unshare failed: Permission denied (Noble 24.04)

[nteodosio]

Required information

• Distribution: Ubuntu
• Distribution version: 24.04
• The output of "snap list --all lxd core20 core22 core24 snapd":

Name    Version                  Rev    Tracking       Publisher   Notes
core20  20230801                 2015   latest/stable  canonical✓  base,disabled
core20  20231123                 2105   latest/stable  canonical✓  base
core22  20231123                 1033   latest/stable  canonical✓  base,disabled
core22  20240111                 1122   latest/stable  canonical✓  base
lxd     5.20-a8d6c52             26955  latest/stable  canonical✓  disabled
lxd     5.20-f3dd836             27049  latest/stable  canonical✓  -
snapd   2.99+gitc562c5d.c562c5d  21095  latest/stable  canonical✓  snapd,disabled
snapd   2.61.1                   20671  latest/stable  canonical✓  snapd

• The output of "lxc info" or if that fails:

config: {}
api_extensions:
- storage_zfs_remove_snapshots
- container_host_shutdown_timeout
- container_stop_priority
- container_syscall_filtering
- auth_pki
- container_last_used_at
- etag
- patch
- usb_devices
- https_allowed_credentials
- image_compression_algorithm
- directory_manipulation
- container_cpu_time
- storage_zfs_use_refquota
- storage_lvm_mount_options
- network
- profile_usedby
- container_push
- container_exec_recording
- certificate_update
- container_exec_signal_handling
- gpu_devices
- container_image_properties
- migration_progress
- id_map
- network_firewall_filtering
- network_routes
- storage
- file_delete
- file_append
- network_dhcp_expiry
- storage_lvm_vg_rename
- storage_lvm_thinpool_rename
- network_vlan
- image_create_aliases
- container_stateless_copy
- container_only_migration
- storage_zfs_clone_copy
- unix_device_rename
- storage_lvm_use_thinpool
- storage_rsync_bwlimit
- network_vxlan_interface
- storage_btrfs_mount_options
- entity_description
- image_force_refresh
- storage_lvm_lv_resizing
- id_map_base
- file_symlinks
- container_push_target
- network_vlan_physical
- storage_images_delete
- container_edit_metadata
- container_snapshot_stateful_migration
- storage_driver_ceph
- storage_ceph_user_name
- resource_limits
- storage_volatile_initial_source
- storage_ceph_force_osd_reuse
- storage_block_filesystem_btrfs
- resources
- kernel_limits
- storage_api_volume_rename
- macaroon_authentication
- network_sriov
- console
- restrict_devlxd
- migration_pre_copy
- infiniband
- maas_network
- devlxd_events
- proxy
- network_dhcp_gateway
- file_get_symlink
- network_leases
- unix_device_hotplug
- storage_api_local_volume_handling
- operation_description
- clustering
- event_lifecycle
- storage_api_remote_volume_handling
- nvidia_runtime
- container_mount_propagation
- container_backup
- devlxd_images
- container_local_cross_pool_handling
- proxy_unix
- proxy_udp
- clustering_join
- proxy_tcp_udp_multi_port_handling
- network_state
- proxy_unix_dac_properties
- container_protection_delete
- unix_priv_drop
- pprof_http
- proxy_haproxy_protocol
- network_hwaddr
- proxy_nat
- network_nat_order
- container_full
- candid_authentication
- backup_compression
- candid_config
- nvidia_runtime_config
- storage_api_volume_snapshots
- storage_unmapped
- projects
- candid_config_key
- network_vxlan_ttl
- container_incremental_copy
- usb_optional_vendorid
- snapshot_scheduling
- snapshot_schedule_aliases
- container_copy_project
- clustering_server_address
- clustering_image_replication
- container_protection_shift
- snapshot_expiry
- container_backup_override_pool
- snapshot_expiry_creation
- network_leases_location
- resources_cpu_socket
- resources_gpu
- resources_numa
- kernel_features
- id_map_current
- event_location
- storage_api_remote_volume_snapshots
- network_nat_address
- container_nic_routes
- rbac
- cluster_internal_copy
- seccomp_notify
- lxc_features
- container_nic_ipvlan
- network_vlan_sriov
- storage_cephfs
- container_nic_ipfilter
- resources_v2
- container_exec_user_group_cwd
- container_syscall_intercept
