diff options
Diffstat (limited to 'libpod')
| -rw-r--r-- | libpod/container_internal_linux.go | 417 | ||||
| -rw-r--r-- | libpod/container_internal_linux_test.go | 34 |
2 files changed, 372 insertions, 79 deletions
diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go index 605b526a4..86a28c176 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" @@ -1276,7 +1276,7 @@ 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()) } @@ -1286,9 +1286,16 @@ 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 @@ -1507,23 +1514,171 @@ 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 @@ -1533,18 +1688,22 @@ 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] @@ -1554,13 +1713,17 @@ 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 != "" { @@ -1570,96 +1733,180 @@ 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 { @@ -1751,3 +1998,23 @@ 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 +} diff --git a/libpod/container_internal_linux_test.go b/libpod/container_internal_linux_test.go index 41c22fb45..1465ffbea 100644 --- a/libpod/container_internal_linux_test.go +++ b/libpod/container_internal_linux_test.go @@ -29,16 +29,42 @@ func TestGenerateUserPasswdEntry(t *testing.T) { Mountpoint: "/does/not/exist/tmp/", }, } - user, err := c.generateUserPasswdEntry() + user, _, _, err := c.generateUserPasswdEntry(0) if err != nil { t.Fatal(err) } - assert.Equal(t, user, "123:x:123:456:container user:/:/bin/sh\n") + assert.Equal(t, user, "123:*:123:456:container user:/:/bin/sh\n") c.config.User = "567" - user, err = c.generateUserPasswdEntry() + user, _, _, err = c.generateUserPasswdEntry(0) if err != nil { t.Fatal(err) } - assert.Equal(t, user, "567:x:567:0:container user:/:/bin/sh\n") + assert.Equal(t, user, "567:*:567:0:container user:/:/bin/sh\n") +} + +func TestGenerateUserGroupEntry(t *testing.T) { + c := Container{ + config: &ContainerConfig{ + Spec: &spec.Spec{}, + ContainerSecurityConfig: ContainerSecurityConfig{ + User: "123:456", + }, + }, + state: &ContainerState{ + Mountpoint: "/does/not/exist/tmp/", + }, + } + group, _, err := c.generateUserGroupEntry(0) + if err != nil { + t.Fatal(err) + } + assert.Equal(t, group, "456:x:456:123\n") + + c.config.User = "567" + group, _, err = c.generateUserGroupEntry(0) + if err != nil { + t.Fatal(err) + } + assert.Equal(t, group, "567:x:567:567\n") } |