// SPDX-License-Identifier: GPL-2.0

  #include <stdio.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <libelf.h>
  #include <gelf.h>
  #include <errno.h>
  #include <unistd.h>
  #include <string.h>
  #include <stdbool.h>

  #include <stdlib.h>

  #include <linux/bpf.h>
  #include <linux/filter.h>

  #include <linux/perf_event.h>

  #include <linux/netlink.h>
  #include <linux/rtnetlink.h>

  #include <linux/types.h>

  #include <sys/socket.h>

  #include <sys/syscall.h>
  #include <sys/ioctl.h>
  #include <sys/mman.h>
  #include <poll.h>

  #include <ctype.h>

  #include <assert.h>

  #include <bpf/bpf.h>

  #include "bpf_load.h"

  #include "perf-sys.h"

  #define DEBUGFS "/sys/kernel/debug/tracing/"

  static char license[128];

  static int kern_version;

  static bool processed_sec[128];

  char bpf_log_buf[BPF_LOG_BUF_SIZE];

  int map_fd[MAX_MAPS];
  int prog_fd[MAX_PROGS];

  int event_fd[MAX_PROGS];

  int prog_cnt;

  int prog_array_fd = -1;

  struct bpf_map_data map_data[MAX_MAPS];

  int map_data_count;

  static int populate_prog_array(const char *event, int prog_fd)
  {
  	int ind = atoi(event), err;

  	err = bpf_map_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);

  	if (err < 0) {
  		printf("failed to store prog_fd in prog_array
  ");
  		return -1;
  	}
  	return 0;
  }

  static int write_kprobe_events(const char *val)
  {
  	int fd, ret, flags;

  	if (val == NULL)
  		return -1;
  	else if (val[0] == '\0')

  		flags = O_WRONLY | O_TRUNC;
  	else
  		flags = O_WRONLY | O_APPEND;

  	fd = open(DEBUGFS "kprobe_events", flags);

  
  	ret = write(fd, val, strlen(val));
  	close(fd);
  
  	return ret;
  }

  static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
  {

  	bool is_socket = strncmp(event, "socket", 6) == 0;

  	bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
  	bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;

  	bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;

  	bool is_raw_tracepoint = strncmp(event, "raw_tracepoint/", 15) == 0;

  	bool is_xdp = strncmp(event, "xdp", 3) == 0;

  	bool is_perf_event = strncmp(event, "perf_event", 10) == 0;

  	bool is_cgroup_skb = strncmp(event, "cgroup/skb", 10) == 0;
  	bool is_cgroup_sk = strncmp(event, "cgroup/sock", 11) == 0;

  	bool is_sockops = strncmp(event, "sockops", 7) == 0;

  	bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;

  	bool is_sk_msg = strncmp(event, "sk_msg", 6) == 0;

  	size_t insns_cnt = size / sizeof(struct bpf_insn);

  	enum bpf_prog_type prog_type;
  	char buf[256];
  	int fd, efd, err, id;
  	struct perf_event_attr attr = {};
  
  	attr.type = PERF_TYPE_TRACEPOINT;
  	attr.sample_type = PERF_SAMPLE_RAW;
  	attr.sample_period = 1;
  	attr.wakeup_events = 1;
  
  	if (is_socket) {
  		prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
  	} else if (is_kprobe || is_kretprobe) {
  		prog_type = BPF_PROG_TYPE_KPROBE;

  	} else if (is_tracepoint) {
  		prog_type = BPF_PROG_TYPE_TRACEPOINT;

  	} else if (is_raw_tracepoint) {
  		prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT;

  	} else if (is_xdp) {
  		prog_type = BPF_PROG_TYPE_XDP;

  	} else if (is_perf_event) {
  		prog_type = BPF_PROG_TYPE_PERF_EVENT;

  	} else if (is_cgroup_skb) {
  		prog_type = BPF_PROG_TYPE_CGROUP_SKB;
  	} else if (is_cgroup_sk) {
  		prog_type = BPF_PROG_TYPE_CGROUP_SOCK;

  	} else if (is_sockops) {
  		prog_type = BPF_PROG_TYPE_SOCK_OPS;

  	} else if (is_sk_skb) {
  		prog_type = BPF_PROG_TYPE_SK_SKB;

  	} else if (is_sk_msg) {
  		prog_type = BPF_PROG_TYPE_SK_MSG;

