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authorGiuseppe Scrivano <gscrivan@redhat.com>2019-03-10 22:38:12 +0100
committerGiuseppe Scrivano <gscrivan@redhat.com>2019-03-11 14:38:42 +0100
commitaf3e73426aa6746333ef8581711ec768e2594530 (patch)
tree1ec4ef787c03d85d30fb8c445b1b3f16bd0e8c09 /pkg
parentddcdc0c1721e50ae8d7d24f831a9ea81ea168699 (diff)
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rootless: allow single mappings
we were playing safe and not allowed any container to have less than 65536 mappings. There are a couple of reasons to change it: - it blocked libpod to work in an environment where newuidmap/newgidmap are not available, or not configured. - not allowed to use different partitions of subuids, where each user has less than 65536 ids available. Hopefully this change in containers/storage: https://github.com/containers/storage/pull/303 will make error clearers if there are not enough IDs for the image that is being used. Closes: https://github.com/containers/libpod/issues/1651 Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Diffstat (limited to 'pkg')
-rw-r--r--pkg/rootless/rootless_linux.go59
1 files changed, 4 insertions, 55 deletions
diff --git a/pkg/rootless/rootless_linux.go b/pkg/rootless/rootless_linux.go
index 933cfa2c2..d43151e8e 100644
--- a/pkg/rootless/rootless_linux.go
+++ b/pkg/rootless/rootless_linux.go
@@ -11,7 +11,6 @@ import (
"os/user"
"runtime"
"strconv"
- "strings"
"sync"
"syscall"
"unsafe"
@@ -192,22 +191,6 @@ func JoinNSPath(path string) (bool, int, error) {
return true, int(ret), nil
}
-const defaultMinimumMappings = 65536
-
-func getMinimumIDs(p string) int {
- content, err := ioutil.ReadFile(p)
- if err != nil {
- logrus.Debugf("error reading data from %q, use a default value of %d", p, defaultMinimumMappings)
- return defaultMinimumMappings
- }
- ret, err := strconv.Atoi(strings.TrimSuffix(string(content), "\n"))
- if err != nil {
- logrus.Debugf("error reading data from %q, use a default value of %d", p, defaultMinimumMappings)
- return defaultMinimumMappings
- }
- return ret + 1
-}
-
// BecomeRootInUserNS re-exec podman in a new userNS. It returns whether podman was re-executed
// into a new user namespace and the return code from the re-executed podman process.
// If podman was re-executed the caller needs to propagate the error code returned by the child
@@ -237,47 +220,18 @@ func BecomeRootInUserNS() (bool, int, error) {
return false, -1, errors.Errorf("cannot re-exec process")
}
- allowSingleIDMapping := os.Getenv("PODMAN_ALLOW_SINGLE_ID_MAPPING_IN_USERNS") != ""
-
var uids, gids []idtools.IDMap
username := os.Getenv("USER")
if username == "" {
user, err := user.LookupId(fmt.Sprintf("%d", os.Getuid()))
- if err != nil && !allowSingleIDMapping {
- if os.IsNotExist(err) {
- return false, 0, errors.Wrapf(err, "/etc/subuid or /etc/subgid does not exist, see subuid/subgid man pages for information on these files")
- }
- return false, 0, errors.Wrapf(err, "could not find user by UID nor USER env was set")
- }
if err == nil {
username = user.Username
}
}
mappings, err := idtools.NewIDMappings(username, username)
- if !allowSingleIDMapping {
- if err != nil {
- return false, -1, err
- }
-
- availableGIDs, availableUIDs := 0, 0
- for _, i := range mappings.UIDs() {
- availableUIDs += i.Size
- }
-
- minUIDs := getMinimumIDs("/proc/sys/kernel/overflowuid")
- if availableUIDs < minUIDs {
- return false, 0, fmt.Errorf("not enough UIDs available for the user, at least %d are needed", minUIDs)
- }
-
- for _, i := range mappings.GIDs() {
- availableGIDs += i.Size
- }
- minGIDs := getMinimumIDs("/proc/sys/kernel/overflowgid")
- if availableGIDs < minGIDs {
- return false, 0, fmt.Errorf("not enough GIDs available for the user, at least %d are needed", minGIDs)
- }
- }
- if err == nil {
+ if err != nil {
+ logrus.Warnf("cannot find mappings for user %s: %v", username, err)
+ } else {
uids = mappings.UIDs()
gids = mappings.GIDs()
}
@@ -285,12 +239,10 @@ func BecomeRootInUserNS() (bool, int, error) {
uidsMapped := false
if mappings != nil && uids != nil {
err := tryMappingTool("newuidmap", pid, os.Getuid(), uids)
- if !allowSingleIDMapping && err != nil {
- return false, 0, err
- }
uidsMapped = err == nil
}
if !uidsMapped {
+ logrus.Warnf("using rootless single mapping into the namespace. This might break some images. Check /etc/subuid and /etc/subgid for adding subids")
setgroups := fmt.Sprintf("/proc/%d/setgroups", pid)
err = ioutil.WriteFile(setgroups, []byte("deny\n"), 0666)
if err != nil {
@@ -307,9 +259,6 @@ func BecomeRootInUserNS() (bool, int, error) {
gidsMapped := false
if mappings != nil && gids != nil {
err := tryMappingTool("newgidmap", pid, os.Getgid(), gids)
- if !allowSingleIDMapping && err != nil {
- return false, 0, err
- }
gidsMapped = err == nil
}
if !gidsMapped {