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Diffstat (limited to 'pkg/sentry/loader/loader.go')
-rw-r--r--pkg/sentry/loader/loader.go132
1 files changed, 87 insertions, 45 deletions
diff --git a/pkg/sentry/loader/loader.go b/pkg/sentry/loader/loader.go
index f5303491d..818941762 100644
--- a/pkg/sentry/loader/loader.go
+++ b/pkg/sentry/loader/loader.go
@@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.
-// Package loader loads a binary into a MemoryManager.
+// Package loader loads an executable file into a MemoryManager.
package loader
import (
@@ -35,6 +35,48 @@ import (
"gvisor.dev/gvisor/pkg/syserror"
)
+// LoadArgs holds specifications for an executable file to be loaded.
+type LoadArgs struct {
+ // MemoryManager is the memory manager to load the executable into.
+ MemoryManager *mm.MemoryManager
+
+ // Mounts is the mount namespace in which to look up Filename.
+ Mounts *fs.MountNamespace
+
+ // Root is the root directory under which to look up Filename.
+ Root *fs.Dirent
+
+ // WorkingDirectory is the working directory under which to look up
+ // Filename.
+ WorkingDirectory *fs.Dirent
+
+ // RemainingTraversals is the maximum number of symlinks to follow to
+ // resolve Filename. This counter is passed by reference to keep it
+ // updated throughout the call stack.
+ RemainingTraversals *uint
+
+ // ResolveFinal indicates whether the final link of Filename should be
+ // resolved, if it is a symlink.
+ ResolveFinal bool
+
+ // Filename is the path for the executable.
+ Filename string
+
+ // File is an open fs.File object of the executable. If File is not
+ // nil, then File will be loaded and Filename will be ignored.
+ File *fs.File
+
+ // Argv is the vector of arguments to pass to the executable.
+ Argv []string
+
+ // Envv is the vector of environment variables to pass to the
+ // executable.
+ Envv []string
+
+ // Features specifies the CPU feature set for the executable.
+ Features *cpuid.FeatureSet
+}
+
// readFull behaves like io.ReadFull for an *fs.File.
func readFull(ctx context.Context, f *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
var total int64
@@ -51,24 +93,24 @@ func readFull(ctx context.Context, f *fs.File, dst usermem.IOSequence, offset in
return total, nil
}
-// openPath opens name for loading.
+// openPath opens args.Filename for loading.
//
-// openPath returns the fs.Dirent and an *fs.File for name, which is not
-// installed in the Task FDTable. The caller takes ownership of both.
+// openPath returns the fs.Dirent and an *fs.File for args.Filename, which is
+// not installed in the Task FDTable. The caller takes ownership of both.
//
-// name must be a readable, executable, regular file.
-func openPath(ctx context.Context, mounts *fs.MountNamespace, root, wd *fs.Dirent, maxTraversals *uint, name string, resolveFinal bool) (*fs.Dirent, *fs.File, error) {
+// args.Filename must be a readable, executable, regular file.
+func openPath(ctx context.Context, args LoadArgs) (*fs.Dirent, *fs.File, error) {
var err error
- if name == "" {
+ if args.Filename == "" {
ctx.Infof("cannot open empty name")
return nil, nil, syserror.ENOENT
}
var d *fs.Dirent
- if resolveFinal {
- d, err = mounts.FindInode(ctx, root, wd, name, maxTraversals)
+ if args.ResolveFinal {
+ d, err = args.Mounts.FindInode(ctx, args.Root, args.WorkingDirectory, args.Filename, args.RemainingTraversals)
} else {
- d, err = mounts.FindLink(ctx, root, wd, name, maxTraversals)
+ d, err = args.Mounts.FindLink(ctx, args.Root, args.WorkingDirectory, args.Filename, args.RemainingTraversals)
}
if err != nil {
return nil, nil, err
@@ -77,11 +119,11 @@ func openPath(ctx context.Context, mounts *fs.MountNamespace, root, wd *fs.Diren
// Open file will take a reference to Dirent, so destroy this one.
defer d.DecRef()
- if !resolveFinal && fs.IsSymlink(d.Inode.StableAttr) {
+ if !args.ResolveFinal && fs.IsSymlink(d.Inode.StableAttr) {
return nil, nil, syserror.ELOOP
}
- return openFile(ctx, nil, d, name)
+ return openFile(ctx, nil, d, args.Filename)
}
// openFile takes that file's Dirent and performs checks on it. If provided a
@@ -182,34 +224,33 @@ const (
maxLoaderAttempts = 6
)
-// loadBinary loads a binary that is pointed to by "file". If nil, the path
-// "filename" is resolved and loaded.
