[PATCH v2] netlink: decode libudev netlink header
Chen Jingpiao
chenjingpiao at gmail.com
Sat Jan 6 04:12:33 UTC 2018
On Fri, 5 Jan 2018 20:49:28 +0530 Harsha Sharma wrote:
> * netlink.c: decode family NETLINK_KOBJECT_UEVENT
> * netlink_kobject_uevent.h: New struct (udev_monitor_netlink_header)
> * netlink_kobject_uevent.c: New file
> * Makefile.am (strace_SOURCES): Add it
> * defs.h: Add decode_netlink_kobject_uevent func
We are prefer:
* defs.h (decode_netlink_kobject_uevent): ...
* netlink.c (decode_netlink): ...
* netlink_kobject_uevent.h: New file.
* netlink_kobject_uevent.c: Likewise.
* Makefile.am (strace_SOURCES): Add them.
>
> Changes in v2:
> * New file netlink_kobject_uevent.c
> * change location of netlink_kobject_uevent.h
> * add comments in netlink_kobject_uevent.h
> * add new files in Makefile.am
> * add func decode_netlink_kobject_uevent in defs.h
> * Use macros from print_fields.h instead of tprintf
> * minor changes in decode_netlink_kobject_uevent (including name)
Move patch changelog ...
>
> Signed-off-by: Harsha Sharma <harshasharmaiitr at gmail.com>
> ---
... here.
> Makefile.am | 2 ++
> defs.h | 3 +++
> netlink.c | 2 +-
> netlink_kobject_uevent.c | 58
++++++++++++++++++++++++++++++++++++++++++++++++
> netlink_kobject_uevent.h | 29 ++++++++++++++++++++++++
> 5 files changed, 93 insertions(+), 1 deletion(-)
> create mode 100644 netlink_kobject_uevent.c
> create mode 100644 netlink_kobject_uevent.h
>
> diff --git a/Makefile.am b/Makefile.am
> index 34da3372..9dace776 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -194,6 +194,8 @@ strace_SOURCES = \
> netlink.c \
> netlink.h \
> netlink_crypto.c \
> + netlink_kobject_uevent.c \
> + netlink_kobject_uevent.h \
> netlink_sock_diag.h \
> netlink_inet_diag.c \
> netlink_netlink_diag.c \
> diff --git a/defs.h b/defs.h
> index bd4267b3..98d04dd5 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -687,6 +687,9 @@ DECL_NETLINK(route);
> DECL_NETLINK(selinux);
> DECL_NETLINK(sock_diag);
>
> +extern void
> +decode_netlink_kobject_uevent(struct tcb *, kernel_ulong_t addr,
> + kernel_ulong_t len, const void *);
> extern int tv_nz(const struct timeval *);
> extern int tv_cmp(const struct timeval *, const struct timeval *);
> extern double tv_float(const struct timeval *);
> diff --git a/netlink.c b/netlink.c
> index 6b9a1f5c..e62e37d9 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -628,7 +628,7 @@ decode_netlink(struct tcb *const tcp,
> const int family = get_fd_nl_family(tcp, fd);
>
> if (family == NETLINK_KOBJECT_UEVENT) {
> - printstrn(tcp, addr, len);
> + decode_netlink_kobject_uevent(tcp, addr, len, NULL);
The last argument is useless.
> return;
> }
>
> diff --git a/netlink_kobject_uevent.c b/netlink_kobject_uevent.c
> new file mode 100644
> index 00000000..5b0e018d
> --- /dev/null
> +++ b/netlink_kobject_uevent.c
> @@ -0,0 +1,58 @@
> +/*
> + * Copyright (c) 2018 Harsha Sharma <harshasharmaiittr at gmail.com>
> + * Copyright (c) 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 "netlink.h"
No need include "netlink.h".
> +#include "print_fields.h"
> +#include "netlink_kobject_uevent.h"
> +
> +
To more empty line.
> +void
> +decode_netlink_kobject_uevent(struct tcb *tcp, kernel_ulong_t addr,
> + kernel_ulong_t len,
> + const void *const opaque_data)
> +{
> + struct udev_monitor_netlink_header uh;
> + const char *prefix = "libudev";
> +
> + if (!umove_or_printaddr(tcp, addr, &uh) &&
> + strcmp(uh.prefix, prefix) == 0) {
> + PRINT_FIELD_CSTRING("{", uh, prefix);
> + PRINT_FIELD_U(", ", uh, magic);
> + PRINT_FIELD_U(", ", uh, header_size);
> + PRINT_FIELD_U(", ", uh, properties_off);
> + PRINT_FIELD_U(", ", uh, properties_len);
> + PRINT_FIELD_U(", ", uh, filter_subsystem_hash);
> + PRINT_FIELD_U(", ", uh, filter_devtype_hash);
> + PRINT_FIELD_U(", ", uh, filter_tag_bloom_hi);
> + PRINT_FIELD_U(", ", uh, filter_tag_bloom_lo);
> + tprints("}");
Do not ignore the messages after the header.
> + } else {
> + printstrn(tcp, addr, len);
> + }
> +}
> diff --git a/netlink_kobject_uevent.h b/netlink_kobject_uevent.h
> new file mode 100644
> index 00000000..8b7c5970
> --- /dev/null
> +++ b/netlink_kobject_uevent.h
> @@ -0,0 +1,29 @@
> +#ifndef STRACE_NETLINK_KOBJECT_UEVENT_H
> +#define STRACE_NETLINK_KOBJECT_UEVENT_H
> +
> +struct udev_monitor_netlink_header {
> + /* "libudev" prefix to distinguish libudev and kernel messages */
> + char prefix[8];
> + /*
> + * magic to protect against daemon <-> library message format mismatch
> + * used in the kernel from socket filter rules;
> + * needs to be stored in network order
> + */
> + unsigned int magic;
> + /* total length of header structure known to the sender */
> + unsigned int header_size;
> + /* properties string buffer */
> + unsigned int properties_off;
> + unsigned int properties_len;
> + /*
> + * hashes of primary device properties strings,
> + * to let libudev subscribers use in-kernel socket filters;
> + * values need to be stored in network order
> + */
> + unsigned int filter_subsystem_hash;
> + unsigned int filter_devtype_hash;
> + unsigned int filter_tag_bloom_hi;
> + unsigned int filter_tag_bloom_lo;
> +};
I think only the comment of "prefix" is useful.
> +
> +#endif /* !STRACE_NETLINK_KOBJECT_UEVENT_H */
> --
> 2.11.0
Without a test.
--
Chen Jingpiao
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