/usr/share/gocode/src/github.com/opencontainers/runc/libcontainer/user/user.go is in golang-github-opencontainers-runc-dev 1.0.0~rc4+dfsg1-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 | package user
import (
"bufio"
"fmt"
"io"
"os"
"strconv"
"strings"
)
const (
minId = 0
maxId = 1<<31 - 1 //for 32-bit systems compatibility
)
var (
ErrRange = fmt.Errorf("uids and gids must be in range %d-%d", minId, maxId)
)
type User struct {
Name string
Pass string
Uid int
Gid int
Gecos string
Home string
Shell string
}
type Group struct {
Name string
Pass string
Gid int
List []string
}
func parseLine(line string, v ...interface{}) {
if line == "" {
return
}
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 {
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:
*e = p
case *int:
// "numbers", with conversion errors ignored because of some misbehaving configuration files.
*e, _ = strconv.Atoi(p)
case *[]string:
// Comma-separated lists.
if p != "" {
*e = strings.Split(p, ",")
} else {
*e = []string{}
}
default:
// 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))
}
}
}
func ParsePasswdFile(path string) ([]User, error) {
passwd, err := os.Open(path)
if err != nil {
return nil, err
}
defer passwd.Close()
return ParsePasswd(passwd)
}
func ParsePasswd(passwd io.Reader) ([]User, error) {
return ParsePasswdFilter(passwd, nil)
}
func ParsePasswdFileFilter(path string, filter func(User) bool) ([]User, error) {
passwd, err := os.Open(path)
if err != nil {
return nil, err
}
defer passwd.Close()
return ParsePasswdFilter(passwd, filter)
}
func ParsePasswdFilter(r io.Reader, filter func(User) bool) ([]User, error) {
if r == nil {
return nil, fmt.Errorf("nil source for passwd-formatted data")
}
var (
s = bufio.NewScanner(r)
out = []User{}
)
for s.Scan() {
if err := s.Err(); err != nil {
return nil, err
}
line := strings.TrimSpace(s.Text())
if line == "" {
continue
}
// see: man 5 passwd
// name:password:UID:GID:GECOS:directory:shell
// Name:Pass:Uid:Gid:Gecos:Home:Shell
// root:x:0:0:root:/root:/bin/bash
// adm:x:3:4:adm:/var/adm:/bin/false
p := User{}
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)
}
}
return out, nil
}
func ParseGroupFile(path string) ([]Group, error) {
group, err := os.Open(path)
if err != nil {
return nil, err
}
defer group.Close()
return ParseGroup(group)
}
func ParseGroup(group io.Reader) ([]Group, error) {
return ParseGroupFilter(group, nil)
}
func ParseGroupFileFilter(path string, filter func(Group) bool) ([]Group, error) {
group, err := os.Open(path)
if err != nil {
return nil, err
}
defer group.Close()
return ParseGroupFilter(group, filter)
}
func ParseGroupFilter(r io.Reader, filter func(Group) bool) ([]Group, error) {
if r == nil {
return nil, fmt.Errorf("nil source for group-formatted data")
}
var (
s = bufio.NewScanner(r)
out = []Group{}
)
for s.Scan() {
if err := s.Err(); err != nil {
return nil, err
}
text := s.Text()
if text == "" {
continue
}
// see: man 5 group
// group_name:password:GID:user_list
// Name:Pass:Gid:List
// root:x:0:root
// adm:x:4:root,adm,daemon
p := Group{}
parseLine(text, &p.Name, &p.Pass, &p.Gid, &p.List)
if filter == nil || filter(p) {
out = append(out, p)
}
}
return out, nil
}
type ExecUser struct {
Uid int
Gid int
Sgids []int
Home string
}
// GetExecUserPath is a wrapper for GetExecUser. It reads data from each of the
// given file paths and uses that data as the arguments to GetExecUser. If the
// files cannot be opened for any reason, the error is ignored and a nil
// io.Reader is passed instead.
func GetExecUserPath(userSpec string, defaults *ExecUser, passwdPath, groupPath string) (*ExecUser, error) {
var passwd, group io.Reader
if passwdFile, err := os.Open(passwdPath); err == nil {
passwd = passwdFile
defer passwdFile.Close()
}
if groupFile, err := os.Open(groupPath); err == nil {
group = groupFile
defer groupFile.Close()
}
return GetExecUser(userSpec, defaults, passwd, group)
}
// GetExecUser parses a user specification string (using the passwd and group
// readers as sources for /etc/passwd and /etc/group data, respectively). In
// the case of blank fields or missing data from the sources, the values in
// defaults is used.
//
// GetExecUser will return an error if a user or group literal could not be
// found in any entry in passwd and group respectively.
