lix/src/libmain/shared.cc
Eelco Dolstra 5396304c73 * Use setre[ug]id() instead of setres[ug]id(), since the former is
more common than the latter (which exists only on Linux and
  FreeBSD).  We don't really care about dropping the saved IDs since
  there apparently is no way to quiry them in any case, so it can't
  influence the build (unlike the effective IDs which are checked by
  Perl for instance).
2004-09-09 15:55:31 +00:00

309 lines
8.9 KiB
C++

#include <iostream>
#include <cctype>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
extern "C" {
#include <aterm2.h>
}
#include "globals.hh"
#include "shared.hh"
#include "config.h"
volatile sig_atomic_t blockInt = 0;
void sigintHandler(int signo)
{
if (!blockInt) {
_isInterrupted = 1;
blockInt = 1;
}
}
void setLogType(string lt)
{
if (lt == "pretty") logType = ltPretty;
else if (lt == "escapes") logType = ltEscapes;
else if (lt == "flat") logType = ltFlat;
else throw UsageError("unknown log type");
}
void checkStoreNotSymlink(Path path)
{
struct stat st;
while (path.size()) {
if (lstat(path.c_str(), &st))
throw SysError(format("getting status of `%1%'") % path);
if (S_ISLNK(st.st_mode))
throw Error(format(
"the path `%1%' is a symlink; "
"this is not allowed for the Nix store and its parent directories")
% path);
path = dirOf(path);
}
}
/* Initialize and reorder arguments, then call the actual argument
processor. */
static void initAndRun(int argc, char * * argv)
{
string root = getEnv("NIX_ROOT");
if (root != "") {
if (chroot(root.c_str()) != 0)
throw SysError(format("changing root to `%1%'") % root);
}
/* Setup Nix paths. */
nixStore = getEnv("NIX_STORE_DIR", canonPath(NIX_STORE_DIR));
nixDataDir = getEnv("NIX_DATA_DIR", canonPath(NIX_DATA_DIR));
nixLogDir = getEnv("NIX_LOG_DIR", canonPath(NIX_LOG_DIR));
nixStateDir = getEnv("NIX_STATE_DIR", canonPath(NIX_STATE_DIR));
nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
/* Check that the store directory and its parent are not
symlinks. */
if (getEnv("NIX_IGNORE_SYMLINK_STORE") != "1")
checkStoreNotSymlink(nixStore);
/* Catch SIGINT. */
struct sigaction act, oact;
act.sa_handler = sigintHandler;
sigfillset(&act.sa_mask);
act.sa_flags = 0;
if (sigaction(SIGINT, &act, &oact))
throw SysError("installing handler for SIGINT");
/* Ignore SIGPIPE. */
act.sa_handler = SIG_IGN;
act.sa_flags = 0;
if (sigaction(SIGPIPE, &act, &oact))
throw SysError("ignoring SIGPIPE");
/* There is no privacy in the Nix system ;-) At least not for
now. In particular, store objects should be readable by
everybody. This prevents nasty surprises when using a shared
store (with the setuid() hack). */
umask(0022);
/* Process the NIX_LOG_TYPE environment variable. */
string lt = getEnv("NIX_LOG_TYPE");
if (lt != "") setLogType(lt);
/* Put the arguments in a vector. */
Strings args, remaining;
while (argc--) args.push_back(*argv++);
args.erase(args.begin());
/* Expand compound dash options (i.e., `-qlf' -> `-q -l -f'), and
ignore options for the ATerm library. */
for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
string arg = *i;
if (string(arg, 0, 4) == "-at-") ;
else if (arg.length() > 2 && arg[0] == '-' && arg[1] != '-') {
for (unsigned int j = 1; j < arg.length(); j++)
if (isalpha(arg[j]))
remaining.push_back((string) "-" + arg[j]);
else {
remaining.push_back(string(arg, j));
break;
}
} else remaining.push_back(arg);
}
args = remaining;
remaining.clear();
/* Process default options. */
for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
string arg = *i;
if (arg == "--verbose" || arg == "-v")
verbosity = (Verbosity) ((int) verbosity + 1);
else if (arg == "--log-type") {
++i;
if (i == args.end()) throw UsageError("`--log-type' requires an argument");
setLogType(*i);
}
else if (arg == "--build-output" || arg == "-B")
; /* !!! obsolete - remove eventually */
else if (arg == "--no-build-output" || arg == "-Q")
buildVerbosity = lvlVomit;
else if (arg == "--help") {
printHelp();
return;
