sys: add string flags

Allow to define string flags in txt descriptions. E.g.:

  filesystem = "ext2", "ext3", "ext4"

and then use it in string type:

  ptr[in, string[filesystem]]

22 files changed, 161 insertions, 165 deletions

diff --git a/host/host.go b/host/host.go
index 49cf78e57..a58964e8c 100644
--- a/host/host.go
+++ b/host/host.go
@@ -60,11 +60,7 @@ func isSupportedSyzkall(c *sys.Call) bool {
 	case "syz_test":
 		return false
 	case "syz_open_dev":
-		ptr, ok := c.Args[0].(*sys.PtrType)
-		if !ok {
-			return true
-		}
-		fname, ok := ptr.Type.(*sys.StrConstType)
+		fname, ok := extractStringConst(c.Args[0])
 		if !ok {
 			panic("first open arg is not a pointer to string const")
 		}
@@ -84,7 +80,7 @@ func isSupportedSyzkall(c *sys.Call) bool {
 			}
 			return false
 		}
-		return check(fname.Val[:len(fname.Val)-1])
+		return check(fname)
 	case "syz_open_pts":
 		return true
 	case "syz_fuse_mount":
@@ -112,17 +108,27 @@ func isSupportedSocket(c *sys.Call) bool {
 }
 
 func isSupportedOpen(c *sys.Call) bool {
-	ptr, ok := c.Args[0].(*sys.PtrType)
-	if !ok {
-		panic("first open arg is not a pointer")
-	}
-	fname, ok := ptr.Type.(*sys.StrConstType)
+	fname, ok := extractStringConst(c.Args[0])
 	if !ok {
 		return true
 	}
-	fd, err := syscall.Open(fname.Val[:len(fname.Val)-1], syscall.O_RDONLY, 0)
+	fd, err := syscall.Open(fname, syscall.O_RDONLY, 0)
 	if fd != -1 {
 		syscall.Close(fd)
 	}
 	return err == nil
 }
+
+func extractStringConst(typ sys.Type) (string, bool) {
+	ptr, ok := typ.(*sys.PtrType)
+	if !ok {
+		panic("first open arg is not a pointer to string const")
+	}
+	str, ok := ptr.Type.(*sys.BufferType)
+	if !ok || str.Kind != sys.BufferString || len(str.Values) != 1 {
+		return "", false
+	}
+	v := str.Values[0]
+	v = v[:len(v)-1] // string terminating \x00
+	return v, true
+}
diff --git a/prog/mutation.go b/prog/mutation.go
index 72535f656..e861725c8 100644
--- a/prog/mutation.go
+++ b/prog/mutation.go
@@ -89,10 +89,8 @@ func (p *Prog) Mutate(rs rand.Source, ncalls int, ct *ChoiceTable) {
 							if r.bin() {
 								arg.Data = mutateData(r, append([]byte{}, arg.Data...), int(0), ^int(0))
 							} else {
-								arg.Data = r.randString(s)
+								arg.Data = r.randString(s, a.Values)
 							}
-						case sys.BufferFilesystem:
-							arg.Data = r.filesystem(s)
 						case sys.BufferFilename:
 							arg.Data = []byte(r.filename(s))
 						case sys.BufferSockaddr:
@@ -170,7 +168,7 @@ func (p *Prog) Mutate(rs rand.Source, ncalls int, ct *ChoiceTable) {
 						p.replaceArg(c, arg, arg1, calls)
 					case *sys.LenType:
 						panic("bad arg returned by mutationArgs: LenType")
-					case *sys.ConstType, *sys.StrConstType:
+					case *sys.ConstType:
 						panic("bad arg returned by mutationArgs: ConstType")
 					default:
 						panic(fmt.Sprintf("bad arg returned by mutationArgs: %#v, type=%#v", *arg, arg.Type))
@@ -322,9 +320,13 @@ func mutationArgs(c *Call) (args, bases []*Arg) {
 		case *sys.LenType:
 			// Size is updated when the size-of arg change.
 			return
-		case *sys.ConstType, *sys.StrConstType:
+		case *sys.ConstType:
 			// Well, this is const.
 			return
+		case *sys.BufferType:
+			if typ.Kind == sys.BufferString && len(typ.Values) == 1 {
+				return // string const
+			}
 		}
 		if arg.Type.Dir() == sys.DirOut {
 			return
diff --git a/prog/prio.go b/prog/prio.go
index 9b0ace782..a6919372d 100644
--- a/prog/prio.go
+++ b/prog/prio.go
@@ -80,7 +80,7 @@ func calcStaticPriorities() [][]float32 {
 				}
 			case *sys.BufferType:
 				switch a.Kind {
-				case sys.BufferBlobRand, sys.BufferBlobRange, sys.BufferFilesystem, sys.BufferAlgType, sys.BufferAlgName:
+				case sys.BufferBlobRand, sys.BufferBlobRange, sys.BufferAlgType, sys.BufferAlgName:
 				case sys.BufferString:
 					noteUsage(0.2, "str")
 				case sys.BufferSockaddr:
diff --git a/prog/prog.go b/prog/prog.go
index 4ffc3e6bf..e3a0febd2 100644
--- a/prog/prog.go
+++ b/prog/prog.go
@@ -101,7 +101,7 @@ func (a *Arg) Value() uintptr {
 
 func (a *Arg) Size() uintptr {
 	switch typ := a.Type.(type) {
-	case *sys.IntType, *sys.LenType, *sys.FlagsType, *sys.ConstType, *sys.StrConstType,
+	case *sys.IntType, *sys.LenType, *sys.FlagsType, *sys.ConstType,
 		*sys.ResourceType, *sys.VmaType, *sys.PtrType:
 		return typ.Size()
 	case *sys.BufferType:
diff --git a/prog/rand.go b/prog/rand.go
index 6415277eb..30d0ba4aa 100644
--- a/prog/rand.go
+++ b/prog/rand.go
@@ -258,7 +258,10 @@ func (r *randGen) sockaddr(s *state) []byte {
 	return data
 }
 
