diff options
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/Makefile | 1 | ||||
| -rw-r--r-- | fs/btrfs/btrfs_inode.h | 7 | ||||
| -rw-r--r-- | fs/btrfs/ctree.h | 31 | ||||
| -rw-r--r-- | fs/btrfs/extent_io.c | 26 | ||||
| -rw-r--r-- | fs/btrfs/file.c | 10 | ||||
| -rw-r--r-- | fs/btrfs/inode.c | 6 | ||||
| -rw-r--r-- | fs/btrfs/ioctl.c | 14 | ||||
| -rw-r--r-- | fs/btrfs/super.c | 3 | ||||
| -rw-r--r-- | fs/btrfs/sysfs.c | 6 | ||||
| -rw-r--r-- | fs/btrfs/verity.c | 738 |
10 files changed, 823 insertions, 19 deletions
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile index cec88a66bd6c..3dcf9bcc2326 100644 --- a/fs/btrfs/Makefile +++ b/fs/btrfs/Makefile @@ -36,6 +36,7 @@ btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o btrfs-$(CONFIG_BTRFS_FS_REF_VERIFY) += ref-verify.o btrfs-$(CONFIG_BLK_DEV_ZONED) += zoned.o +btrfs-$(CONFIG_FS_VERITY) += verity.o btrfs-$(CONFIG_BTRFS_FS_RUN_SANITY_TESTS) += tests/free-space-tests.o \ tests/extent-buffer-tests.o tests/btrfs-tests.o \ diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 1093b00130be..76ee1452c57b 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -51,6 +51,13 @@ enum { * the file range, inode's io_tree). */ BTRFS_INODE_NO_DELALLOC_FLUSH, + /* + * Set when we are working on enabling verity for a file. Computing and + * writing the whole Merkle tree can take a while so we want to prevent + * races where two separate tasks attempt to simultaneously start verity + * on the same file. + */ + BTRFS_INODE_VERITY_IN_PROGRESS, }; /* in memory btrfs inode */ diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 9e3b7a56a78f..f17be4b023cb 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -281,7 +281,8 @@ struct btrfs_super_block { #define BTRFS_FEATURE_COMPAT_RO_SUPP \ (BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE | \ - BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID) + BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID | \ + BTRFS_FEATURE_COMPAT_RO_VERITY) #define BTRFS_FEATURE_COMPAT_RO_SAFE_SET 0ULL #define BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR 0ULL @@ -1512,7 +1513,9 @@ do { \ BTRFS_INODE_COMPRESS | \ BTRFS_INODE_ROOT_ITEM_INIT) -#define BTRFS_INODE_RO_FLAG_MASK (0) +#define BTRFS_INODE_RO_VERITY (1U << 0) + +#define BTRFS_INODE_RO_FLAG_MASK (BTRFS_INODE_RO_VERITY) struct btrfs_map_token { struct extent_buffer *eb; @@ -3791,6 +3794,30 @@ static inline int btrfs_defrag_cancelled(struct btrfs_fs_info *fs_info) return signal_pending(current); } +/* verity.c */ +#ifdef CONFIG_FS_VERITY + +extern const struct fsverity_operations btrfs_verityops; +int btrfs_drop_verity_items(struct btrfs_inode *inode); + +BTRFS_SETGET_FUNCS(verity_descriptor_encryption, struct btrfs_verity_descriptor_item, + encryption, 8); +BTRFS_SETGET_FUNCS(verity_descriptor_size, struct btrfs_verity_descriptor_item, + size, 64); +BTRFS_SETGET_STACK_FUNCS(stack_verity_descriptor_encryption, + struct btrfs_verity_descriptor_item, encryption, 8); +BTRFS_SETGET_STACK_FUNCS(stack_verity_descriptor_size, + struct btrfs_verity_descriptor_item, size, 64); + +#else + +static inline int btrfs_drop_verity_items(struct btrfs_inode *inode) +{ + return 0; +} + +#endif + /* Sanity test specific functions */ #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS void btrfs_test_destroy_inode(struct inode *inode); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 66888b10b00d..96de6e70d06c 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -13,6 +13,7 @@ #include <linux/pagevec.h> #include <linux/prefetch.h> #include <linux/cleancache.h> +#include <linux/fsverity.h> #include "misc.h" #include "extent_io.h" #include "extent-io-tree.h" @@ -2247,18 +2248,6 @@ int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, return bitset; } -/* - * helper function to set a given page up to date if all the - * extents in the tree for that page are up to date - */ -static void check_page_uptodate(struct extent_io_tree *tree, struct page *page) -{ - u64 start = page_offset(page); - u64 end = start + PAGE_SIZE - 1; - if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL)) - SetPageUptodate(page); -} - int free_io_failure(struct extent_io_tree *failure_tree, struct extent_io_tree *io_tree, struct io_failure_record *rec) @@ -2690,7 +2679,15 @@ static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len) start + len <= page_offset(page) + PAGE_SIZE); if (uptodate) { - btrfs_page_set_uptodate(fs_info, page, start, len); + if (fsverity_active(page->mapping->host) && + !PageError(page) && + !PageUptodate(page) && + start < i_size_read(page->mapping->host) && + !fsverity_verify_page(page)) { + btrfs_page_set_error(fs_info, page, start, len); + } else { + btrfs_page_set_uptodate(fs_info, page, start, len); + } } else { btrfs_page_clear_uptodate(fs_info, page, start, len); btrfs_page_set_error(fs_info, page, start, len); @@ -3105,7 +3102,7 @@ readpage_ok: /* Update page status and unlock */ end_page_read(page, uptodate, start, len); endio_readpage_release_extent(&processed, BTRFS_I(inode), - start, end, uptodate); + start, end, PageUptodate(page)); } /* Release the last extent */ endio_readpage_release_extent(&processed, NULL, 0, 0, false); @@ -3706,7 +3703,6 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, /* the get_extent function already copied into the page */ if (test_range_bit(tree, cur, cur_end, EXTENT_UPTODATE, 1, NULL)) { - check_page_uptodate(tree, page); unlock_extent(tree, cur, cur + iosize - 1); end_page_read(page, true, cur, iosize); cur = cur + iosize; diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index d3f2623a2af0..7ff577005d0f 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -16,6 +16,7 @@ #include <linux/btrfs.h> #include <linux/uio.h> #include <linux/iversion.h> +#include <linux/fsverity.h> #include "ctree.h" #include "disk-io.h" #include "transaction.h" @@ -3615,7 +3616,13 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence) static int btrfs_file_open(struct inode *inode, struct file *filp) { + int ret; + filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC; + + ret = fsverity_file_open(inode, filp); + if (ret) + return ret; return generic_file_open(inode, filp); } @@ -3644,6 +3651,9 @@ static ssize_t btrfs_direct_read(struct kiocb *iocb, struct iov_iter *to) struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; + if (fsverity_active(inode)) + return 0; + if (check_direct_read(btrfs_sb(inode->i_sb), to, iocb->ki_pos)) return 0; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index cd5a67ba7e71..766cd35be33d 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -32,6 +32,7 @@ #include <linux/sched/mm.h> #include <linux/iomap.h> #include <asm/unaligned.h> +#include <linux/fsverity.h> #include "misc.h" #include "ctree.h" #include "disk-io.h" @@ -5560,6 +5561,7 @@ void btrfs_evict_inode(struct inode *inode) trace_btrfs_inode_evict(inode); if (!root) { + fsverity_cleanup_inode(inode); clear_inode(inode); return; } @@ -5642,6 +5644,7 @@ no_delete: * to retry these periodically in the future. */ btrfs_remove_delayed_node(BTRFS_I(inode)); + fsverity_cleanup_inode(inode); clear_inode(inode); } @@ -9250,6 +9253,7 @@ static int btrfs_getattr(struct user_namespace *mnt_userns, struct inode *inode = d_inode(path->dentry); u32 blocksize = inode->i_sb->s_blocksize; u32 bi_flags = BTRFS_I(inode)->flags; + u32 bi_ro_flags = BTRFS_I(inode)->ro_flags; stat->result_mask |= STATX_BTIME; stat->btime.tv_sec = BTRFS_I(inode)->i_otime.tv_sec; @@ -9262,6 +9266,8 @@ static int btrfs_getattr(struct user_namespace *mnt_userns, stat->attributes |= STATX_ATTR_IMMUTABLE; if (bi_flags & BTRFS_INODE_NODUMP) stat->attributes |= STATX_ATTR_NODUMP; + if (bi_ro_flags & BTRFS_INODE_RO_VERITY) + stat->attributes |= STATX_ATTR_VERITY; stat->attributes_mask |= (STATX_ATTR_APPEND | STATX_ATTR_COMPRESSED | diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 17aefb5f08ea..85c8b5a87a6a 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -27,6 +27,7 @@ #include <linux/uaccess.h> #include <linux/iversion.h> #include <linux/fileattr.h> +#include <linux/fsverity.h> #include "ctree.h" #include "disk-io.h" #include "export.h" @@ -107,6 +108,7 @@ static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode) { unsigned int iflags = 0; u32 flags = binode->flags; + u32 ro_flags = binode->ro_flags; if (flags & BTRFS_INODE_SYNC) iflags |= FS_SYNC_FL; @@ -122,6 +124,8 @@ static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode) iflags |= FS_DIRSYNC_FL; if (flags & BTRFS_INODE_NODATACOW) iflags |= FS_NOCOW_FL; + if (ro_flags & BTRFS_INODE_RO_VERITY) + iflags |= FS_VERITY_FL; if (flags & BTRFS_INODE_NOCOMPRESS) iflags |= FS_NOCOMP_FL; @@ -149,10 +153,12 @@ void btrfs_sync_inode_flags_to_i_flags(struct inode *inode) new_fl |= S_NOATIME; if (binode->flags & BTRFS_INODE_DIRSYNC) new_fl |= S_DIRSYNC; + if (binode->ro_flags & BTRFS_INODE_RO_VERITY) + new_fl |= S_VERITY; set_mask_bits(&inode->i_flags, - S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC, - new_fl); + S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC | + S_VERITY, new_fl); } /* @@ -5020,6 +5026,10 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_get_subvol_rootref(file, argp); case BTRFS_IOC_INO_LOOKUP_USER: return btrfs_ioctl_ino_lookup_user(file, argp); + case FS_IOC_ENABLE_VERITY: + return fsverity_ioctl_enable(file, (const void __user *)argp); + case FS_IOC_MEASURE_VERITY: + return fsverity_ioctl_measure(file, argp); } return -ENOTTY; diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 0d2e3ab2fc31..2bdc544b4c95 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1353,6 +1353,9 @@ static int btrfs_fill_super(struct super_block *sb, sb->s_op = &btrfs_super_ops; sb->s_d_op = &btrfs_dentry_operations; sb->s_export_op = &btrfs_export_ops; +#ifdef CONFIG_FS_VERITY + sb->s_vop = &btrfs_verityops; +#endif sb->s_xattr = btrfs_xattr_handlers; sb->s_time_gran = 1; #ifdef CONFIG_BTRFS_FS_POSIX_ACL diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index d9d53a255ef9..bfe5e27617b0 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -267,6 +267,9 @@ BTRFS_FEAT_ATTR_INCOMPAT(raid1c34, RAID1C34); #ifdef CONFIG_BTRFS_DEBUG BTRFS_FEAT_ATTR_INCOMPAT(zoned, ZONED); #endif +#ifdef CONFIG_FS_VERITY +BTRFS_FEAT_ATTR_COMPAT_RO(verity, VERITY); +#endif static struct attribute *btrfs_supported_feature_attrs[] = { BTRFS_FEAT_ATTR_PTR(mixed_backref), @@ -285,6 +288,9 @@ static struct attribute *btrfs_supported_feature_attrs[] = { #ifdef CONFIG_BTRFS_DEBUG BTRFS_FEAT_ATTR_PTR(zoned), #endif +#ifdef CONFIG_FS_VERITY + BTRFS_FEAT_ATTR_PTR(verity), +#endif NULL }; diff --git a/fs/btrfs/verity.c b/fs/btrfs/verity.c new file mode 100644 index 000000000000..ac4c2ca45925 --- /dev/null +++ b/fs/btrfs/verity.c @@ -0,0 +1,738 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/init.h> +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/rwsem.h> +#include <linux/xattr.h> +#include <linux/security.h> +#include <linux/posix_acl_xattr.h> +#include <linux/iversion.h> +#include <linux/fsverity.h> +#include <linux/sched/mm.h> +#include "ctree.h" +#include "btrfs_inode.h" +#include "transaction.h" +#include "disk-io.h" +#include "locking.h" + +/* + * Implementation of the interface defined in struct fsverity_operations. + * + * The main question is how and where to store the verity descriptor and the + * Merkle tree. We store both in dedicated btree items in the filesystem tree, + * together with the rest of the inode metadata. This means we'll need to do + * extra work to encrypt them once encryption is supported in btrfs, but btrfs + * has a lot of careful code around i_size and it seems better to make a new key + * type than try and adjust all