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vos: convertROtoRW susceptible to VLDB changes during override prompt

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vos convertROtoRW obtains a VLDB entry, then peforms some setup logic
(including a possible user prompt) before obtaining a volume lock.
This exposes the code to possible time-of-check/time-of-use issues.
After obtaining the volume lock, get a second copy of the VLDB entry
and compare it to the first copy; if it has changed, fail the conversion
with an error message asking the user to re-issue the vos convertROtoRW
command.

Change-Id: I9c1a634cea2e22188869d54b00b7831aed12b1cd
Reviewed-on: http://gerrit.openafs.org/8008
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
This commit is contained in:
Mark Vitale 2012-08-20 17:39:06 -04:00 committed by Derrick Brashear
parent 185699e631
commit 3c489db558
1 changed files with 26 additions and 2 deletions
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28
src/volser/vos.c
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@ -5497,7 +5497,7 @@ ConvertRO(struct cmd_syndesc *as, void *arock)
afs_uint32 volid;
afs_uint32 server;
afs_int32 code, i, same;
struct nvldbentry entry, storeEntry;
struct nvldbentry entry, checkEntry, storeEntry;
afs_int32 vcode;
afs_int32 rwindex = 0;
afs_uint32 rwserver = 0;
@ -5542,6 +5542,7 @@ ConvertRO(struct cmd_syndesc *as, void *arock)
if (as->parms[3].items)
force = 1;
memset(&entry, 0, sizeof(entry));
vcode = VLDB_GetEntryByID(volid, -1, &entry);
if (vcode) {
fprintf(STDERR,
@ -5552,7 +5553,6 @@ ConvertRO(struct cmd_syndesc *as, void *arock)
}
/* use RO volid even if user specified RW or BK volid */
if (volid != entry.volumeId[ROVOL])
volid = entry.volumeId[ROVOL];
@ -5617,6 +5617,30 @@ ConvertRO(struct cmd_syndesc *as, void *arock)
PrintError("", vcode);
return -1;
}
/* make sure the VLDB entry hasn't changed since we started */
memset(&checkEntry, 0, sizeof(checkEntry));
vcode = VLDB_GetEntryByID(volid, -1, &checkEntry);
if (vcode) {
fprintf(STDERR,
"Could not fetch the entry for volume %lu from VLDB\n",
(unsigned long)volid);
PrintError("convertROtoRW ", vcode);
code = vcode;
goto error_exit;
}
MapHostToNetwork(&checkEntry);
entry.flags &= ~VLOP_ALLOPERS; /* clear any stale lock operation flags */
entry.flags |= VLOP_MOVE; /* set to match SetLock operation above */
if (memcmp(&entry, &checkEntry, sizeof(entry)) != 0) {
fprintf(STDERR,
"VLDB entry for volume %lu has changed; please reissue the command.\n",
(unsigned long)volid);
code = -1;
goto error_exit;
}
aconn = UV_Bind(server, AFSCONF_VOLUMEPORT);
code = AFSVolConvertROtoRWvolume(aconn, partition, volid);
if (code) {