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Always use the Darwin sandbox

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Even with "build-use-sandbox = false", we now use sandboxing with a
permissive profile that allows everything except the creation of
setuid/setgid binaries.
This commit is contained in:
Eelco Dolstra 2017-06-06 18:44:49 +02:00
parent d3f780996c
commit 85e93d7b87
No known key found for this signature in database
GPG Key ID: 8170B4726D7198DE
5 changed files with 100 additions and 87 deletions
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4
.gitignore vendored
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@ -48,9 +48,7 @@ perl/Makefile.config
/src/libexpr/nix.tbl
# /src/libstore/
/src/libstore/schema.sql.gen.hh
/src/libstore/sandbox-defaults.sb.gen.hh
/src/libstore/sandbox-network.sb.gen.hh
/src/libstore/*.gen.hh
/src/nix/nix

170
src/libstore/build.cc
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@ -2611,104 +2611,102 @@ void DerivationGoal::runChild()
const char *builder = "invalid";
string sandboxProfile;
if (drv->isBuiltin()) {
;
}
#if __APPLE__
else if (useChroot) {
/* Lots and lots and lots of file functions freak out if they can't stat their full ancestry */
PathSet ancestry;
else {
/* This has to appear before import statements. */
std::string sandboxProfile = "(version 1)\n";
/* We build the ancestry before adding all inputPaths to the store because we know they'll
all have the same parents (the store), and there might be lots of inputs. This isn't
particularly efficient... I doubt it'll be a bottleneck in practice */
for (auto & i : dirsInChroot) {
Path cur = i.first;
while (cur.compare("/") != 0) {
cur = dirOf(cur);
ancestry.insert(cur);
if (useChroot) {
/* Lots and lots and lots of file functions freak out if they can't stat their full ancestry */
PathSet ancestry;
/* We build the ancestry before adding all inputPaths to the store because we know they'll
all have the same parents (the store), and there might be lots of inputs. This isn't
particularly efficient... I doubt it'll be a bottleneck in practice */
for (auto & i : dirsInChroot) {
Path cur = i.first;
while (cur.compare("/") != 0) {
cur = dirOf(cur);
ancestry.insert(cur);
}
}
}
/* And we want the store in there regardless of how empty dirsInChroot. We include the innermost
path component this time, since it's typically /nix/store and we care about that. */
Path cur = worker.store.storeDir;
while (cur.compare("/") != 0) {
ancestry.insert(cur);
cur = dirOf(cur);
}
/* And we want the store in there regardless of how empty dirsInChroot. We include the innermost
path component this time, since it's typically /nix/store and we care about that. */
Path cur = worker.store.storeDir;
while (cur.compare("/") != 0) {
ancestry.insert(cur);
cur = dirOf(cur);
}
/* Add all our input paths to the chroot */
for (auto & i : inputPaths)
dirsInChroot[i] = i;
/* Add all our input paths to the chroot */
for (auto & i : inputPaths)
dirsInChroot[i] = i;
/* This has to appear before import statements */
sandboxProfile += "(version 1)\n";
/* Violations will go to the syslog if you set this. Unfortunately the destination does not appear to be configurable */
if (settings.darwinLogSandboxViolations) {
sandboxProfile += "(deny default)\n";
} else {
sandboxProfile += "(deny default (with no-log))\n";
}
/* Violations will go to the syslog if you set this. Unfortunately the destination does not appear to be configurable */
if (settings.darwinLogSandboxViolations) {
sandboxProfile += "(deny default)\n";
} else {
sandboxProfile += "(deny default (with no-log))\n";
}
sandboxProfile +=
#include "sandbox-defaults.sb.gen.hh"
;
if (fixedOutput)
sandboxProfile +=
#include "sandbox-network.sb.gen.hh"
#include "sandbox-defaults.sb.gen.hh"
;
/* The tmpDir in scope points at the temporary build directory for our derivation. Some packages try different mechanisms
to find temporary directories, so we want to open up a broader place for them to dump their files, if needed. */
Path globalTmpDir = canonPath(getEnv("TMPDIR", "/tmp"), true);
if (fixedOutput)
sandboxProfile +=
#include "sandbox-network.sb.gen.hh"
;
/* They don't like trailing slashes on subpath directives */
if (globalTmpDir.back() == '/') globalTmpDir.pop_back();
/* Our rwx outputs */
sandboxProfile += "(allow file-read* file-write* process-exec\n";
for (auto & i : missingPaths) {
sandboxProfile += (format("\t(subpath \"%1%\")\n") % i.c_str()).str();
}
sandboxProfile += ")\n";
/* Our inputs (transitive dependencies and any impurities computed above)
without file-write* allowed, access() incorrectly returns EPERM
*/
sandboxProfile += "(allow file-read* file-write* process-exec\n";
for (auto & i : dirsInChroot) {
if (i.first != i.second.source)
throw Error(format(
"can't map '%1%' to '%2%': mismatched impure paths not supported on Darwin")
% i.first % i.second.source);
string path = i.first;
struct stat st;
if (lstat(path.c_str(), &st)) {
if (i.second.optional && errno == ENOENT)
continue;
throw SysError(format("getting attributes of path ‘%1%’") % path);
/* Our rwx outputs */
sandboxProfile += "(allow file-read* file-write* process-exec\n";
for (auto & i : missingPaths) {
sandboxProfile += (format("\t(subpath \"%1%\")\n") % i.c_str()).str();
}
if (S_ISDIR(st.st_mode))
sandboxProfile += (format("\t(subpath \"%1%\")\n") % path).str();
else
sandboxProfile += (format("\t(literal \"%1%\")\n") % path).str();
}
sandboxProfile += ")\n";
sandboxProfile += ")\n";
/* 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";
/* Our inputs (transitive dependencies and any impurities computed above)
sandboxProfile += additionalSandboxProfile;
without file-write* allowed, access() incorrectly returns EPERM
*/
sandboxProfile += "(allow file-read* file-write* process-exec\n";
for (auto & i : dirsInChroot) {
if (i.first != i.second.source)
throw Error(format(
"can't map '%1%' to '%2%': mismatched impure paths not supported on Darwin")
% i.first % i.second.source);
string path = i.first;
struct stat st;
if (lstat(path.c_str(), &st)) {
if (i.second.optional && errno == ENOENT)
continue;
throw SysError(format("getting attributes of path ‘%1%’") % path);
}
if (S_ISDIR(st.st_mode))
sandboxProfile += (format("\t(subpath \"%1%\")\n") % path).str();
else
sandboxProfile += (format("\t(literal \"%1%\")\n") % path).str();
}
sandboxProfile += ")\n";
/* 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;
} else
sandboxProfile +=
#include "sandbox-minimal.sb.gen.hh"
;
debug("Generated sandbox profile:");
debug(sandboxProfile);
@ -2717,6 +2715,13 @@ void DerivationGoal::runChild()
writeFile(sandboxFile, sandboxProfile);
/* The tmpDir in scope points at the temporary build directory for our derivation. Some packages try different mechanisms
to find temporary directories, so we want to open up a broader place for them to dump their files, if needed. */
Path globalTmpDir = canonPath(getEnv("TMPDIR", "/tmp"), true);
/* They don't like trailing slashes on subpath directives */
if (globalTmpDir.back() == '/') globalTmpDir.pop_back();
builder = "/usr/bin/sandbox-exec";
args.push_back("sandbox-exec");
args.push_back("-f");
@ -2725,12 +2730,13 @@ void DerivationGoal::runChild()
args.push_back("_GLOBAL_TMP_DIR=" + globalTmpDir);
args.push_back(drv->builder);
}
#endif
#else
else {
builder = drv->builder.c_str();
string builderBasename = baseNameOf(drv->builder);
args.push_back(builderBasename);
}
#endif
for (auto & i : drv->args)
args.push_back(rewriteStrings(i, inputRewrites));

