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-rw-r--r--nix/libstore/build.cc171
1 files changed, 86 insertions, 85 deletions
diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 009fcb2c0c..85a818ba94 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -38,6 +38,9 @@
#if HAVE_SYS_MOUNT_H
#include <sys/mount.h>
#endif
+#if HAVE_SYS_SYSCALL_H
+#include <sys/syscall.h>
+#endif
#if HAVE_SCHED_H
#include <sched.h>
#endif
@@ -48,7 +51,7 @@
#include <linux/fs.h>
#endif
-#define CHROOT_ENABLED HAVE_CHROOT && HAVE_UNSHARE && HAVE_SYS_MOUNT_H && defined(MS_BIND) && defined(MS_PRIVATE) && defined(CLONE_NEWNS)
+#define CHROOT_ENABLED HAVE_CHROOT && HAVE_UNSHARE && HAVE_SYS_MOUNT_H && defined(MS_BIND) && defined(MS_PRIVATE) && defined(CLONE_NEWNS) && defined(SYS_pivot_root)
#if CHROOT_ENABLED
#include <sys/socket.h>
@@ -414,19 +417,6 @@ static void commonChildInit(Pipe & logPipe)
close(fdDevNull);
}
-
-/* Convert a string list to an array of char pointers. Careful: the
- string list should outlive the array. */
-const char * * strings2CharPtrs(const Strings & ss)
-{
- const char * * arr = new const char * [ss.size() + 1];
- const char * * p = arr;
- foreach (Strings::const_iterator, i, ss) *p++ = i->c_str();
- *p = 0;
- return arr;
-}
-
-
/* Restore default handling of SIGPIPE, otherwise some programs will
randomly say "Broken pipe". */
static void restoreSIGPIPE()
@@ -764,7 +754,7 @@ private:
typedef void (DerivationGoal::*GoalState)();
GoalState state;
- /* Stuff we need to pass to initChild(). */
+ /* Stuff we need to pass to runChild(). */
typedef map<Path, Path> DirsInChroot; // maps target path to source path
DirsInChroot dirsInChroot;
typedef map<string, string> Environment;
@@ -828,8 +818,8 @@ private:
/* Start building a derivation. */
void startBuilder();
- /* Initialise the builder's process. */
- void initChild();
+ /* Run the builder's process. */
+ void runChild();
friend int childEntry(void *);
@@ -1612,7 +1602,7 @@ void chmod_(const Path & path, mode_t mode)
int childEntry(void * arg)
{
- ((DerivationGoal *) arg)->initChild();
+ ((DerivationGoal *) arg)->runChild();
return 1;
}
@@ -1759,37 +1749,11 @@ void DerivationGoal::startBuilder()
/* Change ownership of the temporary build directory. */
if (chown(tmpDir.c_str(), buildUser.getUID(), buildUser.getGID()) == -1)
- throw SysError(format("cannot change ownership of `%1%'") % tmpDir);
+ throw SysError(format("cannot change ownership of '%1%'") % tmpDir);
+ }
- /* Check that the Nix store has the appropriate permissions,
- i.e., owned by root and mode 1775 (sticky bit on so that
- the builder can create its output but not mess with the
- outputs of other processes). */
- struct stat st;
- if (stat(settings.nixStore.c_str(), &st) == -1)
- throw SysError(format("cannot stat `%1%'") % settings.nixStore);
- if (!(st.st_mode & S_ISVTX) ||
- ((st.st_mode & S_IRWXG) != S_IRWXG) ||
- (st.st_gid != buildUser.getGID()))
- throw Error(format(
- "builder does not have write permission to `%2%'; "
- "try `chgrp %1% %2%; chmod 1775 %2%'")
- % buildUser.getGID() % settings.nixStore);
- }
-
-
- /* Are we doing a chroot build? Note that fixed-output
- derivations are never done in a chroot, mainly so that
- functions like fetchurl (which needs a proper /etc/resolv.conf)
- work properly. Purity checking for fixed-output derivations
- is somewhat pointless anyway. */
useChroot = settings.useChroot;
- if (fixedOutput) useChroot = false;
-
- /* Hack to allow derivations to disable chroot builds. */
- if (get(drv.env, "__noChroot") == "1") useChroot = false;
-
if (useChroot) {
#if CHROOT_ENABLED
/* Create a temporary directory in which we set up the chroot
@@ -1804,6 +1768,12 @@ void DerivationGoal::startBuilder()
printMsg(lvlChatty, format("setting up chroot environment in `%1%'") % chrootRootDir);
+ if (mkdir(chrootRootDir.c_str(), 0750) == -1)
+ throw SysError(format("cannot create ‘%1%’") % chrootRootDir);
+
+ if (chown(chrootRootDir.c_str(), 0, buildUser.getGID()) == -1)
+ throw SysError(format("cannot change ownership of ‘%1%’") % chrootRootDir);
+
/* Create a writable /tmp in the chroot. Many builders need
