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-rw-r--r--runsc/boot/loader.go7
-rw-r--r--runsc/boot/user.go234
2 files changed, 4 insertions, 237 deletions
diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go
index cf1f47bc7..096b0e9f0 100644
--- a/runsc/boot/loader.go
+++ b/runsc/boot/loader.go
@@ -35,6 +35,7 @@ import (
"gvisor.dev/gvisor/pkg/sentry/control"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/host"
+ "gvisor.dev/gvisor/pkg/sentry/fs/user"
"gvisor.dev/gvisor/pkg/sentry/inet"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
@@ -550,11 +551,11 @@ func (l *Loader) run() error {
// Add the HOME enviroment variable if it is not already set.
var envv []string
if kernel.VFS2Enabled {
- envv, err = maybeAddExecUserHomeVFS2(ctx, l.rootProcArgs.MountNamespaceVFS2,
+ envv, err = user.MaybeAddExecUserHomeVFS2(ctx, l.rootProcArgs.MountNamespaceVFS2,
l.rootProcArgs.Credentials.RealKUID, l.rootProcArgs.Envv)
} else {
- envv, err = maybeAddExecUserHome(ctx, l.rootProcArgs.MountNamespace,
+ envv, err = user.MaybeAddExecUserHome(ctx, l.rootProcArgs.MountNamespace,
l.rootProcArgs.Credentials.RealKUID, l.rootProcArgs.Envv)
}
if err != nil {
@@ -860,7 +861,7 @@ func (l *Loader) executeAsync(args *control.ExecArgs) (kernel.ThreadID, error) {
root := args.MountNamespace.Root()
defer root.DecRef()
ctx := fs.WithRoot(l.k.SupervisorContext(), root)
- envv, err := maybeAddExecUserHome(ctx, args.MountNamespace, args.KUID, args.Envv)
+ envv, err := user.MaybeAddExecUserHome(ctx, args.MountNamespace, args.KUID, args.Envv)
if err != nil {
return 0, err
}
diff --git a/runsc/boot/user.go b/runsc/boot/user.go
deleted file mode 100644
index 332e4fce5..000000000
--- a/runsc/boot/user.go
+++ /dev/null
@@ -1,234 +0,0 @@
-// Copyright 2019 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package boot
-
-import (
- "bufio"
- "fmt"
- "io"
- "strconv"
- "strings"
-
- "gvisor.dev/gvisor/pkg/abi/linux"
- "gvisor.dev/gvisor/pkg/context"
- "gvisor.dev/gvisor/pkg/fspath"
- "gvisor.dev/gvisor/pkg/sentry/fs"
- "gvisor.dev/gvisor/pkg/sentry/kernel/auth"
- "gvisor.dev/gvisor/pkg/sentry/vfs"
- "gvisor.dev/gvisor/pkg/usermem"
-)
-
-type fileReader struct {
- // Ctx is the context for the file reader.
- Ctx context.Context
-
- // File is the file to read from.
- File *fs.File
-}
-
-// Read implements io.Reader.Read.
-func (r *fileReader) Read(buf []byte) (int, error) {
- n, err := r.File.Readv(r.Ctx, usermem.BytesIOSequence(buf))
- return int(n), err
-}
-
-// getExecUserHome returns the home directory of the executing user read from
-// /etc/passwd as read from the container filesystem.
-func getExecUserHome(ctx context.Context, rootMns *fs.MountNamespace, uid auth.KUID) (string, error) {
- // The default user home directory to return if no user matching the user
- // if found in the /etc/passwd found in the image.
- const defaultHome = "/"
-
- // Open the /etc/passwd file from the dirent via the root mount namespace.
- mnsRoot := rootMns.Root()
- maxTraversals := uint(linux.MaxSymlinkTraversals)
- dirent, err := rootMns.FindInode(ctx, mnsRoot, nil, "/etc/passwd", &maxTraversals)
- if err != nil {
- // NOTE: Ignore errors opening the passwd file. If the passwd file
- // doesn't exist we will return the default home directory.
- return defaultHome, nil
- }
- defer dirent.DecRef()
-
- // Check read permissions on the file.
- if err := dirent.Inode.CheckPermission(ctx, fs.PermMask{Read: true}); err != nil {
- // NOTE: Ignore permissions errors here and return default root dir.
- return defaultHome, nil
- }
-
- // Only open regular files. We don't open other files like named pipes as
- // they may block and might present some attack surface to the container.
- // Note that runc does not seem to do this kind of checking.
