On Thu, Aug 18, 2011 at 12:16:00AM -0600, Andreas Dilger wrote: > On 2011-08-16, at 9:25 PM, "Darrick J. Wong" <djwong@xxxxxxxxxx> wrote: > > - Extended attribute blocks that are stored in the inode table -- the h_magic > > field is written by the kernel, but neither the kernel nor e2fsprogs ever > > actually read this field. The field could be reused to checksum the extra > > space since (as far as I can tell) EAs are the only user of that empty space. > > I haven't had a chance to read the document you wrote, but wanted to comment > on xattrs. There is a hash field for each xattr (including internal xattrs), > and one for the external xattr blocks that can be used to validate the xattr > value. > > In addition to the hash for the in-inode xattrs, the inode hash itself would > serve to validate the xattr values. > > I have a patch for e2fsprogs that checks the xattr hash for in-inode xattrs > (currently it is always 0). I surveyed the h_hash/e_hash calculation code; it only covers the name and value fields. Do we care about checksum protection for the extra fields in struct ext4_xattr_header and struct ext4_xattr_entry? I think it would be useful to be able to check the sanity of h_refcount and h_blocks. Possibly that extends to e_value_* as well, though the hash probably covers it. Also, there's no hardware acceleration available for the xattr hash, though I doubt xattrs are especially performance sensitive. --D > > > Please have a look at the design document and please feel free to suggest any > > changes. > > Hopefully soon. > > Cheers, Andreas-- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
