Include namespace inode numbers on process events (#213)

This diff adds the inode number of each namespace the process belongs to, to
process events. Two namespaces were excluded: pid_for_children and
time_for_children, see namespaces(7).

The pid namespace is a bit special as it's not in nsproxy, the user facing pid
level is the last/deepest.

There was an inclusion of mnt ns, that is not used by beats or endpoint, I kept
it but made it fetch from the new "path".

While here, add support for changing the compiler in gen_initramfs.sh by setting
CC. While Fedora includes a ${arch}-linux-gnu-gcc, it doesn't include matching
headers, so I can't really compile the tests locally.

GPL/Events/EbpfEventProto.h

@@ -157,6 +157,16 @@ struct ebpf_file_info {
     uint64_t ctime;
 } __attribute__((packed));
 
+struct ebpf_namespace_info {
+    uint32_t uts_inonum;
+    uint32_t ipc_inonum;
+    uint32_t mnt_inonum;
+    uint32_t net_inonum;
+    uint32_t cgroup_inonum;
+    uint32_t time_inonum;
+    uint32_t pid_inonum;
+} __attribute__((packed));
+
 // Full events follow
 struct ebpf_file_delete_event {
     struct ebpf_event_header hdr;
@@ -223,6 +233,7 @@ struct ebpf_process_fork_event {
     struct ebpf_cred_info creds;
     struct ebpf_tty_dev ctty;
     char comm[TASK_COMM_LEN];
+    struct ebpf_namespace_info ns;
 
     // Variable length fields: pids_ss_cgroup_path
     struct ebpf_varlen_fields_start vl_fields;
@@ -238,6 +249,7 @@ struct ebpf_process_exec_event {
     struct ebpf_cred_info creds;
     struct ebpf_tty_dev ctty;
     char comm[TASK_COMM_LEN];
+    struct ebpf_namespace_info ns;
     uint32_t inode_nlink;
     uint32_t flags;
 
@@ -251,6 +263,7 @@ struct ebpf_process_exit_event {
     struct ebpf_cred_info creds;
     struct ebpf_tty_dev ctty;
     char comm[TASK_COMM_LEN];
+    struct ebpf_namespace_info ns;
     int32_t exit_code;
 
     // Variable length fields: pids_ss_cgroup_path

GPL/Events/File/Probe.bpf.c

@@ -31,11 +31,6 @@ DECL_FUNC_ARG_EXISTS(vfs_rename, rd);
 DECL_FUNC_ARG(do_truncate, filp);
 DECL_FUNC_RET(do_truncate);
 
-static int mntns(const struct task_struct *task)
-{
-    return BPF_CORE_READ(task, nsproxy, mnt_ns, ns.inum);
-}
-
 static int do_unlinkat__enter()
 {
     struct ebpf_events_state state = {};
@@ -129,9 +124,11 @@ static int vfs_unlink__exit(int ret)
     ebpf_cred_info__fill(&event->creds, task);
 
     struct path p;
-    p.dentry     = &state->unlink.de;
-    p.mnt        = state->unlink.mnt;
-    event->mntns = mntns(task);
+    p.dentry = &state->unlink.de;
+    p.mnt    = state->unlink.mnt;
+    struct ebpf_namespace_info ns;
+    ebpf_ns__fill(&ns, task);
+    event->mntns = ns.mnt_inonum;
     bpf_get_current_comm(event->comm, TASK_COMM_LEN);
     ebpf_file_info__fill(&event->finfo, p.dentry);
 
@@ -236,7 +233,9 @@ static void prepare_and_send_file_event(struct file *f,
     struct path p            = BPF_CORE_READ(f, f_path);
     ebpf_pid_info__fill(&event->pids, task);
     ebpf_cred_info__fill(&event->creds, task);
-    event->mntns = mntns(task);
+    struct ebpf_namespace_info ns;
+    ebpf_ns__fill(&ns, task);
+    event->mntns = ns.mnt_inonum;
     bpf_get_current_comm(event->comm, TASK_COMM_LEN);
     ebpf_file_info__fill(&event->finfo, p.dentry);
 
@@ -489,7 +488,9 @@ static int vfs_rename__exit(int ret)
     event->hdr.ts_boot = bpf_ktime_get_boot_ns_helper();
     ebpf_pid_info__fill(&event->pids, task);
     ebpf_cred_info__fill(&event->creds, task);
-    event->mntns = mntns(task);
+    struct ebpf_namespace_info ns;
+    ebpf_ns__fill(&ns, task);
+    event->mntns = ns.mnt_inonum;
     bpf_get_current_comm(event->comm, TASK_COMM_LEN);
     ebpf_file_info__fill(&event->finfo, de);
 
@@ -559,7 +560,9 @@ static void file_modify_event__emit(enum ebpf_file_change_type typ, struct path
     event->change_type = typ;
     ebpf_pid_info__fill(&event->pids, task);
     ebpf_cred_info__fill(&event->creds, task);
-    event->mntns = mntns(task);
+    struct ebpf_namespace_info ns;
+    ebpf_ns__fill(&ns, task);
+    event->mntns = ns.mnt_inonum;
     bpf_get_current_comm(event->comm, TASK_COMM_LEN);
     struct dentry *d = BPF_CORE_READ(path, dentry);
     ebpf_file_info__fill(&event->finfo, d);

