This allows fuse-bpf to call out to userspace to handle pre and post
filters. Any of the inputs may be changed by the prefilter, so we must
handle up to 3 outputs. For the postfilter, our inputs include the
output arguments, so we must handle up to 5 inputs.
As long as you don't request both pre-filter and post-filter in
userspace, we will end up doing fewer round trips to userspace.
Signed-off-by: Daniel Rosenberg <drosen@xxxxxxxxxx>
---
fs/fuse/backing.c | 70 ++++++++++++++++++++++++++++++++++++++++
fs/fuse/dev.c | 2 ++
fs/fuse/fuse_i.h | 42 ++++++++++++++++++++++--
include/linux/bpf_fuse.h | 1 +
4 files changed, 113 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 485b6f1e8503..7a3b1fdb2c56 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -2681,3 +2681,73 @@ void __exit fuse_bpf_cleanup(void)
{
kmem_cache_destroy(fuse_bpf_aio_request_cachep);
}
+
+static ssize_t fuse_bpf_simple_request(struct fuse_mount *fm, struct bpf_fuse_args *fa,
+ unsigned short in_numargs, unsigned short out_numargs,
+ struct bpf_fuse_arg *out_arg_array, bool add_out_to_in)
+{
+ int i;
+ uint32_t max_size;
+ ssize_t res;
+
+ struct fuse_args args = {
+ .nodeid = fa->nodeid,
+ .opcode = fa->opcode,
+ .error_in = fa->error_in,
+ .in_numargs = in_numargs,
+ .out_numargs = out_numargs,
+ .force = !!(fa->flags & FUSE_BPF_FORCE),
+ .out_argvar = !!(fa->flags & FUSE_BPF_OUT_ARGVAR),
+ .is_lookup = !!(fa->flags & FUSE_BPF_IS_LOOKUP),
+ };
+
+ /* Set in args */
+ for (i = 0; i < fa->in_numargs; ++i)
+ args.in_args[i] = (struct fuse_in_arg) {
+ .size = fa->in_args[i].size,
+ .value = fa->in_args[i].value,
+ };
+ if (add_out_to_in) {
+ for (i = 0; i < fa->out_numargs; ++i)
+ args.in_args[fa->in_numargs + i] = (struct fuse_in_arg) {
+ .size = fa->out_args[i].size,
+ .value = fa->out_args[i].value,
+ };
+ }
+
+ /* All out args must be writeable */
+ for (i = 0; i < out_numargs; ++i) {
+ max_size = out_arg_array[i].max_size ?: out_arg_array[i].size;
+ if (!bpf_fuse_get_writeable(&out_arg_array[i], max_size, true))
+ return -ENOMEM;
+ }
+
+ /* Set out args */
+ for (i = 0; i < out_numargs; ++i)
+ args.out_args[i] = (struct fuse_arg) {
+ .size = out_arg_array[i].size,
+ .value = out_arg_array[i].value,
+ };
+
+ res = fuse_simple_request(fm, &args);
+
+ /* update used areas of buffers */
+ for (i = 0; i < out_numargs; ++i)
+ if (out_arg_array[i].flags & BPF_FUSE_VARIABLE_SIZE)
+ out_arg_array[i].size = args.out_args[i].size;
+ fa->ret = args.ret;
+
+ return res;
+}
+
+ssize_t fuse_prefilter_simple_request(struct fuse_mount *fm, struct bpf_fuse_args *fa)
+{
+ return fuse_bpf_simple_request(fm, fa, fa->in_numargs, fa->in_numargs,
+ fa->in_args, false);
+}
+
+ssize_t fuse_postfilter_simple_request(struct fuse_mount *fm, struct bpf_fuse_args *fa)
+{
+ return fuse_bpf_simple_request(fm, fa, fa->in_numargs + fa->out_numargs, fa->out_numargs,
+ fa->out_args, true);
+}
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 626dbbf92874..765bc95bd560 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -520,6 +520,8 @@ ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
BUG_ON(args->out_numargs == 0);
ret = args->out_args[args->out_numargs - 1].size;
}
+ if (args->is_filter)
+ args->ret = req->out.h.error;
fuse_put_request(req);
return ret;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 07b50be2c6e4..a619c6eac6e5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -305,6 +305,17 @@ struct fuse_page_desc {
unsigned int offset;
};
+/* To deal with bpf pre and post filters in userspace calls, we must support
+ * passing the inputs and outputs as inputs, and we must have enough space in
+ * outputs to handle all of the inputs.
