[RFC PATCH v4 12/36] fuse-bpf: Support mknod/unlink/mkdir/rmdir

Daniel Rosenberg
2024-03-29T01:54:26Z

This adds backing support for FUSE_MKNOD, FUSE_MKDIR, FUSE_RMDIR,
and FUSE_UNLINK

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
fs/fuse/backing.c | 342 ++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dir.c | 14 ++
fs/fuse/fuse_i.h | 24 ++++
3 files changed, 380 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 317a3adbbb3e..567f859d300c 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -947,6 +947,348 @@ int fuse_revalidate_backing(struct dentry *entry, unsigned int flags)
return 1;
}

+struct fuse_mknod_args {
+ struct fuse_mknod_in in;
+ struct fuse_buffer name;
+};
+
+static int fuse_mknod_initialize_in(struct bpf_fuse_args *fa, struct fuse_mknod_args *args,
+ struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev)
+{
+ *args = (struct fuse_mknod_args) {
+ .in = (struct fuse_mknod_in) {
+ .mode = mode,
+ .rdev = new_encode_dev(rdev),
+ .umask = current_umask(),
+ },
+ .name = (struct fuse_buffer) {
+ .data = (void *) entry->d_name.name,
+ .size = entry->d_name.len + 1,
+ .flags = BPF_FUSE_IMMUTABLE,
+ },
+ };
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_node_id(dir),
+ .opcode = FUSE_MKNOD,
+ },
+ .in_numargs = 2,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->in),
+ .value = &args->in,
+ },
+ .in_args[1] = (struct bpf_fuse_arg) {
+ .is_buffer = true,
+ .buffer = &args->name,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_mknod_initialize_out(struct bpf_fuse_args *fa, struct fuse_mknod_args *args,
+ struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev)
+{
+ return 0;
+}
+
+static int fuse_mknod_backing(struct bpf_fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev)
+{
+ const struct fuse_mknod_in *fmi = fa->in_args[0].value;
+ struct fuse_inode *fuse_inode = get_fuse_inode(dir);
+ struct inode *backing_inode = fuse_inode->backing_inode;
+ struct path backing_path;
+ struct inode *inode = NULL;
+
+ get_fuse_backing_path(entry, &backing_path);
+ if (!backing_path.dentry)
+ return -EBADF;
+
+ inode_lock_nested(backing_inode, I_MUTEX_PARENT);
+ mode = fmi->mode;
+ if (!IS_POSIXACL(backing_inode))
+ mode &= ~fmi->umask;
+ *out = vfs_mknod(&nop_mnt_idmap, backing_inode, backing_path.dentry, mode,
+ new_decode_dev(fmi->rdev));
+ inode_unlock(backing_inode);
+ if (*out)
+ goto out;
+ if (d_really_is_negative(backing_path.dentry) ||
+ unlikely(d_unhashed(backing_path.dentry))) {
+ *out = -EINVAL;
+ /**
+ * TODO: overlayfs responds to this situation with a
+ * lookupOneLen. Should we do that too?
+ */
+ goto out;
+ }
+ inode = fuse_iget_backing(dir->i_sb, fuse_inode->nodeid, backing_inode);
+ if (IS_ERR(inode)) {
+ *out = PTR_ERR(inode);
+ goto out;
+ }
+ d_instantiate(entry, inode);
+out:
+ path_put(&backing_path);
+ return *out;
+}
+
+static int fuse_mknod_finalize(struct bpf_fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev)
+{
+ return 0;
+}
+
+int fuse_bpf_mknod(int *out, struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev)
+{
+ return bpf_fuse_backing(dir, struct fuse_mknod_args, out,
+ fuse_mknod_initialize_in, fuse_mknod_initialize_out,
+ fuse_mknod_backing, fuse_mknod_finalize,
+ dir, entry, mode, rdev);
+}
+
+struct fuse_mkdir_args {
+ struct fuse_mkdir_in in;
+ struct fuse_buffer name;
+};
+
+static int fuse_mkdir_initialize_in(struct bpf_fuse_args *fa, struct fuse_mkdir_args *args,
+ struct inode *dir, struct dentry *entry, umode_t mode)
+{
+ *args = (struct fuse_mkdir_args) {
+ .in = (struct fuse_mkdir_in) {
+ .mode = mode,
+ .umask = current_umask(),
+ },
+ .name = (struct fuse_buffer) {
+ .data = (void *) entry->d_name.name,
+ .size = entry->d_name.len + 1,
+ .flags = BPF_FUSE_IMMUTABLE,
+ },
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_node_id(dir),
+ .opcode = FUSE_MKDIR,
+ },
+ .in_numargs = 2,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->in),
+ .value = &args->in,
+ },
+ .in_args[1] = (struct bpf_fuse_arg) {
+ .value = &args->name,
+ .is_buffer = true,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_mkdir_initialize_out(struct bpf_fuse_args *fa, struct fuse_mkdir_args *args,
+ struct inode *dir, struct dentry *entry, umode_t mode)
+{
+ return 0;
+}
+
+static int fuse_mkdir_backing(struct bpf_fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry, umode_t mode)
+{
+ const struct fuse_mkdir_in *fmi = fa->in_args[0].value;
+ struct fuse_inode *fuse_inode = get_fuse_inode(dir);
+ struct inode *backing_inode = fuse_inode->backing_inode;
+ struct path backing_path;
+ struct inode *inode = NULL;
+ struct dentry *d;
+
+ get_fuse_backing_path(entry, &backing_path);
+ if (!backing_path.dentry)
+ return -EBADF;
+
+ inode_lock_nested(backing_inode, I_MUTEX_PARENT);
+ mode = fmi->mode;
+ if (!IS_POSIXACL(backing_inode))
+ mode &= ~fmi->umask;
+ *out = vfs_mkdir(&nop_mnt_idmap, backing_inode, backing_path.dentry,
+ mode);
+ if (*out)
+ goto out;
+ if (d_really_is_negative(backing_path.dentry) ||
