[PATCH v3 2/7] Add a general netlink socket parser
Dmitry V. Levin
ldv at altlinux.org
Thu Jun 16 01:36:47 UTC 2016
On Wed, Jun 15, 2016 at 12:43:00PM +0000, Fabien Siron wrote:
> This commit introduces a general socket netlink parser which prints
> the header and a string for the remaining part of the buffer. It doesn't
> handle all the netlink flags and types because the parser needs more
> information. It will be done soon.
>
> * net.c (printsock): Return family.
> (do_msghdr): Call decode_netlink_iov().
> (send, sendto, recv, recvfrom): Call printsockbuf().
> * netlink.c: New file.
> (decode_netlink): New function.
> (_decode_netlink): New static function.
> (decode_iov_netlink): New function.
> * defs.h (decode_netlink, decode_netlink_iov, getfdproto): Add.
> (printsock): Change return type.
> * util.c (getfdproto): Remove the static keyword to the function.
> * Makefile.am (strace_SOURCES): Add netlink.c.
> * xlat/netlink_flags.in: New file.
> * xlat/netlink_types.in: New file.
> ---
> Makefile.am | 1 +
> defs.h | 5 ++-
> net.c | 55 ++++++++++++++++++++++++-------
> netlink.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++
> util.c | 2 +-
> xlat/netlink_flags.in | 6 ++++
> xlat/netlink_types.in | 4 +++
> 7 files changed, 149 insertions(+), 14 deletions(-)
> create mode 100644 netlink.c
> create mode 100644 xlat/netlink_flags.in
> create mode 100644 xlat/netlink_types.in
>
> diff --git a/Makefile.am b/Makefile.am
> index 77e0cc8..ab0e200 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -156,6 +156,7 @@ strace_SOURCES = \
> mtd.c \
> native_defs.h \
> net.c \
> + netlink.c \
> numa.c \
> open.c \
> or1k_atomic.c \
> diff --git a/defs.h b/defs.h
> index ab06921..ee35dab 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -552,6 +552,7 @@ extern const char *signame(const int);
> extern void pathtrace_select(const char *);
> extern int pathtrace_match(struct tcb *);
> extern int getfdpath(struct tcb *, int, char *, unsigned);
> +extern enum sock_proto getfdproto(struct tcb *, int);
>
> extern const char *xlookup(const struct xlat *, const uint64_t);
> extern const char *xlat_search(const struct xlat *, const size_t, const uint64_t);
> @@ -644,7 +645,7 @@ extern void printfd(struct tcb *, int);
> extern bool print_sockaddr_by_inode(const unsigned long, const enum sock_proto);
> extern bool print_sockaddr_by_inode_cached(const unsigned long);
> extern void print_dirfd(struct tcb *, int);
> -extern void printsock(struct tcb *, long, int);
> +extern int printsock(struct tcb *, long, int);
> extern void print_sock_optmgmt(struct tcb *, long, int);
> #ifdef ALPHA
> extern void printrusage32(struct tcb *, long);
> @@ -661,6 +662,8 @@ extern const char *sprintsigmask_n(const char *, const void *, unsigned int);
> extern void printsignal(int);
> extern void tprint_iov(struct tcb *, unsigned long, unsigned long, int decode_iov);
> extern void tprint_iov_upto(struct tcb *, unsigned long, unsigned long, int decode_iov, unsigned long);
> +extern void decode_netlink_iov(struct tcb *, unsigned long, unsigned long, unsigned long);
> +extern void decode_netlink(struct tcb *, unsigned long, unsigned long);
> extern void tprint_open_modes(unsigned int);
