pcap_mm.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2011 - 2013 Daniel Borkmann.
   4  * Subject to the GPL, version 2.
   5  */
   6
   7 #define _GNU_SOURCE
   8 #include <stdio.h>
   9 #include <sys/types.h>
  10 #include <sys/stat.h>
  11 #include <fcntl.h>
  12 #include <unistd.h>
  13 #include <stdbool.h>
  14 #include <sys/mman.h>
  15
  16 #include "pcap_io.h"
  17 #include "xio.h"
  18 #include "xutils.h"
  19 #include "built_in.h"
  20
  21 static size_t map_size = 0;
  22 static char *ptr_va_start, *ptr_va_curr;
  23
  24 static void __pcap_mmap_write_need_remap(int fd)
  25 {
  26         int ret;
  27         off_t pos, map_size_old = map_size;
  28         off_t offset = ptr_va_curr - ptr_va_start;
  29
  30         map_size = PAGE_ALIGN(map_size_old * 10 / 8);
  31
  32         pos = lseek(fd, map_size, SEEK_SET);
  33         if (pos < 0)
  34                 panic("Cannot lseek pcap file!\n");
  35
  36         ret = write_or_die(fd, "", 1);
  37         if (ret != 1)
  38                 panic("Cannot write file!\n");
  39
  40         ptr_va_start = mremap(ptr_va_start, map_size_old, map_size, MREMAP_MAYMOVE);
  41         if (ptr_va_start == MAP_FAILED)
  42                 panic("mmap of file failed!");
  43
  44         ret = madvise(ptr_va_start, map_size, MADV_SEQUENTIAL);
  45         if (ret < 0)
  46                 panic("Failed to give kernel mmap advise!\n");
  47
  48         ptr_va_curr = ptr_va_start + offset;
  49 }
  50
  51 static ssize_t pcap_mm_write(int fd, pcap_pkthdr_t *phdr, enum pcap_type type,
  52                              const uint8_t *packet, size_t len)
  53 {
  54         size_t hdrsize = pcap_get_hdr_length(phdr, type);
  55
  56         if ((off_t) (ptr_va_curr - ptr_va_start) + hdrsize + len > map_size)
  57                 __pcap_mmap_write_need_remap(fd);
  58
  59         fmemcpy(ptr_va_curr, &phdr->raw, hdrsize);
  60         ptr_va_curr += hdrsize;
  61         fmemcpy(ptr_va_curr, packet, len);
  62         ptr_va_curr += len;
  63
  64         return hdrsize + len;
  65 }
  66
  67 static ssize_t pcap_mm_read(int fd, pcap_pkthdr_t *phdr, enum pcap_type type,
  68                             uint8_t *packet, size_t len)
  69 {
  70         size_t hdrsize = pcap_get_hdr_length(phdr, type), hdrlen;
  71
  72         if (unlikely((off_t) (ptr_va_curr + hdrsize - ptr_va_start) > map_size))
  73                 return -EIO;
  74
  75         fmemcpy(&phdr->raw, ptr_va_curr, hdrsize);
  76         ptr_va_curr += hdrsize;
  77         hdrlen = pcap_get_length(phdr, type);
  78
  79         if (unlikely((off_t) (ptr_va_curr + hdrlen - ptr_va_start) > map_size))
  80                 return -EIO;
  81         if (unlikely(hdrlen == 0 || hdrlen > len))
  82                 return -EINVAL;
  83
  84         fmemcpy(packet, ptr_va_curr, hdrlen);
  85         ptr_va_curr += hdrlen;
  86
  87         return hdrsize + hdrlen;
  88 }
  89
  90 static inline off_t ____get_map_size(bool jumbo)
  91 {
  92         int allocsz = jumbo ? 16 : 3;
  93
  94         return PAGE_ALIGN(sizeof(struct pcap_filehdr) + (PAGE_SIZE * allocsz) * 1024);
  95 }
  96
  97 static void __pcap_mm_prepare_access_wr(int fd, bool jumbo)
  98 {
  99         int ret;
 100         off_t pos;
 101         struct stat sb;
 102
 103         map_size = ____get_map_size(jumbo);
 104
