Fix COPY --from=stage when running with user-namespaces#1448
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thaJeztah wants to merge 1 commit intomoby:masterfrom
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Fix COPY --from=stage when running with user-namespaces#1448thaJeztah wants to merge 1 commit intomoby:masterfrom
thaJeztah wants to merge 1 commit intomoby:masterfrom
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Issue was reported in moby/moby issue 34645, and relates to moby/moby PR 38599,
which addressed this issue for the classic builder.
When copying files between stages, file ownership should be preserved;
FROM busybox:latest as build
RUN touch x && chown 1:1 x
FROM busybox:latest
RUN touch y && chown 1:1 y
COPY --from=build x ./
However, when running with user namespaces enabled:
# grep dockremap /etc/sub*id
/etc/subgid:dockremap:500000:65536
/etc/subuid:dockremap:500000:65536
A build would fail, because BuildKit is trying to map the container's UID/GID
to the host:
ERROR: failed to copy file info: failed to chown /var/lib/docker/500000.500000/overlay2/mu5zpgelkig84eo9rlbqdhnn9/merged/x: Container ID 500001 cannot be mapped to a host ID
When looking at the code, I found that `(fb *Backend) Copy()` takes a `action`
argument (`pb.FileActionCopy`), one of its options is wether or not the owner
should be overridden:
// optional owner override
Owner *ChownOpt `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`)
That argument is passed on to `docopy()` (which is called from `(fb *Backend) Copy()`),
however inside `docopy()`, user-mapping is performed, irregardless if `Owner` was set
or not:
ch, err := mapUserToChowner(u, idmap)
if err != nil {
return err
}
opt := []copy.Opt{
func(ci *copy.CopyInfo) {
ci.Chown = ch
This patch makes that step optional, and only performs `mapUserToChowner` if
`action.Owner` is specified.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Member
Author
|
@tonistiigi @AkihiroSuda PTAL: no idea if this is the right fix (and if we have testing in place for user-namespaces); it's just from browsing the code and suspecting this might be the cause of the problem. |
tonistiigi
reviewed
Apr 25, 2020
| if err != nil { | ||
| return err | ||
| var ch copy.Chowner | ||
| if action.Owner != nil { |
Member
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this check here definitely isn't correct. First, action (including owner) is already parsed before calling this function and the result *copy.User passed to this function directly (with a nil check in map). Secondly, this object being nil doesn't carry any meaning as it is just a combination of two possibly nil pointers.
This issue looks to be regression from #1342
Member
|
replaced by #1477 |
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Issue was reported in moby/moby#34645 (comment), and relates to moby/moby#38599, which addressed this issue for the classic builder.
When copying files between stages, file ownership should be preserved;
However, when running with user namespaces enabled:
# grep dockremap /etc/sub*id /etc/subgid:dockremap:500000:65536 /etc/subuid:dockremap:500000:65536A build would fail, because BuildKit is trying to map the container's UID/GID to the host:
When looking at the code, I found that
(fb *Backend) Copy()takes aactionargument (
pb.FileActionCopy), one of its options is wether or not the ownershould be overridden:
buildkit/solver/pb/ops.pb.go
Lines 1457 to 1458 in 226a5db
That argument is passed on to
docopy()(which is called from(fb *Backend) Copy()), however insidedocopy(), user-mapping is performed, irregardless ifOwnerwas set or not:buildkit/solver/llbsolver/file/backend.go
Lines 182 to 189 in 226a5db
This patch makes that step optional, and only performs
mapUserToChownerifaction.Owneris specified, hopefully addressing the issue.