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-rw-r--r--libpod/container_internal_linux.go417
1 files changed, 342 insertions, 75 deletions
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index c61c1a325..0775daa33 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -36,7 +36,7 @@ import (
"github.com/containers/podman/v2/utils"
"github.com/containers/storage/pkg/archive"
securejoin "github.com/cyphar/filepath-securejoin"
- User "github.com/opencontainers/runc/libcontainer/user"
+ runcuser "github.com/opencontainers/runc/libcontainer/user"
spec "github.com/opencontainers/runtime-spec/specs-go"
"github.com/opencontainers/runtime-tools/generate"
"github.com/opencontainers/selinux/go-selinux/label"
@@ -1268,7 +1268,7 @@ func (c *Container) makeBindMounts() error {
// SHM is always added when we mount the container
c.state.BindMounts["/dev/shm"] = c.config.ShmDir
- newPasswd, err := c.generatePasswd()
+ newPasswd, newGroup, err := c.generatePasswdAndGroup()
if err != nil {
return errors.Wrapf(err, "error creating temporary passwd file for container %s", c.ID())
}
@@ -1278,9 +1278,16 @@ func (c *Container) makeBindMounts() error {
// If it already exists, delete so we can recreate
delete(c.state.BindMounts, "/etc/passwd")
}
- logrus.Debugf("adding entry to /etc/passwd for non existent default user")
c.state.BindMounts["/etc/passwd"] = newPasswd
}
+ if newGroup != "" {
+ // Make /etc/group
+ if _, ok := c.state.BindMounts["/etc/group"]; ok {
+ // If it already exists, delete so we can recreate
+ delete(c.state.BindMounts, "/etc/group")
+ }
+ c.state.BindMounts["/etc/group"] = newGroup
+ }
// Make /etc/hostname
// This should never change, so no need to recreate if it exists
@@ -1499,23 +1506,171 @@ func (c *Container) getHosts() string {
return hosts
}
+// generateGroupEntry generates an entry or entries into /etc/group as
+// required by container configuration.
+// Generatlly speaking, we will make an entry under two circumstances:
+// 1. The container is started as a specific user:group, and that group is both
+// numeric, and does not already exist in /etc/group.
+// 2. It is requested that Libpod add the group that launched Podman to
+// /etc/group via AddCurrentUserPasswdEntry (though this does not trigger if
+// the group in question already exists in /etc/passwd).
+// Returns group entry (as a string that can be appended to /etc/group) and any
+// error that occurred.
+func (c *Container) generateGroupEntry() (string, error) {
+ groupString := ""
+
+ // Things we *can't* handle: adding the user we added in
+ // generatePasswdEntry to any *existing* groups.
+ addedGID := 0
+ if c.config.AddCurrentUserPasswdEntry {
+ entry, gid, err := c.generateCurrentUserGroupEntry()
+ if err != nil {
+ return "", err
+ }
+ groupString += entry
+ addedGID = gid
+ }
+ if c.config.User != "" {
+ entry, _, err := c.generateUserGroupEntry(addedGID)
+ if err != nil {
+ return "", err
+ }
+ groupString += entry
+ }
+
+ return groupString, nil
+}
+
+// Make an entry in /etc/group for the group of the user running podman iff we
+// are rootless.
+func (c *Container) generateCurrentUserGroupEntry() (string, int, error) {
+ gid := rootless.GetRootlessGID()
+ if gid == 0 {
+ return "", 0, nil
+ }
+
+ g, err := user.LookupGroupId(strconv.Itoa(gid))
+ if err != nil {
+ return "", 0, errors.Wrapf(err, "failed to get current group")
+ }
+
+ // Lookup group name to see if it exists in the image.
+ _, err = lookup.GetGroup(c.state.Mountpoint, g.Name)
+ if err != runcuser.ErrNoGroupEntries {
+ return "", 0, err
+ }
+
+ // Lookup GID to see if it exists in the image.
+ _, err = lookup.GetGroup(c.state.Mountpoint, g.Gid)
+ if err != runcuser.ErrNoGroupEntries {
+ return "", 0, err
+ }
+
+ // We need to get the username of the rootless user so we can add it to
+ // the group.
