lsns: List network namespaces that are held by a socket

While parsing process's fds, check the network namespace of the socket.
That will provide fuller list of namespaces in the system.

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>

diff --git a/sys-utils/lsns.c b/sys-utils/lsns.c
index 8cf95ad24a4616053f4d3a94f6daff3458ca0429..a3ca21fcb28665bcf81efea39ead0223b94ca885 100644 (file)
--- a/sys-utils/lsns.c
+++ b/sys-utils/lsns.c
@@ -29,6 +29,7 @@
 # include <linux/netlink.h>
 # include <linux/rtnetlink.h>
 # include <linux/net_namespace.h>
+# include <linux/sockios.h>
 #endif
 
 #ifdef HAVE_LINUX_NSFS_H
@@ -51,6 +52,7 @@
 #include "idcache.h"
 #include "fileutils.h"
 #include "column-list-table.h"
+#include "pidfd-utils.h"
 
 #include "debug.h"
 
@@ -420,6 +422,22 @@ error:
        return rc;
 }
 
+static struct lsns_namespace *add_namespace_for_nsfd(struct lsns *ls, int fd, ino_t ino);
+
+static struct lsns_namespace *get_namespace(struct lsns *ls, ino_t ino)
+{
+       struct list_head *p;
+
+       list_for_each(p, &ls->namespaces) {
+               struct lsns_namespace *ns = list_entry(p, struct lsns_namespace, namespaces);
+
+               if (ns->id == ino)
+                       return ns;
+       }
+       return NULL;
+}
+
+
 #ifdef HAVE_LINUX_NET_NAMESPACE_H
 static int netnsid_cache_find(ino_t netino, int *netnsid)
 {
@@ -544,31 +562,54 @@ static int get_netnsid(struct path_cxt *pc, ino_t netino)
 
        return netnsid;
 }
+
+static void add_namespace_from_sock(struct lsns *ls, pid_t pid, uint64_t fd)
+{
+       int pidfd, sk, nsfd;
+       struct stat sb;
+
+       /* This is additional/extra information, ignoring failures. */
+       pidfd = pidfd_open(pid, 0);
+       if (pidfd < 0)
+               return;
+
+       sk = pidfd_getfd(pidfd, (int)fd, 0);
+       if (sk < 0)
+               goto out_pidfd;
+
+       nsfd = ioctl(sk, SIOCGSKNS);
+       if (nsfd < 0)
+               goto out_sk;
+
+       if (fstat(nsfd, &sb) < 0)
+               goto out_nsfd;
+
+       if (get_namespace(ls, sb.st_ino))
+               goto out_nsfd;
+
+       add_namespace_for_nsfd(ls, nsfd, sb.st_ino);
+out_nsfd:
+       close(nsfd);
+out_sk:
+       close(sk);
+out_pidfd:
+       close(pidfd);
+}
 #else
 static int get_netnsid(struct path_cxt *pc __attribute__((__unused__)),
                       ino_t netino __attribute__((__unused__)))
 {
        return LSNS_NETNS_UNUSABLE;
 }
-#endif /* HAVE_LINUX_NET_NAMESPACE_H */
 
-static struct lsns_namespace *add_namespace_for_nsfd(struct lsns *ls, int fd, ino_t ino);
-
-static struct lsns_namespace *get_namespace(struct lsns *ls, ino_t ino)
+static void add_namespace_from_sock(struct lsns *ls __attribute__((__unused__)),
+                                   pid_t pid __attribute__((__unused__)),
+                                   uint64_t fd __attribute__((__unused__)))
 {
-       struct list_head *p;
-
-       list_for_each(p, &ls->namespaces) {
-               struct lsns_namespace *ns = list_entry(p, struct lsns_namespace, namespaces);
-
-               if (ns->id == ino)
-                       return ns;
-       }
-       return NULL;
 }
-
+#endif /* HAVE_LINUX_NET_NAMESPACE_H */
 /* Read namespaces open(2)ed explicitly by the process specified by `pc'. */
-static void read_opened_namespaces(struct lsns *ls, struct path_cxt *pc)
+static void read_opened_namespaces(struct lsns *ls, struct path_cxt *pc, pid_t pid)
 {
        DIR *sub = NULL;
        struct dirent *d = NULL;
@@ -580,8 +621,10 @@ static void read_opened_namespaces(struct lsns *ls, struct path_cxt *pc)
                if (ul_strtou64(d->d_name, &num, 10) != 0)      /* only numbers */
                        continue;
 
-               if (ul_path_statf(pc, &st, 0, "fd/%ju", (uintmax_t) num) == 0
-                   && st.st_dev == ls->nsfs_dev) {
+               if (ul_path_statf(pc, &st, 0, "fd/%ju", (uintmax_t) num))
+                       continue;
+
+               if (st.st_dev == ls->nsfs_dev) {
                        if (get_namespace(ls, st.st_ino))
                                continue;
                        int fd = ul_path_openf(pc, O_RDONLY, "fd/%ju", (uintmax_t) num);
@@ -589,6 +632,8 @@ static void read_opened_namespaces(struct lsns *ls, struct path_cxt *pc)
                                add_namespace_for_nsfd(ls, fd, st.st_ino);
                                close(fd);
                        }
+               } else if ((st.st_mode & S_IFMT) == S_IFSOCK) {
+                       add_namespace_from_sock(ls, pid, num);
                }
        }
 }
@@ -638,7 +683,7 @@ static int read_process(struct lsns *ls, struct path_cxt *pc)
        DBG(PROC, ul_debugobj(p, "new pid=%d", p->pid));
        list_add_tail(&p->processes, &ls->processes);
 
-       read_opened_namespaces(ls, pc);
+       read_opened_namespaces(ls, pc, p->pid);
 done:
        if (rc)
                free(p);