Merge pull request #1142 from hansleidekker/mmap

Add an option to force memory-mapped buffers to be mapped as accessible to 32-bit code

6 files changed, 34 insertions, 10 deletions

diff --git a/pcap-bpf.c b/pcap-bpf.c
index 2898e598..92e73adf 100644
--- a/pcap-bpf.c
+++ b/pcap-bpf.c
@@ -1790,6 +1790,7 @@ pcap_activate_bpf(pcap_t *p)
 #ifdef HAVE_ZEROCOPY_BPF
 	struct bpf_zbuf bz;
 	u_int bufmode, zbufmax;
+	int flags = MAP_ANON;
 #endif
 
 	fd = bpf_open(p->errbuf);
@@ -2092,10 +2093,13 @@ pcap_activate_bpf(pcap_t *p)
 		pb->zbufsize = roundup(v, getpagesize());
 		if (pb->zbufsize > zbufmax)
 			pb->zbufsize = zbufmax;
+#ifdef MAP_32BIT
+		if (pcap_mmap_32bit) flags |= MAP_32BIT;
+#endif
 		pb->zbuf1 = mmap(NULL, pb->zbufsize, PROT_READ | PROT_WRITE,
-		    MAP_ANON, -1, 0);
+		    flags, -1, 0);
 		pb->zbuf2 = mmap(NULL, pb->zbufsize, PROT_READ | PROT_WRITE,
-		    MAP_ANON, -1, 0);
+		    flags, -1, 0);
 		if (pb->zbuf1 == MAP_FAILED || pb->zbuf2 == MAP_FAILED) {
 			pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
 			    errno, "mmap");
diff --git a/pcap-int.h b/pcap-int.h
index fc703bf8..661ba542 100644
--- a/pcap-int.h
+++ b/pcap-int.h
@@ -108,6 +108,11 @@ extern int pcap_new_api;
 extern int pcap_utf_8_mode;
 
 /*
+ * Map packet buffers with 32-bit addresses.
+ */
+extern int pcap_mmap_32bit;
+
+/*
  * Swap byte ordering of unsigned long long timestamp on a big endian
  * machine.
  */
diff --git a/pcap-linux.c b/pcap-linux.c
index 43d2a9f0..871cb662 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -829,7 +829,7 @@ static void	pcap_cleanup_linux( pcap_t *handle )
 	}
 
 	if (handlep->oneshot_buffer != NULL) {
-		free(handlep->oneshot_buffer);
+		munmap(handlep->oneshot_buffer, handle->snapshot);
 		handlep->oneshot_buffer = NULL;
 	}
 
@@ -2661,14 +2661,17 @@ static int
 setup_mmapped(pcap_t *handle, int *status)
 {
 	struct pcap_linux *handlep = handle->priv;
-	int ret;
+	int ret, flags = MAP_ANONYMOUS | MAP_PRIVATE;
 
 	/*
 	 * Attempt to allocate a buffer to hold the contents of one
 	 * packet, for use by the oneshot callback.
 	 */
-	handlep->oneshot_buffer = malloc(handle->snapshot);
-	if (handlep->oneshot_buffer == NULL) {
+#ifdef MAP_32BIT
+	if (pcap_mmap_32bit) flags |= MAP_32BIT;
+#endif
+	handlep->oneshot_buffer = mmap(0, handle->snapshot, PROT_READ | PROT_WRITE, flags, -1, 0);
+	if (handlep->oneshot_buffer == MAP_FAILED) {
 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
 		    errno, "can't allocate oneshot buffer");
 		*status = PCAP_ERROR;
@@ -2681,7 +2684,7 @@ setup_mmapped(pcap_t *handle, int *status)
 	}
 	ret = prepare_tpacket_socket(handle);
 	if (ret == -1) {
-		free(handlep->oneshot_buffer);
+		munmap(handlep->oneshot_buffer, handle->snapshot);
 		handlep->oneshot_buffer = NULL;
 		*status = PCAP_ERROR;
 		return ret;
@@ -2692,7 +2695,7 @@ setup_mmapped(pcap_t *handle, int *status)
 		 * Error attempting to enable memory-mapped capture;
 		 * fail.  create_ring() has set *status.
 		 */
-		free(handlep->oneshot_buffer);
+		munmap(handlep->oneshot_buffer, handle->snapshot);
 		handlep->oneshot_buffer = NULL;
 		return -1;
 	}
@@ -2870,6 +2873,7 @@ create_ring(pcap_t *handle, int *status)
 {
 	struct pcap_linux *handlep = handle->priv;
 	unsigned i, j, frames_per_block;
+	int flags = MAP_SHARED;
 #ifdef HAVE_TPACKET3
 	/*
 	 * For sockets using TPACKET_V2, the extra stuff at the end of a
@@ -3252,8 +3256,10 @@ retry:
 
 	/* memory map the rx ring */
 	handlep->mmapbuflen = req.tp_block_nr * req.tp_block_size;
-	handlep->mmapbuf = mmap(0, handlep->mmapbuflen,
-	    PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0);
+#ifdef MAP_32BIT
+	if (pcap_mmap_32bit) flags |= MAP_32BIT;
+#endif
+	handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ | PROT_WRITE, flags, handle->fd, 0);
 	if (handlep->mmapbuf == MAP_FAILED) {
 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
 		    errno, "can't mmap rx ring");
diff --git a/pcap.c b/pcap.c
index 005103b9..86246048 100644
--- a/pcap.c
+++ b/pcap.c
@@ -230,6 +230,7 @@ pcap_wsockinit(void)
  */
 int pcap_new_api;		/* pcap_lookupdev() always fails */
 int pcap_utf_8_mode;		/* Strings should be in UTF-8. */
+int pcap_mmap_32bit;		/* Map packet buffers with 32-bit addresses. */
 
 int
 pcap_init(unsigned int opts, char *errbuf)
@@ -267,6 +268,10 @@ pcap_init(unsigned int opts, char *errbuf)
 		pcap_utf_8_mode = 1;
 		break;
 
+	case PCAP_MMAP_32BIT:
+		pcap_mmap_32bit = 1;
+		break;
+
 	default:
 		snprintf(errbuf, PCAP_ERRBUF_SIZE, "Unknown options specified");
 		return (PCAP_ERROR);
diff --git a/pcap/pcap.h b/pcap/pcap.h
index 78570744..88b96847 100644
--- a/pcap/pcap.h
+++ b/pcap/pcap.h
@@ -429,6 +429,7 @@ typedef void (*pcap_handler)(u_char *, const struct pcap_pkthdr *,
  */
 #define PCAP_CHAR_ENC_LOCAL	0x00000000U	/* strings are in the local character encoding */
 #define PCAP_CHAR_ENC_UTF_8	0x00000001U	/* strings are in UTF-8 */
+#define PCAP_MMAP_32BIT	0x00000002U	/* map packet buffers with 32-bit addresses */
 
 PCAP_AVAILABLE_1_10
 PCAP_API int	pcap_init(unsigned int, char *);
diff --git a/pcap_init.3pcap b/pcap_init.3pcap
index a807d0ec..f9876d63 100644
--- a/pcap_init.3pcap
+++ b/pcap_init.3pcap
@@ -49,6 +49,9 @@ caller, as being in the local character encoding.
 .B PCAP_CHAR_ENC_UTF_8
 Treat all strings supplied as arguments, and return all strings to the
 caller, as being in UTF-8.
+.B PCAP_MMAP_32BIT
+Map packet buffers with 32-bit addresses.
+.TP
 .PP
 On UNIX-like systems, the local character encoding is assumed to be
 UTF-8, so no character encoding transformations are done.