diff options
Diffstat (limited to 'pkg/sentry')
| -rw-r--r-- | pkg/sentry/control/proc.go | 18 | ||||
| -rw-r--r-- | pkg/sentry/fs/mounts.go | 66 |
2 files changed, 83 insertions, 1 deletions
diff --git a/pkg/sentry/control/proc.go b/pkg/sentry/control/proc.go index 6949a3ae5..289b8ba0e 100644 --- a/pkg/sentry/control/proc.go +++ b/pkg/sentry/control/proc.go @@ -54,6 +54,11 @@ type ExecArgs struct { // Envv is a list of environment variables. Envv []string `json:"envv"` + // Root defines the root directory for the new process. A reference on + // Root must be held for the lifetime of the ExecArgs. If Root is nil, + // it will default to the VFS root. + Root *fs.Dirent + // WorkingDirectory defines the working directory for the new process. WorkingDirectory string `json:"wd"` @@ -99,6 +104,7 @@ func (proc *Proc) Exec(args *ExecArgs, waitStatus *uint32) error { Argv: args.Argv, Envv: args.Envv, WorkingDirectory: args.WorkingDirectory, + Root: args.Root, Credentials: creds, FDMap: fdm, Umask: 0022, @@ -109,8 +115,18 @@ func (proc *Proc) Exec(args *ExecArgs, waitStatus *uint32) error { AbstractSocketNamespace: proc.Kernel.RootAbstractSocketNamespace(), } ctx := initArgs.NewContext(proc.Kernel) - mounter := fs.FileOwnerFromContext(ctx) + if initArgs.Filename == "" { + // Get the full path to the filename from the PATH env variable. + paths := fs.GetPath(initArgs.Envv) + f, err := proc.Kernel.RootMountNamespace().ResolveExecutablePath(ctx, initArgs.WorkingDirectory, initArgs.Argv[0], paths) + if err != nil { + return fmt.Errorf("error finding executable %q in PATH %v: %v", initArgs.Argv[0], paths, err) + } + initArgs.Filename = f + } + + mounter := fs.FileOwnerFromContext(ctx) for appFD, f := range args.FilePayload.Files { enableIoctl := args.StdioIsPty && appFD <= 2 diff --git a/pkg/sentry/fs/mounts.go b/pkg/sentry/fs/mounts.go index 0318f135d..c0a803b2d 100644 --- a/pkg/sentry/fs/mounts.go +++ b/pkg/sentry/fs/mounts.go @@ -16,9 +16,13 @@ package fs import ( "fmt" + "path" + "strings" "sync" "syscall" + "gvisor.googlesource.com/gvisor/pkg/abi/linux" + "gvisor.googlesource.com/gvisor/pkg/log" "gvisor.googlesource.com/gvisor/pkg/refs" "gvisor.googlesource.com/gvisor/pkg/sentry/context" "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth" @@ -509,3 +513,65 @@ func (mns *MountNamespace) SyncAll(ctx context.Context) { defer mns.mu.Unlock() mns.root.SyncAll(ctx) } + +// ResolveExecutablePath resolves the given executable name given a set of +// paths that might contain it. +func (mns *MountNamespace) ResolveExecutablePath(ctx context.Context, wd, name string, paths []string) (string, error) { + // Absolute paths can be used directly. + if path.IsAbs(name) { + return name, nil + } + + // Paths with '/' in them should be joined to the working directory, or + // to the root if working directory is not set. + if strings.IndexByte(name, '/') > 0 { + if wd == "" { + wd = "/" + } + if !path.IsAbs(wd) { + return "", fmt.Errorf("working directory %q must be absolute", wd) + } + return path.Join(wd, name), nil + } + + // Otherwise, We must lookup the name in the paths, starting from the + // calling context's root directory. + root := RootFromContext(ctx) + if root == nil { + // Caller has no root. Don't bother traversing anything. + return "", syserror.ENOENT + } + defer root.DecRef() + for _, p := range paths { + binPath := path.Join(p, name) + d, err := mns.FindInode(ctx, root, nil, binPath, linux.MaxSymlinkTraversals) + if err == syserror.ENOENT || err == syserror.EACCES { + // Didn't find it here. + continue + } + if err != nil { + return "", err + } + defer d.DecRef() + + // Check whether we can read and execute the found file. + if err := d.Inode.CheckPermission(ctx, PermMask{Read: true, Execute: true}); err != nil { + log.Infof("Found executable at %q, but user cannot execute it: %v", binPath, err) + continue + } + return path.Join("/", p, name), nil + } + return "", syserror.ENOENT +} + +// GetPath returns the PATH as a slice of strings given the environemnt +// variables. +func GetPath(env []string) []string { + const prefix = "PATH=" + for _, e := range env { + if strings.HasPrefix(e, prefix) { + return strings.Split(strings.TrimPrefix(e, prefix), ":") + } + } + return nil +} |