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Lookups supplying a backing fd or bpf will need to call through the ioctl to ensure there can be no attempts to fool priveledged processes into inadvertantly performing other actions. Signed-off-by: Daniel Rosenberg --- fs/fuse/dev.c | 56 ++++++++++++++++++++++++++++++++------- fs/fuse/fuse_i.h | 1 + include/uapi/linux/fuse.h | 1 + 3 files changed, 48 insertions(+), 10 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index b413e0bfd61c..e51ec198af3f 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1016,18 +1016,19 @@ static int fuse_copy_one(struct fuse_copy_state *cs= , void *val, unsigned size) =20 /* Copy the fuse-bpf lookup args and verify them */ #ifdef CONFIG_FUSE_BPF -static int fuse_copy_lookup(struct fuse_copy_state *cs, void *val, unsigne= d size) +static int fuse_copy_lookup(struct fuse_copy_state *cs, unsigned via_ioctl= , void *val, unsigned size) { struct fuse_bpf_entry_out *fbeo =3D (struct fuse_bpf_entry_out *)val; struct fuse_bpf_entry *feb =3D container_of(fbeo, struct fuse_bpf_entry, = out[0]); int num_entries =3D size / sizeof(*fbeo); int err; =20 - if (size && size % sizeof(*fbeo) !=3D 0) + if (size && (size % sizeof(*fbeo) !=3D 0 || !via_ioctl)) return -EINVAL; =20 if (num_entries > FUSE_BPF_MAX_ENTRIES) return -EINVAL; + err =3D fuse_copy_one(cs, val, size); if (err) return err; @@ -1036,7 +1037,7 @@ static int fuse_copy_lookup(struct fuse_copy_state *c= s, void *val, unsigned size return err; } #else -static int fuse_copy_lookup(struct fuse_copy_state *cs, void *val, unsigne= d size) +static int fuse_copy_lookup(struct fuse_copy_state *cs, unsigned via_ioctl= , void *val, unsigned size) { return fuse_copy_one(cs, val, size); } @@ -1045,7 +1046,7 @@ static int fuse_copy_lookup(struct fuse_copy_state *c= s, void *val, unsigned size /* Copy request arguments to/from userspace buffer */ static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs, unsigned argpages, struct fuse_arg *args, - int zeroing, unsigned is_lookup) + int zeroing, unsigned is_lookup, unsigned via_ioct) { int err =3D 0; unsigned i; @@ -1055,7 +1056,7 @@ static int fuse_copy_args(struct fuse_copy_state *cs,= unsigned numargs, if (i =3D=3D numargs - 1 && argpages) err =3D fuse_copy_pages(cs, arg->size, zeroing); else if (i =3D=3D numargs - 1 && is_lookup) - err =3D fuse_copy_lookup(cs, arg->value, arg->size); + err =3D fuse_copy_lookup(cs, via_ioct, arg->value, arg->size); else err =3D fuse_copy_one(cs, arg->value, arg->size); } @@ -1333,7 +1334,7 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud,= struct file *file, err =3D fuse_copy_one(cs, &req->in.h, sizeof(req->in.h)); if (!err) err =3D fuse_copy_args(cs, args->in_numargs, args->in_pages, - (struct fuse_arg *) args->in_args, 0, 0); + (struct fuse_arg *) args->in_args, 0, 0, 0); fuse_copy_finish(cs); spin_lock(&fpq->lock); clear_bit(FR_LOCKED, &req->flags); @@ -1872,7 +1873,8 @@ static int copy_out_args(struct fuse_copy_state *cs, = struct fuse_args *args, lastarg->size -=3D diffsize; } return fuse_copy_args(cs, args->out_numargs, args->out_pages, - args->out_args, args->page_zeroing, args->is_lookup); + args->out_args, args->page_zeroing, args->is_lookup, + args->via_ioctl); } =20 /* @@ -1882,7 +1884,7 @@ static int copy_out_args(struct fuse_copy_state *cs, = struct fuse_args *args, * it from the list and copy the rest of the buffer to the request. * The request is finished by calling fuse_request_end(). */ -static ssize_t fuse_dev_do_write(struct fuse_dev *fud, +static ssize_t fuse_dev_do_write(struct fuse_dev *fud, bool from_ioctl, struct fuse_copy_state *cs, size_t nbytes) { int err; @@ -1954,6 +1956,7 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud, if (!req->args->page_replace) cs->move_pages =3D 0; =20 + req->args->via_ioctl =3D from_ioctl; if (oh.error) err =3D nbytes !=3D sizeof(oh) ? -EINVAL : 0; else @@ -1992,7 +1995,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, str= uct iov_iter *from) =20 fuse_copy_init(&cs, 0, from); =20 - return fuse_dev_do_write(fud, &cs, iov_iter_count(from)); + return fuse_dev_do_write(fud, false, &cs, iov_iter_count(from)); } =20 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe, @@ -2073,7 +2076,7 @@ static ssize_t fuse_dev_splice_write(struct pipe_inod= e_info *pipe, if (flags & SPLICE_F_MOVE) cs.move_pages =3D 1; =20 - ret =3D fuse_dev_do_write(fud, &cs, len); + ret =3D fuse_dev_do_write(fud, false, &cs, len); =20 pipe_lock(pipe); out_free: @@ -2286,6 +2289,33 @@ static int fuse_device_clone(struct fuse_conn *fc, s= truct file *new) return 0; } =20 +// Provides an alternate means to respond to a fuse request +static int fuse_handle_ioc_response(struct fuse_dev *dev, void *buff, uint= 32_t size) +{ + struct fuse_copy_state cs; + struct iovec *iov =3D NULL; + struct iov_iter iter; + int res; + + if (size > PAGE_SIZE) + return -EINVAL; + iov =3D (struct iovec *) __get_free_page(GFP_KERNEL); + if (!iov) + return -ENOMEM; + + iov->iov_base =3D buff; + iov->iov_len =3D size; + + iov_iter_init(&iter, READ, iov, 1, size); + fuse_copy_init(&cs, 0, &iter); + + + res =3D fuse_dev_do_write(dev, true, &cs, size); + free_page((unsigned long) iov); + + return res; +} + static long fuse_dev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { @@ -2319,6 +2349,12 @@ static long fuse_dev_ioctl(struct file *file, unsign= ed int cmd, fdput(f); break; default: + if (_IOC_TYPE(cmd) =3D=3D FUSE_DEV_IOC_MAGIC + && _IOC_NR(cmd) =3D=3D _IOC_NR(FUSE_DEV_IOC_BPF_RESPONSE(0)) + && _IOC_DIR(cmd) =3D=3D _IOC_WRITE) { + res =3D fuse_handle_ioc_response(fuse_get_dev(file), (void *) arg, _IOC= _SIZE(cmd)); + break; + } res =3D -ENOTTY; break; } diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index ac61f08fd85d..dd62e78e474c 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -336,6 +336,7 @@ struct fuse_args { bool may_block:1; bool is_ext:1; bool is_lookup:1; + bool via_ioctl:1; struct fuse_in_arg in_args[3]; struct fuse_arg out_args[2]; void (*end)(struct fuse_mount *fm, struct fuse_args *args, int error); diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 0c0a9a8b5c26..74bc15e1d0b7 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -1075,6 +1075,7 @@ struct fuse_notify_retrieve_in { /* Device ioctls: */ #define FUSE_DEV_IOC_MAGIC 229 #define FUSE_DEV_IOC_CLONE _IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t) +#define FUSE_DEV_IOC_BPF_RESPONSE(N) _IOW(FUSE_DEV_IOC_MAGIC, 125, char[N]) =20 struct fuse_lseek_in { uint64_t fh; --=20 2.44.0.478.gd926399ef9-goog