- container_disk_shift
- storage_shifted
- resources_infiniband
- daemon_storage
- instances
- image_types
- resources_disk_sata
- clustering_roles
- images_expiry
- resources_network_firmware
- backup_compression_algorithm
- ceph_data_pool_name
- container_syscall_intercept_mount
- compression_squashfs
- container_raw_mount
- container_nic_routed
- container_syscall_intercept_mount_fuse
- container_disk_ceph
- virtual-machines
- image_profiles
- clustering_architecture
- resources_disk_id
- storage_lvm_stripes
- vm_boot_priority
- unix_hotplug_devices
- api_filtering
- instance_nic_network
- clustering_sizing
- firewall_driver
- projects_limits
- container_syscall_intercept_hugetlbfs
- limits_hugepages
- container_nic_routed_gateway
- projects_restrictions
- custom_volume_snapshot_expiry
- volume_snapshot_scheduling
- trust_ca_certificates
- snapshot_disk_usage
- clustering_edit_roles
- container_nic_routed_host_address
- container_nic_ipvlan_gateway
- resources_usb_pci
- resources_cpu_threads_numa
- resources_cpu_core_die
- api_os
- container_nic_routed_host_table
- container_nic_ipvlan_host_table
- container_nic_ipvlan_mode
- resources_system
- images_push_relay
- network_dns_search
- container_nic_routed_limits
- instance_nic_bridged_vlan
- network_state_bond_bridge
- usedby_consistency
- custom_block_volumes
- clustering_failure_domains
- resources_gpu_mdev
- console_vga_type
- projects_limits_disk
- network_type_macvlan
- network_type_sriov
- container_syscall_intercept_bpf_devices
- network_type_ovn
- projects_networks
- projects_networks_restricted_uplinks
- custom_volume_backup
- backup_override_name
- storage_rsync_compression
- network_type_physical
- network_ovn_external_subnets
- network_ovn_nat
- network_ovn_external_routes_remove
- tpm_device_type
- storage_zfs_clone_copy_rebase
- gpu_mdev
- resources_pci_iommu
- resources_network_usb
- resources_disk_address
- network_physical_ovn_ingress_mode
- network_ovn_dhcp
- network_physical_routes_anycast
- projects_limits_instances
- network_state_vlan
- instance_nic_bridged_port_isolation
- instance_bulk_state_change
- network_gvrp
- instance_pool_move
- gpu_sriov
- pci_device_type
- storage_volume_state
- network_acl
- migration_stateful
- disk_state_quota
- storage_ceph_features
- projects_compression
- projects_images_remote_cache_expiry
- certificate_project
- network_ovn_acl
- projects_images_auto_update
- projects_restricted_cluster_target
- images_default_architecture
- network_ovn_acl_defaults
- gpu_mig
- project_usage
- network_bridge_acl
- warnings
- projects_restricted_backups_and_snapshots
- clustering_join_token
- clustering_description
- server_trusted_proxy
- clustering_update_cert
- storage_api_project
- server_instance_driver_operational
- server_supported_storage_drivers
- event_lifecycle_requestor_address
- resources_gpu_usb
- clustering_evacuation
- network_ovn_nat_address
- network_bgp
- network_forward
- custom_volume_refresh
- network_counters_errors_dropped
- metrics
- image_source_project
- clustering_config
- network_peer
- linux_sysctl
- network_dns
- ovn_nic_acceleration
- certificate_self_renewal
- instance_project_move
- storage_volume_project_move
- cloud_init
- network_dns_nat
- database_leader
- instance_all_projects
- clustering_groups
- ceph_rbd_du
- instance_get_full
- qemu_metrics
- gpu_mig_uuid
- event_project
- clustering_evacuation_live
- instance_allow_inconsistent_copy
- network_state_ovn
- storage_volume_api_filtering
- image_restrictions
- storage_zfs_export
- network_dns_records
- storage_zfs_reserve_space
- network_acl_log
- storage_zfs_blocksize
- metrics_cpu_seconds
- instance_snapshot_never
- certificate_token
- instance_nic_routed_neighbor_probe
- event_hub
- agent_nic_config
- projects_restricted_intercept
- metrics_authentication
- images_target_project
- cluster_migration_inconsistent_copy
- cluster_ovn_chassis
- container_syscall_intercept_sched_setscheduler
- storage_lvm_thinpool_metadata_size
- storage_volume_state_total
- instance_file_head
- instances_nic_host_name
