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Merge branch 'sandbox-profiles' of git://github.com/pikajude/nix

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Temporarily allow derivations to describe their full sandbox profile.
This will be eventually scaled back to a more secure setup, see the
discussion at #695
This commit is contained in:
Shea Levy 2015-11-19 17:44:11 -05:00
commit 5deb7fbdfb
7 changed files with 56 additions and 88 deletions
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18
corepkgs/buildenv.nix
View file

@ -23,10 +23,20 @@ derivation {
# network traffic, so don't do that.
preferLocalBuild = true;
__impureHostDeps = if builtins.currentSystem == "x86_64-darwin" then [
"/usr/lib/libSystem.dylib"
"/usr/lib/system"
] else null;
__sandboxProfile = ''
(allow sysctl-read)
(allow file-read*
(literal "/usr/lib/libSystem.dylib")
(literal "/usr/lib/libSystem.B.dylib")
(literal "/usr/lib/libobjc.A.dylib")
(literal "/usr/lib/libobjc.dylib")
(literal "/usr/lib/libauto.dylib")
(literal "/usr/lib/libc++abi.dylib")
(literal "/usr/lib/libc++.1.dylib")
(literal "/usr/lib/libDiagnosticMessagesClient.dylib")
(subpath "/usr/lib/system")
(subpath "/dev"))
'';
inherit chrootDeps;
}

4
release.nix
View file

@ -97,6 +97,10 @@ let
enableParallelBuilding = true;
__sandboxProfile = lib.sandbox.allowFileRead [
"/etc" "/etc/nix/nix.conf" "/private/etc/nix/nix.conf"
];
makeFlags = "profiledir=$(out)/etc/profile.d";
preBuild = "unset NIX_INDENT_MAKE";

48
src/libstore/build.cc
View file

@ -778,6 +778,12 @@ private:
DirsInChroot dirsInChroot;
typedef map<string, string> Environment;
Environment env;
#if SANDBOX_ENABLED
typedef string SandboxProfile;
SandboxProfile additionalSandboxProfile;
AutoDelete autoDelSandbox;
#endif
/* Hash rewriting. */
HashRewrites rewritesToTmp, rewritesFromTmp;
@ -1919,6 +1925,9 @@ void DerivationGoal::startBuilder()
for (auto & i : closure)
dirsInChroot[i] = i;
#if SANDBOX_ENABLED
additionalSandboxProfile = get(drv->env, "__sandboxProfile");
#else
string allowed = settings.get("allowed-impure-host-deps", string(DEFAULT_ALLOWED_IMPURE_PREFIXES));
PathSet allowedPaths = tokenizeString<StringSet>(allowed);
@ -1944,6 +1953,7 @@ void DerivationGoal::startBuilder()
dirsInChroot[i] = i;
}
#endif
#if CHROOT_ENABLED
/* Create a temporary directory in which we set up the chroot
@ -2439,9 +2449,10 @@ void DerivationGoal::runChild()
const char *builder = "invalid";
string sandboxProfile;
if (isBuiltin(*drv))
if (isBuiltin(*drv)) {
;
else if (useChroot && SANDBOX_ENABLED) {
#if SANDBOX_ENABLED
} else if (useChroot) {
/* Lots and lots and lots of file functions freak out if they can't stat their full ancestry */
PathSet ancestry;
@ -2471,8 +2482,6 @@ void DerivationGoal::runChild()
/* This has to appear before import statements */
sandboxProfile += "(version 1)\n";
sandboxProfile += (format("(import \"%1%/nix/sandbox-defaults.sb\")\n") % settings.nixDataDir).str();
/* Violations will go to the syslog if you set this. Unfortunately the destination does not appear to be configurable */
if (settings.get("darwin-log-sandbox-violations", false)) {
sandboxProfile += "(deny default)\n";
@ -2494,13 +2503,8 @@ void DerivationGoal::runChild()
}
sandboxProfile += ")\n";
/* Our inputs (transitive dependencies and any impurities computed above)
Note that the sandbox profile allows file-write* even though it isn't seemingly necessary. First of all, nix's standard user permissioning
mechanism still prevents builders from writing to input directories, so no security/purity is lost. The reason we allow file-write* is that
denying it means the `access` syscall will return EPERM instead of EACCESS, which confuses a few programs that assume (understandably, since
it appears to be a violation of the POSIX spec) that `access` won't do that, and don't deal with it nicely if it does. The most notable of
these is the entire GHC Haskell ecosystem. */
sandboxProfile += "(allow file-read* file-write* process-exec mach-priv-task-port\n";
/* Our inputs (transitive dependencies and any impurities computed above) */
sandboxProfile += "(allow file-read* process-exec\n";
for (auto & i : dirsInChroot) {
if (i.first != i.second)
throw SysError(format("can't map '%1%' to '%2%': mismatched impure paths not supported on darwin"));
@ -2516,28 +2520,32 @@ void DerivationGoal::runChild()
}
sandboxProfile += ")\n";
/* Our ancestry. N.B: this uses literal on folders, instead of subpath. Without that,
you open up the entire filesystem because you end up with (subpath "/")
Note: file-read-metadata* is not sufficiently permissive for GHC. file-read* is but may
be a security hazard.
TODO: figure out a more appropriate directive.
*/
/* Allow file-read* on full directory hierarchy to self. Allows realpath() */
sandboxProfile += "(allow file-read*\n";
for (auto & i : ancestry) {
sandboxProfile += (format("\t(literal \"%1%\")\n") % i.c_str()).str();
}
sandboxProfile += ")\n";
sandboxProfile += additionalSandboxProfile;
debug("Generated sandbox profile:");
debug(sandboxProfile);
Path sandboxFile = drvPath + ".sb";
if (pathExists(sandboxFile)) deletePath(sandboxFile);
autoDelSandbox.reset(sandboxFile, false);
writeFile(sandboxFile, sandboxProfile);
builder = "/usr/bin/sandbox-exec";
args.push_back("sandbox-exec");
args.push_back("-p");
args.push_back(sandboxProfile);
args.push_back("-f");
args.push_back(sandboxFile);
args.push_back("-D");
args.push_back((format("_GLOBAL_TMP_DIR=%1%") % globalTmpDir).str());
args.push_back("_GLOBAL_TMP_DIR=" + globalTmpDir);
args.push_back(drv->builder);
#endif
} else {
builder = drv->builder.c_str();
string builderBasename = baseNameOf(drv->builder);

