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Re-allow paths in .python-version provided that they resolve to within the versions dir (#2442)

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* Fixes #2430 while still preventing CVE-2022-35861
* Adds a skipped version message to stderr

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>
This commit is contained in:
James Stronz 2022-09-03 14:37:53 -05:00 committed by GitHub
parent fdabd14c2b
commit 47b0ce77c0
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 48 additions and 11 deletions
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25
libexec/pyenv-version-file-read
View file

@ -5,18 +5,33 @@ set -e
VERSION_FILE="$1"
function is_version_safe() {
# As needed, check that the constructed path exists as a child path of PYENV_ROOT/versions
version="$1"
if [[ "$version" == ".." || "$version" == */* ]]; then
# Sanity check the value of version to prevent malicious path-traversal
(
cd "$PYENV_ROOT/versions/$version" &>/dev/null || exit 1
[[ "$PWD" == "$PYENV_ROOT/versions/"* ]]
)
return $?
else
return 0
fi
}
if [ -s "$VERSION_FILE" ]; then
# Read the first non-whitespace word from the specified version file.
# Be careful not to load it whole in case there's something crazy in it.
IFS="${IFS}"$'\r'
IFS="$IFS"$'\r'
sep=
while read -n 1024 -r version _ || [[ $version ]]; do
if [[ -z $version || $version == \#* ]]; then
if [[ -z "$version" || "$version" == \#* ]]; then
# Skip empty lines and comments
continue
elif [ "$version" = ".." ] || [[ $version == */* ]]; then
# The version string is used to construct a path and we skip dubious values.
# This prevents issues such as path traversal (CVE-2022-35861).
elif ! is_version_safe "$version"; then
# CVE-2022-35861 allowed arbitrary code execution in some contexts and is mitigated by is_version_safe.
echo "pyenv: invalid version \`$version' ignored in \`$VERSION_FILE'" >&2
continue
fi
printf "%s%s" "$sep" "$version"

34
test/version-file-read.bats
View file

@ -83,14 +83,36 @@ IN
assert_success "3.9.3:3.8.9:2.7.16"
}
@test "skips relative path traversal" {
@test "skips \`..' relative path traversal" {
echo '..' > my-version
run pyenv-version-file-read my-version
assert_failure "pyenv: invalid version \`..' ignored in \`my-version'"
}
@test "skips glob path traversal" {
cat > my-version <<IN
../*
3.9.3
3.8.9
..
./*
2.7.16
IN
run pyenv-version-file-read my-version
assert_success "3.9.3:3.8.9:2.7.16"
assert_success <<OUT
pyenv: invalid version \`../\*' ignored in \`my-version'
3.9.3
OUT
}
@test "allows relative paths that exist and stay within versions" {
venv=3.10.3/envs/../test
mkdir -p "${PYENV_ROOT}/versions/${venv}"
echo -n "${venv}" > my-version
run pyenv-version-file-read my-version
assert_success "${venv}"
}
@test "skips relative paths that lead outside of versions" {
venv=../3.10.3/envs/test
mkdir -p "${PYENV_ROOT}/versions/${venv}"
echo -n "${venv}" > my-version
run pyenv-version-file-read my-version
assert_failure
}