-func (r *randGen) randString(s *state) []byte {
+func (r *randGen) randString(s *state, vals []string) []byte {
+	if len(vals) != 0 {
+		return []byte(vals[r.Intn(len(vals))])
+	}
 	if len(s.strings) != 0 && r.bin() {
 		// Return an existing string.
 		strings := make([]string, 0, len(s.strings))
@@ -288,20 +291,6 @@ func (r *randGen) randString(s *state) []byte {
 	return buf.Bytes()
 }
 
-func (r *randGen) filesystem(s *state) []byte {
-	dict := []string{"sysfs", "rootfs", "ramfs", "tmpfs", "devtmpfs", "debugfs",
-		"securityfs", "sockfs", "pipefs", "anon_inodefs", "devpts", "ext3", "ext2", "ext4",
-		"hugetlbfs", "vfat", "ecryptfs", "kdbusfs", "fuseblk", "fuse", "rpc_pipefs",
-		"nfs", "nfs4", "nfsd", "binfmt_misc", "autofs", "xfs", "jfs", "msdos", "ntfs",
-		"minix", "hfs", "hfsplus", "qnx4", "ufs", "btrfs", "configfs", "ncpfs", "qnx6",
-		"exofs", "befs", "vxfs", "gfs2", "gfs2meta", "fusectl", "bfs", "nsfs", "efs",
-		"cifs", "efivarfs", "affs", "tracefs", "bdev", "ocfs2", "ocfs2_dlmfs", "hpfs",
-		"proc", "afs", "reiserfs", "jffs2", "romfs", "aio", "sysv", "v7", "udf",
-		"ceph", "pstore", "adfs", "9p", "hostfs", "squashfs", "cramfs", "iso9660",
-		"coda", "nilfs2", "logfs", "overlay", "f2fs", "omfs", "ubifs", "openpromfs"}
-	return []byte(dict[r.Intn(len(dict))] + "\x00")
-}
-
 func (r *randGen) algType(s *state) []byte {
 	dict := []string{"aead", "hash", "rng", "skcipher"}
 	res := make([]byte, 14)
@@ -662,7 +651,7 @@ func (r *randGen) generateArg(s *state, typ sys.Type) (arg *Arg, calls []*Call)
 		// in subsequent calls. For the same reason we do generate pointer/array/struct
 		// output arguments (their elements can be referenced in subsequent calls).
 		switch typ.(type) {
-		case *sys.IntType, *sys.FlagsType, *sys.ConstType, *sys.StrConstType,
+		case *sys.IntType, *sys.FlagsType, *sys.ConstType,
 			*sys.ResourceType, *sys.VmaType:
 			return constArg(typ, 0), nil
 		}
@@ -718,10 +707,7 @@ func (r *randGen) generateArg(s *state, typ sys.Type) (arg *Arg, calls []*Call)
 			}
 			return dataArg(a, data), nil
 		case sys.BufferString:
-			data := r.randString(s)
-			return dataArg(a, data), nil
-		case sys.BufferFilesystem:
-			data := r.filesystem(s)
+			data := r.randString(s, a.Values)
 			return dataArg(a, data), nil
 		case sys.BufferFilename:
 			filename := r.filename(s)
@@ -761,8 +747,6 @@ func (r *randGen) generateArg(s *state, typ sys.Type) (arg *Arg, calls []*Call)
 		return constArg(a, r.flags(a.Vals)), nil
 	case *sys.ConstType:
 		return constArg(a, a.Val), nil
-	case *sys.StrConstType:
-		return dataArg(a, []byte(a.Val)), nil
 	case *sys.IntType:
 		v := r.randInt()
 		switch a.Kind {
diff --git a/sys/README.md b/sys/README.md
index 89638aa12..161c1e73e 100644
--- a/sys/README.md
+++ b/sys/README.md
@@ -44,9 +44,9 @@ rest of the type-options are type-specific:
 		type of the object; direction (in/out/inout)
 	"buffer": a pointer to a memory buffer (like read/write buffer argument), type-options:
 		direction (in/out/inout)
-	"string": a zero-terminated memory buffer (no pointer indirection implied)
-	"strconst": a pointer to a constant string, type-options:
-		the underlying string (for example "/dev/dsp")
+	"string": a zero-terminated memory buffer (no pointer indirection implied), type-options:
+		either a string value in quotes for constant strings (e.g. "foo"),
+		or a reference to string flags
 	"filename": a file/link/dir name
 	"fileoff": offset within a file
 	"len": length of another field (for array it is number of elements), type-options:
@@ -61,6 +61,10 @@ Flags are described as:
 ```
 	flagname = const ["," const]*
 ```
+or for string flags as:
+```
+	flagname = "\"" literal "\"" ["," "\"" literal "\""]*
+```
 
