138 lines
4.5 KiB
Go
138 lines
4.5 KiB
Go
// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package vfs2
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import (
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/fspath"
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"gvisor.dev/gvisor/pkg/sentry/arch"
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"gvisor.dev/gvisor/pkg/sentry/fsbridge"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/loader"
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slinux "gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/syserror"
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"gvisor.dev/gvisor/pkg/usermem"
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)
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// Execve implements linux syscall execve(2).
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func Execve(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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pathnameAddr := args[0].Pointer()
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argvAddr := args[1].Pointer()
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envvAddr := args[2].Pointer()
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return execveat(t, linux.AT_FDCWD, pathnameAddr, argvAddr, envvAddr, 0 /* flags */)
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}
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// Execveat implements linux syscall execveat(2).
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func Execveat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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dirfd := args[0].Int()
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pathnameAddr := args[1].Pointer()
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argvAddr := args[2].Pointer()
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envvAddr := args[3].Pointer()
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flags := args[4].Int()
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return execveat(t, dirfd, pathnameAddr, argvAddr, envvAddr, flags)
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}
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func execveat(t *kernel.Task, dirfd int32, pathnameAddr, argvAddr, envvAddr usermem.Addr, flags int32) (uintptr, *kernel.SyscallControl, error) {
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if flags&^(linux.AT_EMPTY_PATH|linux.AT_SYMLINK_NOFOLLOW) != 0 {
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return 0, nil, syserror.EINVAL
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}
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pathname, err := t.CopyInString(pathnameAddr, linux.PATH_MAX)
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if err != nil {
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return 0, nil, err
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}
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var argv, envv []string
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if argvAddr != 0 {
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var err error
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argv, err = t.CopyInVector(argvAddr, slinux.ExecMaxElemSize, slinux.ExecMaxTotalSize)
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if err != nil {
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return 0, nil, err
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}
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}
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if envvAddr != 0 {
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var err error
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envv, err = t.CopyInVector(envvAddr, slinux.ExecMaxElemSize, slinux.ExecMaxTotalSize)
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if err != nil {
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return 0, nil, err
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}
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}
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root := t.FSContext().RootDirectoryVFS2()
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defer root.DecRef()
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var executable fsbridge.File
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closeOnExec := false
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if path := fspath.Parse(pathname); dirfd != linux.AT_FDCWD && !path.Absolute {
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// We must open the executable ourselves since dirfd is used as the
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// starting point while resolving path, but the task working directory
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// is used as the starting point while resolving interpreters (Linux:
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// fs/binfmt_script.c:load_script() => fs/exec.c:open_exec() =>
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// do_open_execat(fd=AT_FDCWD)), and the loader package is currently
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// incapable of handling this correctly.
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if !path.HasComponents() && flags&linux.AT_EMPTY_PATH == 0 {
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return 0, nil, syserror.ENOENT
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}
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dirfile, dirfileFlags := t.FDTable().GetVFS2(dirfd)
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if dirfile == nil {
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return 0, nil, syserror.EBADF
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}
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start := dirfile.VirtualDentry()
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start.IncRef()
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dirfile.DecRef()
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closeOnExec = dirfileFlags.CloseOnExec
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file, err := t.Kernel().VFS().OpenAt(t, t.Credentials(), &vfs.PathOperation{
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Root: root,
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Start: start,
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Path: path,
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FollowFinalSymlink: flags&linux.AT_SYMLINK_NOFOLLOW == 0,
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}, &vfs.OpenOptions{
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Flags: linux.O_RDONLY,
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FileExec: true,
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})
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start.DecRef()
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if err != nil {
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return 0, nil, err
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}
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defer file.DecRef()
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executable = fsbridge.NewVFSFile(file)
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}
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// Load the new TaskContext.
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mntns := t.MountNamespaceVFS2() // FIXME(jamieliu): useless refcount change
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defer mntns.DecRef()
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wd := t.FSContext().WorkingDirectoryVFS2()
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defer wd.DecRef()
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remainingTraversals := uint(linux.MaxSymlinkTraversals)
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loadArgs := loader.LoadArgs{
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Opener: fsbridge.NewVFSLookup(mntns, root, wd),
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RemainingTraversals: &remainingTraversals,
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ResolveFinal: flags&linux.AT_SYMLINK_NOFOLLOW == 0,
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Filename: pathname,
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File: executable,
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CloseOnExec: closeOnExec,
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Argv: argv,
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Envv: envv,
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Features: t.Arch().FeatureSet(),
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}
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tc, se := t.Kernel().LoadTaskImage(t, loadArgs)
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if se != nil {
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return 0, nil, se.ToError()
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}
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ctrl, err := t.Execve(tc)
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return 0, ctrl, err
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}
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