o5r/plan9port
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

use deterministic handles

Browse source
This commit is contained in:
rsc 2006-06-15 06:25:21 +00:00
parent fa5af68711
commit 6884e49f0c
1 changed files with 15 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

28
src/cmd/vbackup/vnfs.c
View file

@ -207,12 +207,16 @@ unittoull(char *s)
*
* The decrypted handles begin with the following header:
*
* rand[12] random bytes used to make encryption non-deterministic
* len[4] length of handle that follows
* sessid[8] random session id chosen at start time
* len[4] length of handle that follows
*
* If we're pressed for space in the rest of the handle, we could
* probably reduce the amount of randomness.
* probably reduce the amount of sessid bytes. Note that the sessid
* bytes must be consistent during a run of vnfs, or else some
* clients (e.g., Linux 2.4) eventually notice that successive TLookups
* return different handles, and they return "Stale NFS file handle"
* errors to system calls in response (even though we never sent
* that error!).
*
* Security woes aside, the fact that we have to shove everything
* into the handles is quite annoying. We have to encode, in 40 bytes:
@ -231,9 +235,8 @@ unittoull(char *s)
enum
{
RandSize = 16,
SessidSize = 8,
HeaderSize = RandSize+SessidSize,
HeaderSize = SessidSize+4,
MaxHandleSize = Nfs3MaxHandleSize - HeaderSize
};
@ -269,16 +272,13 @@ hencrypt(Nfs3Handle *h)
p = h->h;
memmove(p+HeaderSize, p, h->len);
*(u32int*)p = fastrand();
*(u32int*)(p+4) = fastrand();
*(u32int*)(p+8) = fastrand();
*(u32int*)(p+12) = h->len;
memmove(p+16, sessid, SessidSize);
memmove(p, sessid, SessidSize);
*(u32int*)(p+SessidSize) = h->len;
h->len += HeaderSize;
if(encryptedhandles){
while(h->len < MaxHandleSize)
h->h[h->len++] = fastrand();
h->h[h->len++] = 0;
aes = aesstate;
aesCBCencrypt(h->h, MaxHandleSize, &aes);
}
@ -305,9 +305,11 @@ hdecrypt(Nfs3Handle *h)
aes = aesstate;
aesCBCdecrypt(h->h, h->len, &aes);
}
if(memcmp(h->h+RandSize, sessid, sizeof sessid) != 0)
if(memcmp(h->h, sessid, SessidSize) != 0)
return Nfs3ErrStale; /* give benefit of doubt */
h->len = *(u32int*)(h->h+12); /* XXX byte order */
h->len = *(u32int*)(h->h+SessidSize);
if(h->len >= MaxHandleSize-HeaderSize)
return Nfs3ErrBadHandle;
memmove(h->h, h->h+HeaderSize, h->len);
return Nfs3Ok;
}