[RFC PATCH v4 07/36] fuse-bpf: Add support for access

Daniel Rosenberg
2024-03-29T01:54:15Z

This adds backing support for FUSE_ACCESS

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
fs/fuse/backing.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dir.c | 6 ++++++
fs/fuse/fuse_i.h | 6 ++++++
3 files changed, 59 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 14fcc2032764..a94d99ff9862 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -420,3 +420,50 @@ int fuse_revalidate_backing(struct dentry *entry, unsigned int flags)
return backing_entry->d_op->d_revalidate(backing_entry, flags);
return 1;
}
+
+static int fuse_access_initialize_in(struct bpf_fuse_args *fa, struct fuse_access_in *in,
+ struct inode *inode, int mask)
+{
+ *in = (struct fuse_access_in) {
+ .mask = mask,
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .opcode = FUSE_ACCESS,
+ .nodeid = get_node_id(inode),
+ },
+ .in_numargs = 1,
+ .in_args[0].size = sizeof(*in),
+ .in_args[0].value = in,
+ };
+
+ return 0;
+}
+
+static int fuse_access_initialize_out(struct bpf_fuse_args *fa, struct fuse_access_in *in,
+ struct inode *inode, int mask)
+{
+ return 0;
+}
+
+static int fuse_access_backing(struct bpf_fuse_args *fa, int *out, struct inode *inode, int mask)
+{
+ struct fuse_inode *fi = get_fuse_inode(inode);
+ const struct fuse_access_in *fai = fa->in_args[0].value;
+
+ *out = inode_permission(&nop_mnt_idmap, fi->backing_inode, fai->mask);
+ return 0;
+}
+
+static int fuse_access_finalize(struct bpf_fuse_args *fa, int *out, struct inode *inode, int mask)
+{
+ return 0;
+}
+
+int fuse_bpf_access(int *out, struct inode *inode, int mask)
+{
+ return bpf_fuse_backing(inode, struct fuse_access_in, out,
+ fuse_access_initialize_in, fuse_access_initialize_out,
+ fuse_access_backing, fuse_access_finalize, inode, mask);
+}
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 6503c91886f6..8db6eb6a0848 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1563,6 +1563,9 @@ static int fuse_access(struct inode *inode, int mask)
struct fuse_access_in inarg;
int err;

+ if (fuse_bpf_access(&err, inode, mask))
+ return err;
+
BUG_ON(mask & MAY_NOT_BLOCK);

if (fm->fc->no_access)
@@ -1619,6 +1622,9 @@ static int fuse_permission(struct mnt_idmap *idmap,
if (!fuse_allow_current_process(fc))
return -EACCES;

+ if (fuse_bpf_access(&err, inode, mask))
+ return err;
+
/*
* If attributes are needed, refresh them before proceeding
*/
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index dd62e78e474c..08ee98b7bb95 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1439,6 +1439,7 @@ int parse_fuse_bpf_entry(struct fuse_bpf_entry *fbe, int num_entries);
#ifdef CONFIG_FUSE_BPF

int fuse_bpf_lookup(struct dentry **out, struct inode *dir, struct dentry *entry, unsigned int flags);
+int fuse_bpf_access(int *out, struct inode *inode, int mask);

#else

@@ -1447,6 +1448,11 @@ static inline int fuse_bpf_lookup(struct dentry **out, struct inode *dir, struct
return 0;
}

+static inline int fuse_bpf_access(int *out, struct inode *inode, int mask)
+{
+ return 0;
+}
+
#endif // CONFIG_FUSE_BPF

int fuse_handle_backing(struct fuse_bpf_entry *feb, struct path *backing_path);
--
2.44.0.478.gd926399ef9-goog