Don't read if_counters with if_addr_lock held
Calling into an ifnet implementation with the if_addr_lock already held can cause a LOR and potentially a deadlock, as ifnet implementations typically can take the if_addr_lock after their own locks during configuration. Refactor a sysctl handler that was violating this to read if_counter data in a temporary buffer before the if_addr_lock is taken, and then copying the data in its final location later, when the if_addr_lock is held. PR: 194109 Reported by: Jean-Sebastien Pedron MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D8498 Reviewed by: sbruno
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=308580
@ -1566,8 +1566,8 @@ sysctl_dumpentry(struct radix_node *rn, void *vw)
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}
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static int
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sysctl_iflist_ifml(struct ifnet *ifp, struct rt_addrinfo *info,
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struct walkarg *w, int len)
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sysctl_iflist_ifml(struct ifnet *ifp, const struct if_data *src_ifd,
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struct rt_addrinfo *info, struct walkarg *w, int len)
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{
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struct if_msghdrl *ifm;
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struct if_data *ifd;
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@ -1598,14 +1598,14 @@ sysctl_iflist_ifml(struct ifnet *ifp, struct rt_addrinfo *info,
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ifd = &ifm->ifm_data;
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}
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if_data_copy(ifp, ifd);
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memcpy(ifd, src_ifd, sizeof(*ifd));
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return (SYSCTL_OUT(w->w_req, (caddr_t)ifm, len));
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}
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static int
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sysctl_iflist_ifm(struct ifnet *ifp, struct rt_addrinfo *info,
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struct walkarg *w, int len)
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sysctl_iflist_ifm(struct ifnet *ifp, const struct if_data *src_ifd,
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struct rt_addrinfo *info, struct walkarg *w, int len)
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{
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struct if_msghdr *ifm;
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struct if_data *ifd;
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@ -1630,7 +1630,7 @@ sysctl_iflist_ifm(struct ifnet *ifp, struct rt_addrinfo *info,
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ifd = &ifm->ifm_data;
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}
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if_data_copy(ifp, ifd);
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memcpy(ifd, src_ifd, sizeof(*ifd));
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return (SYSCTL_OUT(w->w_req, (caddr_t)ifm, len));
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}
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@ -1705,15 +1705,18 @@ sysctl_iflist(int af, struct walkarg *w)
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{
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struct ifnet *ifp;
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struct ifaddr *ifa;
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struct if_data ifd;
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struct rt_addrinfo info;
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int len, error = 0;
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struct sockaddr_storage ss;
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bzero((caddr_t)&info, sizeof(info));
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bzero(&ifd, sizeof(ifd));
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IFNET_RLOCK_NOSLEEP();
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TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
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if (w->w_arg && w->w_arg != ifp->if_index)
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continue;
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if_data_copy(ifp, &ifd);
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IF_ADDR_RLOCK(ifp);
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ifa = ifp->if_addr;
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info.rti_info[RTAX_IFP] = ifa->ifa_addr;
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@ -1723,9 +1726,11 @@ sysctl_iflist(int af, struct walkarg *w)
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info.rti_info[RTAX_IFP] = NULL;
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if (w->w_req && w->w_tmem) {
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if (w->w_op == NET_RT_IFLISTL)
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error = sysctl_iflist_ifml(ifp, &info, w, len);
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error = sysctl_iflist_ifml(ifp, &ifd, &info, w,
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len);
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else
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error = sysctl_iflist_ifm(ifp, &info, w, len);
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error = sysctl_iflist_ifm(ifp, &ifd, &info, w,
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len);
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if (error)
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goto done;
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}
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