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git/t/t7450-bad-git-dotfiles.sh
Jeff King bb6832d552 fsck: warn about symlinked dotfiles we'll open with O_NOFOLLOW
In the commits merged in via 204333b015 (Merge branch
'jk/open-dotgitx-with-nofollow', 2021-03-22), we stopped following
symbolic links for .gitattributes, .gitignore, and .mailmap files.

Let's teach fsck to warn that these symlinks are not going to do
anything. Note that this is just a warning, and won't block the objects
via transfer.fsckObjects, since there are reported to be cases of this
in the wild (and even once fixed, they will continue to exist in the
commit history of those projects, but are not particularly dangerous).

Note that we won't add these to the existing gitmodules block in the
fsck code. The logic for gitmodules is a bit more complicated, as we
also check the content of non-symlink instances we find. But for these
new files, there is no content check; we're just looking at the name and
mode of the tree entry (and we can avoid even the complicated name
checks in the common case that the mode doesn't indicate a symlink).

We can reuse the test helper function we defined for .gitmodules, though
(it needs some slight adjustments for the fsck error code, and because
we don't block these symlinks via verify_path()).

Note that I didn't explicitly test the transfer.fsckObjects case here
(nor does the existing .gitmodules test that it blocks a push). The
translation of fsck severities to outcomes is covered in general in
t5504.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-04 11:52:02 +09:00