 ### Structs
 
diff --git a/sys/decl.go b/sys/decl.go
index d5ec9a547..2f86ea87c 100644
--- a/sys/decl.go
+++ b/sys/decl.go
@@ -105,7 +105,6 @@ const (
 	BufferString
 	BufferFilename
 	BufferSockaddr
-	BufferFilesystem
 	BufferAlgType
 	BufferAlgName
 )
@@ -115,6 +114,8 @@ type BufferType struct {
 	Kind       BufferKind
 	RangeBegin uintptr // for BufferBlobRange kind
 	RangeEnd   uintptr // for BufferBlobRange kind
+	SubKind    string
+	Values     []string // possible values for BufferString kind
 }
 
 func (t *BufferType) Size() uintptr {
@@ -123,14 +124,16 @@ func (t *BufferType) Size() uintptr {
 		return 14
 	case BufferAlgName:
 		return 64
+	case BufferString:
+		if len(t.Values) == 1 {
+			return uintptr(len(t.Values[0]))
+		}
 	case BufferBlobRange:
 		if t.RangeBegin == t.RangeEnd {
 			return t.RangeBegin
 		}
-		fallthrough
-	default:
-		panic(fmt.Sprintf("buffer size is not statically known: %v", t.Name()))
 	}
+	panic(fmt.Sprintf("buffer size is not statically known: %v", t.Name()))
 }
 
 func (t *BufferType) Align() uintptr {
@@ -196,20 +199,6 @@ func (t *ConstType) Align() uintptr {
 	return t.Size()
 }
 
-type StrConstType struct {
-	TypeCommon
-	TypeSize uintptr
-	Val      string
-}
-
-func (t *StrConstType) Size() uintptr {
-	return uintptr(len(t.Val))
-}
-
-func (t *StrConstType) Align() uintptr {
-	return 1
-}
-
 type IntKind int
 
 const (
@@ -486,9 +475,8 @@ func ForeachType(meta *Call, f func(Type)) {
 			for _, opt := range a.Options {
 				rec(opt)
 			}
-		case *ResourceType, *BufferType,
-			*VmaType, *LenType, *FlagsType, *ConstType,
-			*StrConstType, *IntType:
+		case *ResourceType, *BufferType, *VmaType, *LenType,
+			*FlagsType, *ConstType, *IntType:
 		default:
 			panic("unknown type")
 		}
diff --git a/sys/dri.txt b/sys/dri.txt
index 3c5753f23..bc35016e4 100644
--- a/sys/dri.txt
+++ b/sys/dri.txt
@@ -10,9 +10,9 @@ resource drm_agp_handle[intptr]
 resource drm_gem_handle[int32]
 resource drm_gem_name[int32]
 
-syz_open_dev$dri(dev strconst["/dev/dri/card#"], id intptr, flags flags[open_flags]) fd_dri
-syz_open_dev$dricontrol(dev strconst["/dev/dri/controlD#"], id intptr, flags flags[open_flags]) fd_dri
-syz_open_dev$drirender(dev strconst["/dev/dri/renderD#"], id intptr, flags flags[open_flags]) fd_dri
+syz_open_dev$dri(dev ptr[in, string["/dev/dri/card#"]], id intptr, flags flags[open_flags]) fd_dri
+syz_open_dev$dricontrol(dev ptr[in, string["/dev/dri/controlD#"]], id intptr, flags flags[open_flags]) fd_dri
+syz_open_dev$drirender(dev ptr[in, string["/dev/dri/renderD#"]], id intptr, flags flags[open_flags]) fd_dri
 
 ioctl$DRM_IOCTL_VERSION(fd fd_dri, cmd const[DRM_IOCTL_VERSION], arg ptr[in, drm_version])
 ioctl$DRM_IOCTL_GET_UNIQUE(fd fd_dri, cmd const[DRM_IOCTL_GET_UNIQUE], arg ptr[in, drm_unique_out])
diff --git a/sys/input.txt b/sys/input.txt
index 236d6c89c..4266c2b2b 100644
--- a/sys/input.txt
+++ b/sys/input.txt
@@ -6,10 +6,10 @@ include <linux/input.h>
 resource fd_evdev[fd]
 
 # There seems to be nothing special we can do with this fd.
-syz_open_dev$mouse(dev strconst["/dev/input/mouse#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$mice(dev strconst["/dev/input/mice"], id const[0], flags flags[open_flags]) fd
+syz_open_dev$mouse(dev ptr[in, string["/dev/input/mouse#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$mice(dev ptr[in, string["/dev/input/mice"]], id const[0], flags flags[open_flags]) fd
 
-syz_open_dev$evdev(dev strconst["/dev/input/event#"], id intptr, flags flags[open_flags]) fd_evdev
+syz_open_dev$evdev(dev ptr[in, string["/dev/input/event#"]], id intptr, flags flags[open_flags]) fd_evdev
 
 write$evdev(fd fd_evdev, data ptr[in, array[input_event]], len bytesize[data])
 
diff --git a/sys/kdbus.txt b/sys/kdbus.txt
index 5d40b8625..97bd49e70 100644
--- a/sys/kdbus.txt
+++ b/sys/kdbus.txt
@@ -6,7 +6,7 @@ include <uapi/linux/fcntl.h>
 
 resource fd_kdbus[fd]
 
