116 lines
4.7 KiB
Diff
116 lines
4.7 KiB
Diff
From b48b2e689270ee7cc8c13464cbae1b5405fcb901 Mon Sep 17 00:00:00 2001
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From: Matt Heon <mheon@redhat.com>
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Date: Wed, 9 Oct 2024 15:23:03 -0400
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Subject: [PATCH 3/4] Properly validate cache IDs and sources
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The `--mount type=cache` argument to the `RUN` instruction in
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Dockerfiles was using `filepath.Join` on user input, allowing
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crafted paths to be used to gain access to paths on the host,
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when the command should normally be limited only to Buildah;s own
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cache and context directories. Switch to `filepath.SecureJoin` to
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resolve the issue.
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Fixes CVE-2024-9675
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Signed-off-by: Matt Heon <mheon@redhat.com>
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Signed-off-by: Danish Prakash <contact@danishpraka.sh>
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---
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internal/volumes/volumes.go | 22 +++++++++++++++-------
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tests/bud.bats | 34 ++++++++++++++++++++++++++++++++++
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2 files changed, 49 insertions(+), 7 deletions(-)
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diff --git a/internal/volumes/volumes.go b/internal/volumes/volumes.go
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index da6b768fdc21..2dd04d9c32a4 100644
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--- a/internal/volumes/volumes.go
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+++ b/internal/volumes/volumes.go
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@@ -23,6 +23,7 @@ import (
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"github.com/containers/storage/pkg/idtools"
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"github.com/containers/storage/pkg/lockfile"
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"github.com/containers/storage/pkg/unshare"
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+ digest "github.com/opencontainers/go-digest"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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selinux "github.com/opencontainers/selinux/go-selinux"
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)
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@@ -374,10 +375,13 @@ func GetCacheMount(args []string, store storage.Store, imageMountLabel string, a
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return newMount, nil, fmt.Errorf("no stage found with name %s", fromStage)
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}
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// path should be /contextDir/specified path
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- newMount.Source = filepath.Join(mountPoint, filepath.Clean(string(filepath.Separator)+newMount.Source))
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+ evaluated, err := copier.Eval(mountPoint, string(filepath.Separator)+newMount.Source, copier.EvalOptions{})
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+ if err != nil {
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+ return newMount, nil, err
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+ }
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+ newMount.Source = evaluated
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} else {
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- // we need to create cache on host if no image is being used
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-
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+ // we need to create the cache directory on the host if no image is being used
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// since type is cache and cache can be reused by consecutive builds
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// create a common cache directory, which persists on hosts within temp lifecycle
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// add subdirectory if specified
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@@ -391,11 +395,15 @@ func GetCacheMount(args []string, store storage.Store, imageMountLabel string, a
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}
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if id != "" {
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- newMount.Source = filepath.Join(cacheParent, filepath.Clean(id))
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- buildahLockFilesDir = filepath.Join(BuildahCacheLockfileDir, filepath.Clean(id))
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+ // Don't let the user control where we place the directory.
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+ dirID := digest.FromString(id).Encoded()[:16]
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+ newMount.Source = filepath.Join(cacheParent, dirID)
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+ buildahLockFilesDir = filepath.Join(BuildahCacheLockfileDir, dirID)
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} else {
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- newMount.Source = filepath.Join(cacheParent, filepath.Clean(newMount.Destination))
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- buildahLockFilesDir = filepath.Join(BuildahCacheLockfileDir, filepath.Clean(newMount.Destination))
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+ // Don't let the user control where we place the directory.
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+ dirID := digest.FromString(newMount.Destination).Encoded()[:16]
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+ newMount.Source = filepath.Join(cacheParent, dirID)
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+ buildahLockFilesDir = filepath.Join(BuildahCacheLockfileDir, dirID)
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}
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idPair := idtools.IDPair{
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UID: uid,
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diff --git a/tests/bud.bats b/tests/bud.bats
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index b6982bbc0ee4..e28fc3dd8add 100644
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--- a/tests/bud.bats
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+++ b/tests/bud.bats
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@@ -6659,3 +6659,37 @@ _EOF
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assert "$status" -eq 2 "exit code from ls"
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expect_output --substring "No such file or directory"
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}
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+
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+@test "build-check-cve-2024-9675" {
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+ _prefetch alpine
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+
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+ touch ${TEST_SCRATCH_DIR}/file.txt
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+
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+ cat > ${TEST_SCRATCH_DIR}/Containerfile <<EOF
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+FROM alpine
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+RUN --mount=type=cache,id=../../../../../../../../../../../$TEST_SCRATCH_DIR,target=/var/tmp \
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+ls -l /var/tmp && cat /var/tmp/file.txt
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+EOF
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+
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+ run_buildah 1 build --no-cache ${TEST_SCRATCH_DIR}
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+ expect_output --substring "cat: can't open '/var/tmp/file.txt': No such file or directory"
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+
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+ cat > ${TEST_SCRATCH_DIR}/Containerfile <<EOF
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+FROM alpine
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+RUN --mount=type=cache,source=../../../../../../../../../../../$TEST_SCRATCH_DIR,target=/var/tmp \
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+ls -l /var/tmp && cat /var/tmp/file.txt
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+EOF
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+
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+ run_buildah 1 build --no-cache ${TEST_SCRATCH_DIR}
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+ expect_output --substring "cat: can't open '/var/tmp/file.txt': No such file or directory"
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+
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+ mkdir ${TEST_SCRATCH_DIR}/cve20249675
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+ cat > ${TEST_SCRATCH_DIR}/cve20249675/Containerfile <<EOF
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+FROM alpine
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+RUN --mount=type=cache,from=testbuild,source=../,target=/var/tmp \
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+ls -l /var/tmp && cat /var/tmp/file.txt
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+EOF
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+
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+ run_buildah 1 build --security-opt label=disable --build-context testbuild=${TEST_SCRATCH_DIR}/cve20249675/ --no-cache ${TEST_SCRATCH_DIR}/cve20249675/
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+ expect_output --substring "cat: can't open '/var/tmp/file.txt': No such file or directory"
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+}
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--
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2.46.0
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