+ unlikely(d_unhashed(backing_path.dentry))) {
+ d = lookup_one_len(entry->d_name.name,
+ backing_path.dentry->d_parent,
+ entry->d_name.len);
+ if (IS_ERR(d)) {
+ *out = PTR_ERR(d);
+ goto out;
+ }
+ dput(backing_path.dentry);
+ backing_path.dentry = d;
+ }
+ inode = fuse_iget_backing(dir->i_sb, fuse_inode->nodeid, backing_inode);
+ if (IS_ERR(inode)) {
+ *out = PTR_ERR(inode);
+ goto out;
+ }
+ d_instantiate(entry, inode);
+out:
+ inode_unlock(backing_inode);
+ path_put(&backing_path);
+ return *out;
+}
+
+static int fuse_mkdir_finalize(struct bpf_fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry, umode_t mode)
+{
+ return 0;
+}
+
+int fuse_bpf_mkdir(int *out, struct inode *dir, struct dentry *entry, umode_t mode)
+{
+ return bpf_fuse_backing(dir, struct fuse_mkdir_args, out,
+ fuse_mkdir_initialize_in, fuse_mkdir_initialize_out,
+ fuse_mkdir_backing, fuse_mkdir_finalize,
+ dir, entry, mode);
+}
+
+static int fuse_rmdir_initialize_in(struct bpf_fuse_args *fa, struct fuse_buffer *name,
+ struct inode *dir, struct dentry *entry)
+{
+ *name = (struct fuse_buffer) {
+ .data = (void *) entry->d_name.name,
+ .size = entry->d_name.len + 1,
+ .flags = BPF_FUSE_IMMUTABLE,
+ };
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_node_id(dir),
+ .opcode = FUSE_RMDIR,
+ },
+ .in_numargs = 1,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .is_buffer = true,
+ .buffer = name,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_rmdir_initialize_out(struct bpf_fuse_args *fa, struct fuse_buffer *name,
+ struct inode *dir, struct dentry *entry)
+{
+ return 0;
+}
+
+static int fuse_rmdir_backing(struct bpf_fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry)
+{
+ struct path backing_path;
+ struct dentry *backing_parent_dentry;
+ struct inode *backing_inode;
+
+ get_fuse_backing_path(entry, &backing_path);
+ if (!backing_path.dentry)
+ return -EBADF;
+
+ backing_parent_dentry = dget_parent(backing_path.dentry);
+ backing_inode = d_inode(backing_parent_dentry);
+
+ inode_lock_nested(backing_inode, I_MUTEX_PARENT);
+ *out = vfs_rmdir(&nop_mnt_idmap, backing_inode, backing_path.dentry);
+ inode_unlock(backing_inode);
+
+ dput(backing_parent_dentry);
+ if (!*out)
+ d_drop(entry);
+ path_put(&backing_path);
+ return *out;
+}
+
+static int fuse_rmdir_finalize(struct bpf_fuse_args *fa, int *out, struct inode *dir, struct dentry *entry)
+{
+ return 0;
+}
+
+int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *entry)
+{
+ return bpf_fuse_backing(dir, struct fuse_buffer, out,
+ fuse_rmdir_initialize_in, fuse_rmdir_initialize_out,
+ fuse_rmdir_backing, fuse_rmdir_finalize,
+ dir, entry);
+}
+
+static int fuse_unlink_initialize_in(struct bpf_fuse_args *fa, struct fuse_buffer *name,
+ struct inode *dir, struct dentry *entry)
+{
+ *name = (struct fuse_buffer) {
+ .data = (void *) entry->d_name.name,
+ .size = entry->d_name.len + 1,
+ .flags = BPF_FUSE_IMMUTABLE,
+ };
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_node_id(dir),
+ .opcode = FUSE_UNLINK,
+ },
+ .in_numargs = 1,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .is_buffer = true,
+ .buffer = name,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_unlink_initialize_out(struct bpf_fuse_args *fa, struct fuse_buffer *name,
+ struct inode *dir, struct dentry *entry)
+{
+ return 0;
+}
+
+static int fuse_unlink_backing(struct bpf_fuse_args *fa, int *out, struct inode *dir, struct dentry *entry)
+{
+ struct path backing_path;
+ struct dentry *backing_parent_dentry;
+ struct inode *backing_inode;
+
+ get_fuse_backing_path(entry, &backing_path);
+ if (!backing_path.dentry)
+ return -EBADF;
+
+ /* TODO Not sure if we should reverify like overlayfs, or get inode from d_parent */
+ backing_parent_dentry = dget_parent(backing_path.dentry);
+ backing_inode = d_inode(backing_parent_dentry);
+
+ inode_lock_nested(backing_inode, I_MUTEX_PARENT);
+ *out = vfs_unlink(&nop_mnt_idmap, backing_inode, backing_path.dentry,
+ NULL);
+ inode_unlock(backing_inode);
+
+ dput(backing_parent_dentry);
+ if (!*out)
+ d_drop(entry);
+ path_put(&backing_path);
+ return *out;
+}
+
+static int fuse_unlink_finalize(struct bpf_fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry)
+{
+ return 0;
+}
+
+int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry)
+{
+ return bpf_fuse_backing(dir, struct fuse_buffer, out,
+ fuse_unlink_initialize_in, fuse_unlink_initialize_out,
+ fuse_unlink_backing, fuse_unlink_finalize,
+ dir, entry);
+}
+
static int fuse_access_initialize_in(struct bpf_fuse_args *fa, struct fuse_access_in *in,
struct inode *inode, int mask)
{
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 09bb4c63fd71..a5b6aef788b2 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -957,6 +957,10 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
struct fuse_mknod_in inarg;
struct fuse_mount *fm = get_fuse_mount(dir);
FUSE_ARGS(args);
+ int err;
+
+ if (fuse_bpf_mknod(&err, dir, entry, mode, rdev))
+ return err;