of our expectations for i_size. + * + * Note that this differs from the implementation in ext4 and f2fs, where + * this data is stored as if it were in the file, but past EOF. However, btrfs + * does not have a widespread mechanism for caching opaque metadata pages, so we + * do pretend that the Merkle tree pages themselves are past EOF for the + * purposes of caching them (as opposed to creating a virtual inode). + * + * fs verity items are stored under two different key types on disk. + * The descriptor items: + * [ inode objectid, BTRFS_VERITY_DESC_ITEM_KEY, offset ] + * + * At offset 0, we store a btrfs_verity_descriptor_item which tracks the + * size of the descriptor item and some extra data for encryption. + * Starting at offset 1, these hold the generic fs verity descriptor. + * The latter are opaque to btrfs, we just read and write them as a blob for + * the higher level verity code. The most common descriptor size is 256 bytes. + * + * The merkle tree items: + * [ inode objectid, BTRFS_VERITY_MERKLE_ITEM_KEY, offset ] + * + * These also start at offset 0, and correspond to the merkle tree bytes. + * So when fsverity asks for page 0 of the merkle tree, we pull up one page + * starting at offset 0 for this key type. These are also opaque to btrfs, + * we're blindly storing whatever fsverity sends down. + */ + +#define MERKLE_START_ALIGN 65536 + +/* + * Compute the logical file offset where we cache the Merkle tree. + * + * @inode: inode of the verity file + * + * For the purposes of caching the Merkle tree pages, as required by + * fs-verity, it is convenient to do size computations in terms of a file + * offset, rather than in terms of page indices. + * + * Use 64K to be sure it's past the last page in the file, even with 64K pages. + * That rounding operation itself can overflow loff_t, so we do it in u64 and + * check. + * + * Returns the file offset on success, negative error code on failure. + */ +static loff_t merkle_file_pos(const struct inode *inode) +{ + u64 sz = inode->i_size; + u64 rounded = round_up(sz, MERKLE_START_ALIGN); + + if (rounded > inode->i_sb->s_maxbytes) + return -EFBIG; + + return rounded; +} + +/* + * Drop all the items for this inode with this key_type. + * + * @inode: inode to drop items for + * @key_type: type of items to drop (BTRFS_VERITY_DESC_ITEM or + * BTRFS_VERITY_MERKLE_ITEM) + * + * Before doing a verity enable we cleanup any existing verity items. + * This is also used to clean up if a verity enable failed half way through. + * + * Returns number of dropped items on success, negative error code on failure. + */ +static int drop_verity_items(struct btrfs_inode *inode, u8 key_type) +{ + struct btrfs_trans_handle *trans; + struct btrfs_root *root = inode->root; + struct btrfs_path *path; + struct btrfs_key key; + int count = 0; + int ret; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + while (1) { + /* 1 for the item being dropped */ + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + goto out; + } + + /* + * Walk backwards through all the items until we find one that + * isn't from our key type or objectid + */ + key.objectid = btrfs_ino(inode); + key.type = key_type; + key.offset = (u64)-1; + + ret = btrfs_search_slot(trans, root, &key, path, -1, 1); + if (ret > 0) { + ret = 0; + /* No more keys of this type, we're done */ + if (path->slots[0] == 0) + break; + path->slots[0]--; + } else if (ret < 0) { + btrfs_end_transaction(trans); + goto out; + } + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + /* No more keys of this type, we're done */ + if (key.objectid != btrfs_ino(inode) || key.type != key_type) + break; + + /* + * This shouldn't be a performance sensitive function because + * it's not used as part of truncate. If it ever becomes + * perf sensitive, change this to walk forward and bulk delete + * items + */ + ret = btrfs_del_items(trans, root, path, path->slots[0], 