 105         ret = fstat(fd, &sb);
 106         if (ret < 0)
 107                 panic("Cannot fstat pcap file!\n");
 108         if (!S_ISREG (sb.st_mode))
 109                 panic("pcap dump file is not a regular file!\n");
 110
 111         pos = lseek(fd, map_size, SEEK_SET);
 112         if (pos < 0)
 113                 panic("Cannot lseek pcap file!\n");
 114
 115         ret = write_or_die(fd, "", 1);
 116         if (ret != 1)
 117                 panic("Cannot write file!\n");
 118
 119         ptr_va_start = mmap(0, map_size, PROT_WRITE, MAP_SHARED, fd, 0);
 120         if (ptr_va_start == MAP_FAILED)
 121                 panic("mmap of file failed!");
 122         ret = madvise(ptr_va_start, map_size, MADV_SEQUENTIAL);
 123         if (ret < 0)
 124                 panic("Failed to give kernel mmap advise!\n");
 125
 126         ptr_va_curr = ptr_va_start + sizeof(struct pcap_filehdr);
 127 }
 128
 129 static void __pcap_mm_prepare_access_rd(int fd)
 130 {
 131         int ret;
 132         struct stat sb;
 133
 134         ret = fstat(fd, &sb);
 135         if (ret < 0)
 136                 panic("Cannot fstat pcap file!\n");
 137         if (!S_ISREG (sb.st_mode))
 138                 panic("pcap dump file is not a regular file!\n");
 139
 140         map_size = sb.st_size;
 141         ptr_va_start = mmap(0, map_size, PROT_READ, MAP_SHARED | MAP_LOCKED, fd, 0);
 142         if (ptr_va_start == MAP_FAILED)
 143                 panic("mmap of file failed!");
 144         ret = madvise(ptr_va_start, map_size, MADV_SEQUENTIAL);
 145         if (ret < 0)
 146                 panic("Failed to give kernel mmap advise!\n");
 147
 148         ptr_va_curr = ptr_va_start + sizeof(struct pcap_filehdr);
 149 }
 150
 151 static void pcap_mm_init_once(void)
 152 {
 153         set_ioprio_be();
 154 }
 155
 156 static int pcap_mm_prepare_access(int fd, enum pcap_mode mode, bool jumbo)
 157 {
 158         switch (mode) {
 159         case PCAP_MODE_RD:
 160                 __pcap_mm_prepare_access_rd(fd);
 161                 break;
 162         case PCAP_MODE_WR:
 163                 __pcap_mm_prepare_access_wr(fd, jumbo);
 164                 break;
 165         default:
 166                 bug();
 167         }
 168
 169         return 0;
 170 }
 171
 172 static void pcap_mm_fsync(int fd)
 173 {
 174         msync(ptr_va_start, (off_t) (ptr_va_curr - ptr_va_start), MS_ASYNC);
 175 }
 176
 177 static void pcap_mm_prepare_close(int fd, enum pcap_mode mode)
 178 {
 179         int ret;
 180
 181         ret = munmap(ptr_va_start, map_size);
 182         if (ret < 0)
 183                 panic("Cannot unmap the pcap file!\n");
 184
 185         if (mode == PCAP_MODE_WR) {
 186                 ret = ftruncate(fd, (off_t) (ptr_va_curr - ptr_va_start));
 187                 if (ret)
 188                         panic("Cannot truncate the pcap file!\n");
 189         }
 190 }
 191
 192 const struct pcap_file_ops pcap_mm_ops = {
 193         .init_once_pcap = pcap_mm_init_once,
 194         .pull_fhdr_pcap = pcap_generic_pull_fhdr,
 195         .push_fhdr_pcap = pcap_generic_push_fhdr,
 196         .prepare_access_pcap = pcap_mm_prepare_access,
 197         .prepare_close_pcap = pcap_mm_prepare_close,
 198         .read_pcap = pcap_mm_read,
 199         .write_pcap = pcap_mm_write,
 200         .fsync_pcap = pcap_mm_fsync,
 201 };