  	} else {
  		printf("Unknown event '%s'
  ", event);

  		return -1;

  	}

  	if (prog_cnt == MAX_PROGS)
  		return -1;

  	fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,

  			      bpf_log_buf, BPF_LOG_BUF_SIZE);

  	if (fd < 0) {

  		printf("bpf_load_program() err=%d
  %s", errno, bpf_log_buf);

  		return -1;
  	}
  
  	prog_fd[prog_cnt++] = fd;

  	if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)

  		return 0;

  	if (is_socket || is_sockops || is_sk_skb || is_sk_msg) {

  		if (is_socket)
  			event += 6;
  		else
  			event += 7;

  		if (*event != '/')
  			return 0;
  		event++;
  		if (!isdigit(*event)) {
  			printf("invalid prog number
  ");
  			return -1;
  		}
  		return populate_prog_array(event, fd);
  	}

  	if (is_raw_tracepoint) {
  		efd = bpf_raw_tracepoint_open(event + 15, fd);
  		if (efd < 0) {
  			printf("tracepoint %s %s
  ", event + 15, strerror(errno));
  			return -1;
  		}
  		event_fd[prog_cnt - 1] = efd;
  		return 0;
  	}

  	if (is_kprobe || is_kretprobe) {

  		bool need_normal_check = true;
  		const char *event_prefix = "";

  		if (is_kprobe)
  			event += 7;
  		else
  			event += 10;

  		if (*event == 0) {
  			printf("event name cannot be empty
  ");
  			return -1;
  		}
  
  		if (isdigit(*event))
  			return populate_prog_array(event, fd);

  #ifdef __x86_64__
  		if (strncmp(event, "sys_", 4) == 0) {

  			snprintf(buf, sizeof(buf), "%c:__x64_%s __x64_%s",
  				is_kprobe ? 'p' : 'r', event, event);
  			err = write_kprobe_events(buf);

  			if (err >= 0) {
  				need_normal_check = false;
  				event_prefix = "__x64_";
  			}
  		}
  #endif
  		if (need_normal_check) {

  			snprintf(buf, sizeof(buf), "%c:%s %s",
  				is_kprobe ? 'p' : 'r', event, event);
  			err = write_kprobe_events(buf);

  			if (err < 0) {
  				printf("failed to create kprobe '%s' error '%s'
  ",
  				       event, strerror(errno));
  				return -1;
  			}

  		}

  		strcpy(buf, DEBUGFS);
  		strcat(buf, "events/kprobes/");

  		strcat(buf, event_prefix);

  		strcat(buf, event);
  		strcat(buf, "/id");
  	} else if (is_tracepoint) {
  		event += 11;
  
  		if (*event == 0) {
  			printf("event name cannot be empty
  ");
  			return -1;
  		}
  		strcpy(buf, DEBUGFS);
  		strcat(buf, "events/");
  		strcat(buf, event);
  		strcat(buf, "/id");
  	}

  
  	efd = open(buf, O_RDONLY, 0);
  	if (efd < 0) {
  		printf("failed to open event %s
  ", event);
  		return -1;
  	}
  
  	err = read(efd, buf, sizeof(buf));
  	if (err < 0 || err >= sizeof(buf)) {
  		printf("read from '%s' failed '%s'
  ", event, strerror(errno));
  		return -1;
  	}
  
  	close(efd);
  
  	buf[err] = 0;
  	id = atoi(buf);
  	attr.config = id;

  	efd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);

  	if (efd < 0) {
  		printf("event %d fd %d err %s
  ", id, efd, strerror(errno));
  		return -1;
  	}
  	event_fd[prog_cnt - 1] = efd;

  	err = ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
  	if (err < 0) {
  		printf("ioctl PERF_EVENT_IOC_ENABLE failed err %s
  ",
  		       strerror(errno));
  		return -1;
  	}
  	err = ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
  	if (err < 0) {
  		printf("ioctl PERF_EVENT_IOC_SET_BPF failed err %s
  ",
  		       strerror(errno));
  		return -1;
  	}

  	return 0;
  }

  static int load_maps(struct bpf_map_data *maps, int nr_maps,
  		     fixup_map_cb fixup_map)

