{"id":"GHSA-x9qq-236j-gj97","summary":"Canonical LXD documentation improvement to make clear restricted.devices.disk=allow without restricted.devices.disk.paths also allows shift=true","details":"### Summary\n\nIf a user has restricted access to a project that is configured with `restricted=true`, they can gain root access on the system by creating a disk device with `shift=true` and creating a setuid root executable. This is possible because the `shift` property is not restricted unless `restricted.devices.disk.paths` is set.\n\n### Details\n\nThe following patch shows the offending code with a possible fix:\n```patch\n--- a/lxd/device/disk.go\n+++ b/lxd/device/disk.go\n@@ -429,17 +429,19 @@ func (d *disk) validateEnvironmentSourcePath() error {\n        if instProject.Name != api.ProjectDefaultName {\n                // If restricted disk paths are in force, then check the disk's source is allowed, and record the\n                // allowed parent path for later user during device start up sequence.\n-               if shared.IsTrue(instProject.Config[\"restricted\"]) && instProject.Config[\"restricted.devices.disk.paths\"] != \"\" {\n-                       allowed, restrictedParentSourcePath := project.CheckRestrictedDevicesDiskPaths(instProject.Config, d.config[\"source\"])\n-                       if !allowed {\n-                               return fmt.Errorf(\"Disk source path %q not allowed by project for disk %q\", d.config[\"source\"], d.name)\n+               if shared.IsTrue(instProject.Config[\"restricted\"]) {\n+                       if instProject.Config[\"restricted.devices.disk.paths\"] != \"\" {\n+                               allowed, restrictedParentSourcePath := project.CheckRestrictedDevicesDiskPaths(instProject.Config, d.config[\"source\"])\n+                               if !allowed {\n+                                       return fmt.Errorf(\"Disk source path %q not allowed by project for disk %q\", d.config[\"source\"], d.name)\n+                               }\n+\n+                               d.restrictedParentSourcePath = shared.HostPath(restrictedParentSourcePath)\n                        }\n\n                        if shared.IsTrue(d.config[\"shift\"]) {\n                                return fmt.Errorf(`The \"shift\" property cannot be used with a restricted source path`)\n                        }\n-\n-                       d.restrictedParentSourcePath = shared.HostPath(restrictedParentSourcePath)\n                }\n        }\n```\n\n### PoC\n\n```bash\n$ lxc project create restricted -c restricted=true -c restricted.devices.disk=allow\n$ lxc project switch restricted\n$ lxc profile device add default root disk path=/ pool=default\n$ lxc init ubuntu:22.04 c1\n$ lxc config device add c1 d1 disk source=/ path=/mnt shift=true\n$ lxc start c1  # no error\n\n$ lxc project set restricted restricted.devices.disk.paths=/  # explicitly allow mounting /\n$ lxc restart c1\nError: Failed to start device \"d1\": The \"shift\" property cannot be used with a restricted source path\n```\n\nCreated https://github.com/canonical/lxd/issues/12606 to improve the documentation as per https://github.com/canonical/lxd/security/advisories/GHSA-x9qq-236j-gj97#advisory-comment-91918","modified":"2025-07-22T14:57:33Z","published":"2023-12-05T23:32:58Z","database_specific":{"github_reviewed_at":"2023-12-05T23:32:58Z","nvd_published_at":null,"cwe_ids":[],"severity":"LOW","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/canonical/lxd/security/advisories/GHSA-x9qq-236j-gj97"},{"type":"WEB","url":"https://github.com/canonical/lxd/issues/12606"},{"type":"WEB","url":"https://github.com/canonical/lxd/commit/ce1bd0dd37bb3810fe6f16c237a4b65257f231f1"},{"type":"PACKAGE","url":"https://github.com/canonical/lxd"}],"affected":[{"package":{"name":"github.com/canonical/lxd","ecosystem":"Go","purl":"pkg:golang/github.com/canonical/lxd"},"ranges":[{"type":"SEMVER","events":[{"introduced":"5.19.0"},{"fixed":"5.20.0"}]}],"versions":["5.19.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2023/12/GHSA-x9qq-236j-gj97/GHSA-x9qq-236j-gj97.json"}},{"package":{"name":"github.com/canonical/lxd","ecosystem":"Go","purl":"pkg:golang/github.com/canonical/lxd"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-20230920084527-cbe39c5d3f14"},{"fixed":"0.0.0-20240118092008-ce1bd0dd37bb"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2023/12/GHSA-x9qq-236j-gj97/GHSA-x9qq-236j-gj97.json"}}],"schema_version":"1.9.0"}