+ username := ""
+ uid := rootless.GetRootlessUID()
+ if uid != 0 {
+ u, err := user.LookupId(strconv.Itoa(uid))
+ if err != nil {
+ return "", 0, errors.Wrapf(err, "failed to get current user to make group entry")
+ }
+ username = u.Username
+ }
+
+ // Make the entry.
+ return fmt.Sprintf("%s:x:%s:%s\n", g.Name, g.Gid, username), gid, nil
+}
+
+// Make an entry in /etc/group for the group the container was specified to run
+// as.
+func (c *Container) generateUserGroupEntry(addedGID int) (string, int, error) {
+ if c.config.User == "" {
+ return "", 0, nil
+ }
+
+ splitUser := strings.SplitN(c.config.User, ":", 2)
+ group := splitUser[0]
+ if len(splitUser) > 1 {
+ group = splitUser[1]
+ }
+
+ gid, err := strconv.ParseUint(group, 10, 32)
+ if err != nil {
+ return "", 0, nil
+ }
+
+ if addedGID != 0 && addedGID == int(gid) {
+ return "", 0, nil
+ }
+
+ // Check if the group already exists
+ _, err = lookup.GetGroup(c.state.Mountpoint, group)
+ if err != runcuser.ErrNoGroupEntries {
+ return "", 0, err
+ }
+
+ return fmt.Sprintf("%d:x:%d:%s\n", gid, gid, splitUser[0]), int(gid), nil
+}
+
+// generatePasswdEntry generates an entry or entries into /etc/passwd as
+// required by container configuration.
+// Generally speaking, we will make an entry under two circumstances:
+// 1. The container is started as a specific user who is not in /etc/passwd.
+// This only triggers if the user is given as a *numeric* ID.
+// 2. It is requested that Libpod add the user that launched Podman to
+// /etc/passwd via AddCurrentUserPasswdEntry (though this does not trigger if
+// the user in question already exists in /etc/passwd) or the UID to be added
+// is 0).
+// Returns password entry (as a string that can be appended to /etc/passwd) and
+// any error that occurred.
+func (c *Container) generatePasswdEntry() (string, error) {
+ passwdString := ""
+
+ addedUID := 0
+ if c.config.AddCurrentUserPasswdEntry {
+ entry, uid, _, err := c.generateCurrentUserPasswdEntry()
+ if err != nil {
+ return "", err
+ }
+ passwdString += entry
+ addedUID = uid
+ }
+ if c.config.User != "" {
+ entry, _, _, err := c.generateUserPasswdEntry(addedUID)
+ if err != nil {
+ return "", err
+ }
+ passwdString += entry
+ }
+
+ return passwdString, nil
+}
+
// generateCurrentUserPasswdEntry generates an /etc/passwd entry for the user
-// running the container engine
-func (c *Container) generateCurrentUserPasswdEntry() (string, error) {
+// running the container engine.
+// Returns a passwd entry for the user, and the UID and GID of the added entry.
+func (c *Container) generateCurrentUserPasswdEntry() (string, int, int, error) {
uid := rootless.GetRootlessUID()
if uid == 0 {
- return "", nil
+ return "", 0, 0, nil
}
- u, err := user.LookupId(strconv.Itoa(rootless.GetRootlessUID()))
+ u, err := user.LookupId(strconv.Itoa(uid))
if err != nil {
- return "", errors.Wrapf(err, "failed to get current user")
+ return "", 0, 0, errors.Wrapf(err, "failed to get current user")
}
// Lookup the user to see if it exists in the container image.
_, err = lookup.GetUser(c.state.Mountpoint, u.Username)
- if err != User.ErrNoPasswdEntries {
- return "", err
+ if err != runcuser.ErrNoPasswdEntries {
+ return "", 0, 0, err
+ }
+
+ // Lookup the UID to see if it exists in the container image.
+ _, err = lookup.GetUser(c.state.Mountpoint, u.Uid)
+ if err != runcuser.ErrNoPasswdEntries {
+ return "", 0, 0, err
}
// If the user's actual home directory exists, or was mounted in - use
@@ -1525,18 +1680,22 @@ func (c *Container) generateCurrentUserPasswdEntry() (string, error) {
homeDir = u.HomeDir
}
- return fmt.Sprintf("%s:x:%s:%s:%s:%s:/bin/sh\n", u.Username, u.Uid, u.Gid, u.Username, homeDir), nil
+ return fmt.Sprintf("%s:*:%s:%s:%s:%s:/bin/sh\n", u.Username, u.Uid, u.Gid, u.Username, homeDir), uid, rootless.GetRootlessGID(), nil
}
// generateUserPasswdEntry generates an /etc/passwd entry for the container user
// to run in the container.
