added cgroup-network that can find the network interface of a cgroup, given a pid in it

.gitignore

@@ -109,3 +109,5 @@ diagrams/plantuml.jar
 netdata.cppcheck
 
 profile/statsd-stress
+src/cgroup-network
+vgcore.*

CMakeLists.txt

@@ -188,6 +188,22 @@ set(FREEIPMI_PLUGIN_SOURCE_FILES
         config.h
         )
 
+set(CGROUP_NETWORK_SOURCE_FILES
+        src/cgroup-network.c
+        src/common.c
+        src/common.h
+        src/clocks.c
+        src/clocks.h
+        src/inlined.h
+        src/log.c
+        src/log.h
+        src/procfile.c
+        src/procfile.h
+        src/web_buffer.c
+        src/web_buffer.h
+        config.h
+        )
+
 include_directories(AFTER .)
 
 add_definitions(-DHAVE_CONFIG_H -DCACHE_DIR="/var/cache/netdata" -DCONFIG_DIR="/etc/netdata" -DLOG_DIR="/var/log/netdata" -DPLUGINS_DIR="/usr/libexec/netdata" -DWEB_DIR="/usr/share/netdata" -DVARLIB_DIR="/var/lib/netdata")
@@ -200,3 +216,6 @@ target_link_libraries (apps.plugin m ${CMAKE_THREAD_LIBS_INIT})
 
 add_executable(freeipmi.plugin ${FREEIPMI_PLUGIN_SOURCE_FILES})
 target_link_libraries (freeipmi.plugin ipmimonitoring)
+
+add_executable(cgroup-network ${CGROUP_NETWORK_SOURCE_FILES})
+target_link_libraries (cgroup-network m ${CMAKE_THREAD_LIBS_INIT})

configure.ac

@@ -148,7 +148,6 @@ AC_HEADER_RESOLV
 
 AC_CHECK_HEADERS_ONCE([sys/prctl.h])
 
-
 # -----------------------------------------------------------------------------
 # operating system detection
 
@@ -425,6 +424,21 @@ AC_MSG_RESULT([${enable_plugin_nfacct}])
 AM_CONDITIONAL([ENABLE_PLUGIN_NFACCT], [test "${enable_plugin_nfacct}" = "yes"])
 
 
+# -----------------------------------------------------------------------------
+# check for setns() - cgroup-network
+
+AC_CHECK_FUNC([setns])
+AC_MSG_CHECKING([if cgroup-network can be enabled])
+if test "$ac_cv_func_setns" = "yes" ; then
+    have_setns="yes"
+    AC_DEFINE([HAVE_SETNS], [1], [Define 1 if you have setns() function])
+else
+    have_setns="no"
+fi
+AC_MSG_RESULT([${have_setns}])
+AM_CONDITIONAL([ENABLE_PLUGIN_CGROUP_NETWORK], [test "${have_setns}" = "yes"])
+
+
 # -----------------------------------------------------------------------------
 # Link-Time-Optimization
 

makeself/install-or-update.sh

@@ -138,7 +138,7 @@ run chown -R ${NETDATA_USER}:${NETDATA_GROUP} /opt/netdata
 # -----------------------------------------------------------------------------
 progress "fix plugin permissions"
 
-for x in apps.plugin freeipmi.plugin
+for x in apps.plugin freeipmi.plugin cgroup-network
 do
     f="usr/libexec/netdata/plugins.d/${x}"
 

netdata-installer.sh

@@ -782,6 +782,12 @@ if [ ${UID} -eq 0 ]
         run chmod 4755 "${NETDATA_PREFIX}/usr/libexec/netdata/plugins.d/freeipmi.plugin"
     fi
 
+    if [ -f "${NETDATA_PREFIX}/usr/libexec/netdata/plugins.d/cgroup-network" ]
+        then
+        run chown root "${NETDATA_PREFIX}/usr/libexec/netdata/plugins.d/cgroup-network"
+        run chmod 4755 "${NETDATA_PREFIX}/usr/libexec/netdata/plugins.d/cgroup-network"
+    fi
+
 else
     run chown "${NETDATA_USER}:${NETDATA_USER}" "${NETDATA_LOG_DIR}"
     run chown -R "${NETDATA_USER}:${NETDATA_USER}" "${NETDATA_PREFIX}/usr/libexec/netdata"

src/Makefile.am

@@ -37,6 +37,10 @@ if ENABLE_PLUGIN_FREEIPMI
 plugins_PROGRAMS += freeipmi.plugin
 endif
 