-openat$kdbus(fd const[AT_FDCWD], file strconst["/dev/kdbus"], flags flags[open_flags], mode const[0]) fd_kdbus
+openat$kdbus(fd const[AT_FDCWD], file ptr[in, string["/dev/kdbus"]], flags flags[open_flags], mode const[0]) fd_kdbus
 ioctl$kdbus_bus_make(fd fd_kdbus, cmd const[KDBUS_CMD_BUS_MAKE], arg ptr[in, kdbus_cmd_bus_make])
 ioctl$kdbus_ep_make(fd fd_kdbus, cmd const[KDBUS_CMD_ENDPOINT_MAKE], arg ptr[in, kdbus_cmd_ep_make])
 ioctl$kdbus_ep_update(fd fd_kdbus, cmd const[KDBUS_CMD_ENDPOINT_UPDATE], arg ptr[in, kdbus_cmd_ep_update])
diff --git a/sys/kvm.txt b/sys/kvm.txt
index b80f4ce72..96e73d74e 100644
--- a/sys/kvm.txt
+++ b/sys/kvm.txt
@@ -9,7 +9,7 @@ resource fd_kvm[fd]
 resource fd_kvmvm[fd]
 resource fd_kvmcpu[fd]
 
-syz_open_dev$kvm(dev strconst["/dev/kvm"], id const[0], flags flags[open_flags]) fd_kvm
+syz_open_dev$kvm(dev ptr[in, string["/dev/kvm"]], id const[0], flags flags[open_flags]) fd_kvm
 
 ioctl$KVM_CREATE_VM(fd fd_kvm, cmd const[KVM_CREATE_VM], type const[0]) fd_kvmvm
 ioctl$KVM_GET_MSR_INDEX_LIST(fd fd_kvm, cmd const[KVM_GET_MSR_INDEX_LIST], arg ptr[in, kvm_msr_list])
@@ -99,7 +99,7 @@ ioctl$KVM_SET_GUEST_DEBUG(fd fd_kvmcpu, cmd const[KVM_SET_GUEST_DEBUG], arg ptr[
 ioctl$KVM_SMI(fd fd_kvmcpu, cmd const[KVM_SMI])
 
 # TODO: extend support (there are some ioctls)
-openat$xenevtchn(fd const[AT_FDCWD], file strconst["/dev/xen/evtchn"], flags flags[open_flags], mode const[0]) fd
+openat$xenevtchn(fd const[AT_FDCWD], file ptr[in, string["/dev/xen/evtchn"]], flags flags[open_flags], mode const[0]) fd
 
 kvm_mem_region_flags = KVM_MEM_LOG_DIRTY_PAGES, KVM_MEM_READONLY, KVM_MEMSLOT_INVALID, KVM_MEMSLOT_INCOHERENT
 kvm_mp_state = KVM_MP_STATE_RUNNABLE, KVM_MP_STATE_UNINITIALIZED, KVM_MP_STATE_INIT_RECEIVED, KVM_MP_STATE_HALTED, KVM_MP_STATE_SIPI_RECEIVED, KVM_MP_STATE_STOPPED, KVM_MP_STATE_CHECK_STOP, KVM_MP_STATE_OPERATING, KVM_MP_STATE_LOAD
diff --git a/sys/random.txt b/sys/random.txt
index 7c8fd11c0..234d1be40 100755
--- a/sys/random.txt
+++ b/sys/random.txt
@@ -5,8 +5,8 @@ include <linux/random.h>
 
 resource fd_random[fd]
 
-syz_open_dev$random(dev strconst["/dev/random"], id const[0], flags flags[open_flags]) fd_random
-syz_open_dev$urandom(dev strconst["/dev/urandom"], id const[0], flags flags[open_flags]) fd_random
+syz_open_dev$random(dev ptr[in, string["/dev/random"]], id const[0], flags flags[open_flags]) fd_random
+syz_open_dev$urandom(dev ptr[in, string["/dev/urandom"]], id const[0], flags flags[open_flags]) fd_random
 
 ioctl$RNDGETENTCNT(fd fd_random, cmd const[RNDGETENTCNT], arg ptr[out, int32])
 ioctl$RNDADDTOENTCNT(fd fd_random, cmd const[RNDADDTOENTCNT], arg ptr[in, int32])
diff --git a/sys/sndcontrol.txt b/sys/sndcontrol.txt
index 3e3b8a359..1ec602f03 100644
--- a/sys/sndcontrol.txt
+++ b/sys/sndcontrol.txt
@@ -5,7 +5,7 @@ include <sound/asound.h>
 
 resource fd_sndctrl[fd]
 
-syz_open_dev$sndctrl(dev strconst["/dev/snd/controlC#"], id intptr, flags flags[open_flags]) fd_sndctrl
+syz_open_dev$sndctrl(dev ptr[in, string["/dev/snd/controlC#"]], id intptr, flags flags[open_flags]) fd_sndctrl
 
 ioctl$SNDRV_CTL_IOCTL_PVERSION(fd fd_sndctrl, cmd const[SNDRV_CTL_IOCTL_PVERSION], arg buffer[out])
 ioctl$SNDRV_CTL_IOCTL_CARD_INFO(fd fd_sndctrl, cmd const[SNDRV_CTL_IOCTL_CARD_INFO], arg buffer[out])
diff --git a/sys/sndseq.txt b/sys/sndseq.txt
index 62a844ed7..40ad7118d 100644
--- a/sys/sndseq.txt
+++ b/sys/sndseq.txt
@@ -6,7 +6,7 @@ include <sound/asequencer.h>
 
 resource fd_sndseq[fd]
 