- image_copy_profile
- container_syscall_intercept_sysinfo
- clustering_evacuation_mode
- resources_pci_vpd
- qemu_raw_conf
- storage_cephfs_fscache
- network_load_balancer
- vsock_api
- instance_ready_state
- network_bgp_holdtime
- storage_volumes_all_projects
- metrics_memory_oom_total
- storage_buckets
- storage_buckets_create_credentials
- metrics_cpu_effective_total
- projects_networks_restricted_access
- storage_buckets_local
- loki
- acme
- internal_metrics
- cluster_join_token_expiry
- remote_token_expiry
- init_preseed
- storage_volumes_created_at
- cpu_hotplug
- projects_networks_zones
- network_txqueuelen
- cluster_member_state
- instances_placement_scriptlet
- storage_pool_source_wipe
- zfs_block_mode
- instance_generation_id
- disk_io_cache
- amd_sev
- storage_pool_loop_resize
- migration_vm_live
- ovn_nic_nesting
- oidc
- network_ovn_l3only
- ovn_nic_acceleration_vdpa
- cluster_healing
- instances_state_total
- auth_user
- security_csm
- instances_rebuild
- numa_cpu_placement
- custom_volume_iso
- network_allocations
- storage_api_remote_volume_snapshot_copy
- zfs_delegate
- operations_get_query_all_projects
- metadata_configuration
- syslog_socket
- event_lifecycle_name_and_project
- instances_nic_limits_priority
- disk_initial_volume_configuration
- operation_wait
- cluster_internal_custom_volume_copy
- disk_io_bus
- storage_cephfs_create_missing
- instance_move_config
api_status: stable
api_version: "1.0"
auth: trusted
public: false
auth_methods:
- tls
auth_user_name: nteodosio
auth_user_method: unix
environment:
  addresses: []
  architectures:
  - x86_64
  - i686
  certificate: |
    -----BEGIN CERTIFICATE-----
    MIICDTCCAZKgAwIBAgIQXgpncTuYjIN6ST1nFYqSczAKBggqhkjOPQQDAzA3MRww
    GgYDVQQKExNsaW51eGNvbnRhaW5lcnMub3JnMRcwFQYDVQQDDA5yb290QGNhbm9u
    aWNhbDAeFw0yMjA4MjIxOTAxMjdaFw0zMjA4MTkxOTAxMjdaMDcxHDAaBgNVBAoT
    E2xpbnV4Y29udGFpbmVycy5vcmcxFzAVBgNVBAMMDnJvb3RAY2Fub25pY2FsMHYw
    EAYHKoZIzj0CAQYFK4EEACIDYgAEi9/JUfZCM0TsYtcRWn4IOjnSXezvRoQXNt7Q
    WW9QEIsjyjjG+BWV3TI2nbvy2IWdgdOvjEdo8subBgfSPPIfJhJQ3kZcDf/9aYju
    U3tf7+oGq67kqaepNLNHfBxRjD3Bo2MwYTAOBgNVHQ8BAf8EBAMCBaAwEwYDVR0l
    BAwwCgYIKwYBBQUHAwEwDAYDVR0TAQH/BAIwADAsBgNVHREEJTAjggljYW5vbmlj
    YWyHBH8AAAGHEAAAAAAAAAAAAAAAAAAAAAEwCgYIKoZIzj0EAwMDaQAwZgIxANRQ
    jJMKjYvuPevThYjQSKwWfHAv3dC9Ln03XJRDtddECQ/LN0d4+gjkR0IEnYJBUQIx
    AJVCLyYeTk1GqT9Ek9WPfW+UJEHA3uYRyZgIZT2QxwcLlXhTLr5yKI+hifVtuoYX
    1g==
    -----END CERTIFICATE-----
  certificate_fingerprint: c4d86491829c4955294e53a9ae1ddabafa696b6af4bba59e0cedaff386c8928b
  driver: qemu | lxc
  driver_version: 8.1.3 | 5.0.3
  firewall: nftables
  kernel: Linux
  kernel_architecture: x86_64
  kernel_features:
    idmapped_mounts: "true"
    netnsid_getifaddrs: "true"
    seccomp_listener: "true"
    seccomp_listener_continue: "true"
    uevent_injection: "true"
    unpriv_fscaps: "true"
  kernel_version: 6.6.0-14-generic
  lxc_features:
    cgroup2: "true"
    core_scheduling: "true"
    devpts_fd: "true"
    idmapped_mounts_v2: "true"
    mount_injection_file: "true"
    network_gateway_device_route: "true"
    network_ipvlan: "true"
    network_l2proxy: "true"
    network_phys_macvlan_mtu: "true"
    network_veth_router: "true"
    pidfd: "true"
    seccomp_allow_deny_syntax: "true"
    seccomp_notify: "true"
    seccomp_proxy_send_notify_fd: "true"
  os_name: Ubuntu
  os_version: "24.04"
  project: default
  server: lxd
  server_clustered: false
  server_event_mode: full-mesh
  server_name: canonical
  server_pid: 21356
  server_version: "5.20"
  storage: dir
  storage_version: "1"
  storage_supported_drivers:
  - name: btrfs
    version: 5.16.2
    remote: false
  - name: ceph
    version: 17.2.6
    remote: true
  - name: cephfs
    version: 17.2.6
    remote: true
  - name: cephobject
    version: 17.2.6
    remote: true
  - name: dir
    version: "1"
    remote: false
  - name: lvm
    version: 2.03.11(2) (2021-01-08) / 1.02.175 (2021-01-08) / 4.48.0
    remote: false
  - name: zfs
    version: 2.2.0-0ubuntu3
    remote: false

