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Diffstat (limited to 'cmd/sharefs/test/raceattr.go')
-rw-r--r--cmd/sharefs/test/raceattr.go122
1 files changed, 0 insertions, 122 deletions
diff --git a/cmd/sharefs/test/raceattr.go b/cmd/sharefs/test/raceattr.go
deleted file mode 100644
index 412cb2b3..00000000
--- a/cmd/sharefs/test/raceattr.go
+++ /dev/null
@@ -1,122 +0,0 @@
-//go:build raceattr
-
-// The raceattr program reproduces vfs inode file attribute race.
-//
-// Even though libfuse high-level API presents the address of a struct stat
-// alongside struct fuse_context, file attributes are actually inherent to the
-// inode, instead of the specific call from userspace. The kernel implementation
-// in fs/fuse/xattr.c appears to make stale data in the inode (set by a previous
-// call) impossible or very unlikely to reach userspace via the stat family of
-// syscalls. However, when using default_permissions to have the VFS check
-// permissions, this race still happens, despite the resulting struct stat being
-// correct when overriding the check via capabilities otherwise.
-//
-// This program reproduces the failure, but because of its continuous nature, it
-// is provided independent of the vm integration test suite.
-package main
-
-import (
- "context"
- "flag"
- "log"
- "os"
- "os/signal"
- "runtime"
- "sync"
- "sync/atomic"
- "syscall"
-)
-
-func newStatAs(
- ctx context.Context, cancel context.CancelFunc,
- n *atomic.Uint64, ok *atomic.Bool,
- uid uint32, pathname string,
- continuous bool,
-) func() {
- return func() {
- runtime.LockOSThread()
- defer cancel()
-
- if _, _, errno := syscall.Syscall(
- syscall.SYS_SETUID, uintptr(uid),
- 0, 0,
- ); errno != 0 {
- cancel()
- log.Printf("cannot set uid to %d: %s", uid, errno)
- }
-
- var stat syscall.Stat_t
- for {
- if ctx.Err() != nil {
- return
- }
-
- if err := syscall.Lstat(pathname, &stat); err != nil {
- // SHAREFS_PERM_DIR not world executable, or
- // SHAREFS_PERM_REG not world readable
- if !continuous {
- cancel()
- }
- ok.Store(true)
- log.Printf("uid %d: %v", uid, err)
- } else if stat.Uid != uid {
- // appears to be unreachable
- if !continuous {
- cancel()
- }
- ok.Store(true)
- log.Printf("got uid %d instead of %d", stat.Uid, uid)
- }
- n.Add(1)
- }
- }
-}
-
-func main() {
- log.SetFlags(0)
- log.SetPrefix("raceattr: ")
-
- p := flag.String("target", "/sdcard/raceattr", "pathname of test file")
- u0 := flag.Int("uid0", 1<<10-1, "first uid")
- u1 := flag.Int("uid1", 1<<10-2, "second uid")
- count := flag.Int("count", 1, "threads per uid")
- continuous := flag.Bool("continuous", false, "keep running even after reproduce")
- flag.Parse()
-
- if os.Geteuid() != 0 {
- log.Fatal("this program must run as root")
- }
-
- ctx, cancel := signal.NotifyContext(
- context.Background(),
- syscall.SIGINT,
- syscall.SIGTERM,
- syscall.SIGHUP,
- )
-
- if err := os.WriteFile(*p, nil, 0); err != nil {
- log.Fatal(err)
- }
-
- var (
- wg sync.WaitGroup
-
- n atomic.Uint64
- ok atomic.Bool
- )
-
- if *count < 1 {
- *count = 1
- }
- for range *count {
- wg.Go(newStatAs(ctx, cancel, &n, &ok, uint32(*u0), *p, *continuous))
- if *u1 >= 0 {
- wg.Go(newStatAs(ctx, cancel, &n, &ok, uint32(*u1), *p, *continuous))
- }
- }
-
- wg.Wait()
- if !*continuous && ok.Load() {
- log.Printf("reproduced after %d calls", n.Load())
- }
-}