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Mon, 26 Sep 2022 16:19:28 -0700 (PDT) Date: Mon, 26 Sep 2022 16:18:18 -0700 In-Reply-To: <20220926231822.994383-1-drosen@google.com> Mime-Version: 1.0 References: <20220926231822.994383-1-drosen@google.com> X-Mailer: git-send-email 2.37.3.998.g577e59143f-goog Message-ID: <20220926231822.994383-23-drosen@google.com> Subject: [PATCH 22/26] fuse-bpf: Add symlink/link support From: Daniel Rosenberg To: Miklos Szeredi , Alexei Starovoitov , Daniel Borkmann , John Fastabend Cc: Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Daniel Rosenberg , Paul Lawrence , Alessio Balsini , David Anderson , Sandeep Patil , linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org, kernel-team@android.com Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Signed-off-by: Daniel Rosenberg Signed-off-by: Paul Lawrence --- fs/fuse/backing.c | 251 ++++++++++++++++++++++++++++++++++++++++++++++ fs/fuse/dir.c | 31 ++++++ fs/fuse/fuse_i.h | 33 ++++++ 3 files changed, 315 insertions(+) diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c index d8c86234f253..485b6f1e8503 100644 --- a/fs/fuse/backing.c +++ b/fs/fuse/backing.c @@ -1951,6 +1951,97 @@ int fuse_unlink_finalize(struct bpf_fuse_args *fa, int *out, return 0; } +int fuse_link_initialize_in(struct bpf_fuse_args *fa, struct fuse_link_in *fli, + struct dentry *entry, struct inode *dir, + struct dentry *newent) +{ + struct inode *src_inode = entry->d_inode; + + *fli = (struct fuse_link_in) { + .oldnodeid = get_node_id(src_inode), + }; + + fa->opcode = FUSE_LINK; + fa->in_numargs = 2; + fa->in_args[0].size = sizeof(*fli); + fa->in_args[0].value = fli; + fa->in_args[1].size = newent->d_name.len + 1; + fa->in_args[1].max_size = NAME_MAX + 1; + fa->in_args[1].value = (void *) newent->d_name.name; + fa->in_args[1].flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE; + + return 0; +} + +int fuse_link_initialize_out(struct bpf_fuse_args *fa, struct fuse_link_in *fli, + struct dentry *entry, struct inode *dir, + struct dentry *newent) +{ + return 0; +} + +int fuse_link_backing(struct bpf_fuse_args *fa, int *out, struct dentry *entry, + struct inode *dir, struct dentry *newent) +{ + struct path backing_old_path; + struct path backing_new_path; + struct dentry *backing_dir_dentry; + struct inode *fuse_new_inode = NULL; + struct fuse_inode *fuse_dir_inode = get_fuse_inode(dir); + struct inode *backing_dir_inode = fuse_dir_inode->backing_inode; + + *out = 0; + get_fuse_backing_path(entry, &backing_old_path); + if (!backing_old_path.dentry) + return -EBADF; + + get_fuse_backing_path(newent, &backing_new_path); + if (!backing_new_path.dentry) { + *out = -EBADF; + goto err_dst_path; + } + + backing_dir_dentry = dget_parent(backing_new_path.dentry); + backing_dir_inode = d_inode(backing_dir_dentry); + + inode_lock_nested(backing_dir_inode, I_MUTEX_PARENT); + *out = vfs_link(backing_old_path.dentry, &init_user_ns, + backing_dir_inode, backing_new_path.dentry, NULL); + inode_unlock(backing_dir_inode); + if (*out) + goto out; + + if (d_really_is_negative(backing_new_path.dentry) || + unlikely(d_unhashed(backing_new_path.dentry))) { + *out = -EINVAL; + /** + * TODO: overlayfs responds to this situation with a + * lookupOneLen. Should we do that too? + */ + goto out; + } + + fuse_new_inode = fuse_iget_backing(dir->i_sb, fuse_dir_inode->nodeid, backing_dir_inode); + if (IS_ERR(fuse_new_inode)) { + *out = PTR_ERR(fuse_new_inode); + goto out; + } + d_instantiate(newent, fuse_new_inode); + +out: + dput(backing_dir_dentry); + path_put(&backing_new_path); +err_dst_path: + path_put(&backing_old_path); + return *out; +} + +int fuse_link_finalize(struct bpf_fuse_args *fa, int *out, struct dentry *entry, + struct inode *dir, struct dentry *newent) +{ + return 0; +} + int fuse_getattr_initialize_in(struct bpf_fuse_args *fa, struct fuse_getattr_io *fgio, const struct dentry *entry, struct