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Debian 從哪裡取得預設 umask？

tag-icon • tag-icon linux debian pam umask
Debian 從哪裡取得預設 umask？

使用新的 ssh 登入：

$ umask
0007

但：

$ find . -maxdepth 1 -name '.*' -type f | xargs grep 007 | less
$ 

# grep 007 /etc/profile
#
# grep -i umask /etc/login.defs
#       UMASK           Default "umask" value.
# UMASK is the default umask value for pam_umask and is used by
# 022 is the "historical" value in Debian for UMASK
UMASK           027
# Other former uses of this variable such as setting the umask when
# grep -i umask /etc/pam.d/common-session
session optional pam_umask.so usergroups

搞什麼？德班發明任意umask？而且 /etc 中沒有其他來源與 007 相符！

系統使用 LDAP（nscld、pam_ldap）進行驗證

更多資訊：這只發生在一位用戶身上。不適用於 root 或其他使用者。一旦我向某個用戶“su”，我就會再次得到​​ 007。

作為根用戶：

# strace -f -o basz.log su baduser

有些東西正在設定這個 umask，但我不知道是什麼：

[...]
2622  open("/etc/group", O_RDONLY|O_CLOEXEC) = 4
2622  _llseek(4, 0, [0], SEEK_CUR)      = 0
2622  fstat64(4, {st_mode=S_IFREG|0644, st_size=1719, ...}) = 0
2622  mmap2(NULL, 1719, PROT_READ, MAP_SHARED, 4, 0) = 0xb7786000
2622  _llseek(4, 1719, [1719], SEEK_SET) = 0
2622  fstat64(4, {st_mode=S_IFREG|0644, st_size=1719, ...}) = 0
2622  munmap(0xb7786000, 1719)          = 0
2622  close(4)                          = 0
2622  socket(PF_FILE, SOCK_STREAM, 0)   = 4
2622  connect(4, {sa_family=AF_FILE, path="/var/run/nslcd/socket"}, 23) = 0
2622  gettimeofday({1404702848, 321946}, NULL) = 0
2622  gettimeofday({1404702848, 322029}, NULL) = 0
2622  poll([{fd=4, events=POLLOUT}], 1, 10000) = 1 ([{fd=4, revents=POLLOUT}])
2622  send(4, "\1\0\0\0\212\23\0\0\361\3\0\0", 12, MSG_NOSIGNAL) = 12
2622  gettimeofday({1404702848, 322363}, NULL) = 0
2622  gettimeofday({1404702848, 322464}, NULL) = 0
2622  poll([{fd=4, events=POLLIN}], 1, 60000) = 1 ([{fd=4, revents=POLLIN|POLLHUP}])
2622  read(4, "\1\0\0\0\212\23\0\0\0\0\0\0\4\0\0\0baduser\1\0\0\0*\361\3\0\0\2\0\0"..., 1024) = 57
2622  gettimeofday({1404702848, 323811}, NULL) = 0
2622  gettimeofday({1404702848, 323898}, NULL) = 0
2622  gettimeofday({1404702848, 323983}, NULL) = 0
2622  gettimeofday({1404702848, 324067}, NULL) = 0
2622  gettimeofday({1404702848, 324170}, NULL) = 0
2622  gettimeofday({1404702848, 324256}, NULL) = 0
2622  gettimeofday({1404702848, 324340}, NULL) = 0
2622  gettimeofday({1404702848, 324434}, NULL) = 0
2622  gettimeofday({1404702848, 324518}, NULL) = 0
2622  gettimeofday({1404702848, 324602}, NULL) = 0
2622  gettimeofday({1404702848, 324686}, NULL) = 0
2622  gettimeofday({1404702848, 324772}, NULL) = 0
2622  poll([{fd=4, events=POLLIN}], 1, 0) = 1 ([{fd=4, revents=POLLIN|POLLHUP}])
2622  read(4, "", 1024)                 = 0
2622  gettimeofday({1404702848, 325036}, NULL) = 0
2622  close(4)                          = 0
2622  umask(0777)                       = 027
2622  umask(07)                         = 0777
[...]

更多資訊：

  • 如果我在 /etc/profile 中寫入“umask 0027”，它也可以工作！
  • 如果我刪除主目錄並重新建立它，問題仍然存在

答案1

答案是：

man pam_umask
usergroups
    If the user is not root, and the user ID is equal to the group ID, and the
    username is the same as primary group name, the umask group bits are set to
    be the same as owner bits (examples: 022 -> 002, 077 -> 007).

男人 ...

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