| 1 | //go:build !windows |
| 2 | |
| 3 | package config |
| 4 | |
| 5 | import ( |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "os" |
| 9 | "syscall" |
| 10 | ) |
| 11 | |
| 12 | func credentialPlatformInspect(_ string, info os.FileInfo) (string, bool, bool, bool, error) { |
| 13 | stat, ok := info.Sys().(*syscall.Stat_t) |
| 14 | if !ok { |
| 15 | return "owner unavailable", false, info.Mode().Perm()&0o200 == 0, false, fmt.Errorf("owner information unavailable") |
| 16 | } |
| 17 | current := int(stat.Uid) == os.Geteuid() |
| 18 | return fmt.Sprintf("uid %d (current uid %d)", stat.Uid, os.Geteuid()), current, info.Mode().Perm()&0o200 == 0, false, nil |
| 19 | } |
| 20 | |
| 21 | func credentialPlatformRepair(path string, expected os.FileInfo, verify func() error) ([]string, error) { |
| 22 | // Mutate the inspected inode, never a path that can be replaced between |
| 23 | // inspection, chmod and rollback. No-follow and nonblocking reject links/FIFOs. |
| 24 | f, err := os.OpenFile(path, os.O_RDONLY|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0) |
| 25 | if err != nil { |
| 26 | return nil, err |
| 27 | } |
| 28 | defer f.Close() |
| 29 | info, err := f.Stat() |
| 30 | if err != nil { |
| 31 | return nil, err |
| 32 | } |
| 33 | if !os.SameFile(expected, info) { |
| 34 | return nil, fmt.Errorf("credential file identity changed") |
| 35 | } |
| 36 | _, owned, _, _, err := credentialPlatformInspect(path, info) |
| 37 | if err != nil || !owned { |
| 38 | return nil, fmt.Errorf("credential owner could not be verified") |
| 39 | } |
| 40 | before := info.Mode().Perm() |
| 41 | after := before | 0o600 |
| 42 | if err := f.Chmod(after); err != nil { |
| 43 | return nil, err |
| 44 | } |
| 45 | actions := []string{} |
| 46 | if after != before { |
| 47 | actions = append(actions, "added owner read/write permission") |
| 48 | } |
| 49 | if err := verify(); err != nil { |
| 50 | if rollbackErr := f.Chmod(before); rollbackErr != nil { |
| 51 | return nil, errors.Join( |
| 52 | fmt.Errorf("verification failed: %w", err), |
| 53 | fmt.Errorf("rollback failed: %w", rollbackErr), |
| 54 | ) |
| 55 | } |
| 56 | return nil, fmt.Errorf("verification failed: %w; changed attributes were restored", err) |
| 57 | } |
| 58 | return actions, nil |
| 59 | } |
| 60 |