Add DirectFS to gofer's seccomp filter options.

Only when directfs is not enabled will allow xattr syscalls.

PiperOrigin-RevId: 613018126

runsc/cmd/gofer.go

@@ -244,6 +244,7 @@ func (g *Gofer) Execute(_ context.Context, f *flag.FlagSet, args ...any) subcomm
 		UDSOpenEnabled:   conf.GetHostUDS().AllowOpen(),
 		UDSCreateEnabled: conf.GetHostUDS().AllowCreate(),
 		ProfileEnabled:   len(profileOpts) > 0,
+		DirectFS:         conf.DirectFS,
 	}
 	if err := filter.Install(opts); err != nil {
 		util.Fatalf("installing seccomp filters: %v", err)

runsc/fsgofer/filter/config.go

@@ -42,13 +42,8 @@ var allowedSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
 	},
 	unix.SYS_EXIT:       seccomp.MatchAll{},
 	unix.SYS_EXIT_GROUP: seccomp.MatchAll{},
-	unix.SYS_FALLOCATE: seccomp.PerArg{
-		seccomp.AnyValue{},
-		seccomp.EqualTo(0),
-	},
-	unix.SYS_FCHMOD:   seccomp.MatchAll{},
-	unix.SYS_FCHMODAT: seccomp.MatchAll{},
-	unix.SYS_FCHOWNAT: seccomp.MatchAll{},
+	unix.SYS_FCHMOD:     seccomp.MatchAll{},
+	unix.SYS_FCHOWNAT:   seccomp.MatchAll{},
 	unix.SYS_FCNTL: seccomp.Or{
 		seccomp.PerArg{
 			seccomp.AnyValue{},
@@ -68,10 +63,8 @@ var allowedSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
 			seccomp.EqualTo(unix.F_ADD_SEALS),
 		},
 	},
-	unix.SYS_FSTAT:     seccomp.MatchAll{},
-	unix.SYS_FSTATFS:   seccomp.MatchAll{},
-	unix.SYS_FSYNC:     seccomp.MatchAll{},
-	unix.SYS_FTRUNCATE: seccomp.MatchAll{},
+	unix.SYS_FSTAT: seccomp.MatchAll{},
+	unix.SYS_FSYNC: seccomp.MatchAll{},
 	unix.SYS_FUTEX: seccomp.Or{
 		seccomp.PerArg{
 			seccomp.AnyValue{},
@@ -108,17 +101,13 @@ var allowedSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
 		seccomp.EqualTo(0),
 		seccomp.EqualTo(0),
 	},
-	unix.SYS_GETDENTS64:   seccomp.MatchAll{},
 	unix.SYS_GETPID:       seccomp.MatchAll{},
 	unix.SYS_GETRANDOM:    seccomp.MatchAll{},
 	unix.SYS_GETTID:       seccomp.MatchAll{},
 	unix.SYS_GETTIMEOFDAY: seccomp.MatchAll{},
-	unix.SYS_LINKAT:       seccomp.MatchAll{},
 	unix.SYS_LSEEK:        seccomp.MatchAll{},
 	unix.SYS_MADVISE:      seccomp.MatchAll{},
 	unix.SYS_MEMFD_CREATE: seccomp.MatchAll{}, // Used by flipcall.PacketWindowAllocator.Init().
-	unix.SYS_MKDIRAT:      seccomp.MatchAll{},
-	unix.SYS_MKNODAT:      seccomp.MatchAll{},
 	unix.SYS_MMAP: seccomp.Or{
 		seccomp.PerArg{
 			seccomp.AnyValue{},
@@ -139,15 +128,14 @@ var allowedSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
 			seccomp.EqualTo(unix.MAP_PRIVATE | unix.MAP_ANONYMOUS | unix.MAP_FIXED),
 		},
 	},
-	unix.SYS_MPROTECT:   seccomp.MatchAll{},
-	unix.SYS_MUNMAP:     seccomp.MatchAll{},
-	unix.SYS_NANOSLEEP:  seccomp.MatchAll{},
-	unix.SYS_OPENAT:     seccomp.MatchAll{},
-	unix.SYS_PPOLL:      seccomp.MatchAll{},
-	unix.SYS_PREAD64:    seccomp.MatchAll{},
-	unix.SYS_PWRITE64:   seccomp.MatchAll{},
-	unix.SYS_READ:       seccomp.MatchAll{},
-	unix.SYS_READLINKAT: seccomp.MatchAll{},
+	unix.SYS_MPROTECT:  seccomp.MatchAll{},
+	unix.SYS_MUNMAP:    seccomp.MatchAll{},
+	unix.SYS_NANOSLEEP: seccomp.MatchAll{},
+	unix.SYS_OPENAT:    seccomp.MatchAll{},
+	unix.SYS_PPOLL:     seccomp.MatchAll{},
+	unix.SYS_PREAD64:   seccomp.MatchAll{},
+	unix.SYS_PWRITE64:  seccomp.MatchAll{},
+	unix.SYS_READ:      seccomp.MatchAll{},
 	unix.SYS_RECVMSG: seccomp.Or{
 		seccomp.PerArg{
 			seccomp.AnyValue{},
@@ -160,7 +148,6 @@ var allowedSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
 			seccomp.EqualTo(unix.MSG_DONTWAIT | unix.MSG_TRUNC | unix.MSG_PEEK),
 		},
 	},
-	unix.SYS_RENAMEAT:        seccomp.MatchAll{},
 	unix.SYS_RESTART_SYSCALL: seccomp.MatchAll{},
 	// May be used by the runtime during panic().
 	unix.SYS_RT_SIGACTION:   seccomp.MatchAll{},
@@ -192,13 +179,10 @@ var allowedSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
 		seccomp.EqualTo(unix.SOCK_SEQPACKET | unix.SOCK_CLOEXEC),
 		seccomp.EqualTo(0),
 	},
-	unix.SYS_SYMLINKAT: seccomp.MatchAll{},
 	unix.SYS_TGKILL: seccomp.PerArg{
 		seccomp.EqualTo(uint64(os.Getpid())),
 	},
-	unix.SYS_UNLINKAT:  seccomp.MatchAll{},
-	unix.SYS_UTIMENSAT: seccomp.MatchAll{},
-	unix.SYS_WRITE:     seccomp.MatchAll{},
+	unix.SYS_WRITE: seccomp.MatchAll{},
 })
 