-func (c *Container) generateUserPasswdEntry() (string, error) {
+// The UID and GID of the added entry will also be returned.
+// Accepts one argument, that being any UID that has already been added to the
+// passwd file by other functions; if it matches the UID we were given, we don't
+// need to do anything.
+func (c *Container) generateUserPasswdEntry(addedUID int) (string, int, int, error) {
var (
groupspec string
gid int
)
if c.config.User == "" {
- return "", nil
+ return "", 0, 0, nil
}
splitSpec := strings.SplitN(c.config.User, ":", 2)
userspec := splitSpec[0]
@@ -1546,13 +1705,17 @@ func (c *Container) generateUserPasswdEntry() (string, error) {
// If a non numeric User, then don't generate passwd
uid, err := strconv.ParseUint(userspec, 10, 32)
if err != nil {
- return "", nil
+ return "", 0, 0, nil
+ }
+
+ if addedUID != 0 && int(uid) == addedUID {
+ return "", 0, 0, nil
}
// Lookup the user to see if it exists in the container image
_, err = lookup.GetUser(c.state.Mountpoint, userspec)
- if err != User.ErrNoPasswdEntries {
- return "", err
+ if err != runcuser.ErrNoPasswdEntries {
+ return "", 0, 0, err
}
if groupspec != "" {
@@ -1562,96 +1725,180 @@ func (c *Container) generateUserPasswdEntry() (string, error) {
} else {
group, err := lookup.GetGroup(c.state.Mountpoint, groupspec)
if err != nil {
- return "", errors.Wrapf(err, "unable to get gid %s from group file", groupspec)
+ return "", 0, 0, errors.Wrapf(err, "unable to get gid %s from group file", groupspec)
}
gid = group.Gid
}
}
- return fmt.Sprintf("%d:x:%d:%d:container user:%s:/bin/sh\n", uid, uid, gid, c.WorkingDir()), nil
+ return fmt.Sprintf("%d:*:%d:%d:container user:%s:/bin/sh\n", uid, uid, gid, c.WorkingDir()), int(uid), gid, nil
}
-// generatePasswd generates a container specific passwd file,
-// iff g.config.User is a number
-func (c *Container) generatePasswd() (string, error) {
+// generatePasswdAndGroup generates container-specific passwd and group files
+// iff g.config.User is a number or we are configured to make a passwd entry for
+// the current user.
+// Returns path to file to mount at /etc/passwd, path to file to mount at
+// /etc/group, and any error that occurred. If no passwd/group file were
+// required, the empty string will be returned for those path (this may occur
+// even if no error happened).
+// This may modify the mounted container's /etc/passwd and /etc/group instead of
+// making copies to bind-mount in, so we don't break useradd (it wants to make a
+// copy of /etc/passwd and rename the copy to /etc/passwd, which is impossible
+// with a bind mount). This is done in cases where the container is *not*
+// read-only. In this case, the function will return nothing ("", "", nil).
+func (c *Container) generatePasswdAndGroup() (string, string, error) {
if !c.config.AddCurrentUserPasswdEntry && c.config.User == "" {
- return "", nil
+ return "", "", nil
}
+
+ needPasswd := true
+ needGroup := true
+
+ // First, check if there's a mount at /etc/passwd or group, we don't
+ // want to interfere with user mounts.
if MountExists(c.config.Spec.Mounts, "/etc/passwd") {
- return "", nil
+ needPasswd = false
}
- // Re-use passwd if possible
- passwdPath := filepath.Join(c.config.StaticDir, "passwd")
- if _, err := os.Stat(passwdPath); err == nil {
- return passwdPath, nil
+ if MountExists(c.config.Spec.Mounts, "/etc/group") {
+ needGroup = false
}
- // Check if container has a /etc/passwd - if it doesn't do nothing.
- passwdPath, err := securejoin.SecureJoin(c.state.Mountpoint, "/etc/passwd")
- if err != nil {
- return "", errors.Wrapf(err, "error creating path to container %s /etc/passwd", c.ID())
+
+ // Next, check if we already made the files. If we didn, don't need to
+ // do anything more.
