| 1 | package host |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "errors" |
| 6 | "io" |
| 7 | "os" |
| 8 | "path/filepath" |
| 9 | |
| 10 | "github.com/carlosframework/platform/internal/instancectl" |
| 11 | "github.com/carlosframework/platform/internal/rootstate" |
| 12 | "github.com/carlosframework/platform/internal/safefile" |
| 13 | "golang.org/x/sys/unix" |
| 14 | ) |
| 15 | |
| 16 | type claimUnitFiles struct{ dir string } |
| 17 | |
| 18 | func (f claimUnitFiles) read(unit string) ([]byte, rootstate.FileIdentity, error) { |
| 19 | if !instancectl.ValidBoundClaimUnit(unit) { |
| 20 | return nil, rootstate.FileIdentity{}, os.ErrPermission |
| 21 | } |
| 22 | file, err := rootstate.OpenTrustedFile(filepath.Join(f.dir, unit)) |
| 23 | if err != nil { |
| 24 | return nil, rootstate.FileIdentity{}, err |
| 25 | } |
| 26 | defer file.Close() |
| 27 | raw, err := io.ReadAll(io.LimitReader(file, rootstate.MaxRecord+1)) |
| 28 | if err != nil { |
| 29 | return nil, rootstate.FileIdentity{}, err |
| 30 | } |
| 31 | if len(raw) > rootstate.MaxRecord { |
| 32 | return nil, rootstate.FileIdentity{}, os.ErrPermission |
| 33 | } |
| 34 | id, err := rootstate.PersistentIdentity(file) |
| 35 | return raw, id, err |
| 36 | } |
| 37 | func (f claimUnitFiles) create(unit string, body []byte) error { |
| 38 | return f.write(unit, rootstate.FileIdentity{}, body) |
| 39 | } |
| 40 | func (f claimUnitFiles) replace(unit string, id rootstate.FileIdentity, body []byte) error { |
| 41 | if id == (rootstate.FileIdentity{}) { |
| 42 | return os.ErrPermission |
| 43 | } |
| 44 | return f.write(unit, id, body) |
| 45 | } |
| 46 | func (f claimUnitFiles) write(unit string, id rootstate.FileIdentity, body []byte) error { |
| 47 | if !instancectl.ValidBoundClaimUnit(unit) { |
| 48 | return os.ErrPermission |
| 49 | } |
| 50 | checked, err := rootstate.Open(f.dir, false, true) |
| 51 | if err != nil { |
| 52 | return err |
| 53 | } |
| 54 | defer checked.Close() |
| 55 | parent, err := safefile.OpenDir(f.dir) |
| 56 | if err != nil { |
| 57 | return err |
| 58 | } |
| 59 | defer parent.Close() |
| 60 | tmp, err := os.CreateTemp(f.dir, ".claim-unit-") |
| 61 | if err != nil { |
| 62 | return err |
| 63 | } |
| 64 | name := filepath.Base(tmp.Name()) |
| 65 | defer unix.Unlinkat(int(parent.Fd()), name, 0) |
| 66 | _, err = tmp.Write(body) |
| 67 | if err == nil { |
| 68 | err = tmp.Chmod(0644) |
| 69 | } |
| 70 | if err == nil { |
| 71 | err = tmp.Sync() |
| 72 | } |
| 73 | if err = errors.Join(err, tmp.Close()); err != nil { |
| 74 | return err |
| 75 | } |
| 76 | flags := uint(unix.RENAME_NOREPLACE) |
| 77 | if id != (rootstate.FileIdentity{}) { |
| 78 | _, current, err := f.read(unit) |
| 79 | if err != nil { |
| 80 | return err |
| 81 | } |
| 82 | if !current.Same(id) { |
| 83 | return os.ErrPermission |
| 84 | } |
| 85 | flags = 0 |
| 86 | } |
| 87 | if err = unix.Renameat2(int(parent.Fd()), name, int(parent.Fd()), unit, flags); err != nil { |
| 88 | return err |
| 89 | } |
| 90 | if err = parent.Sync(); err != nil { |
| 91 | return err |
| 92 | } |
| 93 | got, _, err := f.read(unit) |
| 94 | if err != nil { |
| 95 | return err |
| 96 | } |
| 97 | if !bytes.Equal(got, body) { |
| 98 | return os.ErrPermission |
| 99 | } |
| 100 | return nil |
| 101 | } |
| 102 | |
| 103 | // The flat name is only a routing projection. Root launch and containment |
| 104 | // retain the binding and the private run directory independently of it. |
| 105 | func projectClaimBoundSocket(s claimUnitShape) error { |
| 106 | if !claimFlatSocket(s) { |
| 107 | return nil |
| 108 | } |
| 109 | parent, err := safefile.OpenDir(filepath.Dir(s.Socket)) |
| 110 | if err != nil { |
| 111 | return err |
| 112 | } |
| 113 | defer parent.Close() |
| 114 | name := filepath.Base(s.Socket) |
| 115 | target := claimSocketTarget(s) |
| 116 | if err := unix.Symlinkat(target, int(parent.Fd()), name); err != nil { |
| 117 | if !errors.Is(err, unix.EEXIST) { |
| 118 | return err |
| 119 | } |
| 120 | var buf [4096]byte |
| 121 | n, err := unix.Readlinkat(int(parent.Fd()), name, buf[:]) |
| 122 | if err != nil { |
| 123 | return err |
| 124 | } |
| 125 | if string(buf[:n]) != target { |
| 126 | return os.ErrPermission |
| 127 | } |
| 128 | } |
| 129 | return parent.Sync() |
| 130 | } |
| 131 | |
amadan