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* Before starting a build under some uid, kill all current processes

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running under that uid.
This commit is contained in:
Eelco Dolstra 2005-10-17 17:35:37 +00:00
parent 439823ae80
commit f1b3a418fa
1 changed files with 48 additions and 0 deletions
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48
src/libstore/build.cc
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@ -312,6 +312,50 @@ const char * * strings2CharPtrs(const Strings & ss)
}
static void killUser(uid_t uid)
{
debug(format("killing all processes running under uid `%1%'") % uid);
assert(uid != rootUserId); /* just to be safe... */
/* The system call kill(-1, sig) sends the signal `sig' to all
users to which the current process can send signals. So we
fork a process, switch to uid, and send a mass kill. */
Pid pid;
pid = fork();
switch (pid) {
case -1:
throw SysError("unable to fork");
case 0:
try { /* child */
if (setuid(uid) == -1) abort();
if (kill(-1, SIGKILL) == -1)
throw SysError(format("cannot kill processes for UID `%1%'") % uid);
} catch (exception & e) {
cerr << format("build error: %1%\n") % e.what();
_exit(1);
}
_exit(0);
}
/* parent */
if (pid.wait(true) != 0)
throw Error(format("cannot kill processes for UID `%1%'") % uid);
/* !!! We should really do some check to make sure that there are
no processes left running under `uid', but there is no portable
way to do so (I think). The most reliable way may be `ps -eo
uid | grep -q $uid'. */
}
//////////////////////////////////////////////////////////////////////
@ -1075,6 +1119,10 @@ void DerivationGoal::startBuilder()
getuid() == rootUserId)
{
buildUser = allocBuildUser();
/* Make sure that no other processes are executing under this
uid. */
killUser(buildUser);
/* Change ownership of the temporary build directory. !!! gid */
if (chown(tmpDir.c_str(), buildUser, (gid_t) -1) == -1)