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tar,unzip: postpone creation of symlinks with "suspicious" targets

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This mostly reverts commit bc9bbeb2b8
"libarchive: do not extract unsafe symlinks unless $EXTRACT_UNSAFE_SYMLINKS=1"

Users report that it is somewhat too restrictive. See
https://bugs.busybox.net/show_bug.cgi?id=8411

In particular, this interferes with unpacking of busybox-based
filesystems with links like "sbin/applet" -> "../bin/busybox".

The change is made smaller by deleting ARCHIVE_EXTRACT_QUIET flag -
it is unused since 2010, and removing conditionals on it
allows commonalizing some error message codes.

function                                             old     new   delta
create_or_remember_symlink                             -      94     +94
create_symlinks_from_list                              -      64     +64
tar_main                                            1002    1006      +4
unzip_main                                          2732    2724      -8
data_extract_all                                     984     891     -93
unsafe_symlink_target                                147       -    -147
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 1/2 up/down: 162/-248)          Total: -86 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2018-02-20 15:57:45 +01:00
parent 95121d98e6
commit a84db18fc7
6 changed files with 71 additions and 82 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
testsuite/tar.tests
View File

@ -279,7 +279,7 @@ optional UUDECODE FEATURE_TAR_AUTODETECT FEATURE_SEAMLESS_BZ2
testing "tar does not extract into symlinks" "\
>>/tmp/passwd && uudecode -o input && tar xf input 2>&1 && rm passwd; cat /tmp/passwd; echo \$?
" "\
tar: skipping unsafe symlink to '/tmp/passwd' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
tar: can't create symlink 'passwd' to '/tmp/passwd'
0
" \
"" "\
@ -299,7 +299,7 @@ optional UUDECODE FEATURE_TAR_AUTODETECT FEATURE_SEAMLESS_BZ2
testing "tar -k does not extract into symlinks" "\
>>/tmp/passwd && uudecode -o input && tar xf input -k 2>&1 && rm passwd; cat /tmp/passwd; echo \$?
" "\
tar: skipping unsafe symlink to '/tmp/passwd' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
tar: can't create symlink 'passwd' to '/tmp/passwd'
0
" \
"" "\
@ -324,11 +324,11 @@ rm -rf etc usr
' "\
etc/ssl/certs/3b2716e5.0
etc/ssl/certs/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem
tar: skipping unsafe symlink to '/usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
etc/ssl/certs/f80cc7f6.0
usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt
0
etc/ssl/certs/3b2716e5.0 -> EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem
etc/ssl/certs/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem -> /usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt
etc/ssl/certs/f80cc7f6.0 -> EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem
" \
"" ""
@ -346,9 +346,9 @@ ls symlink/bb_test_evilfile
' "\
anything.txt
symlink
tar: skipping unsafe symlink to '/tmp' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
symlink/bb_test_evilfile
0
tar: can't create symlink 'symlink' to '/tmp'
1
ls: /tmp/bb_test_evilfile: No such file or directory
ls: bb_test_evilfile: No such file or directory
symlink/bb_test_evilfile