+if ENABLE_PLUGIN_CGROUP_NETWORK
+plugins_PROGRAMS += cgroup-network
+endif
+
 netdata_SOURCES = \
 	adaptive_resortable_list.c \
 	adaptive_resortable_list.h \
@@ -244,3 +248,18 @@ freeipmi_plugin_SOURCES = \
 freeipmi_plugin_LDADD = \
 	$(OPTIONAL_IPMIMONITORING_LIBS) \
 	$(NULL)
+
+cgroup_network_SOURCES = \
+    cgroup-network.c \
+	clocks.c clocks.h \
+    common.c common.h \
+    inlined.h \
+    log.c log.h \
+	procfile.c procfile.h \
+	web_buffer.c web_buffer.h \
+    $(NULL)
+
+cgroup_network_LDADD = \
+	$(OPTIONAL_MATH_LIBS) \
+	$(OPTIONAL_LIBCAP_LIBS) \
+	$(NULL)

src/apps_plugin.c

@@ -3197,7 +3197,7 @@ static void parse_args(int argc, char **argv)
             }
         }
 
-        if(strcmp("version", argv[i]) == 0 || strcmp("-v", argv[i]) == 0 || strcmp("-V", argv[i]) == 0) {
+        if(strcmp("version", argv[i]) == 0 || strcmp("-version", argv[i]) == 0 || strcmp("--version", argv[i]) == 0 || strcmp("-v", argv[i]) == 0 || strcmp("-V", argv[i]) == 0) {
             printf("apps.plugin %s\n", VERSION);
             exit(0);
         }

