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authorLinus Torvalds <torvalds@linux-foundation.org>2016-08-07 10:13:14 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2016-08-07 10:13:14 -0400
commite9d488c3114acb6a0a93e99c02f9cd1d656f46c7 (patch)
treeb0342f47b8bb8fa6af3a6d1416e9881ccdb00144 /Documentation
parent337684a1746f93ae107e05d90977b070bb7e39d8 (diff)
parent4af75df6a410ce76d9f60f27b07e5645ecc2c5ed (diff)
Merge tag 'binfmt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/binfmt_misc
Pull binfmt_misc update from James Bottomley: "This update is to allow architecture emulation containers to function such that the emulation binary can be housed outside the container itself. The container and fs parts both have acks from relevant experts. To use the new feature you have to add an F option to your binfmt_misc configuration" From the docs: "The usual behaviour of binfmt_misc is to spawn the binary lazily when the misc format file is invoked. However, this doesn't work very well in the face of mount namespaces and changeroots, so the F mode opens the binary as soon as the emulation is installed and uses the opened image to spawn the emulator, meaning it is always available once installed, regardless of how the environment changes" * tag 'binfmt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/binfmt_misc: binfmt_misc: add F option description to documentation binfmt_misc: add persistent opened binary handler for containers fs: add filp_clone_open API
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/binfmt_misc.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/binfmt_misc.txt b/Documentation/binfmt_misc.txt
index 6b1de7058371..ec83bbce547a 100644
--- a/Documentation/binfmt_misc.txt
+++ b/Documentation/binfmt_misc.txt
@@ -66,6 +66,13 @@ Here is what the fields mean:
This feature should be used with care as the interpreter
will run with root permissions when a setuid binary owned by root
is run with binfmt_misc.
+ 'F' - fix binary. The usual behaviour of binfmt_misc is to spawn the
+ binary lazily when the misc format file is invoked. However,
+ this doesn't work very well in the face of mount namespaces and
+ changeroots, so the F mode opens the binary as soon as the
+ emulation is installed and uses the opened image to spawn the
+ emulator, meaning it is always available once installed,
+ regardless of how the environment changes.
There are some restrictions: