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-rw-r--r--internal/fusefrontend/node_open_create.go29
-rw-r--r--internal/fusefrontend/node_xattr_darwin.go14
-rw-r--r--internal/fusefrontend/root_node.go29
-rw-r--r--internal/fusefrontend_reverse/node_helpers.go2
-rw-r--r--internal/fusefrontend_reverse/node_xattr.go2
-rw-r--r--internal/fusefrontend_reverse/root_node.go4
-rw-r--r--internal/syscallcompat/quirks_linux.go40
-rw-r--r--internal/syscallcompat/sys_common.go8
-rw-r--r--internal/syscallcompat/sys_darwin.go4
-rw-r--r--internal/syscallcompat/sys_freebsd.go3
-rw-r--r--internal/syscallcompat/sys_linux.go4
11 files changed, 95 insertions, 44 deletions
diff --git a/internal/fusefrontend/node_open_create.go b/internal/fusefrontend/node_open_create.go
index 9598559..622d5dc 100644
--- a/internal/fusefrontend/node_open_create.go
+++ b/internal/fusefrontend/node_open_create.go
@@ -2,6 +2,7 @@ package fusefrontend
import (
"context"
+ "os"
"syscall"
"github.com/hanwen/go-fuse/v2/fs"
@@ -12,6 +13,30 @@ import (
"github.com/rfjakob/gocryptfs/v2/internal/tlog"
)
+// mangleOpenCreateFlags is used by Create() and Open() to convert the open flags the user
+// wants to the flags we internally use to open the backing file using Openat().
+// The returned flags always contain O_NOFOLLOW/O_SYMLINK.
+func mangleOpenCreateFlags(flags uint32) (newFlags int) {
+ newFlags = int(flags)
+ // Convert WRONLY to RDWR. We always need read access to do read-modify-write cycles.
+ if (newFlags & syscall.O_ACCMODE) == syscall.O_WRONLY {
+ newFlags = newFlags ^ os.O_WRONLY | os.O_RDWR
+ }
+ // We also cannot open the file in append mode, we need to seek back for RMW
+ newFlags = newFlags &^ os.O_APPEND
+ // O_DIRECT accesses must be aligned in both offset and length. Due to our
+ // crypto header, alignment will be off, even if userspace makes aligned
+ // accesses. Running xfstests generic/013 on ext4 used to trigger lots of
+ // EINVAL errors due to missing alignment. Just fall back to buffered IO.
+ newFlags = newFlags &^ syscallcompat.O_DIRECT
+ // Create and Open are two separate FUSE operations, so O_CREAT should usually not
+ // be part of the Open() flags. Create() will add O_CREAT back itself.
+ newFlags = newFlags &^ syscall.O_CREAT
+ // We always want O_NOFOLLOW/O_SYMLINK to be safe against symlink races
+ newFlags |= syscallcompat.OpenatFlagNofollowSymlink
+ return newFlags
+}
+
// Open - FUSE call. Open already-existing file.
//
// Symlink-safe through Openat().
@@ -23,7 +48,7 @@ func (n *Node) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFl
defer syscall.Close(dirfd)
rn := n.rootNode()
- newFlags := rn.mangleOpenFlags(flags)
+ newFlags := mangleOpenCreateFlags(flags)
// Taking this lock makes sure we don't race openWriteOnlyFile()
rn.openWriteOnlyLock.RLock()
defer rn.openWriteOnlyLock.RUnlock()
@@ -71,7 +96,7 @@ func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint3
if !rn.args.PreserveOwner {
ctx = nil
}
- newFlags := rn.mangleOpenFlags(flags)
+ newFlags := mangleOpenCreateFlags(flags)
// Handle long file name
ctx2 := toFuseCtx(ctx)
if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
diff --git a/internal/fusefrontend/node_xattr_darwin.go b/internal/fusefrontend/node_xattr_darwin.go
index f8f224f..1d25f3d 100644
--- a/internal/fusefrontend/node_xattr_darwin.go
+++ b/internal/fusefrontend/node_xattr_darwin.go
@@ -29,8 +29,8 @@ func (n *Node) getXAttr(cAttr string) (out []byte, errno syscall.Errno) {
}
defer syscall.Close(dirfd)
- // O_NONBLOCK to not block on FIFOs.
- fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NONBLOCK|syscall.O_NOFOLLOW, 0)
+ // O_NONBLOCK to not block on FIFOs, O_SYMLINK to open the symlink itself (if it is one).
+ fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NONBLOCK|syscall.O_SYMLINK, 0)
if err != nil {
return nil, fs.ToErrno(err)
}
@@ -52,10 +52,10 @@ func (n *Node) setXAttr(context *fuse.Context, cAttr string, cData []byte, flags
defer syscall.Close(dirfd)
// O_NONBLOCK to not block on FIFOs.
- fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_WRONLY|syscall.O_NONBLOCK|syscall.O_NOFOLLOW, 0)
+ fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_WRONLY|syscall.O_NONBLOCK|syscall.O_SYMLINK, 0)
// Directories cannot be opened read-write. Retry.
if err == syscall.EISDIR {
- fd, err = syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NONBLOCK|syscall.O_NOFOLLOW, 0)
+ fd, err = syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NONBLOCK|syscall.O_SYMLINK, 0)
}
if err != nil {
fs.ToErrno(err)
@@ -74,10 +74,10 @@ func (n *Node) removeXAttr(cAttr string) (errno syscall.Errno) {
defer syscall.Close(dirfd)
// O_NONBLOCK to not block on FIFOs.
- fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_WRONLY|syscall.O_NONBLOCK|syscall.O_NOFOLLOW, 0)
+ fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_WRONLY|syscall.O_NONBLOCK|syscall.O_SYMLINK, 0)
// Directories cannot be opened read-write. Retry.
if err == syscall.EISDIR {
- fd, err = syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NONBLOCK|syscall.O_NOFOLLOW, 0)
+ fd, err = syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NONBLOCK|syscall.O_SYMLINK, 0)
}
if err != nil {
return fs.ToErrno(err)
@@ -96,7 +96,7 @@ func (n *Node) listXAttr() (out []string, errno syscall.Errno) {
defer syscall.Close(dirfd)
// O_NONBLOCK to not block on FIFOs.
- fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NONBLOCK|syscall.O_NOFOLLOW, 0)
+ fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NONBLOCK|syscall.O_SYMLINK, 0)
if err != nil {
return nil, fs.ToErrno(err)
}
diff --git a/internal/fusefrontend/root_node.go b/internal/fusefrontend/root_node.go
index 489e3c6..38d070d 100644
--- a/internal/fusefrontend/root_node.go
+++ b/internal/fusefrontend/root_node.go
@@ -1,7 +1,6 @@
package fusefrontend
import (
- "os"
"strings"
"sync"
"sync/atomic"
@@ -93,7 +92,9 @@ func NewRootNode(args Args, c *contentenc.ContentEnc, n *nametransform.NameTrans
}
// Suppress the message if the user has already specified -noprealloc
if rn.quirks&syscallcompat.QuirkBtrfsBrokenFalloc != 0 && !args.NoPrealloc {
- syscallcompat.LogQuirk("Btrfs detected, forcing -noprealloc. See https://github.com/rfjakob/gocryptfs/issues/395 for why.")
+ syscallcompat.LogQuirk("Btrfs detected, forcing -noprealloc. " +
+ "Use \"chattr +C\" on the backing directory to enable NOCOW and allow preallocation. " +
+ "See https://github.com/rfjakob/gocryptfs/issues/395 for details.")
}
if statErr == nil {
rn.inoMap.TranslateStat(&st)
@@ -108,30 +109,6 @@ func (rn *RootNode) AfterUnmount() {
rn.dirCache.stats()
}
-// mangleOpenFlags is used by Create() and Open() to convert the open flags the user
-// wants to the flags we internally use to open the backing file.
-// The returned flags always contain O_NOFOLLOW.
-func (rn *RootNode) mangleOpenFlags(flags uint32) (newFlags int) {
- newFlags = int(flags)
- // Convert WRONLY to RDWR. We always need read access to do read-modify-write cycles.
- if (newFlags & syscall.O_ACCMODE) == syscall.O_WRONLY {
- newFlags = newFlags ^ os.O_WRONLY | os.O_RDWR
- }
- // We also cannot open the file in append mode, we need to seek back for RMW
- newFlags = newFlags &^ os.O_APPEND
- // O_DIRECT accesses must be aligned in both offset and length. Due to our
- // crypto header, alignment will be off, even if userspace makes aligned
- // accesses. Running xfstests generic/013 on ext4 used to trigger lots of
- // EINVAL errors due to missing alignment. Just fall back to buffered IO.
- newFlags = newFlags &^ syscallcompat.O_DIRECT
- // Create and Open are two separate FUSE operations, so O_CREAT should not
- // be part of the open flags.
