119 lines
3 KiB
C++
119 lines
3 KiB
C++
#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <pwd.h>
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#include <grp.h>
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#include <iostream>
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#include <vector>
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#include "util.hh"
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#include "../libmain/setuid-common.hh"
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using namespace nix;
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static void secureChown(uid_t uidTarget, gid_t gidTarget,
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const Path & path)
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{
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/* Recursively chown `path' to the specified uid and gid, but only
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if it is currently owned by the Nix account. */
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/* !!! */
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}
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static void runBuilder(string userName,
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string program, int argc, char * * argv)
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{
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struct passwd * pw = getpwnam(userName.c_str());
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if (!pw)
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throw Error(format("the user `%1%' does not exist") % userName);
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gid_t gidBuilders = 1234;
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/* Chown the current directory, *if* it is owned by the Nix
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account. The idea is that the current directory is the
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temporary build directory in /tmp or somewhere else, and we
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don't want to create that directory here. */
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secureChown(pw->pw_uid, gidBuilders, ".");
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/* Set the real, effective and saved gid. Must be done before
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setuid(), otherwise it won't set the real and saved gids. */
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//setgid(gidBuilders);
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/* Set the real, effective and saved uid. */
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setuid(pw->pw_uid);
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if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
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throw Error("cannot setuid");
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/* Execute the program. */
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std::vector<const char *> args;
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args.push_back(program.c_str());
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for (int i = 0; i < argc; ++i)
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args.push_back(argv[i]);
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args.push_back(0);
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if (execve(program.c_str(), (char * *) &args[0], 0) == -1)
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throw SysError(format("cannot execute `%1%'") % program);
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}
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static void run(int argc, char * * argv)
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{
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char * * oldEnviron = environ;
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setuidCleanup();
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if (geteuid() != 0)
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throw Error("nix-setuid-wrapper must be setuid root");
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/* Read the configuration file. It should consist of two words:
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<nix-user-name> <nix-builders-group>
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The first is the privileged account under which the main Nix
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processes run (i.e., the supposed caller). It should match our
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real uid. The second is the Unix group to which the Nix
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builders belong (and nothing else!). */
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/* !!! */
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/* Make sure that we are called by the Nix account, not by someone
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else. */
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// ...
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/* Perform the desired command. */
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if (argc < 2)
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throw Error("invalid arguments");
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string command(argv[1]);
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if (command == "run-builder") {
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/* Syntax: nix-setuid-helper run-builder <username> <program>
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<args...> */
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if (argc < 4) throw Error("missing user name / program name");
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runBuilder(argv[2], argv[3], argc - 4, argv + 4);
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}
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else if (command == "fix-ownership") {
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/* Syntax: nix-setuid-helper <fix-ownership> <path> */
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}
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else throw Error ("invalid command");
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}
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int main(int argc, char * * argv)
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{
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try {
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run(argc, argv);
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} catch (Error & e) {
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std::cerr << e.msg() << std::endl;
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return 1;
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}
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}
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