41 lines
1.6 KiB
Diff
41 lines
1.6 KiB
Diff
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From 6e35f145221347264ea5d4814308ab0624725024 Mon Sep 17 00:00:00 2001
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From: zhangsong34 <zhangsong34@huawei.com>
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Date: Tue, 2 Apr 2019 10:00:20 +0800
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Subject: [PATCH] runc: fix --read-only containers under
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--userns-remap
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reason:fix --read-only containers under --userns-remap
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cherry-pick from:
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https://github.com/opencontainers/runc/pull/1572
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Change-Id: I0f823caf1e72e4d61df9abe5f97fa5605425fd2c
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Signed-off-by: Tycho Andersen <tycho@docker.com>
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Signed-off-by: zhangsong34 <zhangsong34@huawei.com>
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---
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libcontainer/rootfs_linux.go | 9 ++++++++-
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1 file changed, 8 insertions(+), 1 deletion(-)
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diff --git a/libcontainer/rootfs_linux.go b/libcontainer/rootfs_linux.go
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index 53797e9..18a25f2 100644
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--- a/libcontainer/rootfs_linux.go
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+++ b/libcontainer/rootfs_linux.go
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@@ -769,7 +769,14 @@ func remountReadonly(m *configs.Mount) error {
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flags = m.Flags
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)
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for i := 0; i < 5; i++ {
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- if err := syscall.Mount("", dest, "", uintptr(flags|syscall.MS_REMOUNT|syscall.MS_RDONLY), ""); err != nil {
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+ // There is a special case in the kernel for
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+ // MS_REMOUNT | MS_BIND, which allows us to change only the
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+ // flags even as an unprivileged user (i.e. user namespace)
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+ // assuming we don't drop any security related flags (nodev,
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+ // nosuid, etc.). So, let's use that case so that we can do
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+ // this re-mount without failing in a userns.
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+ flags |= syscall.MS_REMOUNT | syscall.MS_BIND | syscall.MS_RDONLY
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+ if err := syscall.Mount("", dest, "", uintptr(flags), ""); err != nil {
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switch err {
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case syscall.EBUSY:
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time.Sleep(100 * time.Millisecond)
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--
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1.8.3.1
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