On Sun, Jun 11, 2017 at 04:42:30PM +0900, Masatake YAMATO wrote: > * socketutils.c (genl_families_xlat): exported function for building > the xlat table. Include linux/genetlink.h. > > * defs.h (genl_families_xlat): add the declaration. > (genl_send_dump_families, genl_parse_families_response): > helper functions. > > Signed-off-by: Masatake YAMATO <yam...@redhat.com> > --- > defs.h | 3 ++ > socketutils.c | 98 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 101 insertions(+) > > diff --git a/defs.h b/defs.h > index 05958fd..eca8058 100644 > --- a/defs.h > +++ b/defs.h > @@ -1025,4 +1025,7 @@ struct dyxlat *dyxlat_new(int allocation); > void dyxlat_delete(struct dyxlat *dyxlat); > struct xlat *dyxlat_get(struct dyxlat *dyxlat); > void dyxlat_may_add_pair(struct dyxlat *dyxlat, uint64_t val, const char > *str); > + > +struct xlat *genl_families_xlat(void); > + > #endif /* !STRACE_DEFS_H */ > diff --git a/socketutils.c b/socketutils.c > index 1e83f87..883fe8b 100644 > --- a/socketutils.c > +++ b/socketutils.c > @@ -37,6 +37,7 @@ > #include <linux/unix_diag.h> > #include <linux/netlink_diag.h> > #include <linux/rtnetlink.h> > +#include <linux/genetlink.h>
<linux/genetlink.h> was introduced in linux 2.6.15, should we add
a configure check?
>
> #include <sys/un.h>
> #ifndef UNIX_PATH_MAX
> @@ -541,3 +542,100 @@ print_sockaddr_by_inode(struct tcb *const tcp, const
> int fd,
> return print_sockaddr_by_inode_cached(inode) ? true :
> print_sockaddr_by_inode_uncached(inode, getfdproto(tcp, fd));
> }
> +
> +/*
> + * Managing the cache for decoding communications of Netlink GENERIC protocol
> + *
> + * As name shown Netlink GENERIC protocol is generic protocol. The
> + * numbers of msg types used in the protocol are not defined
> + * statically. Kernel defines them on demand. So the xlat converted
> + * from header files doesn't help for decoding the protocol. Following
> + * codes are building xlat(dyxlat) at runtime.
> + */
> +static bool
> +genl_send_dump_families(const int fd)
> +{
> + struct {
> + const struct nlmsghdr nlh;
> + struct genlmsghdr gnlh;
> + } req = {
> + .nlh = {
> + .nlmsg_len = sizeof(req),
> + .nlmsg_type = GENL_ID_CTRL,
> + .nlmsg_flags = NLM_F_DUMP|NLM_F_REQUEST|NLM_F_ACK,
Is NLM_F_ACK needed here?
> + },
> + .gnlh = {
> + .cmd = CTRL_CMD_GETFAMILY,
> + }
> + };
> + return send_query(fd, &req, sizeof(req));
> +}
> +
> +static int
> +genl_parse_families_response(const void *const data,
> + const int data_len, const unsigned long inode,
> + void *user_data)
> +{
> + struct dyxlat *dyxlat = user_data;
> + const struct genlmsghdr * const gnlh = data;
> + struct rtattr *attr;
> + int rta_len = data_len - NLMSG_LENGTH(sizeof(*gnlh));
> +
> + char *name = NULL;
> + uint16_t id = 0;
> + bool id_set = false;
> +
> + if (rta_len < 0)
> + return -1;
> + if (gnlh->cmd != CTRL_CMD_NEWFAMILY)
> + return -1;
> + if (gnlh->version != 2)
> + return -1;
> +
> + for (attr = (struct rtattr *) (gnlh + 1);
> + RTA_OK(attr, rta_len);
> + attr = RTA_NEXT(attr, rta_len)) {
> + switch (attr->rta_type) {
> + case CTRL_ATTR_FAMILY_NAME:
> + name = xstrdup(RTA_DATA(attr));
This should be coded more defensively, like unix_parse_response,
we shouldn't assume that RTA_DATA(attr) is NUL-terminated, and that
CTRL_ATTR_FAMILY_NAME attribute is present only once per message.
> + break;
> + case CTRL_ATTR_FAMILY_ID:
> + if (RTA_PAYLOAD(attr) >= 2) {
> + id = *(uint16_t *)(RTA_DATA(attr));
> + id_set = true;
> + }
Let's just save the pointer here, this way we won't need id_set.
> + break;
> + }
> + if (name && id_set) {
> + dyxlat_may_add_pair(dyxlat, id, name);
> + id_set = false;
> + free(name);
> + name = NULL;
> + }
I think we shouldn't leak memory if CTRL_ATTR_FAMILY_NAME attribute
is present without CTRL_ATTR_FAMILY_ID.
--
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