1); + if (ret) { + btrfs_end_transaction(trans); + goto out; + } + count++; + btrfs_release_path(path); + btrfs_end_transaction(trans); + } + ret = count; + btrfs_end_transaction(trans); +out: + btrfs_free_path(path); + return ret; +} + +/* + * Drop all verity items + * + * @inode: inode to drop verity items for + * + * In most contexts where we are dropping verity items, we want to do it for all + * the types of verity items, not a particular one. + * + * Returns: 0 on success, negative error code on failure. + */ +int btrfs_drop_verity_items(struct btrfs_inode *inode) +{ + int ret; + + ret = drop_verity_items(inode, BTRFS_VERITY_DESC_ITEM_KEY); + if (ret < 0) + return ret; + ret = drop_verity_items(inode, BTRFS_VERITY_MERKLE_ITEM_KEY); + if (ret < 0) + return ret; + + return 0; +} + +/* + * Insert and write inode items with a given key type and offset. + * + * @inode: inode to insert for + * @key_type: key type to insert + * @offset: item offset to insert at + * @src: source data to write + * @len: length of source data to write + * + * Write len bytes from src into items of up to 2K length. + * The inserted items will have key (ino, key_type, offset + off) where off is + * consecutively increasing from 0 up to the last item ending at offset + len. + * + * Returns 0 on success and a negative error code on failure. + */ +static int write_key_bytes(struct btrfs_inode *inode, u8 key_type, u64 offset, + const char *src, u64 len) +{ + struct btrfs_trans_handle *trans; + struct btrfs_path *path; + struct btrfs_root *root = inode->root; + struct extent_buffer *leaf; + struct btrfs_key key; + unsigned long copy_bytes; + unsigned long src_offset = 0; + void *data; + int ret = 0; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + while (len > 0) { + /* 1 for the new item being inserted */ + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + break; + } + + key.objectid = btrfs_ino(inode); + key.type = key_type; + key.offset = offset; + + /* + * Insert 2K at a time mostly to be friendly for smaller leaf + * size filesystems + */ + copy_bytes = min_t(u64, len, 2048); + + ret = btrfs_insert_empty_item(trans, root, path, &key, copy_bytes); + if (ret) { + btrfs_end_transaction(trans); + break; + } + + leaf = path->nodes[0]; + + data = btrfs_item_ptr(leaf, path->slots[0], void); + write_extent_buffer(leaf, src + src_offset, + (unsigned long)data, copy_bytes); + offset += copy_bytes; + src_offset += copy_bytes; + len -= copy_bytes; + + btrfs_release_path(path); + btrfs_end_transaction(trans); + } + + btrfs_free_path(path); + return ret; +} + +/* + * Read inode items of the given key type and offset from the btree. + * + * @inode: inode to read items of + * @key_type: key type to read + * @offset: item offset to read from + * @dest: Buffer to read into. This parameter has slightly tricky + * semantics. If it is NULL, the function will not do any copying + * and will just return the size of all the items up to len bytes. + * If dest_page is passed, then the function will kmap_local the + * page and ignore dest, but it must still be non-NULL to avoid the + * counting-only behavior. + * @len: length in bytes to read + * @dest_page: copy into this page instead of the dest buffer + * + * Helper function to read items from the btree. This returns the number of + * bytes read or < 0 for errors. We can return short reads if the items don't + * exist on disk or aren't big enough to fill the desired length. Supports + * reading into a provided buffer (dest) or into the page cache + * + * Returns number of bytes read or a negative error code on failure. + */ +static int read_key_bytes(struct btrfs_inode *inode, u8 key_type, u64 offset, + char *dest, u64 len, struct page *dest_page) +{ + struct btrfs_path *path; + struct btrfs_root *root = inode->root; + struct extent_buffer *leaf; + struct btrfs_key key; + u64 item_end; + u64 copy_end; + int