[RFC PATCH v4 19/36] fuse-bpf: Add xattr support

From: Daniel Rosenberg
Date: Thu Mar 28 2024 - 22:01:53 EST

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This adds support for FUSE_GETXATTR, FUSE_LISTXATTR, FUSE_SETXATTR, and
FUSE_REMOVEXATTR

Signed-off-by: Daniel Rosenberg <drosen@xxxxxxxxxx>
Signed-off-by: Paul Lawrence <paullawrence@xxxxxxxxxx>
---
fs/fuse/backing.c | 349 ++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/fuse_i.h | 30 ++++
fs/fuse/xattr.c | 18 +++
3 files changed, 397 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 2363f392e915..3390ce66e393 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -959,6 +959,355 @@ int fuse_bpf_dir_fsync(int *out, struct inode *inode, struct file *file, loff_t
file, start, end, datasync);
}

+struct fuse_getxattr_args {
+ struct fuse_getxattr_in in;
+ struct fuse_buffer name;
+ struct fuse_buffer value;
+ struct fuse_getxattr_out out;
+};
+
+static int fuse_getxattr_initialize_in(struct bpf_fuse_args *fa,
+ struct fuse_getxattr_args *args,
+ struct dentry *dentry, const char *name, void *value,
+ size_t size)
+{
+ *args = (struct fuse_getxattr_args) {
+ .in.size = size,
+ .name = (struct fuse_buffer) {
+ .data = (void *) name,
+ .size = strlen(name) + 1,
+ .max_size = XATTR_NAME_MAX + 1,
+ .flags = BPF_FUSE_MUST_ALLOCATE | BPF_FUSE_VARIABLE_SIZE,
+ },
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_fuse_inode(dentry->d_inode)->nodeid,
+ .opcode = FUSE_GETXATTR,
+ },
+ .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_getxattr_initialize_out(struct bpf_fuse_args *fa,
+ struct fuse_getxattr_args *args,
+ struct dentry *dentry, const char *name, void *value,
+ size_t size)
+{
+ fa->flags = size ? FUSE_BPF_OUT_ARGVAR : 0;
+ fa->out_numargs = 1;
+ if (size) {
+ args->value = (struct fuse_buffer) {
+ .data = (void *) value,
+ .size = size,
+ .alloc_size = size,
+ .max_size = size,
+ .flags = BPF_FUSE_VARIABLE_SIZE,
+ };
+ fa->out_args[0].is_buffer = true;
+ fa->out_args[0].buffer = &args->value;
+ } else {
+ fa->out_args[0].size = sizeof(args->out);
+ fa->out_args[0].value = &args->out;
+ }
+ return 0;
+}
+
+static int fuse_getxattr_backing(struct bpf_fuse_args *fa, int *out,
+ struct dentry *dentry, const char *name, void *value,
+ size_t size)
+{
+ ssize_t ret;
+
+ if (fa->in_args[1].buffer->flags & BPF_FUSE_MODIFIED) {
+ // Ensure bpf provided string is null terminated
+ char *new_name = fa->in_args[1].buffer->data;
+ new_name[fa->in_args[1].buffer->size - 1] = 0;
+ }
+ ret = vfs_getxattr(&nop_mnt_idmap,
+ get_fuse_dentry(dentry)->backing_path.dentry,
+ fa->in_args[1].buffer->data, value, size);
+
+ if (fa->flags & FUSE_BPF_OUT_ARGVAR)
+ fa->out_args[0].buffer->size = ret;
+ else
+ ((struct fuse_getxattr_out *)fa->out_args[0].value)->size = ret;
+
+ return 0;
+}
+
+static int fuse_getxattr_finalize(struct bpf_fuse_args *fa, int *out,
+ struct dentry *dentry, const char *name, void *value,
+ size_t size)
+{
+ struct fuse_getxattr_out *fgo;
+
+ if (fa->flags & FUSE_BPF_OUT_ARGVAR) {
+ *out = fa->out_args[0].buffer->size;
+ return 0;
+ }
+
+ fgo = fa->out_args[0].value;
+
+ *out = fgo->size;
+ return 0;
+}
+
+int fuse_bpf_getxattr(int *out, struct inode *inode, struct dentry *dentry, const char *name,
+ void *value, size_t size)
+{
+ return bpf_fuse_backing(inode, struct fuse_getxattr_args, out,
+ fuse_getxattr_initialize_in, fuse_getxattr_initialize_out,
+ fuse_getxattr_backing, fuse_getxattr_finalize,
+ dentry, name, value, size);
+}
+
+static int fuse_listxattr_initialize_in(struct bpf_fuse_args *fa,
+ struct fuse_getxattr_args *args,
+ struct dentry *dentry, char *list, size_t size)
+{
+ *args = (struct fuse_getxattr_args) {
+ .in.size = size,
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_fuse_inode(dentry->d_inode)->nodeid,
+ .opcode = FUSE_LISTXATTR,
+ },
+ .in_numargs = 1,
+ .in_args[0] =
+ (struct bpf_fuse_arg) {
+ .size = sizeof(args->in),
+ .value = &args->in,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_listxattr_initialize_out(struct bpf_fuse_args *fa,
+ struct fuse_getxattr_args *args,
+ struct dentry *dentry, char *list, size_t size)
+{
+ fa->out_numargs = 1;
+
+ if (size) {
+ args->value = (struct fuse_buffer) {
+ .data = list,
+ .size = size,
+ .alloc_size = size,
+ .max_size = size,
+ .flags = BPF_FUSE_VARIABLE_SIZE,
+ };
+ fa->flags = FUSE_BPF_OUT_ARGVAR;
+ fa->out_args[0].is_buffer = true;
+ fa->out_args[0].buffer = &args->value;
+ } else {
+ fa->out_args[0].size = sizeof(args->out);
+ fa->out_args[0].value = &args->out;
+ }
+ return 0;
+}
+
+static int fuse_listxattr_backing(struct bpf_fuse_args *fa, ssize_t *out, struct dentry *dentry,
+ char *list, size_t size)
+{
+ *out = vfs_listxattr(get_fuse_dentry(dentry)->backing_path.dentry, list, size);
+
+ if (*out < 0)
+ return *out;
+
+ if (fa->flags & FUSE_BPF_OUT_ARGVAR)
+ fa->out_args[0].buffer->size = *out;
+ else
+ ((struct fuse_getxattr_out *)fa->out_args[0].value)->size = *out;
+
+ return 0;
+}
+
+static int fuse_listxattr_finalize(struct bpf_fuse_args *fa, ssize_t *out, struct dentry *dentry,
+ char *list, size_t size)
+{
+ struct fuse_getxattr_out *fgo;
+
+ if (fa->info.error_in)
+ return 0;
+
+ if (fa->flags & FUSE_BPF_OUT_ARGVAR) {
+ *out = fa->out_args[0].buffer->size;
+ return 0;
+ }
+
+ fgo = fa->out_args[0].value;
+ *out = fgo->size;
+ return 0;
+}
+
+int fuse_bpf_listxattr(ssize_t *out, struct inode *inode, struct dentry *dentry,