+// loadExecutable loads an executable that is pointed to by args.File. If nil,
+// the path args.Filename is resolved and loaded. If the executable is an
+// interpreter script rather than an ELF, the binary of the corresponding
+// interpreter will be loaded.
//
// It returns:
// * loadedELF, description of the loaded binary
// * arch.Context matching the binary arch
// * fs.Dirent of the binary file
-// * Possibly updated argv
-func loadBinary(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamespace, root, wd *fs.Dirent, remainingTraversals *uint, features *cpuid.FeatureSet, filename string, passedFile *fs.File, argv []string, resolveFinal bool) (loadedELF, arch.Context, *fs.Dirent, []string, error) {
+// * Possibly updated args.Argv
+func loadExecutable(ctx context.Context, args LoadArgs) (loadedELF, arch.Context, *fs.Dirent, []string, error) {
for i := 0; i < maxLoaderAttempts; i++ {
var (
d *fs.Dirent
- f *fs.File
err error
)
- if passedFile == nil {
- d, f, err = openPath(ctx, mounts, root, wd, remainingTraversals, filename, resolveFinal)
+ if args.File == nil {
+ d, args.File, err = openPath(ctx, args)
} else {
- d, f, err = openFile(ctx, passedFile, nil, "")
- // Set to nil in case we loop on a Interpreter Script.
- passedFile = nil
+ d, args.File, err = openFile(ctx, args.File, nil, "")
}
if err != nil {
- ctx.Infof("Error opening %s: %v", filename, err)
+ ctx.Infof("Error opening %s: %v", args.Filename, err)
return loadedELF{}, nil, nil, nil, err
}
- defer f.DecRef()
+ defer args.File.DecRef()
// We will return d in the successful case, but defer a DecRef
// for intermediate loops and failure cases.
defer d.DecRef()
@@ -217,9 +258,9 @@ func loadBinary(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamesp
// Check the header. Is this an ELF or interpreter script?
var hdr [4]uint8
// N.B. We assume that reading from a regular file cannot block.
- _, err = readFull(ctx, f, usermem.BytesIOSequence(hdr[:]), 0)
- // Allow unexpected EOF, as a valid executable could be only three
- // bytes (e.g., #!a).
+ _, err = readFull(ctx, args.File, usermem.BytesIOSequence(hdr[:]), 0)
+ // Allow unexpected EOF, as a valid executable could be only
+ // three bytes (e.g., #!a).
if err != nil && err != io.ErrUnexpectedEOF {
if err == io.EOF {
err = syserror.ENOEXEC
@@ -229,33 +270,33 @@ func loadBinary(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamesp
switch {
case bytes.Equal(hdr[:], []byte(elfMagic)):
- loaded, ac, err := loadELF(ctx, m, mounts, root, wd, remainingTraversals, features, f)
+ loaded, ac, err := loadELF(ctx, args)
if err != nil {
ctx.Infof("Error loading ELF: %v", err)
return loadedELF{}, nil, nil, nil, err
}
// An ELF is always terminal. Hold on to d.
d.IncRef()
- return loaded, ac, d, argv, err
+ return loaded, ac, d, args.Argv, err
case bytes.Equal(hdr[:2], []byte(interpreterScriptMagic)):
- newpath, newargv, err := parseInterpreterScript(ctx, filename, f, argv)
+ args.Filename, args.Argv, err = parseInterpreterScript(ctx, args.Filename, args.File, args.Argv)
if err != nil {
ctx.Infof("Error loading interpreter script: %v", err)
return loadedELF{}, nil, nil, nil, err
}
- filename = newpath
- argv = newargv
default:
ctx.Infof("Unknown magic: %v", hdr)
return loadedELF{}, nil, nil, nil, syserror.ENOEXEC
}
+ // Set to nil in case we loop on a Interpreter Script.