copied = 0; + u32 copy_offset; + unsigned long copy_bytes; + unsigned long dest_offset = 0; + void *data; + char *kaddr = dest; + int ret; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + if (dest_page) + path->reada = READA_FORWARD; + + key.objectid = btrfs_ino(inode); + key.type = key_type; + key.offset = offset; + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) { + goto out; + } else if (ret > 0) { + ret = 0; + if (path->slots[0] == 0) + goto out; + path->slots[0]--; + } + + while (len > 0) { + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + + if (key.objectid != btrfs_ino(inode) || key.type != key_type) + break; + + item_end = btrfs_item_size_nr(leaf, path->slots[0]) + key.offset; + + if (copied > 0) { + /* + * Once we've copied something, we want all of the items + * to be sequential + */ + if (key.offset != offset) + break; + } else { + /* + * Our initial offset might be in the middle of an + * item. Make sure it all makes sense. + */ + if (key.offset > offset) + break; + if (item_end <= offset) + break; + } + + /* desc = NULL to just sum all the item lengths */ + if (!dest) + copy_end = item_end; + else + copy_end = min(offset + len, item_end); + + /* Number of bytes in this item we want to copy */ + copy_bytes = copy_end - offset; + + /* Offset from the start of item for copying */ + copy_offset = offset - key.offset; + + if (dest) { + if (dest_page) + kaddr = kmap_local_page(dest_page); + + data = btrfs_item_ptr(leaf, path->slots[0], void); + read_extent_buffer(leaf, kaddr + dest_offset, + (unsigned long)data + copy_offset, + copy_bytes); + + if (dest_page) + kunmap_local(kaddr); + } + + offset += copy_bytes; + dest_offset += copy_bytes; + len -= copy_bytes; + copied += copy_bytes; + + path->slots[0]++; + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { + /* + * We've reached the last slot in this leaf and we need + * to go to the next leaf. + */ + ret = btrfs_next_leaf(root, path); + if (ret < 0) { + break; + } else if (ret > 0) { + ret = 0; + break; + } + } + } +out: + btrfs_free_path(path); + if (!ret) + ret = copied; + return ret; +} + +/* + * Rollback in-progress verity if we encounter an error. + * + * @inode: inode verity had an error for + * + * We try to handle recoverable errors while enabling verity by rolling it back + * and just failing the operation, rather than having an fs level error no + * matter what. However, any error in rollback is unrecoverable. + * + * Returns 0 on success, negative error code on failure. + */ +static int rollback_verity(struct btrfs_inode *inode) +{ + struct btrfs_trans_handle *trans; + struct btrfs_root *root = inode->root; + int ret; + + ASSERT(inode_is_locked(&inode->vfs_inode)); + truncate_inode_pages(inode->vfs_inode.i_mapping, inode->vfs_inode.i_size); + clear_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags); + ret = btrfs_drop_verity_items(inode); + if (ret) { + btrfs_handle_fs_error(root->fs_info, ret, + "failed to drop verity items in rollback %llu", + (u64)inode->vfs_inode.i_ino); + goto out; + } + + /* 1 for updating the inode flag */ + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + btrfs_handle_fs_error(root->fs_info, ret, + "failed to start transaction in verity rollback %llu", + (u64)inode->vfs_inode.i_ino); + goto out; + } + inode->ro_flags &= ~BTRFS_INODE_RO_VERITY; + btrfs_sync_inode_flags_to_i_flags(&inode->vfs_inode); + ret = btrfs_update_inode(trans, root, inode); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto out; + } + btrfs_end_transaction(trans); +out: + return ret; +} + +/* + * Finalize making the file a valid verity file + * + * @inode: inode to be marked as verity + * @desc: contents of the verity descriptor to write (not NULL) + * @desc_size: size of the verity descriptor + * + * Do the actual work of finalizing verity after successfully writing the Merkle + * tree: + * + * - write out the descriptor