  {

  	int i, numa_node;

  	for (i = 0; i < nr_maps; i++) {

  		if (fixup_map) {
  			fixup_map(&maps[i], i);
  			/* Allow userspace to assign map FD prior to creation */
  			if (maps[i].fd != -1) {
  				map_fd[i] = maps[i].fd;
  				continue;
  			}
  		}

  		numa_node = maps[i].def.map_flags & BPF_F_NUMA_NODE ?
  			maps[i].def.numa_node : -1;

  		if (maps[i].def.type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
  		    maps[i].def.type == BPF_MAP_TYPE_HASH_OF_MAPS) {
  			int inner_map_fd = map_fd[maps[i].def.inner_map_idx];

  			map_fd[i] = bpf_create_map_in_map_node(maps[i].def.type,

  							maps[i].name,

  							maps[i].def.key_size,
  							inner_map_fd,
  							maps[i].def.max_entries,

  							maps[i].def.map_flags,
  							numa_node);

  		} else {

  			map_fd[i] = bpf_create_map_node(maps[i].def.type,

  							maps[i].name,

  							maps[i].def.key_size,
  							maps[i].def.value_size,
  							maps[i].def.max_entries,
  							maps[i].def.map_flags,
  							numa_node);

  		}

  		if (map_fd[i] < 0) {

  			printf("failed to create map %d (%s): %d %s
  ",
  			       i, maps[i].name, errno, strerror(errno));

  			return 1;

  		}

  		maps[i].fd = map_fd[i];

  		if (maps[i].def.type == BPF_MAP_TYPE_PROG_ARRAY)

  			prog_array_fd = map_fd[i];

  	}
  	return 0;
  }
  
  static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
  		   GElf_Shdr *shdr, Elf_Data **data)
  {
  	Elf_Scn *scn;
  
  	scn = elf_getscn(elf, i);
  	if (!scn)
  		return 1;
  
  	if (gelf_getshdr(scn, shdr) != shdr)
  		return 2;
  
  	*shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
  	if (!*shname || !shdr->sh_size)
  		return 3;
  
  	*data = elf_getdata(scn, 0);
  	if (!*data || elf_getdata(scn, *data) != NULL)
  		return 4;
  
  	return 0;
  }
  
  static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,

  				GElf_Shdr *shdr, struct bpf_insn *insn,
  				struct bpf_map_data *maps, int nr_maps)

  {
  	int i, nrels;
  
  	nrels = shdr->sh_size / shdr->sh_entsize;
  
  	for (i = 0; i < nrels; i++) {
  		GElf_Sym sym;
  		GElf_Rel rel;
  		unsigned int insn_idx;

  		bool match = false;
  		int j, map_idx;

  
  		gelf_getrel(data, i, &rel);
  
  		insn_idx = rel.r_offset / sizeof(struct bpf_insn);
  
  		gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
  
  		if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
  			printf("invalid relo for insn[%d].code 0x%x
  ",
  			       insn_idx, insn[insn_idx].code);
  			return 1;
  		}
  		insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;

  
  		/* Match FD relocation against recorded map_data[] offset */
  		for (map_idx = 0; map_idx < nr_maps; map_idx++) {
  			if (maps[map_idx].elf_offset == sym.st_value) {
  				match = true;
  				break;
  			}
  		}
  		if (match) {
  			insn[insn_idx].imm = maps[map_idx].fd;
  		} else {
  			printf("invalid relo for insn[%d] no map_data match
  ",
  			       insn_idx);
  			return 1;
  		}

  	}
  
  	return 0;
  }

  static int cmp_symbols(const void *l, const void *r)
  {
  	const GElf_Sym *lsym = (const GElf_Sym *)l;
  	const GElf_Sym *rsym = (const GElf_Sym *)r;
  
  	if (lsym->st_value < rsym->st_value)
  		return -1;
  	else if (lsym->st_value > rsym->st_value)
  		return 1;
  	else
  		return 0;
  }

  static int load_elf_maps_section(struct bpf_map_data *maps, int maps_shndx,
  				 Elf *elf, Elf_Data *symbols, int strtabidx)

  {

  	int map_sz_elf, map_sz_copy;
  	bool validate_zero = false;
  	Elf_Data *data_maps;
  	int i, nr_maps;
  	GElf_Sym *sym;
  	Elf_Scn *scn;
  	int copy_sz;
  
  	if (maps_shndx < 0)
  		return -EINVAL;
  	if (!symbols)
  		return -EINVAL;
  
