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Work around Landlock output inode in compile.com

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This change fixes Landlock Make so that only the output target file is
unveiled, rather than unveiling the directory that contains it. This
gives us a much stronger sandbox. It also helped identify problematic
build code in our repo that should have been using o/tmp instead.

Landlock isn't able to let us unveil files that don't exist. Even if
they do, then once a file is deleted, the sandboxing for it goes away.
This caused problems for Landlock Make because tools like GNU LD will
repeatedly delete and recreate the output file. This change uses the
compile.com wrapper to ensure on changes happen to the output inode.

New binary available on https://justine.lol/make/

Fixes #528
This commit is contained in:
Justine Tunney 2022-08-09 06:28:41 -07:00
parent c464f45692
commit 133c693650
33 changed files with 207 additions and 1346 deletions
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50
tool/build/compile.c
View file

@ -16,7 +16,6 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/bits/safemacros.internal.h"
#include "libc/calls/calls.h"
@ -38,6 +37,7 @@
#include "libc/log/log.h"
#include "libc/macros.internal.h"
#include "libc/math.h"
#include "libc/mem/io.h"
#include "libc/mem/mem.h"
#include "libc/nexgen32e/kcpuids.h"
#include "libc/nexgen32e/x86feature.h"
@ -171,6 +171,7 @@ char *target;
char *output;
char *outpath;
char *command;
char *movepath;
char *shortened;
char *colorflag;
char ccpath[PATH_MAX];
@ -188,6 +189,7 @@ struct timespec signalled;
sigset_t mask;
sigset_t savemask;
char buf[PAGESIZE];
char tmpout[PATH_MAX];
const char *const kSafeEnv[] = {
"ADDR2LINE", // needed by GetAddr2linePath
@ -707,6 +709,24 @@ void ReportResources(void) {
appendw(&output, '\n');
}
bool MovePreservingDestinationInode(const char *from, const char *to) {
bool res;
struct stat st;
int fdin, fdout;
if ((fdin = open(from, O_RDONLY)) == -1) {
return false;
}
fstat(fdin, &st);
if ((fdout = creat(to, st.st_mode)) == -1) {
close(fdin);
return false;
}
res = _copyfd(fdin, fdout, -1) != -1;
close(fdin);
close(fdout);
return res;
}
bool IsNativeExecutable(const char *path) {
bool res;
char buf[4];
@ -737,6 +757,7 @@ int main(int argc, char *argv[]) {
char *s, *p, *q, **envp;
mode = firstnonnull(getenv("MODE"), MODE);
ksnprintf(tmpout, sizeof(tmpout), "%scompile.%d", kTmpPath, getpid());
/*
* parse prefix arguments
@ -835,18 +856,26 @@ int main(int argc, char *argv[]) {
* ingest arguments
*/
for (i = optind; i < argc; ++i) {
if (!movepath && !outpath && target && !strcmp(target, argv[i])) {
outpath = argv[i];
AddArg(tmpout);
movepath = target;
MovePreservingDestinationInode(target, tmpout);
continue;
}
if (argv[i][0] != '-') {
AddArg(argv[i]);
continue;
}
if (startswith(argv[i], "-o")) {
if (!strcmp(argv[i], "-o")) {
AddArg(argv[i]);
AddArg((outpath = argv[++i]));
outpath = argv[++i];
} else {
AddArg(argv[i]);
outpath = argv[i] + 2;
}
AddArg("-o");
AddArg(tmpout);
movepath = outpath;
continue;
}
if (!iscc) {
@ -1091,6 +1120,19 @@ int main(int argc, char *argv[]) {
makedirs(xdirname(target), 0755);
touch(target, 0644);
}
if (movepath) {
if (!MovePreservingDestinationInode(tmpout, movepath)) {
unlink(tmpout);
exitcode = 90;
appends(&output, "\nfailed to move output file\n");
appends(&output, tmpout);
appends(&output, "\n");
appends(&output, movepath);
appends(&output, "\n");
} else {
unlink(tmpout);
}
}
} else {
appendw(&output, '\n');
PrintRed();