Add Loader XDP source files.

src/loader/utils/xdp.c

@@ -0,0 +1,199 @@
+#include <loader/utils/xdp.h>
+
+/**
+ * Finds a BPF map's FD.
+ * 
+ * @param prog A pointer to the XDP program structure.
+ * @param mapname The name of the map to retrieve.
+ * 
+ * @return The map's FD.
+ */
+int FindMapFd(struct xdp_program *prog, const char *map_name)
+{
+    int fd = -1;
+
+    struct bpf_object *obj = xdp_program__bpf_obj(prog);
+
+    if (obj == NULL)
+    {
+        fprintf(stderr, "Error finding BPF object from XDP program.\n");
+
+        goto out;
+    }
+
+    struct bpf_map *map = bpf_object__find_map_by_name(obj, map_name);
+
+    if (!map) 
+    {
+        fprintf(stderr, "Error finding eBPF map: %s\n", map_name);
+
+        goto out;
+    }
+
+    fd = bpf_map__fd(map);
+
+    out:
+        return fd;
+}
+
+/**
+ * Loads a BPF object file.
+ * 
+ * @param file_name The path to the BPF object file.
+ * 
+ * @return XDP program structure (pointer) or NULL.
+ */
+struct xdp_program *LoadBpfObj(const char *file_name)
+{
+    struct xdp_program *prog = xdp_program__open_file(file_name, "xdp_prog", NULL);
+
+    if (prog == NULL)
+    {
+        // The main function handles this error.
+        return NULL;
+    }
+
+    return prog;
+}
+
+/**
+ * Attempts to attach or detach (progfd = -1) a BPF/XDP program to an interface.
+ * 
+ * @param prog A pointer to the XDP program structure.
+ * @param ifidx The index to the interface to attach to.
+ * @param detach If above 0, attempts to detach XDP program.
+ * @param cmd A pointer to a cmdline struct that includes command line arguments (mostly checking for offload/HW mode set).
+ * 
+ * @return 0 on success and 1 on error.
+ */
+int AttachXdp(struct xdp_program *prog, int ifidx, u8 detach, cmdline_t *cmd)
+{
+    int err;
+
+    u32 mode = XDP_MODE_NATIVE;
+    char *smode;
+
+    smode = "DRV/native";
+
+    if (cmd->offload)
+    {
+        smode = "HW/offload";
+
+        mode = XDP_MODE_HW;
+    }
+    else if (cmd->skb)
+    {
+        smode = "SKB/generic";
+        mode = XDP_MODE_SKB;
+    }
+
+    u8 exit = 0;
+
+    while (!exit)
+    {
+        // Try loading program with current mode.
+        int err;
+
+        if (detach)
+        {
+            err = xdp_program__detach(prog, ifidx, mode, 0);
+        }
+        else
+        {
+            err = xdp_program__attach(prog, ifidx, mode, 0);
+        }
+
+        if (err)
+        {
+            if (err)
+            {
+                fprintf(stderr, "Could not attach with mode %s (%s) (%d).\n", smode, strerror(-err), -err);
+            }
+
+            // Decrease mode.
+            switch (mode)
+            {
+                case XDP_MODE_HW:
+                    mode = XDP_MODE_NATIVE;
+                    smode = "DRV/native";
+
+                    break;
+
+                case XDP_MODE_NATIVE:
+                    mode = XDP_MODE_SKB;
+                    smode = "SKB/generic";
+
+                    break;
+
+                case XDP_MODE_SKB:
+                    // Exit loop.
+                    exit = 1;
+                    smode = NULL;
+                    
+                    break;
+            }
+
+            // Retry.
+            continue;
+        }
+        
+        // Success, so break current loop.
+        break;
+    }
+
+    // If exit is set to 1 or smode is NULL, it indicates full failure.
+    if (exit || smode == NULL)
+    {
+        return EXIT_FAILURE;
+    }
+
+    fprintf(stdout, "Loaded XDP program on mode %s.\n", smode);
+
+    return EXIT_SUCCESS;
+}
+
+/**
+ * Updates the filter's BPF map with current config settings.
+ * 
+ * @param filters_map The filter's BPF map FD.
+ * @param cfg A pointer to the config structure.
+ * 
+ * @return Void
+ */
+void UpdateFilters(int filters_map, config__t *cfg)
+{
+    int i;
+
+    // Loop through all filters and delete the map. We do this in the case rules were edited and were put out of order since the key doesn't uniquely map to a specific rule.
+    for (i = 0; i < MAX_FILTERS; i++)
+    {
+        u32 key = i;
+
+        bpf_map_delete_elem(filters_map, &key);
+    }
+
+    // Add a filter to the filter maps.
+    for (i = 0; i < MAX_FILTERS; i++)
+    {
+        // Check if we have a valid ID.
+        if (cfg->filters[i].id < 1)
+        {
+            break;
+        }
+
+        // Create value array (max CPUs in size) since we're using a per CPU map.
+        filter_t filter[MAX_CPUS];
+        memset(filter, 0, sizeof(filter));
+
+        for (int j = 0; j < MAX_CPUS; j++)
+        {
+            filter[j] = cfg->filters[i];
+        }
+
+        // Attempt to update BPF map.
+        if (bpf_map_update_elem(filters_map, &i, &filter, BPF_ANY) == -1)
+        {
+            fprintf(stderr, "Error updating BPF item #%d\n", i);
+        }
+    }
+}

src/loader/utils/xdp.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <bpf.h>
+#include <libbpf.h>
+#include <xdp/libxdp.h>
+
+#include  <common/all.h>
+
+#include <loader/utils/cmdline.h>
+#include <loader/utils/config.h>
+#include <loader/utils/helpers.h>
+
+#define XDP_OBJ_PATH "/etc/xdpfw/xdp_prog.o"
+
+int FindMapFd(struct xdp_program *prog, const char *map_name);
+struct xdp_program *LoadBpfObj(const char *file_name);
+int AttachXdp(struct xdp_program *prog, int ifidx, u8 detach, cmdline_t *cmd);
+void UpdateFilters(int filters_map, config__t *cfg);