On Mon, Sep 11, 2023 at 02:49:46PM +0200, Lorenzo Bianconi wrote:
> Introduce rpc_status netlink support for NFSD in order to dump pending
> RPC requests debugging information from userspace.
>
> Tested-by: Jeff Layton <jlayton@xxxxxxxxxx>
> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
o
Hi Lorenzo,
some minor feedback from my side.
...
> int nfsd_server_nl_rpc_status_get_dumpit(struct sk_buff *skb,
> struct netlink_callback *cb)
> {
> + struct nfsd_net *nn = net_generic(sock_net(skb->sk), nfsd_net_id);
> + int i, ret, rqstp_index;
> +
> + rcu_read_lock();
> +
> + for (i = 0; i < nn->nfsd_serv->sv_nrpools; i++) {
> + struct svc_rqst *rqstp;
> +
> + if (i < cb->args[0]) /* already consumed */
> + continue;
> +
> + rqstp_index = 0;
> + list_for_each_entry_rcu(rqstp,
> + &nn->nfsd_serv->sv_pools[i].sp_all_threads,
> + rq_all) {
> + struct nfsd_genl_rqstp genl_rqstp;
> + unsigned int status_counter;
> +
> + if (rqstp_index++ < cb->args[1]) /* already consumed */
> + continue;
> + /*
> + * Acquire rq_status_counter before parsing the rqst
> + * fields. rq_status_counter is set to an odd value in
> + * order to notify the consumers the rqstp fields are
> + * meaningful.
> + */
> + status_counter =
> + smp_load_acquire(&rqstp->rq_status_counter);
> + if (!(status_counter & 1))
> + continue;
> +
> + genl_rqstp.rq_xid = rqstp->rq_xid;
> + genl_rqstp.rq_flags = rqstp->rq_flags;
> + genl_rqstp.rq_vers = rqstp->rq_vers;
> + genl_rqstp.rq_prog = rqstp->rq_prog;
> + genl_rqstp.rq_proc = rqstp->rq_proc;
> + genl_rqstp.rq_stime = rqstp->rq_stime;
> + genl_rqstp.opcnt = 0;
> + memcpy(&genl_rqstp.daddr, svc_daddr(rqstp),
> + sizeof(struct sockaddr));
> + memcpy(&genl_rqstp.saddr, svc_addr(rqstp),
> + sizeof(struct sockaddr));
> +
> +#ifdef CONFIG_NFSD_V4
> + if (rqstp->rq_vers == NFS4_VERSION &&
> + rqstp->rq_proc == NFSPROC4_COMPOUND) {
> + /* NFSv4 compund */
nit: compound
> + struct nfsd4_compoundargs *args;
> + int j;
> +
> + args = rqstp->rq_argp;
> + genl_rqstp.opcnt = args->opcnt;
> + for (j = 0; j < genl_rqstp.opcnt; j++)
> + genl_rqstp.opnum[j] =
> + args->ops[j].opnum;
> + }
> +#endif /* CONFIG_NFSD_V4 */
> +
> + /*
> + * Acquire rq_status_counter before reporting the rqst
> + * fields to the user.
> + */
> + if (smp_load_acquire(&rqstp->rq_status_counter) !=
> + status_counter)
> + continue;
> +
> + ret = nfsd_genl_rpc_status_compose_msg(skb, cb,
> + &genl_rqstp);
> + if (ret)
> + goto out;
> + }
> + }
> +
> + cb->args[0] = i;
> + cb->args[1] = rqstp_index;
I'm unsure if this is possible, but if the for loop above iterates zero
times, or for all iterations (i < cb->args[0]), then rqstp_index will
be used uninitialised here.
Flagged by Smatch.
> + ret = skb->len;
> +out:
> + rcu_read_unlock();
> +
> + return ret;
> +}
...
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 11c14faa6c67..d787bd38c053 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -62,6 +62,22 @@ struct readdir_cd {
> __be32 err; /* 0, nfserr, or nfserr_eof */
> };
>
> +/* Maximum number of operations per session compound */
> +#define NFSD_MAX_OPS_PER_COMPOUND 50
> +
> +struct nfsd_genl_rqstp {
> + struct sockaddr daddr;
> + struct sockaddr saddr;
> + unsigned long rq_flags;
> + ktime_t rq_stime;
> + __be32 rq_xid;
> + u32 rq_vers;
> + u32 rq_prog;
> + u32 rq_proc;
> + /* NFSv4 compund */
nit: compound
> + u32 opnum[NFSD_MAX_OPS_PER_COMPOUND];
> + u16 opcnt;
> +};
>
> extern struct svc_program nfsd_program;
> extern const struct svc_version nfsd_version2, nfsd_version3, nfsd_version4;
...