- newFlags = newFlags &^ syscall.O_CREAT
- // We always want O_NOFOLLOW to be safe against symlink races
- newFlags |= syscall.O_NOFOLLOW
- return newFlags
-}
-
// reportMitigatedCorruption is used to report a corruption that was transparently
// mitigated and did not return an error to the user. Pass the name of the corrupt
// item (filename for OpenDir(), xattr name for ListXAttr() etc).
diff --git a/internal/fusefrontend_reverse/node_helpers.go b/internal/fusefrontend_reverse/node_helpers.go
index 3165db6..f733689 100644
--- a/internal/fusefrontend_reverse/node_helpers.go
+++ b/internal/fusefrontend_reverse/node_helpers.go
@@ -134,7 +134,7 @@ func (n *Node) lookupLongnameName(ctx context.Context, nameFile string, out *fus
if errno != 0 {
return
}
- if rn.isExcludedPlain(filepath.Join(d.cPath, pName)) {
+ if rn.isExcludedPlain(filepath.Join(d.pPath, pName)) {
errno = syscall.EPERM
return
}
diff --git a/internal/fusefrontend_reverse/node_xattr.go b/internal/fusefrontend_reverse/node_xattr.go
index f22764a..b940339 100644
--- a/internal/fusefrontend_reverse/node_xattr.go
+++ b/internal/fusefrontend_reverse/node_xattr.go
@@ -40,7 +40,7 @@ func (n *Node) Getxattr(ctx context.Context, attr string, dest []byte) (uint32,
} else {
pAttr, err := rn.decryptXattrName(attr)
if err != nil {
- return 0, syscall.EINVAL
+ return 0, noSuchAttributeError
}
pData, errno := n.getXAttr(pAttr)
if errno != 0 {
diff --git a/internal/fusefrontend_reverse/root_node.go b/internal/fusefrontend_reverse/root_node.go
index 420ed22..1a668af 100644
--- a/internal/fusefrontend_reverse/root_node.go
+++ b/internal/fusefrontend_reverse/root_node.go
@@ -13,6 +13,7 @@ import (
"github.com/hanwen/go-fuse/v2/fs"
"github.com/hanwen/go-fuse/v2/fuse"
+ "github.com/rfjakob/gocryptfs/v2/internal/configfile"
"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
"github.com/rfjakob/gocryptfs/v2/internal/exitcodes"
"github.com/rfjakob/gocryptfs/v2/internal/fusefrontend"
@@ -136,7 +137,8 @@ func (rn *RootNode) findLongnameParent(fd int, diriv []byte, longname string) (p
// excluded (used when -exclude is passed by the user).
func (rn *RootNode) isExcludedPlain(pPath string) bool {
// root dir can't be excluded
- if pPath == "" {
+ // Don't exclude gocryptfs.conf too
+ if pPath == "" || pPath == configfile.ConfReverseName {
return false
}
return rn.excluder != nil && rn.excluder.MatchesPath(pPath)
diff --git a/internal/syscallcompat/quirks_linux.go b/internal/syscallcompat/quirks_linux.go
index 87af03d..35f754d 100644
--- a/internal/syscallcompat/quirks_linux.go
+++ b/internal/syscallcompat/quirks_linux.go
@@ -1,11 +1,38 @@
package syscallcompat
import (
+ "syscall"
+
"golang.org/x/sys/unix"
"github.com/rfjakob/gocryptfs/v2/internal/tlog"
)
+// FS_NOCOW_FL is the flag set by "chattr +C" to disable copy-on-write on
+// btrfs. Not exported by golang.org/x/sys/unix, value from linux/fs.h.
+const FS_NOCOW_FL = 0x00800000
+
+// dirHasNoCow checks whether the directory at the given path has the
+// NOCOW (No Copy-on-Write) attribute set (i.e. "chattr +C").
+// When a directory has this attribute, files created within it inherit
+// NOCOW, which makes fallocate work correctly on btrfs because writes
+// go in-place rather than through COW.
+func dirHasNoCow(path string) bool {
+ fd, err := syscall.Open(path, syscall.O_RDONLY|syscall.O_DIRECTORY, 0)
+ if err != nil {
+ tlog.Debug.Printf("dirHasNoCow: Open %q failed: %v", path, err)
+ return false
+ }
+ defer syscall.Close(fd)
+
+ flags, err := unix.IoctlGetInt(fd, unix.FS_IOC_GETFLAGS)
+ if err != nil {
+ tlog.Debug.Printf("dirHasNoCow: FS_IOC_GETFLAGS on %q failed: %v", path, err)
+ return false
+ }
+ return flags&FS_NOCOW_FL != 0
+}
+
// DetectQuirks decides if there are known quirks on the backing filesystem
// that need to be workarounded.