src/cgroup-network.c

@@ -0,0 +1,300 @@
+#include "common.h"
+
+#ifdef HAVE_SETNS
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE             /* See feature_test_macros(7) */
+#endif
+#include <sched.h>
+#endif
+
+// ----------------------------------------------------------------------------
+// callback required by fatal()
+
+void netdata_cleanup_and_exit(int ret) {
+    exit(ret);
+}
+
+struct iface {
+    const char *device;
+    uint32_t hash;
+
+    unsigned int ifindex;
+    unsigned int iflink;
+
+    struct iface *next;
+};
+
+unsigned int read_iface_iflink(const char *prefix, const char *iface) {
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/sys/class/net/%s/iflink", prefix?prefix:"", iface);
+
+    unsigned long long iflink = 0;
+    int ret = read_single_number_file(filename, &iflink);
+    if(ret) error("Cannot read '%s'.", filename);
+
+    return (unsigned int)iflink;
+}
+
+unsigned int read_iface_ifindex(const char *prefix, const char *iface) {
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/sys/class/net/%s/ifindex", prefix?prefix:"", iface);
+
+    unsigned long long ifindex = 0;
+    int ret = read_single_number_file(filename, &ifindex);
+    if(ret) error("Cannot read '%s'.", filename);
+
+    return (unsigned int)ifindex;
+}
+
+struct iface *read_proc_net_dev(const char *prefix) {
+    procfile *ff = NULL;
+    char filename[FILENAME_MAX + 1];
+
+    snprintfz(filename, FILENAME_MAX, "%s%s", prefix?prefix:"", "/proc/net/dev");
+    ff = procfile_open(filename, " \t,:|", PROCFILE_FLAG_DEFAULT);
+    if(unlikely(!ff)) {
+        error("Cannot open file '%s'", filename);
+        return NULL;
+    }
+
+    ff = procfile_readall(ff);
+    if(unlikely(!ff)) {
+        error("Cannot read file '%s'", filename);
+        return NULL;
+    }
+
+    size_t lines = procfile_lines(ff), l;
+    struct iface *root = NULL;
+    for(l = 2; l < lines ;l++) {
+        if (unlikely(procfile_linewords(ff, l) < 1)) continue;
+
+        struct iface *t = callocz(1, sizeof(struct iface));
+        t->device = strdupz(procfile_lineword(ff, l, 0));
+        t->hash = simple_hash(t->device);
+        t->ifindex = read_iface_ifindex(prefix, t->device);
+        t->iflink  = read_iface_iflink(prefix, t->device);
+        t->next = root;
+        root = t;
+    }
+
+    return root;
+}
+
+inline int iface_is_eligible(struct iface *iface) {
+    if(iface->iflink != iface->ifindex)
+        return 1;
+
+    return 0;
+}
+
+int eligible_ifaces(struct iface *root) {
+    int eligible = 0;
+
+    struct iface *t;
+    for(t = root; t ; t = t->next)
+        if(iface_is_eligible(t))
+            eligible++;
+
+    return eligible;
+}
+
+static void continue_as_child(void) {
+    pid_t child = fork();
+    int status;
+    pid_t ret;
+
+    if (child < 0)
+        error("fork() failed");
+
+    /* Only the child returns */
+    if (child == 0)
+        return;
+
+    for (;;) {
+        ret = waitpid(child, &status, WUNTRACED);
+        if ((ret == child) && (WIFSTOPPED(status))) {
+            /* The child suspended so suspend us as well */
+            kill(getpid(), SIGSTOP);
+            kill(child, SIGCONT);
+        } else {
+            break;
+        }
+    }
+
+    /* Return the child's exit code if possible */
+    if (WIFEXITED(status)) {
+        exit(WEXITSTATUS(status));
+    } else if (WIFSIGNALED(status)) {
+        kill(getpid(), WTERMSIG(status));
+    }
+
+    exit(EXIT_FAILURE);
+}
+
+int proc_pid_fd(const char *prefix, const char *ns, pid_t pid) {
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/proc/%d/%s", prefix?prefix:"", (int)pid, ns);
+    int fd = open(filename, O_RDONLY);
+
+    if(fd == -1)
+        error("Cannot open file '%s'", filename);
+
+    return fd;
+}
+
+static struct ns {
+    int nstype;
+    int fd;
+    int status;
+    const char *name;
+    const char *path;
+} all_ns[] = {
+        // { .nstype = CLONE_NEWUSER,   .fd = -1, .status = -1, .name = "user",    .path = "ns/user"   },
+        // { .nstype = CLONE_NEWCGROUP, .fd = -1, .status = -1, .name = "cgroup",  .path = "ns/cgroup" },
+        // { .nstype = CLONE_NEWIPC,    .fd = -1, .status = -1, .name = "ipc",     .path = "ns/ipc"    },
+        // { .nstype = CLONE_NEWUTS,    .fd = -1, .status = -1, .name = "uts",     .path = "ns/uts"    },
+        { .nstype = CLONE_NEWNET,    .fd = -1, .status = -1, .name = "network", .path = "ns/net"    },
+        { .nstype = CLONE_NEWPID,    .fd = -1, .status = -1, .name = "pid",     .path = "ns/pid"    },
