* configure.ac: Verify existence of linux/genetlink.h.
* 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.
Changes in v3 (all suggested by ldv):
* Check whether linux/genetlink.h is available or not.
* Don't add NLM_F_ACK to nlmsg_type when dumping genl families.
* Use xstrndup to extract family name from netlink data.
xstrndup can limits the length of data copied and puts
nul char at the end of buffer.
* Free the buffer for storing family name before overwriting it.
* Remove id_set local variable. id is now a pointer. So NULL
check of id can be used to know whether the value is assigned or not.
* Free the buffer for storing family name even if it is not stored
to dyxlat.
Signed-off-by: Masatake YAMATO <yam...@redhat.com>
---
configure.ac | 1 +
defs.h | 2 ++
socketutils.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 113 insertions(+)
diff --git a/configure.ac b/configure.ac
index dc49d39..0974743 100644
--- a/configure.ac
+++ b/configure.ac
@@ -366,6 +366,7 @@ AC_CHECK_HEADERS(m4_normalize([
linux/falloc.h
linux/fiemap.h
linux/filter.h
+ linux/genetlink.h
linux/hiddev.h
linux/ip_vs.h
linux/ipc.h
diff --git a/defs.h b/defs.h
index 063394e..f50b474 100644
--- a/defs.h
+++ b/defs.h
@@ -511,6 +511,8 @@ void dyxlat_free(struct dyxlat *dyxlat);
struct xlat *dyxlat_get(struct dyxlat *dyxlat);
void dyxlat_add_pair(struct dyxlat *dyxlat, uint64_t val, const char *str);
+struct xlat *genl_families_xlat(void);
+
extern unsigned long get_pagesize(void);
extern int
string_to_uint_ex(const char *str, char **endptr,
diff --git a/socketutils.c b/socketutils.c
index 6486e27..bc18430 100644
--- a/socketutils.c
+++ b/socketutils.c
@@ -37,6 +37,9 @@
#include <linux/unix_diag.h>
#include <linux/netlink_diag.h>
#include <linux/rtnetlink.h>
+#if HAVE_LINUX_GENETLINK_H
+#include <linux/genetlink.h>
+#endif
#include <sys/un.h>
#ifndef UNIX_PATH_MAX
@@ -541,3 +544,110 @@ 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));
}
+
+#ifdef HAVE_LINUX_GENETLINK_H
+/*
+ * 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,
+ },
+ .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 = NULL;
+
+ 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:
+ if (name)
+ free(name);
+ name = xstrndup(RTA_DATA(attr), RTA_PAYLOAD(attr));
+ break;
+ case CTRL_ATTR_FAMILY_ID:
+ if (RTA_PAYLOAD(attr) >= 2)
+ id = (RTA_DATA(attr));
+ break;
+ }
+ if (name && id) {
+ dyxlat_add_pair(dyxlat, *id, name);
+ free(name);
+ name = NULL;
+ id = NULL;
+ }
+ }
+
+ if (name)
+ free(name);
+
+ return 0;
+}
+
+struct xlat *
+genl_families_xlat(void)
+{
+ static struct dyxlat *dyxlat;
+
+ if (!dyxlat) {
+ int fd;
+
+ dyxlat = dyxlat_alloc(32);
+ fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
+ if (fd < 0)
+ goto out;
+
+ if (genl_send_dump_families(fd))
+ receive_responses(fd, 0, GENL_ID_CTRL,
+ genl_parse_families_response, dyxlat);
+ close(fd);
+ }
+
+out:
+ return dyxlat_get(dyxlat);
+}
+#else
+struct xlat *
+genl_families_xlat(void)
+{
+ return NULL;
+}
+#endif
--
2.9.4
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