> extern const char *sprint_open_modes(unsigned int);
> extern void print_seccomp_filter(struct tcb *, unsigned long);
> diff --git a/net.c b/net.c
> index 8cc97da..b1251f6 100644
> --- a/net.c
> +++ b/net.c
> @@ -276,14 +276,14 @@ print_sockaddr(struct tcb *tcp, const sockaddr_buf_t *addr, const int addrlen)
> tprints("}");
> }
>
> -void
> +int
> printsock(struct tcb *tcp, long addr, int addrlen)
> {
> sockaddr_buf_t addrbuf;
>
> if (addrlen < 2) {
> printaddr(addr);
> - return;
> + return -1;
> }
>
> if (addrlen > (int) sizeof(addrbuf))
> @@ -291,10 +291,30 @@ printsock(struct tcb *tcp, long addr, int addrlen)
>
> memset(&addrbuf, 0, sizeof(addrbuf));
> if (umoven_or_printaddr(tcp, addr, addrlen, addrbuf.pad))
> - return;
> + return -1;
> addrbuf.pad[sizeof(addrbuf.pad) - 1] = '\0';
>
> print_sockaddr(tcp, &addrbuf, addrlen);
> +
> + return addrbuf.sa.sa_family;
> +}
> +
> +static void
> +printsockbuf(struct tcb *tcp, int fd, long addr, long addrlen)
> +{
> + enum sock_proto proto;
> + if (show_fd_path > 1)
> + proto = getfdproto(tcp, fd);
> + else
> + proto = SOCK_PROTO_UNKNOWN;
> +
> + switch (proto) {
There is a shorter alternative:
switch (show_fd_path > 1 ? getfdproto(tcp, fd) : SOCK_PROTO_UNKNOWN) {
> + case SOCK_PROTO_NETLINK:
> + decode_netlink(tcp, addr, addrlen);
> + break;
> + default:
> + printstr(tcp, addr, addrlen);
> + }
> }
>
> #include "xlat/scmvals.h"
> @@ -594,12 +614,20 @@ printcmsghdr(struct tcb *tcp, unsigned long addr, size_t len)
> static void
> do_msghdr(struct tcb *tcp, struct msghdr *msg, unsigned long data_size)
> {
> + int family;
> +
> tprintf("{msg_name(%d)=", msg->msg_namelen);
> - printsock(tcp, (long)msg->msg_name, msg->msg_namelen);
> + family = printsock(tcp, (long)msg->msg_name, msg->msg_namelen);
>
> tprintf(", msg_iov(%lu)=", (unsigned long)msg->msg_iovlen);
> - tprint_iov_upto(tcp, (unsigned long)msg->msg_iovlen,
> - (unsigned long)msg->msg_iov, 1, data_size);
> +#ifdef AF_NETLINK
AF_NETLINK is used unconditionally in socketutils.c,
no need to check its availability.
> + if (family == AF_NETLINK)
> + decode_netlink_iov(tcp, (unsigned long) msg->msg_iovlen,
> + (unsigned long) msg->msg_iov, data_size);
> + else
> +#endif
> + tprint_iov_upto(tcp, (unsigned long)msg->msg_iovlen,
> + (unsigned long)msg->msg_iov, 1, data_size);
>
> #ifdef HAVE_STRUCT_MSGHDR_MSG_CONTROL
> tprintf(", msg_controllen=%lu", (unsigned long)msg->msg_controllen);
> @@ -886,7 +914,7 @@ SYS_FUNC(send)
> {
> printfd(tcp, tcp->u_arg[0]);
> tprints(", ");
> - printstr(tcp, tcp->u_arg[1], tcp->u_arg[2]);
> + printsockbuf(tcp, tcp->u_arg[0], tcp->u_arg[1], tcp->u_arg[2]);
> tprintf(", %lu, ", tcp->u_arg[2]);
> /* flags */
> printflags(msg_flags, tcp->u_arg[3], "MSG_???");
> @@ -898,7 +926,7 @@ SYS_FUNC(sendto)
> {
> printfd(tcp, tcp->u_arg[0]);
> tprints(", ");
> - printstr(tcp, tcp->u_arg[1], tcp->u_arg[2]);
> + printsockbuf(tcp, tcp->u_arg[0], tcp->u_arg[1], tcp->u_arg[2]);
> tprintf(", %lu, ", tcp->u_arg[2]);
> /* flags */
> printflags(msg_flags, tcp->u_arg[3], "MSG_???");
> @@ -947,10 +975,11 @@ SYS_FUNC(recv)
> printfd(tcp, tcp->u_arg[0]);
> tprints(", ");
> } else {
> - if (syserror(tcp))
> + if (syserror(tcp)) {
What's this?