+ args.File = nil
}
return loadedELF{}, nil, nil, nil, syserror.ELOOP
}
-// Load loads "file" into a MemoryManager. If file is nil, the path "filename"
-// is resolved and loaded instead.
+// Load loads args.File into a MemoryManager. If args.File is nil, the path
+// args.Filename is resolved and loaded instead.
//
// If Load returns ErrSwitchFile it should be called again with the returned
// path and argv.
@@ -263,37 +304,37 @@ func loadBinary(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamesp
// Preconditions:
// * The Task MemoryManager is empty.
// * Load is called on the Task goroutine.
-func Load(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamespace, root, wd *fs.Dirent, maxTraversals *uint, fs *cpuid.FeatureSet, filename string, file *fs.File, argv, envv []string, resolveFinal bool, extraAuxv []arch.AuxEntry, vdso *VDSO) (abi.OS, arch.Context, string, *syserr.Error) {
- // Load the binary itself.
- loaded, ac, d, argv, err := loadBinary(ctx, m, mounts, root, wd, maxTraversals, fs, filename, file, argv, resolveFinal)
+func Load(ctx context.Context, args LoadArgs, extraAuxv []arch.AuxEntry, vdso *VDSO) (abi.OS, arch.Context, string, *syserr.Error) {
+ // Load the executable itself.
+ loaded, ac, d, newArgv, err := loadExecutable(ctx, args)
if err != nil {
- return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Failed to load %s: %v", filename, err), syserr.FromError(err).ToLinux())
+ return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Failed to load %s: %v", args.Filename, err), syserr.FromError(err).ToLinux())
}
defer d.DecRef()
// Load the VDSO.
- vdsoAddr, err := loadVDSO(ctx, m, vdso, loaded)
+ vdsoAddr, err := loadVDSO(ctx, args.MemoryManager, vdso, loaded)
if err != nil {
return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Error loading VDSO: %v", err), syserr.FromError(err).ToLinux())
}
// Setup the heap. brk starts at the next page after the end of the
- // binary. Userspace can assume that the remainer of the page after
+ // executable. Userspace can assume that the remainer of the page after
// loaded.end is available for its use.
e, ok := loaded.end.RoundUp()
if !ok {
return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("brk overflows: %#x", loaded.end), linux.ENOEXEC)
}
- m.BrkSetup(ctx, e)
+ args.MemoryManager.BrkSetup(ctx, e)
// Allocate our stack.
- stack, err := allocStack(ctx, m, ac)
+ stack, err := allocStack(ctx, args.MemoryManager, ac)
if err != nil {
return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Failed to allocate stack: %v", err), syserr.FromError(err).ToLinux())
}
// Push the original filename to the stack, for AT_EXECFN.
- execfn, err := stack.Push(filename)
+ execfn, err := stack.Push(args.Filename)
if err != nil {
return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Failed to push exec filename: %v", err), syserr.FromError(err).ToLinux())
}
@@ -327,11 +368,12 @@ func Load(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamespace, r
}...)
auxv = append(auxv, extraAuxv...)
- sl, err := stack.Load(argv, envv, auxv)
+ sl, err := stack.Load(newArgv, args.Envv, auxv)
if err != nil {
return 0, nil, "", syserr.NewDynamic(fmt.Sprintf("Failed to load stack: %v", err), syserr.FromError(err).ToLinux())
}
+ m := args.MemoryManager
m.SetArgvStart(sl.ArgvStart)
m.SetArgvEnd(sl.ArgvEnd)
m.SetEnvvStart(sl.EnvvStart)
@@ -342,7 +384,7 @@ func Load(ctx context.Context, m *mm.MemoryManager, mounts *fs.MountNamespace, r
ac.SetIP(uintptr(loaded.entry))
ac.SetStack(uintptr(stack.Bottom))
- name := path.Base(filename)
+ name := path.Base(args.Filename)
if len(name) > linux.TASK_COMM_LEN-1 {
name = name[:linux.TASK_COMM_LEN-1]
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 16:22:12 +0000