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Fix Softnet SUID setup commands #1273

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Fix Softnet SUID setup commands #1273

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48 changes: 36 additions & 12 deletions Sources/tart/Network/Softnet.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -170,9 +170,9 @@ class Softnet: Network {
throw SoftnetError.InitializationFailed(why: "\(sudoBinaryName) not found in PATH")
}

var process = Process()
let process = Process()
process.executableURL = sudoExecutableURL
process.arguments = ["--non-interactive", "softnet", "--help"]
process.arguments = ["--non-interactive", softnetExecutablePath, "--help"]
process.standardInput = nil
process.standardOutput = nil
process.standardError = nil
Expand All @@ -187,24 +187,48 @@ class Softnet: Network {
fputs("Softnet requires a Sudo password to set the SUID bit on the Softnet executable, please enter it below.\n",
stderr)

process = try Process.run(sudoExecutableURL, arguments: [
"sh",
"-c",
"chown root \(softnetExecutablePath) && chmod u+s \(softnetExecutablePath)",
])
try runInteractiveSudo(
executableURL: sudoExecutableURL,
arguments: ["chown", "root", softnetExecutablePath],
failureMessage: "failed to change ownership of Softnet executable with Sudo")

// Set TTY's foreground process group to that of the Sudo process,
// otherwise it will get stopped by a SIGTTIN once user input arrives
if tcsetpgrp(STDIN_FILENO, process.processIdentifier) == -1 {
try runInteractiveSudo(
executableURL: sudoExecutableURL,
arguments: ["chmod", "u+s", softnetExecutablePath],
failureMessage: "failed to configure SUID bit on Softnet executable with Sudo")
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}

private static func runInteractiveSudo(executableURL: URL, arguments: [String], failureMessage: String) throws {
let originalForegroundProcessGroup = tcgetpgrp(STDIN_FILENO)
if originalForegroundProcessGroup == -1 {
let details = Errno(rawValue: CInt(errno))

throw RuntimeError.SoftnetFailed("tcsetpgrp(2) failed: \(details)")
throw RuntimeError.SoftnetFailed("tcgetpgrp(2) failed: \(details)")
}

let process = try Process.run(executableURL, arguments: arguments)

// Set TTY's foreground process group to that of the Sudo process,
// otherwise it will get stopped by a SIGTTIN once user input arrives
try setTerminalForegroundProcessGroup(process.processIdentifier)

process.waitUntilExit()

try setTerminalForegroundProcessGroup(originalForegroundProcessGroup)

if process.terminationStatus != 0 {
throw RuntimeError.SoftnetFailed("failed to configure SUID bit on Softnet executable with Sudo")
throw RuntimeError.SoftnetFailed(failureMessage)
}
}

private static func setTerminalForegroundProcessGroup(_ processGroup: pid_t) throws {
let previousSIGTTOUHandler = signal(SIGTTOU, SIG_IGN)
defer { _ = signal(SIGTTOU, previousSIGTTOUHandler) }

if tcsetpgrp(STDIN_FILENO, processGroup) == -1 {
let details = Errno(rawValue: CInt(errno))

throw RuntimeError.SoftnetFailed("tcsetpgrp(2) failed: \(details)")
}
}
}