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AJvYcCX1+pln5nCx02vK2th3orZQBvmIYrJo/r8xqyyk3GI6fyKjuB1QgpSc1OxONhAJ5jBKudWjMFWbFLrWO+bSNmNpRHyv X-Gm-Message-State: AOJu0YwMefomDnBGqNFtczZimRxk/dbvMlD2t5yUYwtuJ4qkmKRDzlKI PJWbQ7jjkZPer/6yRYttw5hUVIkrcDvwSMH0nYG5zrBsa5Fl67Z68CJgp/th+vFg/Py5qKNO8fJ b4A== X-Google-Smtp-Source: AGHT+IHgSug0jzbXQ+VMbPe8iA95JXmQc6vNb8Aqcyo87ghk95a5rdtG5sohFlX0zvcPZBd2OCeTo3AxAyA= X-Received: from drosen.mtv.corp.google.com ([2620:15c:211:201:fcce:d6ab:804c:b94b]) (user=drosen job=sendgmr) by 2002:a25:c753:0:b0:dd3:f55f:ff02 with SMTP id w80-20020a25c753000000b00dd3f55fff02mr840561ybe.1.1711677283612; Thu, 28 Mar 2024 18:54:43 -0700 (PDT) Date: Thu, 28 Mar 2024 18:53:35 -0700 In-Reply-To: <20240329015351.624249-1-drosen@google.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240329015351.624249-1-drosen@google.com> X-Mailer: git-send-email 2.44.0.478.gd926399ef9-goog Message-ID: <20240329015351.624249-21-drosen@google.com> Subject: [RFC PATCH v4 20/36] fuse-bpf: Add symlink/link support From: Daniel Rosenberg To: Miklos Szeredi , bpf@vger.kernel.org, Alexei Starovoitov Cc: Amir Goldstein , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Eduard Zingerman , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Jonathan Corbet , Joanne Koong , Mykola Lysenko , Christian Brauner , kernel-team@android.com, Daniel Rosenberg , Paul Lawrence X-Patchwork-State: RFC This adds backing support for FUSE_LINK, FUSE_READLINK, and FUSE_SYMLINK Signed-off-by: Daniel Rosenberg --- fs/fuse/backing.c | 327 ++++++++++++++++++++++++++++++++++++++++++++++ fs/fuse/dir.c | 11 ++ fs/fuse/fuse_i.h | 20 +++ 3 files changed, 358 insertions(+) diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c index 3390ce66e393..f18aee297335 100644 --- a/fs/fuse/backing.c +++ b/fs/fuse/backing.c @@ -2490,6 +2490,125 @@ int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry) dir, entry); } +struct fuse_link_args { + struct fuse_link_in in; + struct fuse_buffer name; +}; + +static int fuse_link_initialize_in(struct bpf_fuse_args *fa, struct fuse_link_args *args, + struct dentry *entry, struct inode *dir, + struct dentry *newent) +{ + struct inode *src_inode = entry->d_inode; + + *args = (struct fuse_link_args) { + .in = (struct fuse_link_in) { + .oldnodeid = get_node_id(src_inode), + }, + .name = (struct fuse_buffer) { + .data = (void *) newent->d_name.name, + .size = newent->d_name.len + 1, + .max_size = NAME_MAX + 1, + .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE, + }, + }; + + *fa = (struct bpf_fuse_args) { + .info = (struct bpf_fuse_meta_info) { + .opcode = FUSE_LINK, + }, + .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_link_initialize_out(struct bpf_fuse_args *fa, struct fuse_link_args *args, + struct dentry *entry, struct inode *dir, + struct dentry *newent) +{ + return 0; +} + +static 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, &nop_mnt_idmap, + 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; +} + +static int fuse_link_finalize(struct bpf_fuse_args *fa, int *out, struct dentry *entry, + struct inode *dir, struct dentry *newent) +{ + return 0; +} + +int fuse_bpf_link(int *out, struct inode *inode, struct dentry *entry, + struct inode *newdir, struct dentry *newent) +{ + return bpf_fuse_backing(inode, struct fuse_link_args, out, + fuse_link_initialize_in, fuse_link_initialize_out, + fuse_link_backing, fuse_link_finalize, + entry, newdir, newent); +} + struct fuse_getattr_args { struct