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#!/bin/sh
test_description='check broken or malicious patterns in .git* files
Such as:
- presence of .. in submodule names;
Exercise the name-checking function on a variety of names, and then give a
real-world setup that confirms we catch this in practice.
- nested submodule names
- symlinked .gitmodules, etc
'
. ./test-lib.sh
. "$TEST_DIRECTORY"/lib-pack.sh
test_expect_success 'check names' '
cat >expect <<-\EOF &&
valid
valid/with/paths
EOF
git submodule--helper check-name >actual <<-\EOF &&
valid
valid/with/paths
../foo
/../foo
..\foo
\..\foo
foo/..
foo/../
foo\..
foo\..\
foo/../bar
EOF
test_cmp expect actual
'
test_expect_success 'create innocent subrepo' '
git init innocent &&
git -C innocent commit --allow-empty -m foo
'
test_expect_success 'submodule add refuses invalid names' '
test_must_fail \
git submodule add --name ../../modules/evil "$PWD/innocent" evil
'
test_expect_success 'add evil submodule' '
git submodule add "$PWD/innocent" evil &&
mkdir modules &&
cp -r .git/modules/evil modules &&
write_script modules/evil/hooks/post-checkout <<-\EOF &&
echo >&2 "RUNNING POST CHECKOUT"
EOF
git config -f .gitmodules submodule.evil.update checkout &&
git config -f .gitmodules --rename-section \
submodule.evil submodule.../../modules/evil &&
git add modules &&
git commit -am evil
'
# This step seems like it shouldn't be necessary, since the payload is
# contained entirely in the evil submodule. But due to the vagaries of the
# submodule code, checking out the evil module will fail unless ".git/modules"
# exists. Adding another submodule (with a name that sorts before "evil") is an
# easy way to make sure this is the case in the victim clone.
test_expect_success 'add other submodule' '
git submodule add "$PWD/innocent" another-module &&
git add another-module &&
git commit -am another
'
test_expect_success 'clone evil superproject' '
git clone --recurse-submodules . victim >output 2>&1 &&
! grep "RUNNING POST CHECKOUT" output
'
test_expect_success 'fsck detects evil superproject' '
test_must_fail git fsck
'
test_expect_success 'transfer.fsckObjects detects evil superproject (unpack)' '
rm -rf dst.git &&
git init --bare dst.git &&
git -C dst.git config transfer.fsckObjects true &&
test_must_fail git push dst.git HEAD
'
test_expect_success 'transfer.fsckObjects detects evil superproject (index)' '
rm -rf dst.git &&
git init --bare dst.git &&
git -C dst.git config transfer.fsckObjects true &&
git -C dst.git config transfer.unpackLimit 1 &&
test_must_fail git push dst.git HEAD
'
# Normally our packs contain commits followed by trees followed by blobs. This
# reverses the order, which requires backtracking to find the context of a
# blob. We'll start with a fresh gitmodules-only tree to make it simpler.
test_expect_success 'create oddly ordered pack' '
git checkout --orphan odd &&
git rm -rf --cached . &&
git add .gitmodules &&
git commit -m odd &&
{
pack_header 3 &&
pack_obj $(git rev-parse HEAD:.gitmodules) &&
pack_obj $(git rev-parse HEAD^{tree}) &&
pack_obj $(git rev-parse HEAD)
} >odd.pack &&
pack_trailer odd.pack
'
test_expect_success 'transfer.fsckObjects handles odd pack (unpack)' '
rm -rf dst.git &&
git init --bare dst.git &&
test_must_fail git -C dst.git unpack-objects --strict <odd.pack
'
test_expect_success 'transfer.fsckObjects handles odd pack (index)' '
rm -rf dst.git &&
git init --bare dst.git &&
test_must_fail git -C dst.git index-pack --strict --stdin <odd.pack
'
test_expect_success 'index-pack --strict works for non-repo pack' '
rm -rf dst.git &&
git init --bare dst.git &&
cp odd.pack dst.git &&
test_must_fail git -C dst.git index-pack --strict odd.pack 2>output &&
# Make sure we fail due to bad gitmodules content, not because we
# could not read the blob in the first place.
grep gitmodulesName output
'
check_dotx_symlink () {
fsck_must_fail=test_must_fail
fsck_prefix=error
refuse_index=t
case "$1" in
--warning)
fsck_must_fail=
fsck_prefix=warning
refuse_index=
shift
;;
esac
name=$1
type=$2
path=$3
dir=symlink-$name-$type
test_expect_success "set up repo with symlinked $name ($type)" '
git init $dir &&
(
cd $dir &&
# Make the tree directly to avoid index restrictions.
#
# Because symlinks store the target as a blob, choose
# a pathname that could be parsed as a .gitmodules file
# to trick naive non-symlink-aware checking.
tricky="[foo]bar=true" &&
content=$(git hash-object -w ../.gitmodules) &&
target=$(printf "$tricky" | git hash-object -w --stdin) &&
{
printf "100644 blob $content\t$tricky\n" &&
printf "120000 blob $target\t$path\n"
} >bad-tree
) &&
tree=$(git -C $dir mktree <$dir/bad-tree)
'
test_expect_success "fsck detects symlinked $name ($type)" '
(
cd $dir &&
# Check not only that we fail, but that it is due to the
# symlink detector
$fsck_must_fail git fsck 2>output &&
grep "$fsck_prefix.*tree $tree: ${name}Symlink" output
)
'
test -n "$refuse_index" &&
test_expect_success "refuse to load symlinked $name into index ($type)" '
test_must_fail \
git -C $dir \
-c core.protectntfs \
-c core.protecthfs \
read-tree $tree 2>err &&
grep "invalid path.*$name" err &&
git -C $dir ls-files -s >out &&
test_must_be_empty out
'
}
check_dotx_symlink gitmodules vanilla .gitmodules
check_dotx_symlink gitmodules ntfs ".gitmodules ."
check_dotx_symlink gitmodules hfs ".${u200c}gitmodules"
check_dotx_symlink --warning gitattributes vanilla .gitattributes
check_dotx_symlink --warning gitattributes ntfs ".gitattributes ."
check_dotx_symlink --warning gitattributes hfs ".${u200c}gitattributes"
check_dotx_symlink --warning gitignore vanilla .gitignore
check_dotx_symlink --warning gitignore ntfs ".gitignore ."
check_dotx_symlink --warning gitignore hfs ".${u200c}gitignore"
check_dotx_symlink --warning mailmap vanilla .mailmap
check_dotx_symlink --warning mailmap ntfs ".mailmap ."
check_dotx_symlink --warning mailmap hfs ".${u200c}mailmap"
test_expect_success 'fsck detects non-blob .gitmodules' '
git init non-blob &&
(
cd non-blob &&
# As above, make the funny tree directly to avoid index
# restrictions.
mkdir subdir &&
cp ../.gitmodules subdir/file &&
git add subdir/file &&
git commit -m ok &&
git ls-tree HEAD | sed s/subdir/.gitmodules/ | git mktree &&
test_must_fail git fsck 2>output &&
test_i18ngrep gitmodulesBlob output
)
'
test_expect_success 'fsck detects corrupt .gitmodules' '
git init corrupt &&
(
cd corrupt &&
echo "[broken" >.gitmodules &&
git add .gitmodules &&
git commit -m "broken gitmodules" &&
git fsck 2>output &&
test_i18ngrep gitmodulesParse output &&
test_i18ngrep ! "bad config" output
)
'
test_expect_success MINGW 'prevent git~1 squatting on Windows' '
git init squatting &&
(
cd squatting &&
mkdir a &&
touch a/..git &&
git add a/..git &&
test_tick &&
git commit -m initial &&
modules="$(test_write_lines \
"[submodule \"b.\"]" "url = ." "path = c" \
"[submodule \"b\"]" "url = ." "path = d\\\\a" |
git hash-object -w --stdin)" &&
rev="$(git rev-parse --verify HEAD)" &&
hash="$(echo x | git hash-object -w --stdin)" &&
test_must_fail git update-index --add \
--cacheinfo 160000,$rev,d\\a 2>err &&
test_i18ngrep "Invalid path" err &&
git -c core.protectNTFS=false update-index --add \
--cacheinfo 100644,$modules,.gitmodules \
--cacheinfo 160000,$rev,c \
--cacheinfo 160000,$rev,d\\a \
--cacheinfo 100644,$hash,d./a/x \
--cacheinfo 100644,$hash,d./a/..git &&
test_tick &&
git -c core.protectNTFS=false commit -m "module"
) &&
test_must_fail git -c core.protectNTFS=false \
clone --recurse-submodules squatting squatting-clone 2>err &&
test_i18ngrep -e "directory not empty" -e "not an empty directory" err &&
! grep gitdir squatting-clone/d/a/git~2
'
test_expect_success 'git dirs of sibling submodules must not be nested' '
git init nested &&
test_commit -C nested nested &&
(
cd nested &&
cat >.gitmodules <<-EOF &&
[submodule "hippo"]
url = .
path = thing1
[submodule "hippo/hooks"]
url = .
path = thing2
EOF
git clone . thing1 &&
git clone . thing2 &&
git add .gitmodules thing1 thing2 &&
test_tick &&
git commit -m nested
) &&
test_must_fail git clone --recurse-submodules nested clone 2>err &&
test_i18ngrep "is inside git dir" err
'
test_done