+ if needPasswd {
+ passwdPath := filepath.Join(c.config.StaticDir, "passwd")
+ if _, err := os.Stat(passwdPath); err == nil {
+ needPasswd = false
+ }
}
- if _, err := os.Stat(passwdPath); err != nil {
- if os.IsNotExist(err) {
- return "", nil
+ if needGroup {
+ groupPath := filepath.Join(c.config.StaticDir, "group")
+ if _, err := os.Stat(groupPath); err == nil {
+ needGroup = false
}
- return "", errors.Wrapf(err, "unable to access container %s /etc/passwd", c.ID())
}
- pwd := ""
- if c.config.User != "" {
- entry, err := c.generateUserPasswdEntry()
+
+ // Next, check if the container even has a /etc/passwd or /etc/group.
+ // If it doesn't we don't want to create them ourselves.
+ if needPasswd {
+ exists, err := c.checkFileExistsInRootfs("/etc/passwd")
if err != nil {
- return "", err
+ return "", "", err
}
- pwd += entry
+ needPasswd = exists
}
- if c.config.AddCurrentUserPasswdEntry {
- entry, err := c.generateCurrentUserPasswdEntry()
+ if needGroup {
+ exists, err := c.checkFileExistsInRootfs("/etc/group")
if err != nil {
- return "", err
+ return "", "", err
}
- pwd += entry
+ needGroup = exists
}
- if pwd == "" {
- return "", nil
+
+ // If we don't need a /etc/passwd or /etc/group at this point we can
+ // just return.
+ if !needPasswd && !needGroup {
+ return "", "", nil
}
- // If we are *not* read-only - edit /etc/passwd in the container.
- // This is *gross* (shows up in changes to the container, will be
- // committed to images based on the container) but it actually allows us
- // to add users to the container (a bind mount breaks useradd).
- // We should never get here twice, because generateUserPasswdEntry will
- // not return anything if the user already exists in /etc/passwd.
- if !c.IsReadOnly() {
- containerPasswd, err := securejoin.SecureJoin(c.state.Mountpoint, "/etc/passwd")
+ passwdPath := ""
+ groupPath := ""
+
+ ro := c.IsReadOnly()
+
+ if needPasswd {
+ passwdEntry, err := c.generatePasswdEntry()
if err != nil {
- return "", errors.Wrapf(err, "error looking up location of container %s /etc/passwd", c.ID())
+ return "", "", err
}
- f, err := os.OpenFile(containerPasswd, os.O_APPEND|os.O_WRONLY, 0600)
+ needsWrite := passwdEntry != ""
+ switch {
+ case ro && needsWrite:
+ logrus.Debugf("Making /etc/passwd for container %s", c.ID())
+ originPasswdFile, err := securejoin.SecureJoin(c.state.Mountpoint, "/etc/passwd")
+ if err != nil {
+ return "", "", errors.Wrapf(err, "error creating path to container %s /etc/passwd", c.ID())
+ }
+ orig, err := ioutil.ReadFile(originPasswdFile)
+ if err != nil && !os.IsNotExist(err) {
+ return "", "", errors.Wrapf(err, "unable to read passwd file %s", originPasswdFile)
+ }
+ passwdFile, err := c.writeStringToStaticDir("passwd", string(orig)+passwdEntry)
+ if err != nil {
+ return "", "", errors.Wrapf(err, "failed to create temporary passwd file")
+ }
+ if err := os.Chmod(passwdFile, 0644); err != nil {
+ return "", "", err
+ }
+ passwdPath = passwdFile
+ case !ro && needsWrite:
+ logrus.Debugf("Modifying container %s /etc/passwd", c.ID())
+ containerPasswd, err := securejoin.SecureJoin(c.state.Mountpoint, "/etc/passwd")
+ if err != nil {
+ return "", "", errors.Wrapf(err, "error looking up location of container %s /etc/passwd", c.ID())
+ }
+
+ f, err := os.OpenFile(containerPasswd, os.O_APPEND|os.O_WRONLY, 0600)
+ if err != nil {
+ return "", "", errors.Wrapf(err, "error opening container %s /etc/passwd", c.ID())
+ }
+ defer f.Close()
+
+ if _, err := f.WriteString(passwdEntry); err != nil {
