[PATCH v5] netlink: decode libudev netlink header
Dmitry V. Levin
ldv at altlinux.org
Mon Feb 26 02:10:13 UTC 2018
On Wed, Jan 31, 2018 at 11:32:45PM +0530, Harsha Sharma wrote:
> * defs.h (decode_netlink_kobject_uevent): New prototype.
> * netlink.c (decode_netlink): Decode family kobject_uevent.
> * netlink_kobject_uevent.h: New file.
> * netlink_object_uevent.c: New file.
> * Makefile.am (strace_SOURCES): Add them.
>
> Signed-off-by: Harsha Sharma <harshasharmaiitr at gmail.com>
> ---
> Changes in v5:
> * print filter_* fields in hex
> * print messages after header in correct way
>
> Changes in v4:
> * Minor changes in decode_netlink_kobject_uevent
>
> Changes in v3:
> * Change changelog
> * minor changes in decode_netlink_kobject_uevent
> * omit irrelevant comments in netlink_kobject_uevent.h
>
> 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)
>
> Makefile.am | 2 ++
> defs.h | 3 +++
> netlink.c | 2 +-
> netlink_kobject_uevent.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++
> netlink_kobject_uevent.h | 17 ++++++++++++
> 5 files changed, 90 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 065ab819..20f97b06 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -197,6 +197,8 @@ 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 bbe0ecc9..d80ebc47 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -685,6 +685,9 @@ 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);
> 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 beb6ea4a..a714d29a 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -629,7 +629,7 @@ 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);
> return;
> }
>
> diff --git a/netlink_kobject_uevent.c b/netlink_kobject_uevent.c
> new file mode 100644
> index 00000000..1ff7bd63
> --- /dev/null
> +++ b/netlink_kobject_uevent.c
> @@ -0,0 +1,67 @@
> +/*
> + * Copyright (c) 2018 Harsha Sharma <harshasharmaiitr 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 "print_fields.h"
> +#include "netlink_kobject_uevent.h"
> +
> +#include <arpa/inet.h>
> +
> +void
> +decode_netlink_kobject_uevent(struct tcb *tcp, kernel_ulong_t addr,
> + kernel_ulong_t len)
> +{
> + struct udev_monitor_netlink_header uh;
> + const char *prefix = "libudev";
> +
> + if (len < sizeof(uh)) {
> + printstrn(tcp, addr, len);
> + } else if (!umove_or_printaddr(tcp, addr, &uh)) {
> + if (strcmp(uh.prefix, prefix) == 0) {
> + PRINT_FIELD_CSTRING("{{", uh, prefix);
> + tprintf(", magic=htonl(%#x)", ntohl(uh.magic));
> + PRINT_FIELD_U(", ", uh, header_size);
> + PRINT_FIELD_U(", ", uh, properties_off);
> + PRINT_FIELD_U(", ", uh, properties_len);
> + tprintf(", filter_subsystem_hash=htonl(%#x)", ntohl(uh.filter_subsystem_hash));
> + tprintf(", filter_devtype_hash=htonl(%#x)", ntohl(uh.filter_devtype_hash));
> + tprintf(", filter_tag_bloom_hi=htonl(%#x)", ntohl(uh.filter_tag_bloom_hi));
> + tprintf(", filter_tag_bloom_lo=htonl(%#x)", ntohl(uh.filter_tag_bloom_lo));
> + tprints("}");
> + const size_t offset = CMSG_ALIGN(sizeof(uh));
> + if (len > offset) {
> + tprints(", ");
> + printstrn(tcp, addr + offset , len - offset);
> + }
Are you sure the use of CMSG_ALIGN is correct here?
It aligns on size_t boundary which is strange here given that
sizeof(size_t) is architecture-dependent while netlink packets should not be,
otherwise 32-bit clients won't be able to handle netlink packets sent by
a 64-bit kernel.
--
ldv
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