  	/* Get data for maps section via elf index */
  	scn = elf_getscn(elf, maps_shndx);
  	if (scn)
  		data_maps = elf_getdata(scn, NULL);
  	if (!scn || !data_maps) {
  		printf("Failed to get Elf_Data from maps section %d
  ",
  		       maps_shndx);
  		return -EINVAL;
  	}

  	/* For each map get corrosponding symbol table entry */
  	sym = calloc(MAX_MAPS+1, sizeof(GElf_Sym));
  	for (i = 0, nr_maps = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
  		assert(nr_maps < MAX_MAPS+1);
  		if (!gelf_getsym(symbols, i, &sym[nr_maps]))

  			continue;

  		if (sym[nr_maps].st_shndx != maps_shndx)

  			continue;

  		/* Only increment iif maps section */

  		nr_maps++;
  	}

  	/* Align to map_fd[] order, via sort on offset in sym.st_value */
  	qsort(sym, nr_maps, sizeof(GElf_Sym), cmp_symbols);
  
  	/* Keeping compatible with ELF maps section changes
  	 * ------------------------------------------------

  	 * The program size of struct bpf_load_map_def is known by loader

  	 * code, but struct stored in ELF file can be different.
  	 *
  	 * Unfortunately sym[i].st_size is zero.  To calculate the
  	 * struct size stored in the ELF file, assume all struct have
  	 * the same size, and simply divide with number of map
  	 * symbols.
  	 */
  	map_sz_elf = data_maps->d_size / nr_maps;

  	map_sz_copy = sizeof(struct bpf_load_map_def);

  	if (map_sz_elf < map_sz_copy) {
  		/*
  		 * Backward compat, loading older ELF file with
  		 * smaller struct, keeping remaining bytes zero.
  		 */
  		map_sz_copy = map_sz_elf;
  	} else if (map_sz_elf > map_sz_copy) {
  		/*
  		 * Forward compat, loading newer ELF file with larger
  		 * struct with unknown features. Assume zero means
  		 * feature not used.  Thus, validate rest of struct
  		 * data is zero.
  		 */
  		validate_zero = true;
  	}

  	/* Memcpy relevant part of ELF maps data to loader maps */

  	for (i = 0; i < nr_maps; i++) {

  		struct bpf_load_map_def *def;

  		unsigned char *addr, *end;

  		const char *map_name;
  		size_t offset;
  
  		map_name = elf_strptr(elf, strtabidx, sym[i].st_name);
  		maps[i].name = strdup(map_name);
  		if (!maps[i].name) {

  			printf("strdup(%s): %s(%d)
  ", map_name,
  			       strerror(errno), errno);

  			free(sym);
  			return -errno;
  		}
  
  		/* Symbol value is offset into ELF maps section data area */
  		offset = sym[i].st_value;

  		def = (struct bpf_load_map_def *)(data_maps->d_buf + offset);

  		maps[i].elf_offset = offset;

  		memset(&maps[i].def, 0, sizeof(struct bpf_load_map_def));

  		memcpy(&maps[i].def, def, map_sz_copy);
  
  		/* Verify no newer features were requested */
  		if (validate_zero) {

  			addr = (unsigned char *) def + map_sz_copy;
  			end  = (unsigned char *) def + map_sz_elf;

  			for (; addr < end; addr++) {
  				if (*addr != 0) {
  					free(sym);
  					return -EFBIG;
  				}
  			}

  		}
  	}

  	free(sym);

  	return nr_maps;

  }
  
  static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)

  {

  	int fd, i, ret, maps_shndx = -1, strtabidx = -1;

  	Elf *elf;
  	GElf_Ehdr ehdr;
  	GElf_Shdr shdr, shdr_prog;

  	Elf_Data *data, *data_prog, *data_maps = NULL, *symbols = NULL;

  	char *shname, *shname_prog;
  	int nr_maps = 0;

  	/* reset global variables */
  	kern_version = 0;
  	memset(license, 0, sizeof(license));
  	memset(processed_sec, 0, sizeof(processed_sec));

  	if (elf_version(EV_CURRENT) == EV_NONE)
  		return 1;
  
  	fd = open(path, O_RDONLY, 0);
  	if (fd < 0)
  		return 1;
  
  	elf = elf_begin(fd, ELF_C_READ, NULL);
  
  	if (!elf)
  		return 1;
  
  	if (gelf_getehdr(elf, &ehdr) != &ehdr)
  		return 1;