GPL/Events/Helpers.h

@@ -306,6 +306,27 @@ static void ebpf_comm__fill(char *comm, size_t len, const struct task_struct *ta
     read_kernel_str_or_empty_str(comm, len, BPF_CORE_READ(task, comm));
 }
 
+static void ebpf_ns__fill(struct ebpf_namespace_info *nsi, const struct task_struct *task)
+{
+    struct pid *pid;
+    int pid_level;
+
+    nsi->uts_inonum    = BPF_CORE_READ(task, nsproxy, uts_ns, ns.inum);
+    nsi->ipc_inonum    = BPF_CORE_READ(task, nsproxy, ipc_ns, ns.inum);
+    nsi->mnt_inonum    = BPF_CORE_READ(task, nsproxy, mnt_ns, ns.inum);
+    nsi->net_inonum    = BPF_CORE_READ(task, nsproxy, net_ns, ns.inum);
+    nsi->cgroup_inonum = BPF_CORE_READ(task, nsproxy, cgroup_ns, ns.inum);
+    nsi->time_inonum   = BPF_CORE_READ(task, nsproxy, time_ns, ns.inum);
+
+    pid = BPF_CORE_READ(task, thread_pid);
+    if (pid == NULL) {
+        nsi->pid_inonum = 0;
+        return;
+    }
+    pid_level       = BPF_CORE_READ(pid, level);
+    nsi->pid_inonum = BPF_CORE_READ(pid, numbers[pid_level].ns, ns.inum);
+}
+
 struct {
     __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
     __type(key, u32);

GPL/Events/Process/Probe.bpf.c

@@ -60,6 +60,7 @@ int BPF_PROG(sched_process_fork, const struct task_struct *parent, const struct
     ebpf_cred_info__fill(&event->creds, parent);
     ebpf_ctty__fill(&event->ctty, child);
     ebpf_comm__fill(event->comm, sizeof(event->comm), child);
+    ebpf_ns__fill(&event->ns, child);
 
     // Variable length fields
     ebpf_vl_fields__init(&event->vl_fields);
@@ -111,6 +112,7 @@ int BPF_PROG(sched_process_exec,
     ebpf_cred_info__fill(&event->creds, task);
     ebpf_ctty__fill(&event->ctty, task);
     ebpf_comm__fill(event->comm, sizeof(event->comm), task);
+    ebpf_ns__fill(&event->ns, task);
 
     // set setuid and setgid flags
     struct file *f        = BPF_CORE_READ(binprm, file);
@@ -211,6 +213,7 @@ static int taskstats_exit__enter(const struct task_struct *task, int group_dead)
     ebpf_cred_info__fill(&event->creds, task);
     ebpf_ctty__fill(&event->ctty, task);
     ebpf_comm__fill(event->comm, sizeof(event->comm), task);
+    ebpf_ns__fill(&event->ns, task);
 
     // Variable length fields
     ebpf_vl_fields__init(&event->vl_fields);

non-GPL/Events/EventsTrace/EventsTrace.c

@@ -414,6 +414,26 @@ static void out_file_info(const char *name, struct ebpf_file_info *finfo)
     out_object_end();
 }
 
+static void out_ns_info(const char *name, struct ebpf_namespace_info *ns)
+{
+    printf("\"%s\":", name);
+    out_object_start();
+    out_uint("uts", ns->uts_inonum);
+    out_comma();
+    out_uint("ipc", ns->ipc_inonum);
+    out_comma();
+    out_uint("mnt", ns->mnt_inonum);
+    out_comma();
+    out_uint("net", ns->net_inonum);
+    out_comma();
+    out_uint("cgroup", ns->cgroup_inonum);
+    out_comma();
+    out_uint("time", ns->time_inonum);
+    out_comma();
+    out_uint("pid", ns->pid_inonum);
+    out_object_end();
+}
+
 static void out_null_delimited_string_array(const char *name, char *buf, size_t buf_size)
 {
     // buf is an array (argv, env etc.) with multiple values delimited by a '\0'
@@ -768,6 +788,9 @@ static void out_process_fork(struct ebpf_process_fork_event *evt)
     out_comma();
 
     out_string("comm", evt->comm);
+    out_comma();
+
+    out_ns_info("ns", &evt->ns);
 
     struct ebpf_varlen_field *field;
     FOR_EACH_VARLEN_FIELD(evt->vl_fields, field)

testing/scripts/gen_initramfs.sh

@@ -56,7 +56,7 @@ build_testbins() {
     for c_src in *.c; do
         local bin_path=bin/$arch/$(basename $c_src .c)
 