-syz_open_dev$sndseq(dev strconst["/dev/snd/seq"], id const[0], flags flags[open_flags]) fd_sndseq
+syz_open_dev$sndseq(dev ptr[in, string["/dev/snd/seq"]], id const[0], flags flags[open_flags]) fd_sndseq
 write$sndseq(fd fd_sndseq, data ptr[in, array[snd_seq_event]], len bytesize[data])
 
 ioctl$SNDRV_SEQ_IOCTL_PVERSION(fd fd_sndseq, cmd const[SNDRV_SEQ_IOCTL_PVERSION], arg ptr[out, int32])
diff --git a/sys/sndtimer.txt b/sys/sndtimer.txt
index 67e0a13a8..f7eebc2af 100644
--- a/sys/sndtimer.txt
+++ b/sys/sndtimer.txt
@@ -5,7 +5,7 @@ include <sound/asound.h>
 
 resource fd_sndtimer[fd]
 
-syz_open_dev$sndtimer(dev strconst["/dev/snd/timer"], id const[0], flags flags[open_flags]) fd_sndtimer
+syz_open_dev$sndtimer(dev ptr[in, string["/dev/snd/timer"]], id const[0], flags flags[open_flags]) fd_sndtimer
 
 ioctl$SNDRV_TIMER_IOCTL_PVERSION(fd fd_sndtimer, cmd const[SNDRV_TIMER_IOCTL_PVERSION], arg ptr[out, int32])
 ioctl$SNDRV_TIMER_IOCTL_NEXT_DEVICE(fd fd_sndtimer, cmd const[SNDRV_TIMER_IOCTL_NEXT_DEVICE], arg ptr[in, snd_timer_id])
diff --git a/sys/sys.txt b/sys/sys.txt
index 13d2d2830..c6da9a800 100644
--- a/sys/sys.txt
+++ b/sys/sys.txt
@@ -345,14 +345,16 @@ getdents64(fd fd_dir, ent buffer[out], count len[ent])
 name_to_handle_at(fd fd_dir, file filename, handle ptr[in, file_handle], mnt ptr[out, int32], flags flags[name_to_handle_at_flags])
 open_by_handle_at(mountdirfd fd, handle ptr[in, file_handle], flags flags[open_flags])
 
-mount(src filename, dst filename, type filesystem, flags flags[mount_flags], data buffer[in])
-mount$fs(src filesystem, dst filename, type filesystem, flags flags[mount_flags], data buffer[in])
+mount(src filename, dst filename, type ptr[in, string[filesystem]], flags flags[mount_flags], data buffer[in])
+mount$fs(src ptr[in, string[filesystem]], dst filename, type ptr[in, string[filesystem]], flags flags[mount_flags], data buffer[in])
 umount2(path filename, flags flags[umount_flags])
 pivot_root(new_root filename, put_old filename)
 
-sysfs$1(option flags[sysfs_opt1], fsname ptr[in, string])
-sysfs$2(option flags[sysfs_opt2], fsindex intptr, fsname buffer[out])
-sysfs$3(option flags[sysfs_opt3])
+filesystem = "sysfs", "rootfs", "ramfs", "tmpfs", "devtmpfs", "debugfs", "securityfs", "sockfs", "pipefs", "anon_inodefs", "devpts", "ext3", "ext2", "ext4", "hugetlbfs", "vfat", "ecryptfs", "kdbusfs", "fuseblk", "fuse", "rpc_pipefs", "nfs", "nfs4", "nfsd", "binfmt_misc", "autofs", "xfs", "jfs", "msdos", "ntfs", "minix", "hfs", "hfsplus", "qnx4", "ufs", "btrfs", "configfs", "ncpfs", "qnx6", "exofs", "befs", "vxfs", "gfs2", "gfs2meta", "fusectl", "bfs", "nsfs", "efs", "cifs", "efivarfs", "affs", "tracefs", "bdev", "ocfs2", "ocfs2_dlmfs", "hpfs", "proc", "afs", "reiserfs", "jffs2", "romfs", "aio", "sysv", "v7", "udf", "ceph", "pstore", "adfs", "9p", "hostfs", "squashfs", "cramfs", "iso9660", "coda", "nilfs2", "logfs", "overlay", "f2fs", "omfs", "ubifs", "openpromfs"
+
+sysfs$1(option const[1], fsname ptr[in, string])
+sysfs$2(option const[2], fsindex intptr, fsname buffer[out])
+sysfs$3(option const[3])
 statfs(path filename, buf buffer[out])
 fstatfs(fd fd, buf buffer[out])
 
