Fix SafeTarFile symlinks extraction #775
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symlinks like sbin/halt -> ../bin/busybox were mistakenly dropped before. Co-authored-by: Andrew Fasano <[email protected]>
Absolute targets were converted before, but it was too simple to be right other than when the link target was in the same directory. With this change absolute symlinks like /sbin/ls -> /bin/busybox are converted to /sbin/ls -> ../bin/busybox Co-authored-by: Andrew Fasano <[email protected]>
tests/integration/archive/tar/__input__/symlinks.tar:
test/
|-- bin
| `-- busybox
`-- sbin
|-- cp -> /test/bin/busybox
|-- find -> ../bin/../bin/busybox
|-- ln -> /test/bin/../bin/busybox
|-- ls -> ../bin/busybox
|-- mv -> ../../bin/busybox
`-- rm -> ../../../bin/busybox
is extracted as
tests/integration/archive/tar/__output__/symlinks.tar_extract/
└── test
├── bin
│ └── busybox
└── sbin
├── cp -> ../bin/busybox
├── find -> ../bin/busybox
├── ln -> ../bin/busybox
├── ls -> ../bin/busybox
└── mv -> ../../bin/busybox
Please note, that `rm` is missing, as that is a path traversal attempt.
----
The symlinks.tar test file is created with this script in a docker container:
rm -rf /test symlinks.tar
mkdir -p /test/bin
echo binary > /test/bin/busybox
mkdir -p /test/sbin
ln -s ../bin/busybox /test/sbin/ls
ln -s ../bin/../bin/busybox /test/sbin/find
ln -s ../../bin/busybox /test/sbin/mv
ln -s ../../../bin/busybox /test/sbin/rm
ln -s /test/bin/busybox /test/sbin/cp
ln -s /test/bin/../bin/busybox /test/sbin/ln
tar cPf /symlinks.tar /test/
tar tvPf /symlinks.tar
Due to the previous absolute-symlink extraction fix, the following updates are made: tests/integration/archive/tar/__output__/absolute.tar_extract/absolute/absolute-symlink - -> absolute/absolute-file + -> absolute-file tests/integration/archive/tar/__output__/absolute.tar_extract/absolute/link_to_etc_shadow - -> etc/shadow + -> ../etc/shadow
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Based on the work of @AndrewFasano in PR #770 this should fix most of the tar symlink extraction problems reported.
Related issue: #769