+ */
+#define FUSE_EXTENDED_MAX_ARGS_IN (FUSE_MAX_ARGS_IN + FUSE_MAX_ARGS_OUT)
+#if FUSE_MAX_ARGS_IN > FUSE_MAX_ARGS_OUT
+#define FUSE_EXTENDED_MAX_ARGS_OUT FUSE_MAX_ARGS_IN
+#else
+#define FUSE_EXTENDED_MAX_ARGS_OUT FUSE_MAX_ARGS_OUT
+#endif
+
struct fuse_args {
uint64_t nodeid;
uint32_t opcode;
@@ -321,9 +332,11 @@ struct fuse_args {
bool page_zeroing:1;
bool page_replace:1;
bool may_block:1;
+ bool is_filter:1;
bool is_lookup:1;
- struct fuse_in_arg in_args[3];
- struct fuse_arg out_args[2];
+ uint32_t ret;
+ struct fuse_in_arg in_args[FUSE_EXTENDED_MAX_ARGS_IN];
+ struct fuse_arg out_args[FUSE_EXTENDED_MAX_ARGS_OUT];
void (*end)(struct fuse_mount *fm, struct fuse_args *args, int error);
};
@@ -1936,6 +1949,9 @@ static inline void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatf
int __init fuse_bpf_init(void);
void __exit fuse_bpf_cleanup(void);
+ssize_t fuse_prefilter_simple_request(struct fuse_mount *fm, struct bpf_fuse_args *args);
+ssize_t fuse_postfilter_simple_request(struct fuse_mount *fm, struct bpf_fuse_args *args);
+
static inline void fuse_bpf_set_in_ends(struct bpf_fuse_args *fa)
{
int i;
@@ -1994,9 +2010,11 @@ static inline void fuse_bpf_free_alloced(struct bpf_fuse_args *fa)
backing, finalize, args...) \
({ \
struct fuse_inode *fuse_inode = get_fuse_inode(inode); \
+ struct fuse_mount *fm = get_fuse_mount(inode); \
struct bpf_fuse_args fa = { 0 }; \
bool initialized = false; \
bool handled = false; \
+ bool locked; \
ssize_t res; \
int bpf_next; \
io feo = { 0 }; \
@@ -2021,6 +2039,16 @@ static inline void fuse_bpf_free_alloced(struct bpf_fuse_args *fa)
break; \
} \
\
+ if (bpf_next == BPF_FUSE_USER_PREFILTER) { \
+ locked = fuse_lock_inode(inode); \
+ res = fuse_prefilter_simple_request(fm, &fa); \
+ fuse_unlock_inode(inode, locked); \
+ if (res < 0) { \
+ error = res; \
+ break; \
+ } \
+ bpf_next = fa.ret; \
+ } \
fuse_bpf_set_in_immutable(&fa); \
\
error = initialize_out(&fa, &feo, args); \
@@ -2051,6 +2079,16 @@ static inline void fuse_bpf_free_alloced(struct bpf_fuse_args *fa)
break; \
} \
\
+ if (!(bpf_next == BPF_FUSE_USER_POSTFILTER)) \
+ break; \
+ \
+ locked = fuse_lock_inode(inode); \
+ res = fuse_postfilter_simple_request(fm, &fa); \
+ fuse_unlock_inode(inode, locked); \
+ if (res < 0) { \
+ error = res; \
+ break; \
+ } \
} while (false); \
\
if (initialized && handled) { \
diff --git a/include/linux/bpf_fuse.h b/include/linux/bpf_fuse.h
index ef5c8fdaffee..2802ca71ddd1 100644
--- a/include/linux/bpf_fuse.h
+++ b/include/linux/bpf_fuse.h
@@ -40,6 +40,7 @@ struct bpf_fuse_args {
uint32_t in_numargs;
uint32_t out_numargs;
uint32_t flags;
+ uint32_t ret;
struct bpf_fuse_arg in_args[FUSE_MAX_ARGS_IN];
struct bpf_fuse_arg out_args[FUSE_MAX_ARGS_OUT];
};
--
2.37.3.998.g577e59143f-goog