+ return "", "", errors.Wrapf(err, "unable to append to container %s /etc/passwd", c.ID())
+ }
+ default:
+ logrus.Debugf("Not modifying container %s /etc/passwd", c.ID())
+ }
+ }
+ if needGroup {
+ groupEntry, err := c.generateGroupEntry()
if err != nil {
- return "", errors.Wrapf(err, "error opening container %s /etc/passwd", c.ID())
+ return "", "", err
}
- defer f.Close()
- if _, err := f.WriteString(pwd); err != nil {
- return "", errors.Wrapf(err, "unable to append to container %s /etc/passwd", c.ID())
- }
+ needsWrite := groupEntry != ""
+ switch {
+ case ro && needsWrite:
+ logrus.Debugf("Making /etc/group for container %s", c.ID())
+ originGroupFile, err := securejoin.SecureJoin(c.state.Mountpoint, "/etc/group")
+ if err != nil {
+ return "", "", errors.Wrapf(err, "error creating path to container %s /etc/group", c.ID())
+ }
+ orig, err := ioutil.ReadFile(originGroupFile)
+ if err != nil && !os.IsNotExist(err) {
+ return "", "", errors.Wrapf(err, "unable to read group file %s", originGroupFile)
+ }
+ groupFile, err := c.writeStringToStaticDir("group", string(orig)+groupEntry)
+ if err != nil {
+ return "", "", errors.Wrapf(err, "failed to create temporary group file")
+ }
+ if err := os.Chmod(groupFile, 0644); err != nil {
+ return "", "", err
+ }
+ groupPath = groupFile
+ case !ro && needsWrite:
+ logrus.Debugf("Modifying container %s /etc/group", c.ID())
+ containerGroup, err := securejoin.SecureJoin(c.state.Mountpoint, "/etc/group")
+ if err != nil {
+ return "", "", errors.Wrapf(err, "error looking up location of container %s /etc/group", c.ID())
+ }
- return "", nil
- }
+ f, err := os.OpenFile(containerGroup, os.O_APPEND|os.O_WRONLY, 0600)
+ if err != nil {
+ return "", "", errors.Wrapf(err, "error opening container %s /etc/group", c.ID())
+ }
+ defer f.Close()
- originPasswdFile := filepath.Join(c.state.Mountpoint, "/etc/passwd")
- orig, err := ioutil.ReadFile(originPasswdFile)
- if err != nil && !os.IsNotExist(err) {
- return "", errors.Wrapf(err, "unable to read passwd file %s", originPasswdFile)
- }
- passwdFile, err := c.writeStringToStaticDir("passwd", string(orig)+pwd)
- if err != nil {
- return "", errors.Wrapf(err, "failed to create temporary passwd file")
- }
- if err := os.Chmod(passwdFile, 0644); err != nil {
- return "", err
+ if _, err := f.WriteString(groupEntry); err != nil {
+ return "", "", errors.Wrapf(err, "unable to append to container %s /etc/group", c.ID())
+ }
+ default:
+ logrus.Debugf("Not modifying container %s /etc/group", c.ID())
+ }
}
- return passwdFile, nil
+
+ return passwdPath, groupPath, nil
}
func (c *Container) copyOwnerAndPerms(source, dest string) error {
@@ -1743,3 +1990,23 @@ func (c *Container) copyTimezoneFile(zonePath string) (string, error) {
func (c *Container) cleanupOverlayMounts() error {
return overlay.CleanupContent(c.config.StaticDir)
}
+
+// Check if a file exists at the given path in the container's root filesystem.
+// Container must already be mounted for this to be used.
+func (c *Container) checkFileExistsInRootfs(file string) (bool, error) {
+ checkPath, err := securejoin.SecureJoin(c.state.Mountpoint, file)
+ if err != nil {
+ return false, errors.Wrapf(err, "cannot create path to container %s file %q", c.ID(), file)
+ }
+ stat, err := os.Stat(checkPath)
+ if err != nil {
+ if os.IsNotExist(err) {
+ return false, nil
+ }
+ return false, errors.Wrapf(err, "error accessing container %s file %q", c.ID(), file)
+ }
+ if stat.IsDir() {
+ return false, nil
+ }
+ return true, nil
+}