kstat *stat, u32 request_mask, unsigned int flags) @@ -2215,6 +2306,166 @@ int fuse_statfs_finalize(struct bpf_fuse_args *fa, int *out, return 0; } +int fuse_get_link_initialize_in(struct bpf_fuse_args *fa, struct fuse_dummy_io *unused, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + /* + * TODO + * If we want to handle changing these things, we'll need to copy + * the lower fs's data into our own buffer, and provide our own callback + * to free that buffer. + * + * Pre could change the name we're looking at + * postfilter can change the name we return + * + * We ought to only make that buffer if it's been requested, so leaving + * this unimplemented for the moment + */ + *fa = (struct bpf_fuse_args) { + .opcode = FUSE_READLINK, + .nodeid = get_node_id(inode), + .in_numargs = 1, + .in_args[0] = (struct bpf_fuse_arg) { + .size = dentry->d_name.len + 1, + .max_size = NAME_MAX + 1, + .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE, + .value = (void *) dentry->d_name.name, + }, + /* + * .out_argvar = 1, + * .out_numargs = 1, + * .out_args[0].size = , + * .out_args[0].value = , + */ + }; + + return 0; +} + +int fuse_get_link_initialize_out(struct bpf_fuse_args *fa, struct fuse_dummy_io *unused, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + /* + * .out_argvar = 1, + * .out_numargs = 1, + * .out_args[0].size = , + * .out_args[0].value = , + */ + + return 0; +} + +int fuse_get_link_backing(struct bpf_fuse_args *fa, const char **out, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + struct path backing_path; + + if (!dentry) { + *out = ERR_PTR(-ECHILD); + return PTR_ERR(*out); + } + + get_fuse_backing_path(dentry, &backing_path); + if (!backing_path.dentry) { + *out = ERR_PTR(-ECHILD); + return PTR_ERR(*out); + } + + /* + * TODO: If we want to do our own thing, copy the data and then call the + * callback + */ + *out = vfs_get_link(backing_path.dentry, callback); + + path_put(&backing_path); + return 0; +} + +int fuse_get_link_finalize(struct bpf_fuse_args *fa, const char **out, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + return 0; +} + +int fuse_symlink_initialize_in(struct bpf_fuse_args *fa, struct fuse_dummy_io *unused, + struct inode *dir, struct dentry *entry, const char *link, int len) +{ + *fa = (struct bpf_fuse_args) { + .nodeid = get_node_id(dir), + .opcode = FUSE_SYMLINK, + .in_numargs = 2, + .in_args[0] = (struct bpf_fuse_arg) { + .size = entry->d_name.len + 1, + .flags = BPF_FUSE_IMMUTABLE, + .value = (void *) entry->d_name.name, + }, + .in_args[1] = (struct bpf_fuse_arg) { + .size = len, + .max_size = PATH_MAX, + .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE, + .value = (void *) link, + }, + }; + + return 0; +} + +int fuse_symlink_initialize_out(struct bpf_fuse_args *fa, struct fuse_dummy_io *unused, + struct inode *dir, struct dentry *entry, const char *link, int len) +{ + return 0; +} + +int fuse_symlink_backing(struct bpf_fuse_args *fa, int *out, + struct inode *dir, struct dentry *entry, const char *link, int len) +{ + 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; + + *out = 0; + //TODO Actually deal with changing the backing entry in symlink + get_fuse_backing_path(entry, &backing_path); + if (!backing_path.dentry) + return -EBADF; + + inode_lock_nested(backing_inode, I_MUTEX_PARENT); + *out = vfs_symlink(&init_user_ns, backing_inode, backing_path.dentry, + link); + 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; +} + +int fuse_symlink_finalize(struct bpf_fuse_args *fa, int *out, + struct inode *dir, struct dentry *entry, const char *link, int len) +{ + return 0; +} + int fuse_readdir_initialize_in(struct bpf_fuse_args *fa, struct fuse_read_io *frio, struct file *file, struct dir_context *ctx, bool *force_again, bool *allow_force, bool is_continued) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index af1f715a405d..a4fd1cb018be 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -967,6 +967,16 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, unsigned len = strlen(link) + 1; FUSE_ARGS(args); +#ifdef CONFIG_FUSE_BPF + int err; + + if (fuse_bpf_backing(dir, struct fuse_dummy_io, err, + fuse_symlink_initialize_in, fuse_symlink_initialize_out, + fuse_symlink_backing, fuse_symlink_finalize, + dir, entry, link, len)) + return err; +#endif + args.opcode = FUSE_SYMLINK; args.in_numargs = 2; args.in_args[0].size = entry->d_name.len + 1; @@ -1198,6 +1208,14 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, struct fuse_mount *fm = get_fuse_mount(inode); FUSE_ARGS(args); +#ifdef CONFIG_FUSE_BPF + if (fuse_bpf_backing(inode, struct fuse_link_in, err, + fuse_link_initialize_in, fuse_link_initialize_out, + fuse_link_backing, fuse_link_finalize, entry, + newdir, newent)) + return err; +#endif + memset(&inarg, 0, sizeof(inarg)); inarg.oldnodeid = get_node_id(inode); args.opcode = FUSE_LINK; @@ -1609,6 +1627,19 @@ static const char *fuse_get_link(struct dentry *dentry, struct inode *inode, if (fuse_is_bad(inode)) goto out_err; +#ifdef CONFIG_FUSE_BPF + { + const char *out = NULL; + + if (fuse_bpf_backing(inode, struct fuse_dummy_io, out, + fuse_get_link_initialize_in, fuse_get_link_initialize_out, + fuse_get_link_backing, + fuse_get_link_finalize, + inode, dentry, callback)) + return out; + } +#endif + if (fc->cache_symlinks) return page_get_link(dentry, inode, callback); diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index b313a45c7774..cbfd56d669c7 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1504,6 +1504,17 @@ int fuse_unlink_backing(struct bpf_fuse_args *fa, int *out, int fuse_unlink_finalize(struct bpf_fuse_args *fa, int *out, struct inode *dir, struct dentry *entry); +int fuse_link_initialize_in(struct bpf_fuse_args *fa, struct fuse_link_in *fli, + struct dentry *entry, struct inode *dir, + struct dentry *newent); +int fuse_link_initialize_out(struct bpf_fuse_args *fa, struct fuse_link_in *fli, + struct dentry *entry, struct inode *dir, + struct dentry *newent); +int fuse_link_backing(struct bpf_fuse_args *fa, int *out, struct dentry *entry, + struct inode *dir, struct dentry *newent); +int fuse_link_finalize(struct bpf_fuse_args *fa, int *out, struct dentry *entry, + struct inode *dir, struct dentry *newent); + int fuse_release_initialize_in(struct bpf_fuse_args *fa, struct fuse_release_in *fri, struct inode *inode, struct file *file); int fuse_release_initialize_out(struct bpf_fuse_args *fa, struct fuse_release_in *fri, @@ -1742,6 +1753,28 @@ int fuse_statfs_backing(struct bpf_fuse_args *fa, int *out, int fuse_statfs_finalize(struct bpf_fuse_args *fa, int *out, struct dentry *dentry, struct kstatfs *buf); +int fuse_get_link_initialize_in(struct bpf_fuse_args *fa, struct fuse_dummy_io *dummy, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback); +int fuse_get_link_initialize_out(struct bpf_fuse_args *fa, struct fuse_dummy_io *dummy, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback); +int fuse_get_link_backing(struct bpf_fuse_args *fa, const char **out, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback); +int fuse_get_link_finalize(struct bpf_fuse_args *fa, const char **out, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback); + +int fuse_symlink_initialize_in(struct bpf_fuse_args *fa, struct fuse_dummy_io *unused, + struct inode *dir, struct dentry *entry, const char *link, int len); +int fuse_symlink_initialize_out(struct bpf_fuse_args *fa, struct fuse_dummy_io *unused, + struct inode *dir, struct dentry *entry, const char *link, int len); +int fuse_symlink_backing(struct bpf_fuse_args *fa, int *out, + struct inode *dir, struct dentry *entry, const char *link, int len); +int fuse_symlink_finalize(struct bpf_fuse_args *fa, int *out, + struct inode *dir, struct dentry *entry, const char *link, int len); + struct fuse_read_io { struct fuse_read_in fri; struct fuse_read_out fro;