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Fix runc run "permission denied" when rootless #3753

Merged
merged 3 commits into from
Mar 28, 2023
Merged

Fix runc run "permission denied" when rootless #3753

merged 3 commits into from
Mar 28, 2023

Commits on Mar 27, 2023

  1. Dockefile: bump go go 1.20 

    Go 1.20.2 has an important fix to an issue described in [1].

Switch from using Go 1.19 from Dockerfile, which is used for release
binaries and some CI.

[1] golang/go#58624

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
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    kolyshkin committed Mar 27, 2023
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  2. Fix runc run "permission denied" when rootless 

    Since commit 957d97b was made to fix issue [7],
a few things happened:

- a similar functionality appeared in go 1.20 [1], so the issue
  mentioned in the comment (being removed) is no longer true;
- a bug in runc was found [2], which also affects go [3];
- the bug was fixed in go 1.21 [4] and 1.20.2 [5];
- a similar fix was made to x/sys/unix.Faccessat [6].

The essense of [2] is, even if a (non-root) user that the container is
run as does not have execute permission bit set for the executable, it
should still work in case runc has the CAP_DAC_OVERRIDE capability set.

To fix this [2] without reintroducing the older bug [7]:
- drop own Eaccess implementation;
- use the one from x/sys/unix for Go 1.19 (depends on [6]);
- do not use anything when Go 1.20+ is used.

NOTE it is virtually impossible to fix the bug [2] when Go 1.20 or Go
1.20.1 is used because of [3].

A test case is added by a separate commit.

Fixes: opencontainers#3715.

[1] https://go-review.googlesource.com/c/go/+/414824
[2] opencontainers#3715
[3] https://go.dev/issue/58552
[4] https://go-review.googlesource.com/c/go/+/468735
[5] https://go-review.googlesource.com/c/go/+/469956
[6] https://go-review.googlesource.com/c/sys/+/468877
[7] opencontainers#3520

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
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    kolyshkin committed Mar 27, 2023
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  3. tests/int: test for CAP_DAC_OVERRIDE 

    This is a test case for issue reported as opencontainers#3715. In short, even if a
(non-root) user that the container is run as does not have execute
permission bit set for the executable, it should still work in case runc
has the CAP_DAC_OVERRIDE capability set.

Note that since the upstream golang is also broken (see [1]), this test
will fail for Go 1.20 and 1.20.1 (fix is in Go 1.20.2 as per [2]).

[1] https://go.dev/issue/58552
[2] https://go-review.googlesource.com/c/go/+/469956

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
    @kolyshkin
    kolyshkin committed Mar 27, 2023
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