//
// Examples of valid user specifications are:
// * ""
// * "user"
// * "uid"
// * "user:group"
// * "uid:gid
// * "user:gid"
// * "uid:group"
//
// It should be noted that if you specify a numeric user or group id, they will
// not be evaluated as usernames (only the metadata will be filled). So attempting
// 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) {
if defaults == nil {
defaults = new(ExecUser)
}
// Copy over defaults.
user := &ExecUser{
Uid: defaults.Uid,
Gid: defaults.Gid,
Sgids: defaults.Sgids,
Home: defaults.Home,
}
// Sgids slice *cannot* be nil.
if user.Sgids == nil {
user.Sgids = []int{}
}
// 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
// Atoi *twice* for each iteration over lines.
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
}
if uidErr == nil {
// If the userArg is numeric, always treat it as a UID.
return uidArg == u.Uid
}
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 %s: %v", userArg, err)
}
var matchedUserName string
if len(users) > 0 {
// First match wins, even if there's more than one matching entry.
matchedUserName = users[0].Name
user.Uid = users[0].Uid
user.Gid = users[0].Gid
user.Home = users[0].Home
} else if userArg != "" {
// If we can't find a user with the given username, the only other valid
// option is if it's a numeric username with no associated entry in passwd.
if uidErr != nil {
// Not numeric.
return nil, fmt.Errorf("unable to find user %s: %v", userArg, ErrNoPasswdEntries)
}
user.Uid = uidArg
// Must be inside valid uid range.
if user.Uid < minId || user.Uid > maxId {
return nil, ErrRange
}
// Okay, so it's numeric. We can just roll with this.
}
// On to the groups. If we matched a username, we need to do this because of
// the supplementary group IDs.
if groupArg != "" || matchedUserName != "" {
groups, err := ParseGroupFilter(group, func(g Group) bool {
// If the group argument isn't explicit, we'll just search for it.
if groupArg == "" {
// Check if user is a member of this group.
for _, u := range g.List {
if u == matchedUserName {
return true
}
}
return false
}
if gidErr == nil {
// If the groupArg is numeric, always treat it as a GID.
return gidArg == g.Gid
}
return g.Name == groupArg
})
if err != nil && group != nil {
return nil, fmt.Errorf("unable to find groups for spec %v: %v", matchedUserName, err)
}
// Only start modifying user.Gid if it is in explicit form.
if groupArg != "" {
if len(groups) > 0 {
// First match wins, even if there's more than one matching entry.
user.Gid = groups[0].Gid
} else {
// If we can't find a group with the given name, the only other valid
// option is if it's a numeric group name with no associated entry in group.
if gidErr != nil {
// Not numeric.
return nil, fmt.Errorf("unable to find group %s: %v", groupArg, ErrNoGroupEntries)
}
user.Gid = gidArg
// Must be inside valid gid range.
if user.Gid < minId || user.Gid > maxId {
return nil, ErrRange
}
// Okay, so it's numeric. We can just roll with this.
}
} else if len(groups) > 0 && uidErr != nil {
// Supplementary group ids only make sense if in the implicit form for non-numeric users.
user.Sgids = make([]int, len(groups))
for i, group := range groups {
user.Sgids[i] = group.Gid
}
}
}
return user, nil
}
// GetAdditionalGroups looks up a list of groups by name or group id
// against the given /etc/group formatted data. If a group name cannot
// be found, an error will be returned. If a group id cannot be found,
// or the given group data is nil, the id will be returned as-is
// provided it is in the legal range.
func GetAdditionalGroups(additionalGroups []string, group io.Reader) ([]int, error) {
var groups = []Group{}
if group != nil {
var err error
groups, err = ParseGroupFilter(group, func(g Group) bool {
for _, ag := range additionalGroups {
if g.Name == ag || strconv.Itoa(g.Gid) == ag {
return true
}
}
return false
})
if err != nil {
return nil, fmt.Errorf("Unable to find additional groups %v: %v", additionalGroups, err)
}
}
gidMap := make(map[int]struct{})
for _, ag := range additionalGroups {
var found bool
for _, g := range groups {
// if we found a matched group either by name or gid, take the
// first matched as correct
if g.Name == ag || strconv.Itoa(g.Gid) == ag {
if _, ok := gidMap[g.Gid]; !ok {
gidMap[g.Gid] = struct{}{}
found = true
break
}
}
}
// we asked for a group but didn't find it. let's check to see
// if we wanted a numeric group
if !found {
gid, err := strconv.Atoi(ag)
if err != nil {
return nil, fmt.Errorf("Unable to find group %s", ag)
}
// Ensure gid is inside gid range.
if gid < minId || gid > maxId {
return nil, ErrRange
}
gidMap[gid] = struct{}{}
}
}
gids := []int{}
for gid := range gidMap {
gids = append(gids, gid)
}
return gids, nil
}
// GetAdditionalGroupsPath is a wrapper around GetAdditionalGroups
// that opens the groupPath given and gives it as an argument to
// GetAdditionalGroups.
func GetAdditionalGroupsPath(additionalGroups []string, groupPath string) ([]int, error) {
var group io.Reader
if groupFile, err := os.Open(groupPath); err == nil {
group = groupFile
defer groupFile.Close()
}
return GetAdditionalGroups(additionalGroups, group)
}
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