Andreas Henriksson wrote:
On ons, 2008-07-16 at 15:53 -0700, Stephen Hemminger wrote:
The netlink message in question is marked as type ERROR but the errno
encoded in the message is zero.
if (h->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
if (l < sizeof(struct nlmsgerr)) {
fprintf(stderr, "ERROR truncated\n");
} else {
errno = -err->error;
if (errno == 0) {
if (answer)
memcpy(answer, h, h->nlmsg_len);
return 0;
}
perror("RTNETLINK answers");
}
So the netlink library just treats as a successful return.
Why? This seems like a really bad idea to me, and none of the callers in
iproute benefits from this as far as I can see.
Just ripping out the errno == 0 special casing looks like and option to
me, unless anyone can find a reason for it.
NLMSG_ERROR with errno == 0 is a netlink ACK message.
(It'll give an error message and an error exit code! The message will be
strange, but lets blame the kernel for that cosmetic issue. Atleast the
user got some kind of notification.)
Moving the "return 0;" inside the "if (answer)" would be another
(atleast for iproutes callers of the library functions)...
To me it looks like the problem is in the kernel sending back
a NLMSG_ERROR with errno of zero. Some code path isn't setting
it up properly.
None the less, it would be be good if the application wouldn't poop it's
pants when it can be avoided - broken kernel or not.
The fix in this case is to propagate the return value from
dev_change_flags().
rtnetlink: propagate error from dev_change_flags in do_setlink()
Andreas Henriksson <[EMAIL PROTECTED]> reported that unlike ifconfig,
iproute doesn't report an error when setting an interface up fails.
Propagate the return value from dev_change_flags() to fix this.
Signed-off-by: Patrick McHardy <[EMAIL PROTECTED]>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a9a7721..ffde766 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -867,7 +867,9 @@ static int do_setlink(struct net_device *dev, struct
ifinfomsg *ifm,
if (ifm->ifi_change)
flags = (flags & ifm->ifi_change) |
(dev->flags & ~ifm->ifi_change);
- dev_change_flags(dev, flags);
+ err = dev_change_flags(dev, flags);
+ if (err < 0)
+ goto errout;
}
if (tb[IFLA_TXQLEN])
