Mengapa saya tidak bisa membuat file dengan nama yang diawali dengan “passwd.” di "/ etc"?

9

Saya memiliki PC dengan Ubuntu 16.04 terinstal. Baru-baru ini saya ingin menginstal beberapa paket tetapi kesulitan menginstalnya. Setelah beberapa penggalian, saya menemukan bahwa kegagalan tersebut tampaknya terkait dengan sistem akun pengguna linux. Masalahnya adalah bahwa file apa pun dengan nama yang diawali dengan passwd.tidak dapat dibuat di /etcjalur.

# ls /etc/passwd.*
ls: cannot access '/etc/passwd.*': No such file or directory

# touch /etc/passwd.test-test-test
touch: cannot touch '/etc/passwd.test-test-test': Permission denied

# ls /etc/passwe.*
ls: cannot access '/etc/passwe.*': No such file or directory

# touch /etc/passwe.test-test-test
#

Saya bisa membuat file itu di jalur lain, seperti /atau /usr, tetapi tidak di /etc, dan saya bisa membuat file dengan nama file lain /etc, tetapi tidak dengan nama file yang diawali oleh passwd.. Saya tidak dapat mereproduksi masalah ini dengan PC lain.

Saya sudah mencoba perintah lain:

  • nano /etc/shadow.xxx
  • echo xxx > /etc/shadow.xxx
  • touch /etc/test-temp-file && mv /etc/test-temp-file /etc/shadow.xxx
  • systemctl stop apparmor
  • Mulai ulang sistem

Tidak ada yang berhasil.

Apa yang bisa menyebabkan masalah ini?

Berikut adalah beberapa output perintah debug:

# ls -ld /etc
drwxr-xr-x 136 root root 12288 Aug 12 10:07 /etc

# lsattr -d /etc
----------I--e-- /etc

# ls -dZ /etc
? /etc

# type -a touch
touch is /usr/bin/touch
touch is /bin/touch

# file "$(command -v touch)"
/usr/bin/touch: symbolic link to /bin/touch

Berikut stracehasilnya:

# strace touch /etc/passwd.test-test-test
execve("/usr/bin/touch", ["touch", "/etc/passwd.test-test-test"], [/* 22 vars */]) = 0
brk(NULL)                               = 0x8da000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=80559, ...}) = 0
mmap(NULL, 80559, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9bc360e000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\t\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9bc360d000
mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9bc3033000
mprotect(0x7f9bc31f3000, 2097152, PROT_NONE) = 0
mmap(0x7f9bc33f3000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f9bc33f3000
mmap(0x7f9bc33f9000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f9bc33f9000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9bc360c000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9bc360b000
arch_prctl(ARCH_SET_FS, 0x7f9bc360c700) = 0
mprotect(0x7f9bc33f3000, 16384, PROT_READ) = 0
mprotect(0x60e000, 4096, PROT_READ)     = 0
mprotect(0x7f9bc3622000, 4096, PROT_READ) = 0
munmap(0x7f9bc360e000, 80559)           = 0
brk(NULL)                               = 0x8da000
brk(0x8fb000)                           = 0x8fb000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=1668976, ...}) = 0
mmap(NULL, 1668976, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9bc3473000
close(3)                                = 0
open("/etc/passwd.test-test-test", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666) = -1 EACCES (Permission denied)
utimensat(AT_FDCWD, "/etc/passwd.test-test-test", NULL, 0) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2995, ...}) = 0
read(3, "# Locale name alias data base.\n#"..., 4096) = 2995
read(3, "", 4096)                       = 0
close(3)                                = 0
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, "touch: ", 7touch: )                  = 7
write(2, "cannot touch '/etc/passwd.test-t"..., 41cannot touch '/etc/passwd.test-test-test') = 41
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, ": Permission denied", 19: Permission denied)     = 19
write(2, "\n", 1
)                       = 1
close(1)                                = 0
close(2)                                = 0
exit_group(1)                           = ?
+++ exited with 1 +++
ubuntu permissions EFANZH
sumber
2
apa yang ls -ld /etcdikatakan? Bagaimana dengan lsattr -d /etc? Jika Anda menggunakan SELinux, apa ls -dZ /etcisinya? Jika Anda menggunakan AppArmor, apa kata perintah yang setara (saya tidak tahu apa itu) katakan? Bagaimana ini /etc/berbeda dari /etcpada PC lain? Jalankan perintah yang sama di sana dan cari perbedaannya.
NickD
Apakah touchfungsi atau skrip atau sesuatu? Apa yang dilaporkan type -a touchdan file "$(command -v touch)"dilaporkan? Saya tidak dapat mereproduksi pada kotak 16.04 saya.
muru
@NickD Saya telah membandingkan semua output perintah kecuali untuk yang AppArmor karena saya tidak menemukan cara untuk menampilkan informasi terkait folder. Hasilnya sama.
EFanZh
1
Hanya untuk memastikan: Anda melakukan ini root, kan?
Panki
1
Ubuntu rupanya menggunakan apparmor, lihat: help.ubuntu.com/community/AppArmor
Rafael Kitover

Jawaban:

6

Saya menemukan alasannya. Itu karena ISecTP (Keamanan Titik Akhir untuk Pencegahan Ancaman Linux) diinstal pada PC saya. Ini termasuk " Access Protection ", yang menggunakan antarmuka kernel fanotify, atau injeksi modul khusus ke dalam kernel (dapat dikonfigurasi yang mana di antaranya ), menyebabkan akses ke jalur arbitrer ditolak. Saya tidak menyadarinya karena saya bukan satu-satunya yang menggunakan PC. Setelah menghapusnya, semuanya baik-baik saja sekarang.

Terima kasih semuanya, atas bantuan Anda!

EFANZH
sumber
Sangat menarik, saya belum pernah mendengar perangkat lunak seperti ini, sejauh yang saya tahu semua orang menggunakan baik selinux atau apparmor.
Rafael Kitover
Terima kasih telah memberikan pembaruan. Bila Anda bisa, terimalah jawaban Anda sendiri.
roaima