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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2013-01-16 05:21:24 +0100 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2014-09-13 20:15:58 -0700 |
| commit | ca291567072e0dc3650db1ed499dc3f414dc2c03 (patch) | |
| tree | 3e38c990bfbf96c774312581872dac958602187c /man7/namespaces.7 | |
| parent | e13b53a6116cfa602001b98fe05bf7d455c5618a (diff) | |
| download | man-pages-ca291567072e0dc3650db1ed499dc3f414dc2c03.tar.gz | |
namespaces.7: Explain why unshare() and setns() do not change caller's PID namespace
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Diffstat (limited to 'man7/namespaces.7')
| -rw-r--r-- | man7/namespaces.7 | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/man7/namespaces.7 b/man7/namespaces.7 index 9a95e2407c..031e8919d3 100644 --- a/man7/namespaces.7 +++ b/man7/namespaces.7 @@ -416,6 +416,25 @@ then it isn't necessary to change the root directory: a new procfs instance can be mounted directly over .IR /proc .) +Calls to +.BR setns (2) +that specify a PID namespace file descriptor +and calls to +.BR unshare (2) +with the +.BR CLONE_NEWPID +flag cause children subsequently created +by the caller to be placed in a different PID namespace from the caller. +These calls do not, however, +change the PID namespace of the calling process, +because doing so would change the caller's idea of its own PID +(as reported by +.BR getpid ()), +which would break many applications and libraries. +To put things another way: +a process's PID namespace membership is determined when the process is created +and cannot be changed thereafter. + Every thread in a process must be in the same PID namespace. For this reason, the two following call sequences will fail: |