jasder
/
runc
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

libcontainer: user: general cleanups 

Some of the code was quite confusing inside libcontainer/user, so
refactor and comment it so future maintainers can understand what's
going and what edge cases we have to deal with.

Signed-off-by: Aleksa Sarai <asarai@suse.de>
This commit is contained in:
Aleksa Sarai 2016-03-30 22:50:14 +11:00
parent 4468dd5890
commit 3cfff676b1
1 changed files with 29 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
libcontainer/user/user.go
View File

@ -15,7 +15,7 @@ const (
)
var (
ErrRange = fmt.Errorf("Uids and gids must be in range %d-%d", minId, maxId)
ErrRange = fmt.Errorf("uids and gids must be in range %d-%d", minId, maxId)
)
type User struct {
@ -42,29 +42,30 @@ func parseLine(line string, v ...interface{}) {
parts := strings.Split(line, ":")
for i, p := range parts {
// Ignore cases where we don't have enough fields to populate the arguments.
// Some configuration files like to misbehave.
if len(v) <= i {
// if we have more "parts" than we have places to put them, bail for great "tolerance" of naughty configuration files
break
}
// Use the type of the argument to figure out how to parse it, scanf() style.
// This is legit.
switch e := v[i].(type) {
case *string:
// "root", "adm", "/bin/bash"
*e = p
case *int:
// "0", "4", "1000"
// ignore string to int conversion errors, for great "tolerance" of naughty configuration files
// "numbers", with conversion errors ignored because of some misbehaving configuration files.
*e, _ = strconv.Atoi(p)
case *[]string:
// "", "root", "root,adm,daemon"
// Comma-separated lists.
if p != "" {
*e = strings.Split(p, ",")
} else {
*e = []string{}
}
default:
// panic, because this is a programming/logic error, not a runtime one
panic("parseLine expects only pointers! argument " + strconv.Itoa(i) + " is not a pointer!")
// Someone goof'd when writing code using this function. Scream so they can hear us.
panic(fmt.Sprintf("parseLine only accepts {*string, *int, *[]string} as arguments! %#v is not a pointer!", e))
}
}
}
@ -106,8 +107,8 @@ func ParsePasswdFilter(r io.Reader, filter func(User) bool) ([]User, error) {
return nil, err
}
text := strings.TrimSpace(s.Text())
if text == "" {
line := strings.TrimSpace(s.Text())
if line == "" {
continue
}
@ -117,10 +118,7 @@ func ParsePasswdFilter(r io.Reader, filter func(User) bool) ([]User, error) {
// root:x:0:0:root:/root:/bin/bash
// adm:x:3:4:adm:/var/adm:/bin/false
p := User{}
parseLine(
text,
&p.Name, &p.Pass, &p.Uid, &p.Gid, &p.Gecos, &p.Home, &p.Shell,
)
parseLine(line, &p.Name, &p.Pass, &p.Uid, &p.Gid, &p.Gecos, &p.Home, &p.Shell)
if filter == nil || filter(p) {
out = append(out, p)
@ -135,6 +133,7 @@ func ParseGroupFile(path string) ([]Group, error) {
if err != nil {
return nil, err
}
defer group.Close()
return ParseGroup(group)
}
@ -178,10 +177,7 @@ func ParseGroupFilter(r io.Reader, filter func(Group) bool) ([]Group, error) {
// root:x:0:root
// adm:x:4:root,adm,daemon
p := Group{}
parseLine(
text,
&p.Name, &p.Pass, &p.Gid, &p.List,
)
parseLine(text, &p.Name, &p.Pass, &p.Gid, &p.List)
if filter == nil || filter(p) {
out = append(out, p)
@ -192,9 +188,10 @@ func ParseGroupFilter(r io.Reader, filter func(Group) bool) ([]Group, error) {
}
type ExecUser struct {
Uid, Gid int
Sgids []int
Home string
Uid int
Gid int
Sgids []int
Home string
}
// GetExecUserPath is a wrapper for GetExecUser. It reads data from each of the
@ -241,10 +238,6 @@ func GetExecUserPath(userSpec string, defaults *ExecUser, passwdPath, groupPath
// to parse a user with user.Name = "1337" will produce the user with a UID of
// 1337.
func GetExecUser(userSpec string, defaults *ExecUser, passwd, group io.Reader) (*ExecUser, error) {
var (
userArg, groupArg string
)
if defaults == nil {
defaults = new(ExecUser)
}
@ -262,7 +255,8 @@ func GetExecUser(userSpec string, defaults *ExecUser, passwd, group io.Reader) (
user.Sgids = []int{}
}
// allow for userArg to have either "user" syntax, or optionally "user:group" syntax
// Allow for userArg to have either "user" syntax, or optionally "user:group" syntax
var userArg, groupArg string
parseLine(userSpec, &userArg, &groupArg)
// Convert userArg and groupArg to be numeric, so we don't have to execute
@ -270,8 +264,10 @@ func GetExecUser(userSpec string, defaults *ExecUser, passwd, group io.Reader) (
uidArg, uidErr := strconv.Atoi(userArg)
gidArg, gidErr := strconv.Atoi(groupArg)
// Find the matching user.
users, err := ParsePasswdFilter(passwd, func(u User) bool {
if userArg == "" {
// Default to current state of the user.
return u.Uid == user.Uid
}
@ -282,11 +278,13 @@ func GetExecUser(userSpec string, defaults *ExecUser, passwd, group io.Reader) (
return u.Name == userArg
})
// If we can't find the user, we have to bail.
if err != nil && passwd != nil {
if userArg == "" {
userArg = strconv.Itoa(user.Uid)
}
return nil, fmt.Errorf("Unable to find user %v: %v", userArg, err)
return nil, fmt.Errorf("unable to find user %s: %v", userArg, err)
}
var matchedUserName string
@ -340,10 +338,10 @@ func GetExecUser(userSpec string, defaults *ExecUser, passwd, group io.Reader) (
return nil, fmt.Errorf("unable to find groups for spec %v: %v", matchedUserName, err)
}
haveGroup := groups != nil && len(groups) > 0
// Only start modifying user.Gid if it is in explicit form.
if groupArg != "" {
if haveGroup {
// if we found any group entries that matched our filter, let's take the first one as "correct"
if len(groups) > 0 {
// First match wins, even if there's more than one matching entry.
user.Gid = groups[0].Gid
} else if groupArg != "" {
// If we can't find a group with the given name, the only other valid
@ -355,7 +353,7 @@ func GetExecUser(userSpec string, defaults *ExecUser, passwd, group io.Reader) (
}
user.Gid = gidArg
// Ensure gid is inside gid range.
// Must be inside valid gid range.
if user.Gid < minId || user.Gid > maxId {
return nil, ErrRange
}