@@ -463,55 +465,55 @@ membarrier(cmd const[1], flags const[0])
 # These devices are relatively safe (don't reboot and don't corrupt kernel memory).
 # They need a more comprehensive support. But let at least open them for now,
 # maybe fuzzer will be able to skrew them in a useful way.
-syz_open_dev$floppy(dev strconst["/dev/fd#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$pktcdvd(dev strconst["/dev/pktcdvd/control"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$lightnvm(dev strconst["/dev/lightnvm/control"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$vcs(dev strconst["/dev/vcs"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$vcsn(dev strconst["/dev/vcs#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$vcsa(dev strconst["/dev/vcsa#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$vga_arbiter(dev strconst["/dev/vga_arbiter"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$vhci(dev strconst["/dev/vhci"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$userio(dev strconst["/dev/userio"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$rtc(dev strconst["/dev/rtc"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$rfkill(dev strconst["/dev/rfkill"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$qat_adf_ctl(dev strconst["/dev/qat_adf_ctl"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$ppp(dev strconst["/dev/ppp"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$mixer(dev strconst["/dev/mixer"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$irnet(dev strconst["/dev/irnet"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$hwrng(dev strconst["/dev/hwrng"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$hpet(dev strconst["/dev/hpet"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$hidraw0(dev strconst["/dev/hidraw0"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$fb0(dev strconst["/dev/fb0"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$cuse(dev strconst["/dev/cuse"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$console(dev strconst["/dev/console"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$capi20(dev strconst["/dev/capi20"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$autofs(dev strconst["/dev/autofs"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$binder(dev strconst["/dev/binder"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$ion(dev strconst["/dev/ion"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$keychord(dev strconst["/dev/keychord"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$zygote(dev strconst["/dev/socket/zygote"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$sw_sync(dev strconst["/dev/sw_sync"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$sr(dev strconst["/dev/sr0"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$sequencer(dev strconst["/dev/sequencer"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$sequencer2(dev strconst["/dev/sequencer2"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$dsp(dev strconst["/dev/dsp"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$audio(dev strconst["/dev/audio"], id const[0], flags flags[open_flags]) fd
-syz_open_dev$usbmon(dev strconst["/dev/usbmon#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$sg(dev strconst["/dev/sg#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$midi(dev strconst["/dev/midi#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$loop(dev strconst["/dev/loop#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$ircomm(dev strconst["/dev/ircomm#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$dspn(dev strconst["/dev/dsp#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$dmmidi(dev strconst["/dev/dmmidi#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$admmidi(dev strconst["/dev/admmidi#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$adsp(dev strconst["/dev/adsp#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$amidi(dev strconst["/dev/amidi#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$audion(dev strconst["/dev/audio#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$usb(dev strconst["/dev/bus/usb/00#/00#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$sndhw(dev strconst["/dev/snd/hwC#D#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$sndmidi(dev strconst["/dev/snd/midiC#D#"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$sndpcmc(dev strconst["/dev/snd/pcmC#D#c"], id intptr, flags flags[open_flags]) fd
-syz_open_dev$sndpcmp(dev strconst["/dev/snd/pcmC#D#p"], id intptr, flags flags[open_flags]) fd
+syz_open_dev$floppy(dev ptr[in, string["/dev/fd#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$pktcdvd(dev ptr[in, string["/dev/pktcdvd/control"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$lightnvm(dev ptr[in, string["/dev/lightnvm/control"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$vcs(dev ptr[in, string["/dev/vcs"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$vcsn(dev ptr[in, string["/dev/vcs#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$vcsa(dev ptr[in, string["/dev/vcsa#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$vga_arbiter(dev ptr[in, string["/dev/vga_arbiter"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$vhci(dev ptr[in, string["/dev/vhci"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$userio(dev ptr[in, string["/dev/userio"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$rtc(dev ptr[in, string["/dev/rtc"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$rfkill(dev ptr[in, string["/dev/rfkill"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$qat_adf_ctl(dev ptr[in, string["/dev/qat_adf_ctl"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$ppp(dev ptr[in, string["/dev/ppp"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$mixer(dev ptr[in, string["/dev/mixer"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$irnet(dev ptr[in, string["/dev/irnet"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$hwrng(dev ptr[in, string["/dev/hwrng"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$hpet(dev ptr[in, string["/dev/hpet"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$hidraw0(dev ptr[in, string["/dev/hidraw0"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$fb0(dev ptr[in, string["/dev/fb0"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$cuse(dev ptr[in, string["/dev/cuse"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$console(dev ptr[in, string["/dev/console"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$capi20(dev ptr[in, string["/dev/capi20"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$autofs(dev ptr[in, string["/dev/autofs"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$binder(dev ptr[in, string["/dev/binder"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$ion(dev ptr[in, string["/dev/ion"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$keychord(dev ptr[in, string["/dev/keychord"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$zygote(dev ptr[in, string["/dev/socket/zygote"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$sw_sync(dev ptr[in, string["/dev/sw_sync"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$sr(dev ptr[in, string["/dev/sr0"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$sequencer(dev ptr[in, string["/dev/sequencer"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$sequencer2(dev ptr[in, string["/dev/sequencer2"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$dsp(dev ptr[in, string["/dev/dsp"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$audio(dev ptr[in, string["/dev/audio"]], id const[0], flags flags[open_flags]) fd
+syz_open_dev$usbmon(dev ptr[in, string["/dev/usbmon#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$sg(dev ptr[in, string["/dev/sg#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$midi(dev ptr[in, string["/dev/midi#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$loop(dev ptr[in, string["/dev/loop#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$ircomm(dev ptr[in, string["/dev/ircomm#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$dspn(dev ptr[in, string["/dev/dsp#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$dmmidi(dev ptr[in, string["/dev/dmmidi#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$admmidi(dev ptr[in, string["/dev/admmidi#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$adsp(dev ptr[in, string["/dev/adsp#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$amidi(dev ptr[in, string["/dev/amidi#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$audion(dev ptr[in, string["/dev/audio#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$usb(dev ptr[in, string["/dev/bus/usb/00#/00#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$sndhw(dev ptr[in, string["/dev/snd/hwC#D#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$sndmidi(dev ptr[in, string["/dev/snd/midiC#D#"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$sndpcmc(dev ptr[in, string["/dev/snd/pcmC#D#c"]], id intptr, flags flags[open_flags]) fd
+syz_open_dev$sndpcmp(dev ptr[in, string["/dev/snd/pcmC#D#p"]], id intptr, flags flags[open_flags]) fd
 
