From ac97c2a2f19f5b6dae4302f2d24cebc4991538fe Mon Sep 17 00:00:00 2001 From: Tianon Gravi Date: Fri, 27 Dec 2013 10:47:42 -0700 Subject: [PATCH 1/2] Move UserLookup functionality into a separate pkg/user submodule that implements proper parsing of /etc/passwd and /etc/group, and use that to add support for "docker run -u user:group" and for getting supplementary groups (if ":group" is not specified) Docker-DCO-1.1-Signed-off-by: Andrew Page (github: tianon) --- user/MAINTAINERS | 1 + user/user.go | 245 ++++++++++++++++++++++++++++++++++++++++++++++ user/user_test.go | 94 ++++++++++++++++++ 3 files changed, 340 insertions(+) create mode 100644 user/MAINTAINERS create mode 100644 user/user.go create mode 100644 user/user_test.go diff --git a/user/MAINTAINERS b/user/MAINTAINERS new file mode 100644 index 0000000..18e05a3 --- /dev/null +++ b/user/MAINTAINERS @@ -0,0 +1 @@ +Tianon Gravi (@tianon) diff --git a/user/user.go b/user/user.go new file mode 100644 index 0000000..30fc90f --- /dev/null +++ b/user/user.go @@ -0,0 +1,245 @@ +package user + +import ( + "bufio" + "fmt" + "io" + "os" + "reflect" + "strconv" + "strings" +) + +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 { + 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 + } + + t := reflect.TypeOf(v[i]) + if t.Kind() != reflect.Ptr { + // 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!") + } + + switch t.Elem().Kind() { + case reflect.String: + // "root", "adm", "/bin/bash" + *v[i].(*string) = p + case reflect.Int: + // "0", "4", "1000" + *v[i].(*int), _ = strconv.Atoi(p) + // ignore string to int conversion errors, for great "tolerance" of naughty configuration files + case reflect.Slice, reflect.Array: + // "", "root", "root,adm,daemon" + list := []string{} + if p != "" { + list = strings.Split(p, ",") + } + *v[i].(*[]string) = list + } + } +} + +func ParsePasswd() ([]*User, error) { + return ParsePasswdFilter(nil) +} + +func ParsePasswdFilter(filter func(*User) bool) ([]*User, error) { + f, err := os.Open("/etc/passwd") + if err != nil { + return nil, err + } + defer f.Close() + return parsePasswdFile(f, filter) +} + +func parsePasswdFile(r io.Reader, filter func(*User) bool) ([]*User, error) { + var ( + s = bufio.NewScanner(r) + out = []*User{} + ) + + for s.Scan() { + if err := s.Err(); err != nil { + return nil, err + } + + text := strings.TrimSpace(s.Text()) + if text == "" { + 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( + text, + &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 ParseGroup() ([]*Group, error) { + return ParseGroupFilter(nil) +} + +func ParseGroupFilter(filter func(*Group) bool) ([]*Group, error) { + f, err := os.Open("/etc/group") + if err != nil { + return nil, err + } + defer f.Close() + return parseGroupFile(f, filter) +} + +func parseGroupFile(r io.Reader, filter func(*Group) bool) ([]*Group, error) { + 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 +} + +// Given a string like "user", "1000", "user:group", "1000:1000", returns the uid, gid, and list of supplementary group IDs, if possible. +func GetUserGroupSupplementary(userSpec string, defaultUid int, defaultGid int) (int, int, []int, error) { + var ( + uid = defaultUid + gid = defaultGid + suppGids = []int{} + + userArg, groupArg string + ) + + // allow for userArg to have either "user" syntax, or optionally "user:group" syntax + parseLine(userSpec, &userArg, &groupArg) + + users, err := ParsePasswdFilter(func(u *User) bool { + if userArg == "" { + return u.Uid == uid + } + return u.Name == userArg || strconv.Itoa(u.Uid) == userArg + }) + if err != nil && !os.IsNotExist(err) { + if userArg == "" { + userArg = strconv.Itoa(uid) + } + return 0, 0, nil, fmt.Errorf("Unable to find user %v: %v", userArg, err) + } + + haveUser := users != nil && len(users) > 0 + if haveUser { + // if we found any user entries that matched our filter, let's take the first one as "correct" + uid = users[0].Uid + gid = users[0].Gid + } else if userArg != "" { + // we asked for a user but didn't find them... let's check to see if we wanted a numeric user + uid, err = strconv.Atoi(userArg) + if err != nil { + // not numeric - we have to bail + return 0, 0, nil, fmt.Errorf("Unable to find user %v", userArg) + } + + // if userArg couldn't be found in /etc/passwd but is numeric, just roll with it - this is legit + } + + if groupArg != "" || (haveUser && users[0].Name != "") { + groups, err := ParseGroupFilter(func(g *Group) bool { + if groupArg != "" { + return g.Name == groupArg || strconv.Itoa(g.Gid) == groupArg + } + for _, u := range g.List { + if u == users[0].Name { + return true + } + } + return false + }) + if err != nil && !os.IsNotExist(err) { + return 0, 0, nil, fmt.Errorf("Unable to find groups for user %v: %v", users[0].Name, err) + } + + haveGroup := groups != nil && len(groups) > 0 + if groupArg != "" { + if haveGroup { + // if we found any group entries that matched our filter, let's take the first one as "correct" + gid = groups[0].Gid + } else { + // we asked for a group but didn't find id... let's check to see if we wanted a numeric group + gid, err = strconv.Atoi(groupArg) + if err != nil { + // not numeric - we have to bail + return 0, 0, nil, fmt.Errorf("Unable to find group %v", groupArg) + } + + // if groupArg couldn't be found in /etc/group but is numeric, just roll with it - this is legit + } + } else if haveGroup { + suppGids = make([]int, len(groups)) + for i, group := range groups { + suppGids[i] = group.Gid + } + } + } + + return uid, gid, suppGids, nil +} diff --git a/user/user_test.go b/user/user_test.go new file mode 100644 index 0000000..136632c --- /dev/null +++ b/user/user_test.go @@ -0,0 +1,94 @@ +package user + +import ( + "strings" + "testing" +) + +func TestUserParseLine(t *testing.T) { + var ( + a, b string + c []string + d int + ) + + parseLine("", &a, &b) + if a != "" || b != "" { + t.Fatalf("a and b should be empty ('%v', '%v')", a, b) + } + + parseLine("a", &a, &b) + if a != "a" || b != "" { + t.Fatalf("a should be 'a' and b should be empty ('%v', '%v')", a, b) + } + + parseLine("bad boys:corny cows", &a, &b) + if a != "bad boys" || b != "corny cows" { + t.Fatalf("a should be 'bad boys' and b should be 'corny cows' ('%v', '%v')", a, b) + } + + parseLine("", &c) + if len(c) != 0 { + t.Fatalf("c should be empty (%#v)", c) + } + + parseLine("d,e,f:g:h:i,j,k", &c, &a, &b, &c) + if a != "g" || b != "h" || len(c) != 3 || c[0] != "i" || c[1] != "j" || c[2] != "k" { + t.Fatalf("a should be 'g', b should be 'h', and c should be ['i','j','k'] ('%v', '%v', '%#v')", a, b, c) + } + + parseLine("::::::::::", &a, &b, &c) + if a != "" || b != "" || len(c) != 0 { + t.Fatalf("a, b, and c should all be empty ('%v', '%v', '%#v')", a, b, c) + } + + parseLine("not a number", &d) + if d != 0 { + t.Fatalf("d should be 0 (%v)", d) + } + + parseLine("b:12:c", &a, &d, &b) + if a != "b" || b != "c" || d != 12 { + t.Fatalf("a should be 'b' and b should be 'c', and d should be 12 ('%v', '%v', %v)", a, b, d) + } +} + +func TestUserParsePasswd(t *testing.T) { + users, err := parsePasswdFile(strings.NewReader(` +root:x:0:0:root:/root:/bin/bash +adm:x:3:4:adm:/var/adm:/bin/false +this is just some garbage data +`), nil) + if err != nil { + t.Fatalf("Unexpected error: %v", err) + } + if len(users) != 3 { + t.Fatalf("Expected 3 users, got %v", len(users)) + } + if users[0].Uid != 0 || users[0].Name != "root" { + t.Fatalf("Expected users[0] to be 0 - root, got %v - %v", users[0].Uid, users[0].Name) + } + if users[1].Uid != 3 || users[1].Name != "adm" { + t.Fatalf("Expected users[1] to be 3 - adm, got %v - %v", users[1].Uid, users[1].Name) + } +} + +func TestUserParseGroup(t *testing.T) { + groups, err := parseGroupFile(strings.NewReader(` +root:x:0:root +adm:x:4:root,adm,daemon +this is just some garbage data +`), nil) + if err != nil { + t.Fatalf("Unexpected error: %v", err) + } + if len(groups) != 3 { + t.Fatalf("Expected 3 groups, got %v", len(groups)) + } + if groups[0].Gid != 0 || groups[0].Name != "root" || len(groups[0].List) != 1 { + t.Fatalf("Expected groups[0] to be 0 - root - 1 member, got %v - %v - %v", groups[0].Gid, groups[0].Name, len(groups[0].List)) + } + if groups[1].Gid != 4 || groups[1].Name != "adm" || len(groups[1].List) != 3 { + t.Fatalf("Expected groups[1] to be 4 - adm - 3 members, got %v - %v - %v", groups[1].Gid, groups[1].Name, len(groups[1].List)) + } +} From 91ac5f5f609d12f5aa5ea10a1c0542da57f6cecb Mon Sep 17 00:00:00 2001 From: Michael Crosby Date: Fri, 17 Jan 2014 13:41:38 -0800 Subject: [PATCH 2/2] Use type switch instead of reflection Docker-DCO-1.1-Signed-off-by: Michael Crosby (github: crosbymichael) --- user/user.go | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-) diff --git a/user/user.go b/user/user.go index 30fc90f..1672f7e 100644 --- a/user/user.go +++ b/user/user.go @@ -5,7 +5,6 @@ import ( "fmt" "io" "os" - "reflect" "strconv" "strings" ) @@ -39,28 +38,25 @@ func parseLine(line string, v ...interface{}) { break } - t := reflect.TypeOf(v[i]) - if t.Kind() != reflect.Ptr { + 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 + *e, _ = strconv.Atoi(p) + case *[]string: + // "", "root", "root,adm,daemon" + 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!") } - - switch t.Elem().Kind() { - case reflect.String: - // "root", "adm", "/bin/bash" - *v[i].(*string) = p - case reflect.Int: - // "0", "4", "1000" - *v[i].(*int), _ = strconv.Atoi(p) - // ignore string to int conversion errors, for great "tolerance" of naughty configuration files - case reflect.Slice, reflect.Array: - // "", "root", "root,adm,daemon" - list := []string{} - if p != "" { - list = strings.Split(p, ",") - } - *v[i].(*[]string) = list - } } }