"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",
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