 
 
@@ -1167,9 +1169,6 @@ ioprio_which_uid = IOPRIO_WHO_USER
 setxattr_flags = XATTR_CREATE, XATTR_REPLACE
 ns_type = 0, CLONE_NEWIPC, CLONE_NEWNET, CLONE_NEWUTS
 personality_flags = PER_LINUX, PER_SVR4, PER_SVR3, PER_OSR5, PER_WYSEV386, PER_ISCR4, PER_BSD, PER_XENIX, PER_LINUX32, PER_IRIX32, PER_IRIXN32, PER_IRIX64, PER_RISCOS, PER_SOLARIS, PER_UW7, PER_OSF4, PER_HPUX, ADDR_NO_RANDOMIZE, MMAP_PAGE_ZERO, ADDR_COMPAT_LAYOUT, READ_IMPLIES_EXEC, ADDR_LIMIT_32BIT, SHORT_INODE, WHOLE_SECONDS, STICKY_TIMEOUTS, ADDR_LIMIT_3GB
-sysfs_opt1 = 1
-sysfs_opt2 = 2
-sysfs_opt3 = 3
 clock_id = CLOCK_REALTIME, CLOCK_REALTIME_COARSE, CLOCK_MONOTONIC, CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_RAW, CLOCK_BOOTTIME, CLOCK_PROCESS_CPUTIME_ID, CLOCK_THREAD_CPUTIME_ID
 sigprocmask_how = SIG_BLOCK, SIG_UNBLOCK, SIG_SETMASK
 getitimer_which = ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF
diff --git a/sys/tlk_device.txt b/sys/tlk_device.txt
index 7535d16f7..1d5bd8229 100644
--- a/sys/tlk_device.txt
+++ b/sys/tlk_device.txt
@@ -12,7 +12,7 @@ include <security/tlk_driver/ote_protocol.h>
 resource fd_tlk[fd]
 resource te_session_id[int32]
 
-syz_open_dev$tlk_device(dev strconst["/dev/tlk_device"], id const[0], flags flags[open_flags]) fd_tlk
+syz_open_dev$tlk_device(dev ptr[in, string["/dev/tlk_device"]], id const[0], flags flags[open_flags]) fd_tlk
 
 ioctl$TE_IOCTL_OPEN_CLIENT_SESSION(fd fd_tlk, cmd const[TE_IOCTL_OPEN_CLIENT_SESSION], arg ptr[inout, te_opensession])
 ioctl$TE_IOCTL_CLOSE_CLIENT_SESSION(fd fd_tlk, cmd const[TE_IOCTL_CLOSE_CLIENT_SESSION], arg ptr[inout, te_closesession])
diff --git a/sys/tty.txt b/sys/tty.txt
index 67b11b754..e9717806c 100644
--- a/sys/tty.txt
+++ b/sys/tty.txt
@@ -8,7 +8,7 @@ include <uapi/linux/fcntl.h>
 
 resource fd_tty[fd]
 
-openat$ptmx(fd const[AT_FDCWD], file strconst["/dev/ptmx"], flags flags[open_flags], mode const[0]) fd_tty
+openat$ptmx(fd const[AT_FDCWD], file ptr[in, string["/dev/ptmx"]], flags flags[open_flags], mode const[0]) fd_tty
 syz_open_pts(fd fd_tty, flags flags[open_flags]) fd_tty
 ioctl$TCGETS(fd fd_tty, cmd const[TCGETS], arg ptr[out, termios])
 ioctl$TCSETS(fd fd_tty, cmd const[TCSETS], arg ptr[in, termios])
diff --git a/sys/tun.txt b/sys/tun.txt
index 04e640786..a730ed86a 100755
--- a/sys/tun.txt
+++ b/sys/tun.txt
@@ -6,7 +6,7 @@ include <linux/virtio_net.h>
 
 resource fd_tun[fd]
 
