[PATCH v2 01/16] netlink: introduce a dummy netlink attributes parser
Dmitry V. Levin
ldv at altlinux.org
Sun Jun 18 08:19:50 UTC 2017
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.
> }
>
> 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.
--
ldv
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