From 7a11ed5a77a631ea055dd09fbaca3111e5530085 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Fri, 10 Jan 2020 22:22:37 +0100 Subject: [PATCH] libpod: fix --userns=keep-id with big UIDs when creating a keep-id namespace, we split the original user namespace in: inner ns | outer ns | size: 0 | 1 | ID ID | 0 | 1 ID+1 | ID+1 | availableIds - ID When the user ID is bigger than the number of available subuids/subgids we fail to create the user namespace because the first slice is bigger than the available number of IDs and the third one has a negative size. Fix it by not using more than the available number of IDs in the first slice and creating the third one only if there are other IDs left. When the user ID is bigger than the number of additional IDs, there will be a gap between the two mappings so the IDs between the maximum additional ID and the user ID won't be present inside of the namespace. Closes: https://github.com/containers/libpod/issues/4838 Signed-off-by: Giuseppe Scrivano --- pkg/util/utils.go | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/pkg/util/utils.go b/pkg/util/utils.go index c9d09b8b5703..9269f611547a 100644 --- a/pkg/util/utils.go +++ b/pkg/util/utils.go @@ -335,6 +335,13 @@ func ParseIDMapping(mode namespaces.UsernsMode, UIDMapSlice, GIDMapSlice []strin return nil, errors.New("cannot specify subuidmap or subgidmap with --userns=keep-id") } if rootless.IsRootless() { + min := func(a, b int) int { + if a < b { + return a + } + return b + } + uid := rootless.GetRootlessUID() gid := rootless.GetRootlessGID() @@ -352,13 +359,17 @@ func ParseIDMapping(mode namespaces.UsernsMode, UIDMapSlice, GIDMapSlice []strin options.UIDMap, options.GIDMap = nil, nil - options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: uid}) + options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: min(uid, maxUID)}) options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid, HostID: 0, Size: 1}) - options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid + 1, HostID: uid + 1, Size: maxUID - uid}) + if maxUID > uid { + options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid + 1, HostID: uid + 1, Size: maxUID - uid}) + } - options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: gid}) + options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: min(gid, maxGID)}) options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid, HostID: 0, Size: 1}) - options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid + 1, HostID: gid + 1, Size: maxGID - gid}) + if maxGID > gid { + options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid + 1, HostID: gid + 1, Size: maxGID - gid}) + } options.HostUIDMapping = false options.HostGIDMapping = false