}
else if (arg == "--version") {
cout << format("%1% (Nix) %2%") % programId % NIX_VERSION << endl;
return;
}
else if (arg == "--keep-failed" || arg == "-K")
keepFailed = true;
else if (arg == "--keep-going" || arg == "-k")
keepGoing = true;
else if (arg == "--fallback")
tryFallback = true;
else if (arg == "--max-jobs" || arg == "-j") {
++i;
if (i == args.end()) throw UsageError("`--max-jobs' requires an argument");
istringstream str(*i);
int n;
str >> n;
if (!str || !str.eof() || n < 0)
throw UsageError(format("`--max-jobs' requires a non-negative integer"));
maxBuildJobs = n;
}
else remaining.push_back(arg);
}
run(remaining);
}
#if HAVE_SETREUID
#define _setuid(uid) setreuid(uid, uid)
#define _setgid(gid) setregid(gid, gid)
#else
/* Only works properly when run by root. */
#define _setuid(uid) setuid(uid)
#define _setgid(gid) setgid(gid)
#endif
void switchToNixUser()
{
#if SETUID_HACK
/* Don't do anything if this is not a setuid binary. */
if (getuid() == geteuid() && getgid() == getegid()) return;
/* Here we set the uid and gid to the Nix user and group,
respectively, IF the current (real) user is a member of the Nix
group. Otherwise we just drop all privileges. */
/* Lookup the Nix gid. */
struct group * gr = getgrnam(NIX_GROUP);
if (!gr) {
cerr << format("missing group `%1%'\n") % NIX_GROUP;
exit(1);
}
/* Get the supplementary group IDs for the current user. */
int maxGids = 512, nrGids;
gid_t gids[maxGids];
if ((nrGids = getgroups(maxGids, gids)) == -1) {
cerr << format("unable to query gids\n");
exit(1);
}
/* !!! Apparently it is unspecified whether getgroups() includes
the effective gid. In that case the following test is always
true *if* the program is installed setgid (which we do when we
have setreuid()). On Linux this doesn't appear to be the
case, but we should switch to the real gid before doing this
test, and then switch back to the saved gid. */
/* Check that the current user is a member of the Nix group. */
bool found = false;
for (int i = 0; i < nrGids; ++i)
if (gids[i] == gr->gr_gid) {
found = true;
break;
}
if (!found) {
/* Not in the Nix group - drop all root/Nix privileges. */
_setgid(getgid());
_setuid(getuid());
return;
}
/* Set the real, effective and saved gids to gr->gr_gid. Also
make very sure that this succeeded. We switch the gid first
because we cannot do it after we have dropped root uid. */
if (_setgid(gr->gr_gid) != 0 ||
getgid() != gr->gr_gid ||
getegid() != gr->gr_gid)
{
cerr << format("unable to set gid to `%1%'\n") % NIX_GROUP;
exit(1);
}
/* Lookup the Nix uid. */
struct passwd * pw = getpwnam(NIX_USER);
if (!pw) {
cerr << format("missing user `%1%'\n") % NIX_USER;
exit(1);
}
/* This will drop all root privileges, setting the real, effective
and saved uids to pw->pw_uid. Also make very sure that this
succeeded.*/
if (_setuid(pw->pw_uid) != 0 ||
getuid() != pw->pw_uid ||
geteuid() != pw->pw_uid)
{
cerr << format("unable to set uid to `%1%'\n") % NIX_USER;
exit(1);
}
#endif
}
static char buf[1024];
int main(int argc, char * * argv)
{
/* If we are setuid root, we have to get rid of the excess
privileges ASAP. */
switchToNixUser();
/* ATerm setup. */
ATerm bottomOfStack;
ATinit(argc, argv, &bottomOfStack);
/* Turn on buffering for cerr. */
#if HAVE_PUBSETBUF
cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));
#endif
try {
try {
initAndRun(argc, argv);
} catch (...) {
/* Subtle: we have to make sure that any `interrupted'
condition is discharged before we reach printMsg()
below, since otherwise it will throw an (uncaught)
exception. */
blockInt = 1; /* ignore further SIGINTs */
_isInterrupted = 0;
throw;
}
} catch (UsageError & e) {
printMsg(lvlError,
format(
"error: %1%\n"
"Try `%2% --help' for more information.")
% e.what() % programId);
return 1;
} catch (Error & e) {
printMsg(lvlError, format("error: %1%") % e.msg());
return 1;
} catch (exception & e) {
printMsg(lvlError, format("error: %1%") % e.what());
return 1;
}
return 0;
}