//
@@ -21,10 +48,19 @@ func DetectQuirks(cipherdir string) (q uint64) {
// Preallocation on Btrfs is broken ( https://github.com/rfjakob/gocryptfs/issues/395 )
// and slow ( https://github.com/rfjakob/gocryptfs/issues/63 ).
//
+ // The root cause is that btrfs COW allocates new blocks on write even for
+ // preallocated extents, defeating the purpose of fallocate. However, if the
+ // backing directory has the NOCOW attribute (chattr +C), writes go in-place
+ // and fallocate works correctly.
+ //
// Cast to uint32 avoids compile error on arm: "constant 2435016766 overflows int32"
if uint32(st.Type) == unix.BTRFS_SUPER_MAGIC {
- // LogQuirk is called in fusefrontend/root_node.go
- q |= QuirkBtrfsBrokenFalloc
+ if dirHasNoCow(cipherdir) {
+ tlog.Debug.Printf("DetectQuirks: Btrfs detected but cipherdir has NOCOW attribute (chattr +C), fallocate should work correctly")
+ } else {
+ // LogQuirk is called in fusefrontend/root_node.go
+ q |= QuirkBtrfsBrokenFalloc
+ }
}
return q
diff --git a/internal/syscallcompat/sys_common.go b/internal/syscallcompat/sys_common.go
index e95373a..4f84d98 100644
--- a/internal/syscallcompat/sys_common.go
+++ b/internal/syscallcompat/sys_common.go
@@ -54,10 +54,10 @@ func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
flags |= syscall.O_EXCL
}
} else {
- // If O_CREAT is not used, we should use O_NOFOLLOW
- if flags&syscall.O_NOFOLLOW == 0 {
- tlog.Warn.Printf("Openat: O_NOFOLLOW missing: flags = %#x", flags)
- flags |= syscall.O_NOFOLLOW
+ // If O_CREAT is not used, we should use O_NOFOLLOW or O_SYMLINK
+ if flags&(unix.O_NOFOLLOW|OpenatFlagNofollowSymlink) == 0 {
+ tlog.Warn.Printf("Openat: O_NOFOLLOW/O_SYMLINK missing: flags = %#x", flags)
+ flags |= unix.O_NOFOLLOW
}
}
diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go
index 248b5a2..52d4e0f 100644
--- a/internal/syscallcompat/sys_darwin.go
+++ b/internal/syscallcompat/sys_darwin.go
@@ -29,6 +29,10 @@ const (
// Only exists on Linux. Define here to fix build failure, even though
// we will never see this flag.
RENAME_WHITEOUT = 1 << 30
+
+ // On Darwin we use O_SYMLINK which allows opening a symlink itself.
+ // On Linux, we only have O_NOFOLLOW.
+ OpenatFlagNofollowSymlink = unix.O_SYMLINK
)
// Unfortunately fsetattrlist does not have a syscall wrapper yet.
diff --git a/internal/syscallcompat/sys_freebsd.go b/internal/syscallcompat/sys_freebsd.go
index ec2c402..874e920 100644
--- a/internal/syscallcompat/sys_freebsd.go
+++ b/internal/syscallcompat/sys_freebsd.go
@@ -26,6 +26,9 @@ const (
// ENODATA is only defined on Linux, but FreeBSD provides ENOATTR
ENODATA = unix.ENOATTR
+
+ // On FreeBSD, we only have O_NOFOLLOW.
+ OpenatFlagNofollowSymlink = unix.O_NOFOLLOW
)
// EnospcPrealloc is supposed to preallocate ciphertext space without
diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go
index faa7ffc..4669d8a 100644
--- a/internal/syscallcompat/sys_linux.go
+++ b/internal/syscallcompat/sys_linux.go
@@ -31,6 +31,10 @@ const (
// Only defined on Linux
ENODATA = unix.ENODATA
+
+ // On Darwin we use O_SYMLINK which allows opening a symlink itself.
+ // On Linux, we only have O_NOFOLLOW.
+ OpenatFlagNofollowSymlink = unix.O_NOFOLLOW
)
var preallocWarn sync.Once
generated by cgit v1.2.3 (git 2.39.1) at 2026-02-26 02:12:12 +0000