-        ${arch}-linux-gnu-gcc -g -static $c_src -o $bin_path \
+        ${CC-${arch}-linux-gnu-gcc} -g -static $c_src -o $bin_path \
             || exit_error "compilation of $c_src for $arch failed (see above)"
     done
 

testing/testrunner/ebpf_test.go

@@ -94,6 +94,11 @@ func ForkExit(t *testing.T, et *Runner) {
 	require.Equal(t, forkEvent.ChildPids.Sid, forkEvent.ParentPids.Sid)
 	require.Equal(t, forkEvent.ChildPids.Pgid, forkEvent.ParentPids.Pgid)
 	require.NotEqual(t, forkEvent.ChildPids.Tgid, forkEvent.ParentPids.Tgid)
+
+	// Check if all namespace values match /proc/self/ns/*
+	ns, err := FetchNsFromProc()
+	require.NoError(t, err)
+	require.Equal(t, forkEvent.Ns, ns)
 }
 
 func ForkExec(t *testing.T, et *Runner) {
@@ -154,7 +159,6 @@ func ForkExec(t *testing.T, et *Runner) {
 	require.Equal(t, execEvent.Env[0], "TEST_ENV_KEY1=TEST_ENV_VAL1")
 	require.Equal(t, execEvent.Env[1], "TEST_ENV_KEY2=TEST_ENV_VAL2")
 	require.Equal(t, execEvent.Cwd, "/")
-
 }
 
 func FileCreate(t *testing.T, et *Runner) {
@@ -185,7 +189,6 @@ func FileCreate(t *testing.T, et *Runner) {
 }
 
 func FileDelete(t *testing.T, et *Runner) {
-
 	var binOutput struct {
 		PidInfo      TestPidInfo `json:"pid_info"`
 		FileNameOrig string      `json:"filename_orig"`
@@ -426,7 +429,6 @@ func Tcpv4ConnectionAttempt(t *testing.T, et *Runner) {
 	require.Equal(t, ev.Net.DestPort, binOutput.ServerPort)
 	require.Equal(t, ev.Net.NetNs, binOutput.NetNs)
 	require.Equal(t, ev.Comm, "tcpv4_connect")
-
 }
 
 func Tcpv4ConnectionAccept(t *testing.T, et *Runner) {
@@ -665,5 +667,4 @@ func TestEbpf(t *testing.T) {
 			run.Stop()
 		})
 	}
-
 }

testing/testrunner/utils.go

@@ -18,6 +18,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -90,11 +91,22 @@ type FileInfo struct {
 	Ctime uint64 `json:"ctime"`
 }
 
+type NsInfo struct {
+	Uts    uint32 `json:"uts"`
+	Ipc    uint32 `json:"ipc"`
+	Mnt    uint32 `json:"mnt"`
+	Net    uint32 `json:"net"`
+	Cgroup uint32 `json:"cgroup"`
+	Time   uint32 `json:"time"`
+	Pid    uint32 `json:"pid"`
+}
+
 type ProcessForkEvent struct {
 	ParentPids PidInfo  `json:"parent_pids"`
 	ChildPids  PidInfo  `json:"child_pids"`
 	Creds      CredInfo `json:"creds"`
 	Ctty       TtyInfo  `json:"ctty"`
+	Ns         NsInfo   `json:"ns"`
 }
 
 type ProcessExecEvent struct {
@@ -195,8 +207,10 @@ var testBinaryPath = "/"
 var eventsTracePath = "/EventsTrace"
 
 // Path to the TC filter test binary and probe. This one is weird and lives outside the rest of the test binaries
-var tcTestPath = "/BPFTcFilterTests"
-var tcObjPath = "/TcFilter.bpf.o"
+var (
+	tcTestPath = "/BPFTcFilterTests"
+	tcObjPath  = "/TcFilter.bpf.o"
+)
 
 // init will run at startup and figure out if we're running in the bluebox test env or not,
 // and set paths for the binaries as needed
@@ -327,3 +341,49 @@ func PrintDebugOutputOnFail() {
 
 	fmt.Println("BPF test failed, see errors and stacktrace above")
 }
+
+func FetchNsFromProc() (NsInfo, error) {
+	var ns NsInfo
+
+	fetch := func(name string, dst *uint32) error {
+		s, err := os.Readlink("/proc/self/ns/" + name)
+		if err != nil {
+			return err
+		}
+		start := strings.IndexByte(s, '[')
+		if start == -1 {
+			return fmt.Errorf("`[` not found for ns %s", name)
+		}
+		start++
+		end := strings.IndexByte(s, ']')
+		if end == -1 {
+			return fmt.Errorf("`]` not found for ns %s", name)
+		}
+		v, err := strconv.Atoi(s[start:end])
+		if err != nil {
+			return err
+		}
+		*dst = uint32(v)
+		return nil
+	}
+
+	calls := []struct {
+		name string
+		dst  *uint32
+	}{
+		{"uts", &ns.Uts},
+		{"ipc", &ns.Ipc},
+		{"mnt", &ns.Mnt},
+		{"net", &ns.Net},
+		{"cgroup", &ns.Cgroup},
+		{"time", &ns.Time},
+		{"pid", &ns.Pid},
+	}
+	for _, call := range calls {
+		if err := fetch(call.name, call.dst); err != nil {
+			return ns, err
+		}
+	}
+
+	return ns, nil
+}