+ char *list, size_t size)
+{
+ return bpf_fuse_backing(inode, struct fuse_getxattr_args, out,
+ fuse_listxattr_initialize_in, fuse_listxattr_initialize_out,
+ fuse_listxattr_backing, fuse_listxattr_finalize,
+ dentry, list, size);
+}
+
+struct fuse_setxattr_args {
+ struct fuse_setxattr_in in;
+ struct fuse_buffer name;
+ struct fuse_buffer value;
+};
+
+static int fuse_setxattr_initialize_in(struct bpf_fuse_args *fa,
+ struct fuse_setxattr_args *args,
+ struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ *args = (struct fuse_setxattr_args) {
+ .in = (struct fuse_setxattr_in) {
+ .size = size,
+ .flags = flags,
+ },
+ .name = (struct fuse_buffer) {
+ .data = (void *) name,
+ .size = strlen(name) + 1,
+ .max_size = XATTR_NAME_MAX + 1,
+ .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE,
+ },
+ .value =(struct fuse_buffer) {
+ .data = (void *) value,
+ .size = size,
+ .max_size = XATTR_SIZE_MAX,
+ .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE,
+ },
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_fuse_inode(dentry->d_inode)->nodeid,
+ .opcode = FUSE_SETXATTR,
+ },
+ .in_numargs = 3,
+ .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,
+ },
+ .in_args[2] = (struct bpf_fuse_arg) {
+ .is_buffer = true,
+ .buffer = &args->value,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_setxattr_initialize_out(struct bpf_fuse_args *fa,
+ struct fuse_setxattr_args *args,
+ struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ return 0;
+}
+
+static int fuse_setxattr_backing(struct bpf_fuse_args *fa, int *out, struct dentry *dentry,
+ const char *name, const void *value, size_t size,
+ int flags)
+{
+ // TODO Ensure we actually use filter values
+ *out = vfs_setxattr(&nop_mnt_idmap,
+ get_fuse_dentry(dentry)->backing_path.dentry, name,
+ value, size, flags);
+ return 0;
+}
+
+static int fuse_setxattr_finalize(struct bpf_fuse_args *fa, int *out, struct dentry *dentry,
+ const char *name, const void *value, size_t size,
+ int flags)
+{
+ return 0;
+}
+
+int fuse_bpf_setxattr(int *out, struct inode *inode, struct dentry *dentry,
+ const char *name, const void *value, size_t size, int flags)
+{
+ return bpf_fuse_backing(inode, struct fuse_setxattr_args, out,
+ fuse_setxattr_initialize_in, fuse_setxattr_initialize_out,
+ fuse_setxattr_backing, fuse_setxattr_finalize,
+ dentry, name, value, size, flags);
+}
+
+static int fuse_removexattr_initialize_in(struct bpf_fuse_args *fa,
+ struct fuse_buffer *in,
+ struct dentry *dentry, const char *name)
+{
+ *in = (struct fuse_buffer) {
+ .data = (void *) name,
+ .size = strlen(name) + 1,
+ .max_size = XATTR_NAME_MAX + 1,
+ .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE,
+ };
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_fuse_inode(dentry->d_inode)->nodeid,
+ .opcode = FUSE_REMOVEXATTR,
+ },
+ .in_numargs = 1,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .is_buffer = true,
+ .buffer = in,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_removexattr_initialize_out(struct bpf_fuse_args *fa,
+ struct fuse_buffer *in,
+ struct dentry *dentry, const char *name)
+{
+ return 0;
+}
+
+static int fuse_removexattr_backing(struct bpf_fuse_args *fa, int *out,
+ struct dentry *dentry, const char *name)
+{
+ struct path *backing_path = &get_fuse_dentry(dentry)->backing_path;
+
+ /* TODO account for changes of the name by prefilter */
+ *out = vfs_removexattr(&nop_mnt_idmap, backing_path->dentry, name);
+ return 0;
+}
+
+static int fuse_removexattr_finalize(struct bpf_fuse_args *fa, int *out,
+ struct dentry *dentry, const char *name)
+{
+ return 0;
+}
+
+int fuse_bpf_removexattr(int *out, struct inode *inode, struct dentry *dentry, const char *name)
+{
+ return bpf_fuse_backing(inode, struct fuse_buffer, out,
+ fuse_removexattr_initialize_in, fuse_removexattr_initialize_out,
+ fuse_removexattr_backing, fuse_removexattr_finalize,
+ dentry, name);
+}
+
static inline void fuse_bpf_aio_put(struct fuse_bpf_aio_req *aio_req)
{
if (refcount_dec_and_test(&aio_req->ref))
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a95d543c79ae..127758575ddc 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1459,6 +1459,13 @@ int fuse_bpf_copy_file_range(ssize_t *out, struct inode *inode, struct file *fil
size_t len, unsigned int flags);
int fuse_bpf_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync);
int fuse_bpf_dir_fsync(int *out, struct inode *inode, struct file *file, loff_t start, loff_t end, int datasync);
+int fuse_bpf_getxattr(int *out, struct inode *inode, struct dentry *dentry,
+ const char *name, void *value, size_t size);
+int fuse_bpf_listxattr(ssize_t *out, struct inode *inode, struct dentry *dentry, char *list, size_t size);
+int fuse_bpf_setxattr(int *out, struct inode *inode, struct dentry *dentry,
+ const char *name, const void *value, size_t size,
+ int flags);
+int fuse_bpf_removexattr(int *out, struct inode *inode, struct dentry *dentry, const char *name);
int fuse_bpf_file_read_iter(ssize_t *out, struct inode *inode, struct kiocb *iocb, struct iov_iter *to);
int fuse_bpf_file_write_iter(ssize_t *out, struct inode *inode, struct kiocb *iocb, struct iov_iter *from);
int fuse_bpf_file_fallocate(int *out, struct inode *inode, struct file *file, int mode, loff_t offset, loff_t length);
@@ -1553,6 +1560,29 @@ static inline int fuse_bpf_dir_fsync(int *out, struct inode *inode, struct file
return 0;
}