fuse_getattr_in in; struct fuse_attr_out out; @@ -2786,6 +2905,214 @@ int fuse_bpf_statfs(int *out, struct inode *inode, struct dentry *dentry, struct dentry, buf); } +struct fuse_get_link_args { + struct fuse_buffer name; + struct fuse_buffer path; +}; + +static int fuse_get_link_initialize_in(struct bpf_fuse_args *fa, struct fuse_get_link_args *args, + 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 + */ + *args = (struct fuse_get_link_args) { + .name = (struct fuse_buffer) { + .data = (void *) dentry->d_name.name, + .size = dentry->d_name.len + 1, + .max_size = NAME_MAX + 1, + .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE, + }, + }; + + *fa = (struct bpf_fuse_args) { + .info = (struct bpf_fuse_meta_info) { + .opcode = FUSE_READLINK, + .nodeid = get_node_id(inode), + }, + .in_numargs = 1, + .in_args[0] = (struct bpf_fuse_arg) { + .is_buffer = true, + .buffer = &args->name, + }, + }; + + return 0; +} + +static int fuse_get_link_initialize_out(struct bpf_fuse_args *fa, struct fuse_get_link_args *args, + struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + // TODO +#if 0 + args->path = (struct fuse_buffer) { + .data = NULL, + .size = 0, + .max_size = PATH_MAX, + .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE, + }; + fa->out_numargs = 1; + fa->out_args[0].is_buffer = true; + fa->out_args[0].buffer = &args->path; +#endif + + return 0; +} + +static 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; +} + +static 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_bpf_get_link(const char **out, struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + return bpf_fuse_backing(inode, struct fuse_get_link_args, out, + fuse_get_link_initialize_in, fuse_get_link_initialize_out, + fuse_get_link_backing, fuse_get_link_finalize, + inode, dentry, callback); +} + +struct fuse_symlink_args { + struct fuse_buffer name; + struct fuse_buffer path; +}; + +static int fuse_symlink_initialize_in(struct bpf_fuse_args *fa, struct fuse_symlink_args *args, + struct inode *dir, struct dentry *entry, const char *link, int len) +{ + *args = (struct fuse_symlink_args) { + .name = (struct fuse_buffer) { + .data = (void *) entry->d_name.name, + .size = entry->d_name.len + 1, + .flags = BPF_FUSE_IMMUTABLE, + }, + .path = (struct fuse_buffer) { + .data = (void *) link, + .size = len, + .max_size = PATH_MAX, + .flags = BPF_FUSE_VARIABLE_SIZE | BPF_FUSE_MUST_ALLOCATE, + }, + }; + *fa = (struct bpf_fuse_args) { + .info = (struct bpf_fuse_meta_info) { + .nodeid = get_node_id(dir), + .opcode = FUSE_SYMLINK, + }, + .in_numargs = 2, + .in_args[0] = (struct bpf_fuse_arg) { + .is_buffer = true, + .buffer = &args->name, + }, + .in_args[1] = (struct bpf_fuse_arg) { + .is_buffer = true, + .buffer = &args->path, + }, + }; + + return 0; +} + +static int fuse_symlink_initialize_out(struct bpf_fuse_args *fa, struct fuse_symlink_args *args, + struct inode *dir, struct dentry *entry, const char *link, int len) +{ + return 0; +} + +static 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(&nop_mnt_idmap, 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; +} + +static 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_bpf_symlink(int *out, struct inode *dir, struct dentry *entry, const char *link, int len) +{ + return bpf_fuse_backing(dir, struct fuse_symlink_args, out, + fuse_symlink_initialize_in, fuse_symlink_initialize_out, + fuse_symlink_backing, fuse_symlink_finalize, + dir, entry, link, len); +} + struct fuse_read_args { struct fuse_read_in in; struct fuse_read_out out; diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 77d231ab1d9c..08f93a981665 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1033,6 +1033,10 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir, struct fuse_mount *fm = get_fuse_mount(dir); unsigned len = strlen(link) + 1; FUSE_ARGS(args); + int err; + + if (fuse_bpf_symlink(&err, dir, entry, link, len)) + return err; args.opcode = FUSE_SYMLINK; args.in_numargs = 2; @@ -1239,6 +1243,9 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, struct fuse_mount *fm = get_fuse_mount(inode); FUSE_ARGS(args); + if (fuse_bpf_link(&err, inode, entry, newdir, newent)) + return err; + memset(&inarg, 0, sizeof(inarg)); inarg.oldnodeid = get_node_id(inode); args.opcode = FUSE_LINK; @@ -1741,12 +1748,16 @@ static const char *fuse_get_link(struct dentry *dentry, struct inode *inode, { struct fuse_conn *fc = get_fuse_conn(inode); struct page *page; + const char *out = NULL; int err; err = -EIO; if (fuse_is_bad(inode)) goto out_err; + if (fuse_bpf_get_link(&out, inode, dentry, callback)) + return out; + 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 127758575ddc..8ae6ad967f95 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1450,6 +1450,7 @@ int fuse_bpf_rename2(int *out, struct inode *olddir, struct dentry *oldent, int fuse_bpf_rename(int *out, struct inode *olddir, struct dentry *oldent, struct inode *newdir, struct dentry *newent); int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry); +int fuse_bpf_link(int *out, struct inode *inode, struct dentry *entry, struct inode *dir, struct dentry *newent); int fuse_bpf_release(int *out, struct inode *inode, struct fuse_file *ff); int fuse_bpf_releasedir(int *out, struct inode *inode, struct fuse_file *ff); int fuse_bpf_flush(int *out, struct inode *inode, struct file *file, fl_owner_t id); @@ -1474,6 +1475,9 @@ int fuse_bpf_getattr(int *out, struct inode *inode, const struct dentry *entry, u32 request_mask, unsigned int flags); int fuse_bpf_setattr(int *out, struct inode *inode, struct dentry *dentry, struct iattr *attr, struct file *file); int fuse_bpf_statfs(int *out, struct inode *inode, struct dentry *dentry, struct kstatfs *buf); +int fuse_bpf_get_link(const char **out, struct inode *inode, struct dentry *dentry, + struct delayed_call *callback); +int fuse_bpf_symlink(int *out, struct inode *dir, struct dentry *entry, const char *link, int len); int fuse_bpf_readdir(int *out, struct inode *inode, struct file *file, struct dir_context *ctx); int fuse_bpf_access(int *out, struct inode *inode, int mask); @@ -1523,6 +1527,11 @@ static inline int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *en return 0; } +static inline int fuse_bpf_link(int *out, struct inode *inode, struct dentry *entry, struct inode *dir, struct dentry *newent) +{ + return 0; +} + static inline int fuse_bpf_release(int *out, struct inode *inode, struct file *file) { return 0; @@ -1619,6 +1628,17 @@ static inline int fuse_bpf_statfs(int *out, struct inode *inode, struct dentry * return 0; } +static inline int fuse_bpf_get_link(const char **out, struct inode *inode, struct dentry *dentry, + struct delayed_call *callback) +{ + return 0; +} + +static inline int fuse_bpf_symlink(int *out, struct inode *dir, struct dentry *entry, const char *link, int len) +{ + return 0; +} + static inline int fuse_bpf_readdir(int *out, struct inode *inode, struct file *file, struct dir_context *ctx) { return 0;