git/t/t7416-submodule-dash-url.sh
Jonathan Nieder 1a3609e402 fsck: reject URL with empty host in .gitmodules
Git's URL parser interprets

	https:///example.com/repo.git

to have no host and a path of "example.com/repo.git".  Curl, on the
other hand, internally redirects it to https://example.com/repo.git.  As
a result, until "credential: parse URL without host as empty host, not
unset", tricking a user into fetching from such a URL would cause Git to
send credentials for another host to example.com.

Teach fsck to block and detect .gitmodules files using such a URL to
prevent sharing them with Git versions that are not yet protected.

A relative URL in a .gitmodules file could also be used to trigger this.
The relative URL resolver used for .gitmodules does not normalize
sequences of slashes and can follow ".." components out of the path part
and to the host part of a URL, meaning that such a relative URL can be
used to traverse from a https://foo.example.com/innocent superproject to
a https:///attacker.example.com/exploit submodule. Fortunately,
redundant extra slashes in .gitmodules are rare, so we can catch this by
detecting one after a leading sequence of "./" and "../" components.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
2020-04-19 16:10:58 -07:00

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Executable File

#!/bin/sh
test_description='check handling of disallowed .gitmodule urls'
. ./test-lib.sh
test_expect_success 'create submodule with protected dash in url' '
git init upstream &&
git -C upstream commit --allow-empty -m base &&
mv upstream ./-upstream &&
git submodule add ./-upstream sub &&
git add sub .gitmodules &&
git commit -m submodule
'
test_expect_success 'clone can recurse submodule' '
test_when_finished "rm -rf dst" &&
git clone --recurse-submodules . dst &&
echo base >expect &&
git -C dst/sub log -1 --format=%s >actual &&
test_cmp expect actual
'
test_expect_success 'fsck accepts protected dash' '
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
git push dst HEAD
'
test_expect_success 'remove ./ protection from .gitmodules url' '
perl -i -pe "s{\./}{}" .gitmodules &&
git commit -am "drop protection"
'
test_expect_success 'clone rejects unprotected dash' '
test_when_finished "rm -rf dst" &&
test_must_fail git clone --recurse-submodules . dst 2>err &&
test_i18ngrep ignoring err
'
test_expect_success 'fsck rejects unprotected dash' '
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'trailing backslash is handled correctly' '
git init testmodule &&
test_commit -C testmodule c &&
git submodule add ./testmodule &&
: ensure that the name ends in a double backslash &&
sed -e "s|\\(submodule \"testmodule\\)\"|\\1\\\\\\\\\"|" \
-e "s|url = .*|url = \" --should-not-be-an-option\"|" \
<.gitmodules >.new &&
mv .new .gitmodules &&
git commit -am "Add testmodule" &&
test_must_fail git clone --verbose --recurse-submodules . dolly 2>err &&
test_i18ngrep ! "unknown option" err
'
test_expect_success 'fsck rejects missing URL scheme' '
git checkout --orphan missing-scheme &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = http::one.example.com/foo.git
EOF
git add .gitmodules &&
test_tick &&
git commit -m "gitmodules with missing URL scheme" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck rejects relative URL resolving to missing scheme' '
git checkout --orphan relative-missing-scheme &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = "..\\../.\\../:one.example.com/foo.git"
EOF
git add .gitmodules &&
test_tick &&
git commit -m "gitmodules with relative URL that strips off scheme" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck rejects empty URL scheme' '
git checkout --orphan empty-scheme &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = http::://one.example.com/foo.git
EOF
git add .gitmodules &&
test_tick &&
git commit -m "gitmodules with empty URL scheme" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck rejects relative URL resolving to empty scheme' '
git checkout --orphan relative-empty-scheme &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = ../../../:://one.example.com/foo.git
EOF
git add .gitmodules &&
test_tick &&
git commit -m "relative gitmodules URL resolving to empty scheme" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck rejects empty hostname' '
git checkout --orphan empty-host &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = http:///one.example.com/foo.git
EOF
git add .gitmodules &&
test_tick &&
git commit -m "gitmodules with extra slashes" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck rejects relative url that produced empty hostname' '
git checkout --orphan messy-relative &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = ../../..//one.example.com/foo.git
EOF
git add .gitmodules &&
test_tick &&
git commit -m "gitmodules abusing relative_path" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck permits embedded newline with unrecognized scheme' '
git checkout --orphan newscheme &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = "data://acjbkd%0akajfdickajkd"
EOF
git add .gitmodules &&
git commit -m "gitmodules with unrecognized scheme" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
git push dst HEAD
'
test_expect_success 'fsck rejects embedded newline in url' '
# create an orphan branch to avoid existing .gitmodules objects
git checkout --orphan newline &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = "https://one.example.com?%0ahost=two.example.com/foo.git"
EOF
git add .gitmodules &&
git commit -m "gitmodules with newline" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_expect_success 'fsck rejects embedded newline in relative url' '
git checkout --orphan relative-newline &&
cat >.gitmodules <<-\EOF &&
[submodule "foo"]
url = "./%0ahost=two.example.com/foo.git"
EOF
git add .gitmodules &&
git commit -m "relative url with newline" &&
test_when_finished "rm -rf dst" &&
git init --bare dst &&
git -C dst config transfer.fsckObjects true &&
test_must_fail git push dst HEAD 2>err &&
grep gitmodulesUrl err
'
test_done