> printaddr(tcp->u_arg[1]);
> - else
> - printstr(tcp, tcp->u_arg[1], tcp->u_rval);
> + } else
> + printsockbuf(tcp, tcp->u_arg[0], tcp->u_arg[1],
> + tcp->u_rval);
>
> tprintf(", %lu, ", tcp->u_arg[2]);
> printflags(msg_flags, tcp->u_arg[3], "MSG_???");
> @@ -966,11 +995,13 @@ SYS_FUNC(recvfrom)
> printfd(tcp, tcp->u_arg[0]);
> tprints(", ");
> } else {
> +
> /* buf */
And this?
> if (syserror(tcp)) {
> printaddr(tcp->u_arg[1]);
> } else {
> - printstr(tcp, tcp->u_arg[1], tcp->u_rval);
> + printsockbuf(tcp, tcp->u_arg[0], tcp->u_arg[1],
> + tcp->u_rval);
> }
> /* len */
> tprintf(", %lu, ", tcp->u_arg[2]);
> diff --git a/netlink.c b/netlink.c
> new file mode 100644
> index 0000000..30116dd
> --- /dev/null
> +++ b/netlink.c
> @@ -0,0 +1,90 @@
> +/*
> + * Copyright (c) 2016 Fabien Siron <fabien.siron at epita.fr>
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + * 3. The name of the author may not be used to endorse or promote products
> + * derived from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include "defs.h"
> +#include <sys/socket.h>
> +#include <linux/netlink.h>
> +#include "xlat/netlink_flags.h"
> +#include "xlat/netlink_types.h"
> +
> +void
> +decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long size)
> +{
> + struct nlmsghdr nlmsghdr;
> +
> + if (size < sizeof(struct nlmsghdr)) {
> + printaddr((unsigned long)addr);
addr is of type unsigned long, no need to cast.
> + return;
> + }
> + if (umove_or_printaddr(tcp, (unsigned long)addr, &nlmsghdr))
> + return;
> + tprintf("{{len=%u, type=", nlmsghdr.nlmsg_len);
> +
> + printxval(netlink_types, nlmsghdr.nlmsg_type, "NLMSG_???");
> +
> + tprints(", flags=");
> + printflags(netlink_flags, nlmsghdr.nlmsg_flags, "NLM_F_???");
> + /* manage get/new requests */
> +
> + tprintf(", seq=%u, pid=%u}", nlmsghdr.nlmsg_seq,
> + nlmsghdr.nlmsg_pid);
> +
> + if (size - sizeof(struct nlmsghdr) > 0) {
> + tprints(", ");
> + printstr(tcp, (unsigned long)addr + sizeof(struct nlmsghdr),
> + size - sizeof(struct nlmsghdr));
> + }
> +
> + tprints("}");
> +}
> +
> +static bool
> +_decode_netlink(struct tcb *tcp, void *elem_buf, size_t elem_size,
names starting with underscore are reserved and shouldn't be used.
> + void *opaque_data) {
> + const unsigned long *iov;
> + unsigned long addr, size;
> +
> + iov = elem_buf;
> +
> + addr = iov[0];
> + size = iov[1];
This won't work properly when sizeof(unsigned long) != elem_size,
see print_iovec for example how to handle this difference.
> +
> + decode_netlink(tcp, addr, size);
See print_iovec for example how to print struct iovec.
> +
> + return true;
> +}
> +
> +void
> +decode_netlink_iov(struct tcb *tcp, unsigned long len, unsigned long addr,
> + unsigned long data_size)
> +{
> + unsigned long iov[2];
> +
> + print_array(tcp, addr, len, iov, current_wordsize * 2,
> + umoven_or_printaddr, _decode_netlink, 0);
> +}
data_size shouldn't be ignored, see tprint_iov_upto for example
how to take it into account.
--
ldv
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