  	/* clear all kprobes */

  	i = write_kprobe_events("");

  	/* scan over all elf sections to get license and map info */
  	for (i = 1; i < ehdr.e_shnum; i++) {
  
  		if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
  			continue;
  
  		if (0) /* helpful for llvm debugging */
  			printf("section %d:%s data %p size %zd link %d flags %d
  ",
  			       i, shname, data->d_buf, data->d_size,
  			       shdr.sh_link, (int) shdr.sh_flags);
  
  		if (strcmp(shname, "license") == 0) {
  			processed_sec[i] = true;
  			memcpy(license, data->d_buf, data->d_size);

  		} else if (strcmp(shname, "version") == 0) {
  			processed_sec[i] = true;
  			if (data->d_size != sizeof(int)) {
  				printf("invalid size of version section %zd
  ",
  				       data->d_size);
  				return 1;
  			}
  			memcpy(&kern_version, data->d_buf, sizeof(int));

  		} else if (strcmp(shname, "maps") == 0) {

  			int j;

  			maps_shndx = i;
  			data_maps = data;

  			for (j = 0; j < MAX_MAPS; j++)
  				map_data[j].fd = -1;

  		} else if (shdr.sh_type == SHT_SYMTAB) {

  			strtabidx = shdr.sh_link;

  			symbols = data;
  		}
  	}

  	ret = 1;
  
  	if (!symbols) {
  		printf("missing SHT_SYMTAB section
  ");
  		goto done;
  	}
  
  	if (data_maps) {

  		nr_maps = load_elf_maps_section(map_data, maps_shndx,
  						elf, symbols, strtabidx);
  		if (nr_maps < 0) {
  			printf("Error: Failed loading ELF maps (errno:%d):%s
  ",
  			       nr_maps, strerror(-nr_maps));

  			goto done;
  		}

  		if (load_maps(map_data, nr_maps, fixup_map))

  			goto done;

  		map_data_count = nr_maps;

  
  		processed_sec[maps_shndx] = true;
  	}

  	/* process all relo sections, and rewrite bpf insns for maps */

  	for (i = 1; i < ehdr.e_shnum; i++) {

  		if (processed_sec[i])
  			continue;

  
  		if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
  			continue;

  		if (shdr.sh_type == SHT_REL) {
  			struct bpf_insn *insns;

  			/* locate prog sec that need map fixup (relocations) */

  			if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
  				    &shdr_prog, &data_prog))
  				continue;

  			if (shdr_prog.sh_type != SHT_PROGBITS ||
  			    !(shdr_prog.sh_flags & SHF_EXECINSTR))
  				continue;

  			insns = (struct bpf_insn *) data_prog->d_buf;

  			processed_sec[i] = true; /* relo section */

  			if (parse_relo_and_apply(data, symbols, &shdr, insns,
  						 map_data, nr_maps))

  				continue;

  		}
  	}

  	/* load programs */

  	for (i = 1; i < ehdr.e_shnum; i++) {
  
  		if (processed_sec[i])
  			continue;
  
  		if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
  			continue;

  		if (memcmp(shname, "kprobe/", 7) == 0 ||
  		    memcmp(shname, "kretprobe/", 10) == 0 ||

  		    memcmp(shname, "tracepoint/", 11) == 0 ||

  		    memcmp(shname, "raw_tracepoint/", 15) == 0 ||

  		    memcmp(shname, "xdp", 3) == 0 ||

  		    memcmp(shname, "perf_event", 10) == 0 ||

  		    memcmp(shname, "socket", 6) == 0 ||

  		    memcmp(shname, "cgroup/", 7) == 0 ||

  		    memcmp(shname, "sockops", 7) == 0 ||

  		    memcmp(shname, "sk_skb", 6) == 0 ||
  		    memcmp(shname, "sk_msg", 6) == 0) {

  			ret = load_and_attach(shname, data->d_buf,
  					      data->d_size);
  			if (ret != 0)
  				goto done;
  		}

  	}

  done:

  	close(fd);

  	return ret;
  }
  
  int load_bpf_file(char *path)
  {
  	return do_load_bpf_file(path, NULL);
  }
  
  int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map)
  {
  	return do_load_bpf_file(path, fixup_map);

  }