specconv: emit an error when using MS_PRIVATE with --no-pivot #1606
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I'm not sure if it's better that we have an error here or if we have some sort of warning message. I didn't want to add a warning message here initially because it would be the first logging we did as part of |
Due to the semantics of chroot(2) when it comes to mount namespaces, it is not generally safe to use MS_PRIVATE as a mount propgation when using chroot(2). The reason for this is that this effectively results in a set of mount references being held by the chroot'd namespace which the namespace cannot free. pivot_root(2) does not have this issue because the @old_root can be unmounted by the process. Ultimately, --no-pivot is not really necessary anymore as a commonly used option since f8e6b5a ("rootfs: make pivot_root not use a temporary directory") resolved the read-only issue. But if someone really needs to use it, MS_PRIVATE is never a good idea. Signed-off-by: Aleksa Sarai <[email protected]>
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What if we moved this into |
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@crosbymichael You mean in |
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Oh, sorry. I didn't read the filename correctly. LGTM |
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LGTM |
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Due to the semantics of chroot(2) when it comes to mount namespaces, it
is not generally safe to use MS_PRIVATE as a mount propgation when using
chroot(2). The reason for this is that this effectively results in a set
of mount references being held by the chroot'd namespace which the
namespace cannot free. pivot_root(2) does not have this issue because
the @old_root can be unmounted by the process.
Ultimately, --no-pivot is not really necessary anymore as a commonly
used option since f8e6b5a ("rootfs: make pivot_root not use a
temporary directory") resolved the read-only issue. But if someone
really needs to use it, MS_PRIVATE is never a good idea.
Fixes #1602
Signed-off-by: Aleksa Sarai [email protected]