jochen
021d860ca4
The records send the operator to "the controller's terminal", and nothing reaches it (hq issue 343). mesh-cli holds no credential: it asks the engine on its own machine over a socket. The engine reads the asking account from the kernel (SO_PEERCRED), never from the program, and asks the controller on mesh.control.<node>.cli, its own node's subject, so the bus server says which node asked. The controller decides what the line may do; nothing received on the socket is run or applied here, and the socket has no network address (ADR 0004 stands). The local protocol is the SDK's go/cli package, at a pseudo-version of its branch until that merges and is tagged go/v0.1.8.
51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
//go:build linux
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package meshcli
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import (
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"errors"
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"fmt"
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"net"
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"os"
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"syscall"
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)
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// peerCredentials is the user id of the process at the other end, as the kernel recorded it when it connected
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// (SO_PEERCRED). Nothing the process says is read.
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func peerCredentials(conn *net.UnixConn) (uint32, error) {
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raw, err := conn.SyscallConn()
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if err != nil {
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return 0, err
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}
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var cred *syscall.Ucred
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var inner error
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if err := raw.Control(func(fd uintptr) {
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cred, inner = syscall.GetsockoptUcred(int(fd), syscall.SOL_SOCKET, syscall.SO_PEERCRED)
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}); err != nil {
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return 0, err
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}
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if inner != nil {
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return 0, inner
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}
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if cred == nil {
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return 0, errors.New("the kernel gave no credentials")
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}
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return cred.Uid, nil
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}
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// notOwnDirectory says what is wrong with the socket's directory, or nothing: it must be a directory, not a
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// link, owned by the account the engine runs as.
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func notOwnDirectory(dir string) string {
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info, err := os.Lstat(dir)
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if err != nil {
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return err.Error()
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}
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if info.Mode()&os.ModeSymlink != 0 || !info.IsDir() {
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return dir + " is not a directory the engine made"
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}
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if st, ok := info.Sys().(*syscall.Stat_t); ok && int(st.Uid) != os.Geteuid() {
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return fmt.Sprintf("%s belongs to user id %d, not to the engine's account", dir, st.Uid)
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}
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return ""
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}
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