[PATCH v2 01/16] netlink: introduce a dummy netlink attributes parser
JingPiao Chen
chenjingpiao at gmail.com
Sun Jun 18 09:54:05 UTC 2017
On Sun, Jun 18, 2017 at 11:19:50AM +0300, Dmitry V. Levin wrote:
> On Sun, Jun 18, 2017 at 01:18:28PM +0800, JingPiao Chen wrote:
> > * defs.h (decode_nlattr): New prototype.
>
> This is moved to nlattr.h by patch 13/16; why not put it there in the
> first place?
>
> > * linux/unix_diag.h (UNIX_DIAG_*): New enum.
> > * nlattr.c: New file.
> > * Makefile.am (strace_SOURCES): Add it.
> > * netlink_sock_diag.c: Include "xlat/unix_diag_attrs.h".
> > (decode_unix_diag_msg): Use decode_nlattr.
> > * xlat/unix_diag_attrs.in: New file.
> >
> > co-authored-by: Fabien Siron <fabien.siron at epita.fr>
> > ---
> > Makefile.am | 1 +
> > defs.h | 3 ++
> > linux/unix_diag.h | 11 +++-
> > netlink_sock_diag.c | 8 +++
> > nlattr.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++++
> > xlat/unix_diag_attrs.in | 8 +++
> > 6 files changed, 160 insertions(+), 2 deletions(-)
> > create mode 100644 nlattr.c
> > create mode 100644 xlat/unix_diag_attrs.in
> >
> > diff --git a/Makefile.am b/Makefile.am
> > index e22d480..132b5e1 100644
> > --- a/Makefile.am
> > +++ b/Makefile.am
> > @@ -173,6 +173,7 @@ strace_SOURCES = \
> > net.c \
> > netlink.c \
> > netlink_sock_diag.c \
> > + nlattr.c \
> > nsfs.c \
> > nsfs.h \
> > nsig.h \
> > diff --git a/defs.h b/defs.h
> > index 487e51b..19653f3 100644
> > --- a/defs.h
> > +++ b/defs.h
> > @@ -632,6 +632,9 @@ tprint_iov_upto(struct tcb *, kernel_ulong_t len, kernel_ulong_t addr,
> >
> > extern void
> > decode_netlink(struct tcb *, int fd, kernel_ulong_t addr, kernel_ulong_t len);
> > +extern void
> > +decode_nlattr(struct tcb *, kernel_ulong_t addr, kernel_ulong_t len,
> > + const struct xlat *, const char *);
> >
> > extern void tprint_open_modes(unsigned int);
> > extern const char *sprint_open_modes(unsigned int);
> > diff --git a/linux/unix_diag.h b/linux/unix_diag.h
> > index a6b62ba..3c9d99f 100644
> > --- a/linux/unix_diag.h
> > +++ b/linux/unix_diag.h
> > @@ -27,7 +27,14 @@ struct unix_diag_msg {
> > uint32_t udiag_cookie[2];
> > };
> >
> > -#define UNIX_DIAG_NAME 0
> > -#define UNIX_DIAG_PEER 2
> > +enum {
> > + UNIX_DIAG_NAME,
> > + UNIX_DIAG_VFS,
> > + UNIX_DIAG_PEER,
> > + UNIX_DIAG_ICONS,
> > + UNIX_DIAG_RQLEN,
> > + UNIX_DIAG_MEMINFO,
> > + UNIX_DIAG_SHUTDOWN,
> > +};
> >
> > #endif /* !STRACE_LINUX_UNIX_DIAG_H */
> > diff --git a/netlink_sock_diag.c b/netlink_sock_diag.c
> > index 8dbfd07..e515810 100644
> > --- a/netlink_sock_diag.c
> > +++ b/netlink_sock_diag.c
> > @@ -55,6 +55,7 @@
> > # include "xlat/smc_states.h"
> > #endif
> >
> > +#include "xlat/unix_diag_attrs.h"
> > #include "xlat/unix_diag_show.h"
> >
> > static void
> > @@ -135,6 +136,13 @@ decode_unix_diag_msg(struct tcb *const tcp,
> > } else
> > tprints("...");
> > tprints("}");
> > +
> > + if (len > NLA_ALIGN(sizeof(msg))) {
> > + tprints(", ");
> > + decode_nlattr(tcp, addr + NLA_ALIGN(sizeof(msg)),
> > + len - NLA_ALIGN(sizeof(msg)),
> > + unix_diag_attrs, "UNIX_DIAG_???");
> > + }
>
> Please move this to "!umoven_or_printaddr" branch of the "if" statement
> above.