 var udsCommonSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
@@ -231,6 +215,28 @@ var udsCreateSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule
 	unix.SYS_LISTEN:  seccomp.MatchAll{},
 })
 
-var xattrSyscalls = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
-	unix.SYS_FGETXATTR: seccomp.MatchAll{},
+var lisafsFilters = seccomp.MakeSyscallRules(map[uintptr]seccomp.SyscallRule{
+	unix.SYS_FALLOCATE: seccomp.PerArg{
+		seccomp.AnyValue{},
+		seccomp.EqualTo(0),
+	},
+	unix.SYS_FCHMODAT:   seccomp.MatchAll{},
+	unix.SYS_FGETXATTR:  seccomp.MatchAll{},
+	unix.SYS_FSTATFS:    seccomp.MatchAll{},
+	unix.SYS_GETDENTS64: seccomp.MatchAll{},
+	unix.SYS_LINKAT: seccomp.PerArg{
+		seccomp.NonNegativeFD{},
+		seccomp.AnyValue{},
+		seccomp.NonNegativeFD{},
+		seccomp.AnyValue{},
+		seccomp.EqualTo(0),
+	},
+	unix.SYS_MKDIRAT:    seccomp.MatchAll{},
+	unix.SYS_MKNODAT:    seccomp.MatchAll{},
+	unix.SYS_READLINKAT: seccomp.MatchAll{},
+	unix.SYS_RENAMEAT:   seccomp.MatchAll{},
+	unix.SYS_SYMLINKAT:  seccomp.MatchAll{},
+	unix.SYS_FTRUNCATE:  seccomp.MatchAll{},
+	unix.SYS_UNLINKAT:   seccomp.MatchAll{},
+	unix.SYS_UTIMENSAT:  seccomp.MatchAll{},
 })

runsc/fsgofer/filter/filter.go

@@ -27,6 +27,7 @@ type Options struct {
 	UDSOpenEnabled   bool
 	UDSCreateEnabled bool
 	ProfileEnabled   bool
+	DirectFS         bool
 }
 
 // Install installs seccomp filters.
@@ -53,8 +54,10 @@ func Install(opt Options) error {
 	// when not enabled.
 	s.Merge(instrumentationFilters())
 
-	// TODO(b/317993245): add HostFilesystem to Options.
-	s.Merge(xattrSyscalls)
+	// When DirectFS is not enabled, filters for LisaFS are installed.
+	if !opt.DirectFS {
+		s.Merge(lisafsFilters)
+	}
 
 	return seccomp.Install(s, seccomp.DenyNewExecMappings, seccomp.DefaultProgramOptions())
 }