-syz_open_dev$tun(dev strconst["/dev/net/tun"], id const[0], flags flags[open_flags]) fd_tun
+syz_open_dev$tun(dev ptr[in, string["/dev/net/tun"]], id const[0], flags flags[open_flags]) fd_tun
 write$tun(fd fd_tun, buf ptr[in, tun_buffer], count len[buf])
 
 ioctl$TUNGETFEATURES(fd fd_tun, cmd const[TUNGETFEATURES], arg ptr[out, int32])
diff --git a/sysgen/sysgen.go b/sysgen/sysgen.go
index 7159ef70c..6913b9c81 100644
--- a/sysgen/sysgen.go
+++ b/sysgen/sysgen.go
@@ -407,19 +407,27 @@ func generateArg(
 		opt = false
 		fmt.Fprintf(out, "&PtrType{%v, Type: &BufferType{%v, Kind: BufferBlobRand}}", ptrCommonHdr, common())
 	case "string":
-		if want := 0; len(a) != want {
-			failf("wrong number of arguments for %v arg %v, want %v, got %v", typ, name, want, len(a))
+		if len(a) != 0 && len(a) != 1 {
+			failf("wrong number of arguments for %v arg %v, want 0 or 1, got %v", typ, name, len(a))
 		}
-		fmt.Fprintf(out, "&BufferType{%v, Kind: BufferString}", common())
-	case "filesystem":
-		canBeArg = true
-		if want := 0; len(a) != want {
-			failf("wrong number of arguments for %v arg %v, want %v, got %v", typ, name, want, len(a))
+		var vals []string
+		subkind := ""
+		if len(a) == 1 {
+			if a[0][0] == '"' {
+				vals = append(vals, a[0][1:len(a[0])-1])
+			} else {
+				ok := false
+				vals, ok = desc.StrFlags[a[0]]
+				if !ok {
+					failf("unknown string flags %v", a[0])
+				}
+				subkind = a[0]
+			}
+			for i, s := range vals {
+				vals[i] = s + "\x00"
+			}
 		}
-		ptrCommonHdr := common()
-		dir = "in"
-		opt = false
-		fmt.Fprintf(out, "&PtrType{%v, Type: &BufferType{%v, Kind: BufferFilesystem}}", ptrCommonHdr, common())
+		fmt.Fprintf(out, "&BufferType{%v, Kind: BufferString, SubKind: %q, Values: %#v}", common(), subkind, vals)
 	case "sockaddr":
 		if want := 0; len(a) != want {
 			failf("wrong number of arguments for %v arg %v, want %v, got %v", typ, name, want, len(a))
@@ -503,15 +511,6 @@ func generateArg(
 			skipSyscall(fmt.Sprintf("missing const %v", a[0]))
 		}
 		fmt.Fprintf(out, "&ConstType{%v, TypeSize: %v, BigEndian: %v, Val: uintptr(%v)}", common(), size, bigEndian, val)
-	case "strconst":
-		canBeArg = true
-		if want := 1; len(a) != want {
-			failf("wrong number of arguments for %v arg %v, want %v, got %v", typ, name, want, len(a))
-		}
-		ptrCommonHdr := common()
-		dir = "in"
-		opt = false
-		fmt.Fprintf(out, "&PtrType{%v, Type: &StrConstType{%v, Val: \"%v\"}}", ptrCommonHdr, common(), a[0]+"\\x00")
 	case "int8", "int16", "int32", "int64", "intptr", "int16be", "int32be", "int64be", "intptrbe":
 		canBeArg = true
 		size, bigEndian := decodeIntType(typ)
diff --git a/sysparser/lexer.go b/sysparser/lexer.go
index 18143c901..a3b8f58ed 100644
--- a/sysparser/lexer.go
+++ b/sysparser/lexer.go
@@ -18,6 +18,7 @@ type Description struct {
 	Structs   map[string]Struct
 	Unnamed   map[string][]string
 	Flags     map[string][]string
+	StrFlags  map[string][]string
 	Resources map[string]Resource
 }
 
@@ -51,6 +52,7 @@ func Parse(in io.Reader) *Description {
 	structs := make(map[string]Struct)
 	unnamed := make(map[string][]string)
 	flags := make(map[string][]string)
+	strflags := make(map[string][]string)
 	resources := make(map[string]Resource)
 	var str *Struct
 	for p.Scan() {
@@ -192,12 +194,24 @@ func Parse(in io.Reader) *Description {
 				case '=':
 					// flag
 					p.Parse('=')
-					vals := []string{p.Ident()}
-					for !p.EOF() {
+					str := p.Char() == '"'
+					var vals []string
+					for {
+						v := p.Ident()
+						if str {
+							v = v[1 : len(v)-1]
+						}
+						vals = append(vals, v)
+						if p.EOF() {
+							break
+						}
 						p.Parse(',')
-						vals = append(vals, p.Ident())
 					}
-					flags[name] = vals
+					if str {
+						strflags[name] = vals
+					} else {
+						flags[name] = vals
+					}
 				case '{', '[':
 					p.Parse(ch)
 					if _, ok := structs[name]; ok {
@@ -224,6 +238,7 @@ func Parse(in io.Reader) *Description {
 		Structs:   structs,
 		Unnamed:   unnamed,
 		Flags:     flags,
+		StrFlags:  strflags,
 		Resources: resources,
 	}
 }
diff --git a/sysparser/parser.go b/sysparser/parser.go
index 590847b0e..d5021eee6 100644
--- a/sysparser/parser.go
+++ b/sysparser/parser.go
@@ -70,11 +70,10 @@ func (p *parser) Ident() string {
 	start, end := p.i, 0
 	if p.Char() == '"' {
 		p.Parse('"')
-		start++
 		for p.Char() != '"' {
 			p.i++
 		}
-		end = p.i
+		end = p.i + 1
 		p.Parse('"')
 	} else {
 		for p.i < len(p.s) &&