+static inline int fuse_bpf_getxattr(int *out, struct inode *inode, struct dentry *dentry,
+ const char *name, void *value, size_t size)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_listxattr(ssize_t *out, struct inode *inode, struct dentry *dentry, char *list, size_t size)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_setxattr(int *out, struct inode *inode, struct dentry *dentry,
+ const char *name, const void *value, size_t size,
+ int flags)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_removexattr(int *out, struct inode *inode, struct dentry *dentry, const char *name)
+{
+ return 0;
+}
+
static inline int fuse_bpf_file_read_iter(ssize_t *out, struct inode *inode, struct kiocb *iocb, struct iov_iter *to)
{
return 0;
diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 5b423fdbb13f..394441397a8a 100644
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -118,6 +118,9 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
if (fuse_is_bad(inode))
return -EIO;

+ if (fuse_bpf_listxattr(&ret, inode, entry, list, size))
+ return ret;
+
if (!fuse_allow_current_process(fm->fc))
return -EACCES;

@@ -182,9 +185,14 @@ static int fuse_xattr_get(const struct xattr_handler *handler,
struct dentry *dentry, struct inode *inode,
const char *name, void *value, size_t size)
{
+ int err;
+
if (fuse_is_bad(inode))
return -EIO;

+ if (fuse_bpf_getxattr(&err, inode, dentry, name, value, size))
+ return err;
+
return fuse_getxattr(inode, name, value, size);
}

@@ -194,9 +202,19 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
const char *name, const void *value, size_t size,
int flags)
{
+ int err;
+ bool handled;
+
if (fuse_is_bad(inode))
return -EIO;

+ if (value)
+ handled = fuse_bpf_setxattr(&err, inode, dentry, name, value, size, flags);
+ else
+ handled = fuse_bpf_removexattr(&err, inode, dentry, name);
+ if (handled)
+ return err;
+
if (!value)
return fuse_removexattr(inode, name);

--
2.44.0.478.gd926399ef9-goog

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