fs/verity/read_metadata.c

Source file repositories/reference/linux-study-clean/fs/verity/read_metadata.c

File Facts

System
Linux kernel
Corpus path
fs/verity/read_metadata.c
Extension
.c
Size
5234 bytes
Lines
205
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

if (IS_ERR(page)) {
			err = PTR_ERR(page);
			fsverity_err(inode,
				     "Error %d reading Merkle tree page %lu",
				     err, index);
			break;
		}

		virt = kmap_local_page(page);
		if (copy_to_user(buf, virt + offs_in_page, bytes_to_copy)) {
			kunmap_local(virt);
			put_page(page);
			err = -EFAULT;
			break;
		}
		kunmap_local(virt);
		put_page(page);

		retval += bytes_to_copy;
		buf += bytes_to_copy;
		offset += bytes_to_copy;

		if (fatal_signal_pending(current))  {
			err = -EINTR;
			break;
		}
		cond_resched();
		offs_in_page = 0;
	}
	return retval ? retval : err;
}

/* Copy the requested portion of the buffer to userspace. */
static int fsverity_read_buffer(void __user *dst, u64 offset, int length,
				const void *src, size_t src_length)
{
	if (offset >= src_length)
		return 0;
	src += offset;
	src_length -= offset;

	length = min_t(size_t, length, src_length);

	if (copy_to_user(dst, src, length))
		return -EFAULT;

	return length;
}

static int fsverity_read_descriptor(struct inode *inode,
				    void __user *buf, u64 offset, int length)
{
	struct fsverity_descriptor *desc;
	size_t desc_size;
	int res;

	res = fsverity_get_descriptor(inode, &desc);
	if (res)
		return res;

	/* don't include the builtin signature */
	desc_size = offsetof(struct fsverity_descriptor, signature);
	desc->sig_size = 0;

	res = fsverity_read_buffer(buf, offset, length, desc, desc_size);

	kfree(desc);
	return res;
}

static int fsverity_read_signature(struct inode *inode,
				   void __user *buf, u64 offset, int length)
{
	struct fsverity_descriptor *desc;
	int res;

	res = fsverity_get_descriptor(inode, &desc);
	if (res)
		return res;

	if (desc->sig_size == 0) {
		res = -ENODATA;
		goto out;
	}

	/*
	 * Include only the builtin signature.  fsverity_get_descriptor()
	 * already verified that sig_size is in-bounds.
	 */
	res = fsverity_read_buffer(buf, offset, length, desc->signature,

Annotation

Implementation Notes