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Server/driver protocols: no longer allow third-party copies.

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Before safecopies, the IO_ENDPT and DL_ENDPT message fields were needed
to know which actual process to copy data from/to, as that process may
not always be the caller. Now that we have full safecopy support, these
fields have become useless for that purpose: the owner of the grant is
*always* the caller. Allowing the caller to supply another endpoint is
in fact dangerous, because the callee may then end up using a grant
from a third party. One could call this a variant of the confused
deputy problem.

From now on, safecopy calls should always use the caller's endpoint as
grant owner. This fully obsoletes the DL_ENDPT field in the
inet/ethernet protocol. IO_ENDPT has other uses besides identifying the
grant owner though. This patch renames IO_ENDPT to USER_ENDPT, not only
because that is a more fitting name (it should never be used for I/O
after all), but also in order to intentionally break any old system
source code outside the base system. If this patch breaks your code,
fixing it is fairly simple:

- DL_ENDPT should be replaced with m_source;
- IO_ENDPT should be replaced with m_source when used for safecopies;
- IO_ENDPT should be replaced with USER_ENDPT for any other use, e.g.
  when setting REP_ENDPT, matching requests in CANCEL calls, getting
  DEV_SELECT flags, and retrieving of the real user process's endpoint
  in DEV_OPEN.

The changes in this patch are binary backward compatible.
This commit is contained in:
David van Moolenbroek
2011-04-11 17:35:05 +00:00
parent 4e86b0d53f
commit c51cd5fe91
52 changed files with 351 additions and 343 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/fxp/fxp.c
+3 -3
View File
@@ -1093,7 +1093,7 @@ static void fxp_writev_s(const message *mp, int from_int)
assert(!(fp->fxp_flags & FF_SEND_AVAIL));
assert(!(fp->fxp_flags & FF_PACK_SENT));
iov_endpt= mp->DL_ENDPT;
iov_endpt= mp->m_source;
iov_grant= mp->DL_GRANT;
size= 0;
@@ -1228,7 +1228,7 @@ int from_int;
packlen= rfd_res & RFDSZ_SIZE;
iov_endpt = mp->DL_ENDPT;
iov_endpt = mp->m_source;
iov_grant = mp->DL_GRANT;
size= 0;
@@ -1541,7 +1541,7 @@ static void fxp_getstat_s(message *mp)
stats.ets_CDheartbeat= 0;
stats.ets_OWC= fp->fxp_stat.sc_tx_latecol;
r= sys_safecopyto(mp->DL_ENDPT, mp->DL_GRANT, 0, (vir_bytes)&stats,
r= sys_safecopyto(mp->m_source, mp->DL_GRANT, 0, (vir_bytes)&stats,
sizeof(stats), D);
if (r != OK)
panic("fxp_getstat_s: sys_safecopyto failed: %d", r);