items + * - mark the inode with the verity flag + * - mark the ro compat bit + * - clear the in progress bit + * + * Returns 0 on success, negative error code on failure. + */ +static int finish_verity(struct btrfs_inode *inode, const void *desc, + size_t desc_size) +{ + struct btrfs_trans_handle *trans = NULL; + struct btrfs_root *root = inode->root; + struct btrfs_verity_descriptor_item item; + int ret; + + /* Write out the descriptor item */ + memset(&item, 0, sizeof(item)); + btrfs_set_stack_verity_descriptor_size(&item, desc_size); + ret = write_key_bytes(inode, BTRFS_VERITY_DESC_ITEM_KEY, 0, + (const char *)&item, sizeof(item)); + if (ret) + goto out; + + /* Write out the descriptor itself */ + ret = write_key_bytes(inode, BTRFS_VERITY_DESC_ITEM_KEY, 1, + desc, desc_size); + if (ret) + goto out; + + /* 1 for updating the inode flag */ + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + goto out; + } + inode->ro_flags |= BTRFS_INODE_RO_VERITY; + btrfs_sync_inode_flags_to_i_flags(&inode->vfs_inode); + ret = btrfs_update_inode(trans, root, inode); + if (ret) + goto end_trans; + clear_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags); + btrfs_set_fs_compat_ro(root->fs_info, VERITY); +end_trans: + btrfs_end_transaction(trans); +out: + return ret; + +} + +/* + * fsverity op that begins enabling verity. + * + * @filp: file to enable verity on + * + * Begin enabling fsverity for the file. We drop any existing verity items + * and set the in progress bit. + * + * Returns 0 on success, negative error code on failure. + */ +static int btrfs_begin_enable_verity(struct file *filp) +{ + struct btrfs_inode *inode = BTRFS_I(file_inode(filp)); + int ret; + + ASSERT(inode_is_locked(file_inode(filp))); + + if (test_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags)) + return -EBUSY; + + ret = btrfs_drop_verity_items(inode); + if (ret) + return ret; + + set_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags); + + return 0; +} + +/* + * fsverity op that ends enabling verity. + * + * @filp: file we are finishing enabling verity on + * @desc: verity descriptor to write out (NULL in error conditions) + * @desc_size: size of the verity descriptor (variable with signatures) + * @merkle_tree_size: size of the merkle tree in bytes + * + * If desc is null, then VFS is signaling an error occurred during verity + * enable, and we should try to rollback. Otherwise, attempt to finish verity. + * + * Returns 0 on success, negative error code on error. + */ +static int btrfs_end_enable_verity(struct file *filp, const void *desc, + size_t desc_size, u64 merkle_tree_size) +{ + struct btrfs_inode *inode = BTRFS_I(file_inode(filp)); + int ret = 0; + int rollback_ret; + + ASSERT(inode_is_locked(file_inode(filp))); + + if (desc == NULL) + goto rollback; + + ret = finish_verity(inode, desc, desc_size); + if (ret) + goto rollback; + return ret; + +rollback: + rollback_ret = rollback_verity(inode); + if (rollback_ret) + btrfs_err(inode->root->fs_info, + "failed to rollback verity items: %d", rollback_ret); + return ret; +} + +/* + * fsverity op that gets the struct fsverity_descriptor. + * + * @inode: inode to get the descriptor of + * @buf: output buffer for the descriptor contents + * @buf_size: size of the output buffer. 0 to query the size + * + * fsverity does a two pass setup for reading the descriptor, in the first pass + * it calls with buf_size = 0 to query the size of the descriptor, and then in + * the second pass it actually reads the descriptor off disk. + * + * Returns the size on success or a negative error code on failure. + */ +static int btrfs_get_verity_descriptor(struct inode *inode, void *buf, + size_t buf_size) +{ + u64 true_size; + int ret = 0; + struct btrfs_verity_descriptor_item item; + + memset(&item, 0, sizeof(item)); + ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_DESC_ITEM_KEY, 0, + (char *)&item, sizeof(item), NULL); + if (ret < 0) + return ret; + + if (item.reserved[0] != 0 || item.reserved[1] != 0) + return -EUCLEAN; + + true_size = btrfs_stack_verity_descriptor_size(&item); + if (true_size > INT_MAX) + return -EUCLEAN; + + if (buf_size == 0) + return true_size; + if (buf_size < true_size) + return -ERANGE; + + ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_DESC_ITEM_KEY, 1, + buf, buf_size, NULL); + if (ret < 0) + return ret; + if (ret != true_size) + return -EIO; + + return true_size; +} + +/* + * fsverity op that reads and caches a merkle tree page. + * + * @inode: inode to read a merkle tree page for + * @index: page index relative to the start of the merkle tree + * @num_ra_pages: number of pages to readahead. Optional, we ignore it + * + * The Merkle tree is stored in the filesystem btree, but its pages are cached + * with a logical position past EOF in the inode's mapping. + * + * Returns the page we read, or an ERR_PTR on error. + */ +static struct page *btrfs_read_merkle_tree_page(struct inode *inode, + pgoff_t index, + unsigned long num_ra_pages) +{ + struct page *page; + u64 off = (u64)index << PAGE_SHIFT; + loff_t merkle_pos = merkle_file_pos(inode); + int ret; + + if (merkle_pos < 0) + return ERR_PTR(merkle_pos); + if (merkle_pos > inode->i_sb->s_maxbytes - off - PAGE_SIZE) + return ERR_PTR(-EFBIG); + index += merkle_pos >> PAGE_SHIFT; +again: + page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED); + if (page) { + if (PageUptodate(page)) + return page; + + lock_page(page); + /* + * We only insert uptodate pages, so !Uptodate has to be + * an error + */ + if (!PageUptodate(page)) { + unlock_page(page); + put_page(page); + return ERR_PTR(-EIO); + } + unlock_page(page); + return page; + } + + page = __page_cache_alloc(mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS)); + if (!page) + return ERR_PTR(-ENOMEM); + + /* + * Merkle item keys are indexed from byte 0 in the merkle tree. + * They have the form: + * + * [ inode objectid, BTRFS_MERKLE_ITEM_KEY, offset in bytes ] + */ + ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_MERKLE_ITEM_KEY, off, + page_address(page), PAGE_SIZE, page); + if (ret < 0) { + put_page(page); + return ERR_PTR(ret); + } + if (ret < PAGE_SIZE) + memzero_page(page, ret, PAGE_SIZE - ret); + + SetPageUptodate(page); + ret = add_to_page_cache_lru(page, inode->i_mapping, index, GFP_NOFS); + + if (!ret) { + /* Inserted and ready for fsverity */ + unlock_page(page); + } else { + put_page(page); + /* Did someone race us into inserting this page? */ + if (ret == -EEXIST) + goto again; + page = ERR_PTR(ret); + } + return page; +} + +/* + * fsverity op that writes a Merkle tree block into the btree. + * + * @inode: inode to write a Merkle tree block for + * @buf: Merkle tree data block to write + * @index: index of the block in the Merkle tree + * @log_blocksize: log base 2 of the Merkle tree block size + * + * Note that the block size could be different from the page size, so it is not + * safe to assume that index is a page index. + * + * Returns 0 on success or negative error code on failure + */ +static int btrfs_write_merkle_tree_block(struct inode *inode, const void *buf, + u64 index, int log_blocksize) +{ + u64 off = index << log_blocksize; + u64 len = 1ULL << log_blocksize; + loff_t merkle_pos = merkle_file_pos(inode); + + if (merkle_pos < 0) + return merkle_pos; + if (merkle_pos > inode->i_sb->s_maxbytes - off - len) + return -EFBIG; + + return write_key_bytes(BTRFS_I(inode), BTRFS_VERITY_MERKLE_ITEM_KEY, + off, buf, len); +} + +const struct fsverity_operations btrfs_verityops = { + .begin_enable_verity = btrfs_begin_enable_verity, + .end_enable_verity = btrfs_end_enable_verity, + .get_verity_descriptor = btrfs_get_verity_descriptor, + .read_merkle_tree_page = btrfs_read_merkle_tree_page, + .write_merkle_tree_block = btrfs_write_merkle_tree_block, +}; |