1
src/libstore/local.mk
View file

@ -33,4 +33,3 @@ $(d)/local-store.cc: $(d)/schema.sql.hh
clean-files += $(d)/schema.sql.hh
$(eval $(call install-file-in, $(d)/nix-store.pc, $(prefix)/lib/pkgconfig, 0644))
$(eval $(call install-file-in, $(d)/sandbox-defaults.sb, $(datadir)/nix, 0644))

63
src/libstore/sandbox-defaults.sb.in
View file

@ -1,63 +0,0 @@
(allow file-read* file-write-data (literal "/dev/null"))
(allow ipc-posix*)
(allow mach-lookup (global-name "com.apple.SecurityServer"))
(allow file-read*
(literal "/dev/dtracehelper")
(literal "/dev/tty")
(literal "/dev/autofs_nowait")
(literal "/System/Library/CoreServices/SystemVersion.plist")
(literal "/private/var/run/systemkeychaincheck.done")
(literal "/private/etc/protocols")
(literal "/private/var/tmp")
(literal "/private/var/db")
(subpath "/private/var/db/mds"))
(allow file-read*
(subpath "/usr/share/icu")
(subpath "/usr/share/locale")
(subpath "/usr/share/zoneinfo"))
(allow file-write*
(literal "/dev/tty")
(literal "/dev/dtracehelper")
(literal "/mds"))
(allow file-ioctl (literal "/dev/dtracehelper"))
(allow file-read-metadata
(literal "/var")
(literal "/tmp")
; symlinks
(literal "@sysconfdir@")
(literal "@sysconfdir@/nix")
(literal "@sysconfdir@/nix/nix.conf")
(literal "/etc/resolv.conf")
(literal "/private/etc/resolv.conf"))
(allow file-read*
(literal "/private@sysconfdir@/nix/nix.conf")
(literal "/private/var/run/resolv.conf"))
; some builders use filehandles other than stdin/stdout
(allow file*
(subpath "/dev/fd")
(literal "/dev/ptmx")
(regex #"^/dev/[pt]ty.*$"))
; allow everything inside TMP
(allow file* process-exec
(subpath (param "_GLOBAL_TMP_DIR"))
(subpath "/private/tmp"))
(allow process-fork)
(allow sysctl-read)
(allow signal (target same-sandbox))
; allow getpwuid (for git and other packages)
(allow mach-lookup
(global-name "com.apple.system.notification_center")
(global-name "com.apple.system.opendirectoryd.libinfo"))
; allow local networking
(allow network* (local ip) (remote unix-socket))

8
src/libutil/util.cc
View file

@ -599,6 +599,8 @@ string drainFD(int fd)
//////////////////////////////////////////////////////////////////////
AutoDelete::AutoDelete() : del{false} {}
AutoDelete::AutoDelete(const string & p, bool recursive) : path(p)
{
del = true;
@ -626,6 +628,12 @@ void AutoDelete::cancel()
del = false;
}
void AutoDelete::reset(const Path & p, bool recursive) {
path = p;
this->recursive = recursive;
del = true;
}
//////////////////////////////////////////////////////////////////////

2
src/libutil/util.hh
View file

@ -199,9 +199,11 @@ class AutoDelete
bool del;
bool recursive;
public:
AutoDelete();
AutoDelete(const Path & p, bool recursive = true);
~AutoDelete();
void cancel();
void reset(const Path & p, bool recursive = true);
operator Path() const { return path; }
};