this. (Of course they should really respect $TMPDIR
instead.) */
@@ -1830,7 +1800,8 @@ void DerivationGoal::startBuilder()
% (buildUser.enabled() ? buildUser.getGID() : getgid())).str());
/* Create /etc/hosts with localhost entry. */
- writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n");
+ if (!fixedOutput)
+ writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n");
/* Bind-mount a user-configurable set of directories from the
host file system. */
@@ -1853,8 +1824,12 @@ void DerivationGoal::startBuilder()
can be bind-mounted). !!! As an extra security
precaution, make the fake Nix store only writable by the
build user. */
- createDirs(chrootRootDir + settings.nixStore);
- chmod_(chrootRootDir + settings.nixStore, 01777);
+ Path chrootStoreDir = chrootRootDir + settings.nixStore;
+ createDirs(chrootStoreDir);
+ chmod_(chrootStoreDir, 01775);
+
+ if (chown(chrootStoreDir.c_str(), 0, buildUser.getGID()) == -1)
+ throw SysError(format("cannot change ownership of ‘%1%’") % chrootStoreDir);
foreach (PathSet::iterator, i, inputPaths) {
struct stat st;
@@ -1963,14 +1938,17 @@ void DerivationGoal::startBuilder()
*/
#if CHROOT_ENABLED
if (useChroot) {
- char stack[32 * 1024];
- pid = clone(childEntry, stack + sizeof(stack) - 8,
- CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWNET | CLONE_NEWIPC | CLONE_NEWUTS | SIGCHLD, this);
+ char stack[32 * 1024];
+ int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS | SIGCHLD;
+ if (!fixedOutput) flags |= CLONE_NEWNET;
+ pid = clone(childEntry, stack + sizeof(stack) - 8, flags, this);
+ if (pid == -1)
+ throw SysError("cloning builder process");
} else
#endif
{
pid = fork();
- if (pid == 0) initChild();
+ if (pid == 0) runChild();
}
if (pid == -1) throw SysError("unable to fork");
@@ -1993,7 +1971,7 @@ void DerivationGoal::startBuilder()
}
-void DerivationGoal::initChild()
+void DerivationGoal::runChild()
{
/* Warning: in the child we should absolutely not make any SQLite
calls! */
@@ -2022,9 +2000,11 @@ void DerivationGoal::initChild()
/* Set the hostname etc. to fixed values. */
char hostname[] = "localhost";
- sethostname(hostname, sizeof(hostname));
+ if (sethostname(hostname, sizeof(hostname)) == -1)
+ throw SysError("cannot set host name");
char domainname[] = "(none)"; // kernel default
- setdomainname(domainname, sizeof(domainname));
+ if (setdomainname(domainname, sizeof(domainname)) == -1)
+ throw SysError("cannot set domain name");
/* Make all filesystems private. This is necessary
because subtrees may have been mounted as "shared"
@@ -2042,12 +2022,17 @@ void DerivationGoal::initChild()
throw SysError(format("unable to make filesystem `%1%' private") % fs);
}
+ /* Bind-mount chroot directory to itself, to treat it as a
+ different filesystem from /, as needed for pivot_root. */
+ if (mount(chrootRootDir.c_str(), chrootRootDir.c_str(), 0, MS_BIND, 0) == -1)
+ throw SysError(format("unable to bind mount ‘%1%’") % chrootRootDir);
+
/* Set up a nearly empty /dev, unless the user asked to
bind-mount the host /dev. */
+ Strings ss;
if (dirsInChroot.find("/dev") == dirsInChroot.end()) {
createDirs(chrootRootDir + "/dev/shm");
createDirs(chrootRootDir + "/dev/pts");
- Strings ss;
ss.push_back("/dev/full");
#ifdef __linux__
if (pathExists("/dev/kvm"))
@@ -2058,13 +2043,24 @@ void DerivationGoal::initChild()
ss.push_back("/dev/tty");
ss.push_back("/dev/urandom");
ss.push_back("/dev/zero");
- foreach (Strings::iterator, i, ss) dirsInChroot[*i] = *i;
createSymlink("/proc/self/fd", chrootRootDir + "/dev/fd");
createSymlink("/proc/self/fd/0", chrootRootDir + "/dev/stdin");
createSymlink("/proc/self/fd/1", chrootRootDir + "/dev/stdout");
createSymlink("/proc/self/fd/2", chrootRootDir + "/dev/stderr");
}
+ /* Fixed-output derivations typically need to access the
+ network, so give them access to /etc/resolv.conf and so
+ on. */
+ if (fixedOutput) {
+ ss.push_back("/etc/resolv.conf");
+ ss.push_back("/etc/nsswitch.conf");
+ ss.push_back("/etc/services");
+ ss.push_back("/etc/hosts");
+ }
+
+ for (auto & i : ss) dirsInChroot[i] = i;
+
/* Bind-mount all the directories from the "host"
filesystem that we want in the chroot
environment. */
