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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /fs/f2fs/verity.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/f2fs/verity.c')
-rw-r--r--fs/f2fs/verity.c292
1 files changed, 292 insertions, 0 deletions
diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c
new file mode 100644
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+++ b/fs/f2fs/verity.c
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+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/f2fs/verity.c: fs-verity support for f2fs
+ *
+ * Copyright 2019 Google LLC
+ */
+
+/*
+ * Implementation of fsverity_operations for f2fs.
+ *
+ * Like ext4, f2fs stores the verity metadata (Merkle tree and
+ * fsverity_descriptor) past the end of the file, starting at the first 64K
+ * boundary beyond i_size. This approach works because (a) verity files are
+ * readonly, and (b) pages fully beyond i_size aren't visible to userspace but
+ * can be read/written internally by f2fs with only some relatively small
+ * changes to f2fs. Extended attributes cannot be used because (a) f2fs limits
+ * the total size of an inode's xattr entries to 4096 bytes, which wouldn't be
+ * enough for even a single Merkle tree block, and (b) f2fs encryption doesn't
+ * encrypt xattrs, yet the verity metadata *must* be encrypted when the file is
+ * because it contains hashes of the plaintext data.
+ *
+ * Using a 64K boundary rather than a 4K one keeps things ready for
+ * architectures with 64K pages, and it doesn't necessarily waste space on-disk
+ * since there can be a hole between i_size and the start of the Merkle tree.
+ */
+
+#include <linux/f2fs_fs.h>
+
+#include "f2fs.h"
+#include "xattr.h"
+
+#define F2FS_VERIFY_VER (1)
+
+static inline loff_t f2fs_verity_metadata_pos(const struct inode *inode)
+{
+ return round_up(inode->i_size, 65536);
+}
+
+/*
+ * Read some verity metadata from the inode. __vfs_read() can't be used because
+ * we need to read beyond i_size.
+ */
+static int pagecache_read(struct inode *inode, void *buf, size_t count,
+ loff_t pos)
+{
+ while (count) {
+ size_t n = min_t(size_t, count,
+ PAGE_SIZE - offset_in_page(pos));
+ struct page *page;
+
+ page = read_mapping_page(inode->i_mapping, pos >> PAGE_SHIFT,
+ NULL);
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ memcpy_from_page(buf, page, offset_in_page(pos), n);
+
+ put_page(page);
+
+ buf += n;
+ pos += n;
+ count -= n;
+ }
+ return 0;
+}
+
+/*
+ * Write some verity metadata to the inode for FS_IOC_ENABLE_VERITY.
+ * kernel_write() can't be used because the file descriptor is readonly.
+ */
+static int pagecache_write(struct inode *inode, const void *buf, size_t count,
+ loff_t pos)
+{
+ struct address_space *mapping = inode->i_mapping;
+ const struct address_space_operations *aops = mapping->a_ops;
+
+ if (pos + count > inode->i_sb->s_maxbytes)
+ return -EFBIG;
+
+ while (count) {
+ size_t n = min_t(size_t, count,
+ PAGE_SIZE - offset_in_page(pos));
+ struct page *page;
+ void *fsdata = NULL;
+ int res;
+
+ res = aops->write_begin(NULL, mapping, pos, n, &page, &fsdata);
+ if (res)
+ return res;
+
+ memcpy_to_page(page, offset_in_page(pos), buf, n);
+
+ res = aops->write_end(NULL, mapping, pos, n, n, page, fsdata);
+ if (res < 0)
+ return res;
+ if (res != n)
+ return -EIO;
+
+ buf += n;
+ pos += n;
+ count -= n;
+ }
+ return 0;
+}
+
+/*
+ * Format of f2fs verity xattr. This points to the location of the verity
+ * descriptor within the file data rather than containing it directly because
+ * the verity descriptor *must* be encrypted when f2fs encryption is used. But,
+ * f2fs encryption does not encrypt xattrs.
+ */
+struct fsverity_descriptor_location {
+ __le32 version;
+ __le32 size;
+ __le64 pos;
+};
+
+static int f2fs_begin_enable_verity(struct file *filp)
+{
+ struct inode *inode = file_inode(filp);
+ int err;
+
+ if (f2fs_verity_in_progress(inode))
+ return -EBUSY;
+
+ if (f2fs_is_atomic_file(inode))
+ return -EOPNOTSUPP;
+
+ /*
+ * Since the file was opened readonly, we have to initialize the quotas
+ * here and not rely on ->open() doing it. This must be done before
+ * evicting the inline data.
+ */
+ err = f2fs_dquot_initialize(inode);
+ if (err)
+ return err;
+
+ err = f2fs_convert_inline_inode(inode);
+ if (err)
+ return err;
+
+ set_inode_flag(inode, FI_VERITY_IN_PROGRESS);
+ return 0;
+}
+
+static int f2fs_end_enable_verity(struct file *filp, const void *desc,
+ size_t desc_size, u64 merkle_tree_size)
+{
+ struct inode *inode = file_inode(filp);
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ u64 desc_pos = f2fs_verity_metadata_pos(inode) + merkle_tree_size;
+ struct fsverity_descriptor_location dloc = {
+ .version = cpu_to_le32(F2FS_VERIFY_VER),
+ .size = cpu_to_le32(desc_size),
+ .pos = cpu_to_le64(desc_pos),
+ };
+ int err = 0, err2 = 0;
+
+ /*
+ * If an error already occurred (which fs/verity/ signals by passing
+ * desc == NULL), then only clean-up is needed.