- if !fs.IsRegular(dirent.Inode.StableAttr) {
- return defaultHome, nil
- }
-
- f, err := dirent.Inode.GetFile(ctx, dirent, fs.FileFlags{Read: true, Directory: false})
- if err != nil {
- return "", err
- }
- defer f.DecRef()
-
- r := &fileReader{
- Ctx: ctx,
- File: f,
- }
-
- return findHomeInPasswd(uint32(uid), r, defaultHome)
-}
-
-type fileReaderVFS2 struct {
- ctx context.Context
- fd *vfs.FileDescription
-}
-
-func (r *fileReaderVFS2) Read(buf []byte) (int, error) {
- n, err := r.fd.Read(r.ctx, usermem.BytesIOSequence(buf), vfs.ReadOptions{})
- return int(n), err
-}
-
-func getExecUserHomeVFS2(ctx context.Context, mns *vfs.MountNamespace, uid auth.KUID) (string, error) {
- const defaultHome = "/"
-
- root := mns.Root()
- defer root.DecRef()
-
- creds := auth.CredentialsFromContext(ctx)
-
- target := &vfs.PathOperation{
- Root: root,
- Start: root,
- Path: fspath.Parse("/etc/passwd"),
- }
-
- opts := &vfs.OpenOptions{
- Flags: linux.O_RDONLY,
- }
-
- fd, err := root.Mount().Filesystem().VirtualFilesystem().OpenAt(ctx, creds, target, opts)
- if err != nil {
- return defaultHome, nil
- }
- defer fd.DecRef()
-
- r := &fileReaderVFS2{
- ctx: ctx,
- fd: fd,
- }
-
- homeDir, err := findHomeInPasswd(uint32(uid), r, defaultHome)
- if err != nil {
- return "", err
- }
-
- return homeDir, nil
-}
-
-// maybeAddExecUserHome returns a new slice with the HOME enviroment variable
-// set if the slice does not already contain it, otherwise it returns the
-// original slice unmodified.
-func maybeAddExecUserHome(ctx context.Context, mns *fs.MountNamespace, uid auth.KUID, envv []string) ([]string, error) {
- // Check if the envv already contains HOME.
- for _, env := range envv {
- if strings.HasPrefix(env, "HOME=") {
- // We have it. Return the original slice unmodified.
- return envv, nil
- }
- }
-
- // Read /etc/passwd for the user's HOME directory and set the HOME
- // environment variable as required by POSIX if it is not overridden by
- // the user.
- homeDir, err := getExecUserHome(ctx, mns, uid)
- if err != nil {
- return nil, fmt.Errorf("error reading exec user: %v", err)
- }
-
- return append(envv, "HOME="+homeDir), nil
-}
-
-func maybeAddExecUserHomeVFS2(ctx context.Context, vmns *vfs.MountNamespace, uid auth.KUID, envv []string) ([]string, error) {
- // Check if the envv already contains HOME.
- for _, env := range envv {
- if strings.HasPrefix(env, "HOME=") {
- // We have it. Return the original slice unmodified.
- return envv, nil
- }
- }
-
- // Read /etc/passwd for the user's HOME directory and set the HOME
- // environment variable as required by POSIX if it is not overridden by
- // the user.
- homeDir, err := getExecUserHomeVFS2(ctx, vmns, uid)
- if err != nil {
- return nil, fmt.Errorf("error reading exec user: %v", err)
- }
- return append(envv, "HOME="+homeDir), nil
-}
-
-// findHomeInPasswd parses a passwd file and returns the given user's home
-// directory. This function does it's best to replicate the runc's behavior.
-func findHomeInPasswd(uid uint32, passwd io.Reader, defaultHome string) (string, error) {
- s := bufio.NewScanner(passwd)
-
- for s.Scan() {
- if err := s.Err(); err != nil {
- return "", err
- }
-
- line := strings.TrimSpace(s.Text())
- if line == "" {
- continue
- }
-
- // Pull out part of passwd entry. Loosely parse the passwd entry as some
- // passwd files could be poorly written and for compatibility with runc.
- //
- // Per 'man 5 passwd'
- // /etc/passwd contains one line for each user account, with seven
- // fields delimited by colons (“:”). These fields are:
- //
- // - login name
- // - optional encrypted password
- // - numerical user ID
- // - numerical group ID
- // - user name or comment field
- // - user home directory
- // - optional user command interpreter
- parts := strings.Split(line, ":")
-
- found := false
- homeDir := ""
- for i, p := range parts {
- switch i {
- case 2:
- parsedUID, err := strconv.ParseUint(p, 10, 32)
- if err == nil && parsedUID == uint64(uid) {
- found = true
- }
- case 5:
- homeDir = p
- }
- }
- if found {
- // NOTE: If the uid is present but the home directory is not
- // present in the /etc/passwd entry we return an empty string. This
- // is, for better or worse, what runc does.
- return homeDir, nil
- }
- }
-
- return defaultHome, nil
-}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 07:57:24 +0000