@@ -2114,13 +2110,26 @@ void DerivationGoal::initChild()
chmod_(chrootRootDir + "/dev/pts/ptmx", 0666);
}
- /* Do the chroot(). Below we do a chdir() to the
- temporary build directory to make sure the current
- directory is in the chroot. (Actually the order
- doesn't matter, since due to the bind mount tmpDir and
- tmpRootDit/tmpDir are the same directories.) */
- if (chroot(chrootRootDir.c_str()) == -1)
- throw SysError(format("cannot change root directory to `%1%'") % chrootRootDir);
+ /* Do the chroot(). */
+ if (chdir(chrootRootDir.c_str()) == -1)
+ throw SysError(format("cannot change directory to '%1%'") % chrootRootDir);
+
+ if (mkdir("real-root", 0) == -1)
+ throw SysError("cannot create real-root directory");
+
+#define pivot_root(new_root, put_old) (syscall(SYS_pivot_root, new_root, put_old))
+ if (pivot_root(".", "real-root") == -1)
+ throw SysError(format("cannot pivot old root directory onto '%1%'") % (chrootRootDir + "/real-root"));
+#undef pivot_root
+
+ if (chroot(".") == -1)
+ throw SysError(format("cannot change root directory to '%1%'") % chrootRootDir);
+
+ if (umount2("real-root", MNT_DETACH) == -1)
+ throw SysError("cannot unmount real root filesystem");
+
+ if (rmdir("real-root") == -1)
+ throw SysError("cannot remove real-root directory");
}
#endif
@@ -2159,11 +2168,7 @@ void DerivationGoal::initChild()
Strings envStrs;
foreach (Environment::const_iterator, i, env)
envStrs.push_back(rewriteHashes(i->first + "=" + i->second, rewritesToTmp));
- const char * * envArr = strings2CharPtrs(envStrs);
-
- Path program = drv.builder.c_str();
- std::vector<const char *> args; /* careful with c_str()! */
- string user; /* must be here for its c_str()! */
+ auto envArr = stringsToCharPtrs(envStrs);
/* If we are running in `build-users' mode, then switch to the
user we allocated above. Make sure that we drop all root
@@ -2189,29 +2194,25 @@ void DerivationGoal::initChild()
}
/* Fill in the arguments. */
+ Strings args;
string builderBasename = baseNameOf(drv.builder);
- args.push_back(builderBasename.c_str());
- foreach (Strings::iterator, i, drv.args) {
- auto re = rewriteHashes(*i, rewritesToTmp);
- auto cstr = new char[re.length()+1];
- std::strcpy(cstr, re.c_str());
-
- args.push_back(cstr);
- }
- args.push_back(0);
+ args.push_back(builderBasename);
+ foreach (Strings::iterator, i, drv.args)
+ args.push_back(rewriteHashes(*i, rewritesToTmp));
+ auto argArr = stringsToCharPtrs(args);
restoreSIGPIPE();
/* Indicate that we managed to set up the build environment. */
- writeToStderr("\n");
+ writeFull(STDERR_FILENO, "\n");
/* Execute the program. This should not return. */
- execve(program.c_str(), (char * *) &args[0], (char * *) envArr);
+ execve(drv.builder.c_str(), (char * *) &argArr[0], (char * *) &envArr[0]);
throw SysError(format("executing `%1%'") % drv.builder);
} catch (std::exception & e) {
- writeToStderr("while setting up the build environment: " + string(e.what()) + "\n");
+ writeFull(STDERR_FILENO, "while setting up the build environment: " + string(e.what()) + "\n");
_exit(1);
}
@@ -2526,7 +2527,7 @@ void DerivationGoal::handleChildOutput(int fd, const string & data)
BZ2_bzWrite(&err, bzLogFile, (unsigned char *) data.data(), data.size());
if (err != BZ_OK) throw Error(format("cannot write to compressed log file (BZip2 error = %1%)") % err);
} else if (fdLogFile != -1)
- writeFull(fdLogFile, (unsigned char *) data.data(), data.size());
+ writeFull(fdLogFile, data);
}
if (hook && fd == hook->fromHook.readSide)
@@ -2836,7 +2837,7 @@ void SubstitutionGoal::tryToRun()
args.push_back("--substitute");
args.push_back(storePath);
args.push_back(destPath);
- const char * * argArr = strings2CharPtrs(args);
+ auto argArr = stringsToCharPtrs(args);
/* Fork the substitute program. */
pid = startProcess([&]() {
@@ -2846,7 +2847,7 @@ void SubstitutionGoal::tryToRun()
if (dup2(outPipe.writeSide, STDOUT_FILENO) == -1)
throw SysError("cannot dup output pipe into stdout");
- execv(sub.c_str(), (char * *) argArr);
+ execv(sub.c_str(), (char * *) &argArr[0]);
throw SysError(format("executing `%1%'") % sub);
});
generated by cgit v1.2.3 (git 2.25.4) at 2024-06-11 01:48:56 +0000