if (!fm->fc->dont_mask)
mode &= ~current_umask();
@@ -1003,6 +1007,10 @@ static int fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
struct fuse_mkdir_in inarg;
struct fuse_mount *fm = get_fuse_mount(dir);
FUSE_ARGS(args);
+ int err;
+
+ if (fuse_bpf_mkdir(&err, dir, entry, mode))
+ return err;

if (!fm->fc->dont_mask)
mode &= ~current_umask();
@@ -1089,6 +1097,9 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
if (fuse_is_bad(dir))
return -EIO;

+ if (fuse_bpf_unlink(&err, dir, entry))
+ return err;
+
args.opcode = FUSE_UNLINK;
args.nodeid = get_node_id(dir);
args.in_numargs = 1;
@@ -1112,6 +1123,9 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
if (fuse_is_bad(dir))
return -EIO;

+ if (fuse_bpf_rmdir(&err, dir, entry))
+ return err;
+
args.opcode = FUSE_RMDIR;
args.nodeid = get_node_id(dir);
args.in_numargs = 1;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a133010fde1c..9b176f78999f 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1441,6 +1441,10 @@ int parse_fuse_bpf_entry(struct fuse_bpf_entry *fbe, int num_entries);
int fuse_bpf_open(int *err, struct inode *inode, struct file *file, bool isdir);
int fuse_bpf_create_open(int *out, struct inode *dir, struct dentry *entry,
struct file *file, unsigned int flags, umode_t mode);
+int fuse_bpf_mknod(int *out, struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev);
+int fuse_bpf_mkdir(int *out, struct inode *dir, struct dentry *entry, umode_t mode);
+int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *entry);
+int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry);
int fuse_bpf_release(int *out, struct inode *inode, struct fuse_file *ff);
int fuse_bpf_releasedir(int *out, struct inode *inode, struct fuse_file *ff);
int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence);
@@ -1461,6 +1465,26 @@ static inline int fuse_bpf_create_open(int *out, struct inode *dir, struct dentr
return 0;
}

+static inline int fuse_bpf_mknod(int *out, struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_mkdir(int *out, struct inode *dir, struct dentry *entry, umode_t mode)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *entry)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry)
+{
+ return 0;
+}
+
static inline int fuse_bpf_release(int *out, struct inode *inode, struct file *file)
{
return 0;
--
2.44.0.478.gd926399ef9-goog