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Change subordinate range-owning user to be a system user

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Change user/group creation to use flags to adduser/useradd to enforce it
being a system user. Use system user defaults that auto-create a
matching group. These changes allow us to remove all group creation
code, and in doing so we also removed the code that finds available uid,
gid integers and use post-creation query to gather the system-generated
uid and gid.

The only added complexity is that today distros don't auto-create
subordinate ID ranges for a new ID if it is a system ID, so we now need
to handle finding a free range and then calling the `usermod` tool to
add the ranges for that ID. Note that this requires the distro supports
the `-v` and `-w` flags on `usermod` for subordinate ID range additions.

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
This commit is contained in:
Phil Estes 2016-03-16 18:44:10 -04:00
parent 98910db2c0
commit ca88852656
2 changed files with 125 additions and 90 deletions
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6
idtools/idtools.go
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@ -155,6 +155,9 @@ func parseSubgid(username string) (ranges, error) {
return parseSubidFile(subgidFileName, username)
}
// parseSubidFile will read the appropriate file (/etc/subuid or /etc/subgid)
// and return all found ranges for a specified username. If the special value
// "ALL" is supplied for username, then all ranges in the file will be returned
func parseSubidFile(path, username string) (ranges, error) {
var rangeList ranges
@ -178,8 +181,7 @@ func parseSubidFile(path, username string) (ranges, error) {
if len(parts) != 3 {
return rangeList, fmt.Errorf("Cannot parse subuid/gid information: Format not correct for %s file", path)
}
if parts[0] == username {
// return the first entry for a user; ignores potential for multiple ranges per user
if parts[0] == username || username == "ALL" {
startid, err := strconv.Atoi(parts[1])
if err != nil {
return rangeList, fmt.Errorf("String to int conversion failed during subuid/gid parsing of %s: %v", path, err)