallet 是否能够将这些 sudo 权限传递给请求它的进程？
我不知道非 root 用户进程如何以任何方式更改 root 拥有的只读文件？
答案1
应用程序不需要 root 权限来执行此操作：如果它可以写入包含的目录，则它可以删除 root 拥有的文件并将其替换为自己的文件。请注意，文件的索引节点已更改：这意味着原始文件已被删除。