Issue description

I did this before and it worked fine. Now I get error with unshare:

% lxc start p
% lxc console -t vga p
unshare: unshare failed: Permission denied

Steps to reproduce

1. Create an instance. I used lxc launch prompting:ubuntu-23.10-desktop p --vm --console=vga -c limits.cpu=4 -c limits.memory=4GiB.
2. Maybe reboot (I don't know what triggered the problem so...).
3. lxc start p && lxc console -t vga p

Information to attach

• Any relevant kernel output (dmesg)
• Container log (lxc info NAME --show-log)
• Container configuration (lxc config show NAME --expanded)
• Main daemon log (at /var/log/lxd/lxd.log or /var/snap/lxd/common/lxd/logs/lxd.log)

time="2024-02-13T14:02:33+01:00" level=warning msg=" - Couldn't find the CGroup network priority controller, per-instance network priority will be ignored. Please use per-device limits.priority instead"

• Output of the client with --debug
• Output of the daemon with --debug (alternatively output of lxc monitor while reproducing the issue)
• Journal:

fev 13 14:13:40 canonical kernel: audit: type=1400 audit(1707830020.167:316): apparmor="DENIED" operation="userns_create" class="namespace" info="User namespace creation restricted" error=-13 profile="unconfined" pid=33007 comm="unshare" requested="userns_create" denied="userns_create"

[nteodosio]

Found the way to get past that error right here, #11920:

% >/etc/apparmor.d/usr.bin.unshare cat <<EOF
abi <abi/4.0>,
include <tunables/global>
/usr/bin/unshare flags=(unconfined) {
  userns,
  # Site-specific additions and overrides. See local/README for details.
  include if exists <local/usr.bin.unshare>
}
EOF
% apparmor_parser -r /etc/apparmor.d/usr.bin.unshare

[tomponline]

@simondeziel please can you look into this?

[tomponline]

@simondeziel this will be solved by re-enabling globally disabling restricted userns right?

[simondeziel]

@nteodosio to workaround this temporarily, can you try (as root):

echo "==> Disabling Apparmor unprivileged userns mediation"
echo 0 > /proc/sys/kernel/apparmor_restrict_unprivileged_userns

echo "==> Disabling Apparmor unprivileged unconfined mediation"
echo 0 > /proc/sys/kernel/apparmor_restrict_unprivileged_unconfined

[simondeziel]

This is the PR to have those keys disabled by LXD: canonical/lxd-pkg-snap#327

[tomponline]

This should be fixed in latest/edge now and will be in the LXD 5.21 release.

[DiogoConstantino]

Just some feedback: I'm on Mantic with LXD 5.21, I'm still experiencing this issue.

[tomponline]

@DiogoConstantino did you try the workaround here?

#12882 (comment)

[tomponline]

@DiogoConstantino is it specifically with lxc console you're seeing the issue with?

[DiogoConstantino]

I did not test the workaround, because I rather have that working to secure my system, and this is not a show stopper for me.

This is specifically with lxc console, I haven't tested in any other way.

Meanwhile, I tested this on 24.04, and it did worked as expected. It appears to be a 23.10 specific issue, and due to the nearby EOL, I don't think it's a big deal. I just want people to know about it in case they also experience it in the next few weeks.

[tomponline]

Meanwhile, I tested this on 24.04, and it did worked as expected. It appears to be a 23.10 specific issue, and due to the nearby EOL, I don't think it's a big deal. I just want people to know about it in case they also experience it in the next few weeks.

Thanks for clarification. :)