+        { .nstype = CLONE_NEWNS,     .fd = -1, .status = -1, .name = "mount",   .path = "ns/mnt"    },
+
+        // terminator
+        { .nstype = 0,               .fd = -1, .status = -1, .name = NULL,      .path = NULL        }
+};
+
+int switch_namespace(const char *prefix, pid_t pid) {
+#ifdef HAVE_SETNS
+
+    int i;
+    for(i = 0; all_ns[i].name ; i++)
+        all_ns[i].fd = proc_pid_fd(prefix, all_ns[i].path, pid);
+
+    int root_fd = proc_pid_fd(prefix, "root", pid);
+    int cwd_fd  = proc_pid_fd(prefix, "cwd", pid);
+
+    setgroups(0, NULL);
+
+    // 2 passes - found it at nsenter source code
+    // this is related CLONE_NEWUSER functionality
+
+    int pass, errors = 0;
+    for(pass = 0; pass < 2 ;pass++) {
+        for(i = 0; all_ns[i].name ; i++) {
+            if (all_ns[i].fd != -1 && all_ns[i].status == -1) {
+                if(setns(all_ns[i].fd, all_ns[i].nstype) == -1) {
+                    if(pass == 1) {
+                        all_ns[i].status = 0;
+                        error("Cannot switch to %s namespace of pid %d", all_ns[i].name, (int) pid);
+                        errors++;
+                    }
+                }
+                else
+                    all_ns[i].status = 1;
+            }
+        }
+    }
+
+    setgroups(0, NULL);
+
+    if(root_fd != -1) {
+        if(fchdir(root_fd) < 0)
+            error("Cannot fchdir() to pid %d root directory", (int)pid);
+
+        if(chroot(".") < 0)
+            error("Cannot chroot() to pid %d root directory", (int)pid);
+
+        close(root_fd);
+    }
+
+    if(cwd_fd != -1) {
+        if(fchdir(cwd_fd) < 0)
+            error("Cannot fchdir() to pid %d current working directory", (int)pid);
+
+        close(cwd_fd);
+    }
+
+    int do_fork = 0;
+    for(i = 0; all_ns[i].name ; i++)
+        if(all_ns[i].fd != -1) {
+
+            // CLONE_NEWPID requires a fork() to become effective
+            if(all_ns[i].nstype == CLONE_NEWPID && all_ns[i].status)
+                do_fork = 1;
+
+            close(all_ns[i].fd);
+        }
+
+    if(do_fork)
+        continue_as_child();
+
+    return 0;
+
+#else
+
+    errno = ENOSYS;
+    error("setns() is missing on this system.");
+    return 1;
+
+#endif
+}
+
+void usage(void) {
+    fprintf(stderr, "%s -p PID\n", program_name);
+    exit(1);
+}
+
+int main(int argc, char **argv) {
+    pid_t pid = 0;
+
+    program_name = argv[0];
+    program_version = VERSION;
+    error_log_syslog = 0;
+
+    if(argc == 2 && (!strcmp(argv[1], "version") || !strcmp(argv[1], "-version") || !strcmp(argv[1], "--version") || !strcmp(argv[1], "-v") || !strcmp(argv[1], "-V"))) {
+        fprintf(stderr, "cgroup-network %s\n", VERSION);
+        exit(0);
+    }
+
+    if(argc != 3 || strcmp(argv[1], "-p") != 0)
+        usage();
+
+    pid = atoi(argv[2]);
+    if(pid <= 0)
+        fatal("Invalid pid %d", (int)pid);
+
+    struct iface *host, *cgroup, *h, *c;
+    const char *prefix = getenv("NETDATA_HOST_PREFIX");
+
+    host = read_proc_net_dev(prefix);
+    if(!host)
+        fatal("cannot read host interface list.");
+
+    if(!eligible_ifaces(host))
+        fatal("there are no double-linked host interfaces available.");
+
+    if(switch_namespace(prefix, pid))
+        fatal("cannot switch to the namespace of pid %u", (unsigned int)pid);
+
+    cgroup = read_proc_net_dev(NULL);
+    if(!cgroup)
+        fatal("cannot read cgroup interface list.");
+
+    if(!eligible_ifaces(cgroup))
+        fatal("there are not double-linked cgroup interfaces available.");
+
+    int found = 0;
+    for(h = host; h ; h = h->next) {
+        if(iface_is_eligible(h)) {
+            for (c = cgroup; c; c = c->next) {
+                if(iface_is_eligible(c) && h->ifindex == c->iflink && h->iflink == c->ifindex) {
+                    printf("%s\n", h->device);
+                    found++;
+                }
+            }
+        }
+    }
+
+    if(!found)
+        return 1;
+
+    return 0;
+}

src/freeipmi_plugin.c

@@ -1433,7 +1433,7 @@ int main (int argc, char **argv) {
                 continue;
             }
         }
-        else if(strcmp("version", argv[i]) == 0 || strcmp("-v", argv[i]) == 0 || strcmp("-V", argv[i]) == 0) {
+        else if(strcmp("version", argv[i]) == 0 || strcmp("-version", argv[i]) == 0 || strcmp("--version", argv[i]) == 0 || strcmp("-v", argv[i]) == 0 || strcmp("-V", argv[i]) == 0) {
             printf("freeipmi.plugin %s\n", VERSION);
             exit(0);
         }