6
src/libstore/local.mk
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@ -36,7 +36,9 @@ libstore_CXXFLAGS = \
$(d)/local-store.cc: $(d)/schema.sql.gen.hh
$(d)/build.cc: $(d)/sandbox-defaults.sb.gen.hh $(d)/sandbox-network.sb.gen.hh
sandbox-headers = $(d)/sandbox-defaults.sb.gen.hh $(d)/sandbox-network.sb.gen.hh $(d)/sandbox-minimal.sb.gen.hh
$(d)/build.cc: $(sandbox-headers)
%.gen.hh: %
@echo 'R"foo(' >> $@.tmp
@ -44,6 +46,6 @@ $(d)/build.cc: $(d)/sandbox-defaults.sb.gen.hh $(d)/sandbox-network.sb.gen.hh
@echo ')foo"' >> $@.tmp
@mv $@.tmp $@
clean-files += $(d)/schema.sql.gen.hh $(d)/sandbox-defaults.sb.gen.hh $(d)/sandbox-network.sb.gen.hh
clean-files += $(d)/schema.sql.gen.hh $(sandbox-headers)
$(eval $(call install-file-in, $(d)/nix-store.pc, $(prefix)/lib/pkgconfig, 0644))

2
src/libstore/sandbox-defaults.sb
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@ -1,5 +1,7 @@
(define TMPDIR (param "_GLOBAL_TMP_DIR"))
(deny default)
; Disallow creating setuid/setgid binaries, since that
; would allow breaking build user isolation.
(deny file-write-setugid)

5
src/libstore/sandbox-minimal.sb Normal file
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@ -0,0 +1,5 @@
(allow default)
; Disallow creating setuid/setgid binaries, since that
; would allow breaking build user isolation.
(deny file-write-setugid)