Your expected output is
{udiag_family=AF_UNIX, udiag_type=SOCK_STREAM
, udiag_state=TCP_FIN_WAIT1, udiag_ino=0
, udiag_cookie=[0, 0], {nla=0, nla_type=INET_DIAG_NONE}}
or
{udiag_family=AF_UNIX, udiag_type=SOCK_STREAM
, udiag_state=TCP_FIN_WAIT1, udiag_ino=0
, udiag_cookie=[0, 0]}, {nla=0, nla_type=INET_DIAG_NONE}
second output I using following implementation:
diff --git a/netlink_sock_diag.c b/netlink_sock_diag.c
index 8dbfd07..f92253e 100644
--- a/netlink_sock_diag.c
+++ b/netlink_sock_diag.c
@@ -113,7 +115,8 @@ decode_unix_diag_msg(struct tcb *const tcp,
const kernel_ulong_t len)
{
struct unix_diag_msg msg = { .udiag_family = family };
- const size_t offset = sizeof(msg.udiag_family);
+ size_t offset = sizeof(msg.udiag_family);
+ bool decode_nla = false;
tprints("{udiag_family=");
printxval(addrfams, msg.udiag_family, "AF_???");
@@ -131,10 +134,18 @@ decode_unix_diag_msg(struct tcb *const tcp,
", udiag_cookie=[%" PRIu32 ", %" PRIu32 "]",
msg.udiag_ino,
msg.udiag_cookie[0], msg.udiag_cookie[1]);
+ decode_nla = true;
}
} else
tprints("...");
tprints("}");
+
+ offset = NLMSG_ALIGN(sizeof(msg));
+ if (decode_nla && len > offset) {
+ tprints(", ");
+ decode_nlattr(tcp, addr + offset, len - offset,
+ unix_diag_attrs, "UNIX_DIAG_???");
+ }
}
static void
>
> > }
> >
> > static void
> > diff --git a/nlattr.c b/nlattr.c
> > new file mode 100644
> > index 0000000..827f109
> > --- /dev/null
> > +++ b/nlattr.c
> > @@ -0,0 +1,131 @@
> > +/*
> > + * Copyright (c) 2016 Fabien Siron <fabien.siron at epita.fr>
> > + * Copyright (c) 2017 JingPiao Chen <chenjingpiao at gmail.com>
> > + * Copyright (c) 2016-2017 The strace developers.
> > + * 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 <linux/netlink.h>
> > +
> > +static bool
> > +fetch_nlattr(struct tcb *const tcp, struct nlattr *const nlattr,
> > + const kernel_ulong_t addr, const kernel_ulong_t len)
> > +{
> > + if (len < sizeof(struct nlattr)) {
> > + printstrn(tcp, addr, len);
> > + return false;
> > + }
> > +
> > + if (umove_or_printaddr(tcp, addr, nlattr))
> > + return false;
> > +
> > + return true;
> > +}
> > +
> > +static void
> > +print_nlattr(const struct nlattr *const nla,
> > + const struct xlat *const table,
> > + const char *const dflt)
> > +{
> > + tprintf("{nla_len=%u, nla_type=", nla->nla_len);
> > + if (nla->nla_type & NLA_F_NESTED)
> > + tprints("NLA_F_NESTED|");
> > + if (nla->nla_type & NLA_F_NET_BYTEORDER)
> > + tprints("NLA_F_NET_BYTEORDER|");
> > + printxval(table, nla->nla_type & NLA_TYPE_MASK, dflt);
> > + tprints("}");
> > +}
> > +
> > +static void
> > +decode_nlattr_with_data(struct tcb *tcp,
> > + const struct nlattr *const nla,
> > + kernel_ulong_t addr,
> > + kernel_ulong_t len,
> > + const struct xlat *const table,
> > + const char *const dflt)
> > +{
> > + tprints("{");
> > +
> > + print_nlattr(nla, table, dflt);
> > +
> > + unsigned int nla_len = nla->nla_len > len ? len : nla->nla_len;
> > +
> > + if (nla_len > NLA_HDRLEN) {
> > + tprints(", ");
> > + printstrn(tcp, addr + NLA_HDRLEN, nla_len - NLA_HDRLEN);
> > + }
> > +
> > + tprints("}");
>
> This would result to {{nla_len=%u, nla_type=%s}} in case of (nla_len <= NLA_HDRLEN).
> I suggest printing these extra braces if (nla_len > NLA_HDRLEN) only.
--
JingPiao Chen
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