+ */
+ if (desc == NULL)
+ goto cleanup;
+
+ /* Append the verity descriptor. */
+ err = pagecache_write(inode, desc, desc_size, desc_pos);
+ if (err)
+ goto cleanup;
+
+ /*
+ * Write all pages (both data and verity metadata). Note that this must
+ * happen before clearing FI_VERITY_IN_PROGRESS; otherwise pages beyond
+ * i_size won't be written properly. For crash consistency, this also
+ * must happen before the verity inode flag gets persisted.
+ */
+ err = filemap_write_and_wait(inode->i_mapping);
+ if (err)
+ goto cleanup;
+
+ /* Set the verity xattr. */
+ err = f2fs_setxattr(inode, F2FS_XATTR_INDEX_VERITY,
+ F2FS_XATTR_NAME_VERITY, &dloc, sizeof(dloc),
+ NULL, XATTR_CREATE);
+ if (err)
+ goto cleanup;
+
+ /* Finally, set the verity inode flag. */
+ file_set_verity(inode);
+ f2fs_set_inode_flags(inode);
+ f2fs_mark_inode_dirty_sync(inode, true);
+
+ clear_inode_flag(inode, FI_VERITY_IN_PROGRESS);
+ return 0;
+
+cleanup:
+ /*
+ * Verity failed to be enabled, so clean up by truncating any verity
+ * metadata that was written beyond i_size (both from cache and from
+ * disk) and clearing FI_VERITY_IN_PROGRESS.
+ *
+ * Taking i_gc_rwsem[WRITE] is needed to stop f2fs garbage collection
+ * from re-instantiating cached pages we are truncating (since unlike
+ * normal file accesses, garbage collection isn't limited by i_size).
+ */
+ f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+ truncate_inode_pages(inode->i_mapping, inode->i_size);
+ err2 = f2fs_truncate(inode);
+ if (err2) {
+ f2fs_err(sbi, "Truncating verity metadata failed (errno=%d)",
+ err2);
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ }
+ f2fs_up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+ clear_inode_flag(inode, FI_VERITY_IN_PROGRESS);
+ return err ?: err2;
+}
+
+static int f2fs_get_verity_descriptor(struct inode *inode, void *buf,
+ size_t buf_size)
+{
+ struct fsverity_descriptor_location dloc;
+ int res;
+ u32 size;
+ u64 pos;
+
+ /* Get the descriptor location */
+ res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_VERITY,
+ F2FS_XATTR_NAME_VERITY, &dloc, sizeof(dloc), NULL);
+ if (res < 0 && res != -ERANGE)
+ return res;
+ if (res != sizeof(dloc) || dloc.version != cpu_to_le32(F2FS_VERIFY_VER)) {
+ f2fs_warn(F2FS_I_SB(inode), "unknown verity xattr format");
+ return -EINVAL;
+ }
+ size = le32_to_cpu(dloc.size);
+ pos = le64_to_cpu(dloc.pos);
+
+ /* Get the descriptor */
+ if (pos + size < pos || pos + size > inode->i_sb->s_maxbytes ||
+ pos < f2fs_verity_metadata_pos(inode) || size > INT_MAX) {
+ f2fs_warn(F2FS_I_SB(inode), "invalid verity xattr");
+ f2fs_handle_error(F2FS_I_SB(inode),
+ ERROR_CORRUPTED_VERITY_XATTR);
+ return -EFSCORRUPTED;
+ }
+ if (buf_size) {
+ if (size > buf_size)
+ return -ERANGE;
+ res = pagecache_read(inode, buf, size, pos);
+ if (res)
+ return res;
+ }
+ return size;
+}
+
+static struct page *f2fs_read_merkle_tree_page(struct inode *inode,
+ pgoff_t index,
+ unsigned long num_ra_pages)
+{
+ struct page *page;
+
+ index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT;
+
+ page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED);
+ if (!page || !PageUptodate(page)) {
+ DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index);
+
+ if (page)
+ put_page(page);
+ else if (num_ra_pages > 1)
+ page_cache_ra_unbounded(&ractl, num_ra_pages, 0);
+ page = read_mapping_page(inode->i_mapping, index, NULL);
+ }
+ return page;
+}
+
+static int f2fs_write_merkle_tree_block(struct inode *inode, const void *buf,
+ u64 pos, unsigned int size)
+{
+ pos += f2fs_verity_metadata_pos(inode);
+
+ return pagecache_write(inode, buf, size, pos);
+}
+
+const struct fsverity_operations f2fs_verityops = {
+ .begin_enable_verity = f2fs_begin_enable_verity,
+ .end_enable_verity = f2fs_end_enable_verity,
+ .get_verity_descriptor = f2fs_get_verity_descriptor,
+ .read_merkle_tree_page = f2fs_read_merkle_tree_page,
+ .write_merkle_tree_block = f2fs_write_merkle_tree_block,
+};