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197 lines
5.1 KiB
Diff
197 lines
5.1 KiB
Diff
pppd: Implement support for precompiled pcap filters
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This patch implements support for precompiled pcap filters which is useful to
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support dial-on-demand on memory constrained embedded devices without having
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to link the full libpcap into pppd to generate the filters during runtime.
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Two new options are introduced; "precompiled-pass-filter" specifies a pre-
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compiled filter file containing rules to match packets which should be passed,
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"precompiled-active-filter" specifies a filter file containing rules to match
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packets which are treated as active.
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Signed-off-by: Jo-Philipp Wich <jo@mein.io>
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--- a/pppd/Makefile.linux
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+++ b/pppd/Makefile.linux
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@@ -50,6 +50,9 @@ MPPE=y
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# and that the kernel driver support PPP packet filtering.
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#FILTER=y
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+# Support for precompiled filters
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+PRECOMPILED_FILTER=y
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+
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# Uncomment the next line to enable multilink PPP (enabled by default)
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# Linux distributions: Please leave multilink ENABLED in your builds
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# of pppd!
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@@ -183,6 +186,14 @@ CFLAGS += -DPPP_FILTER -I$(STAGING_DIR)
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endif
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endif
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+ifdef PRECOMPILED_FILTER
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+PPPDSRCS += pcap_pcc.c
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+HEADERS += pcap_pcc.h
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+PPPDOBJS += pcap_pcc.o
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+LIBS += $(STAGING_DIR)/usr/lib/libpcap.a
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+CFLAGS += -DPPP_FILTER -DPPP_PRECOMPILED_FILTER -I$(STAGING_DIR)/usr/include
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+endif
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+
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ifdef HAVE_INET6
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PPPDSRCS += ipv6cp.c eui64.c
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HEADERS += ipv6cp.h eui64.h
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--- a/pppd/options.c
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+++ b/pppd/options.c
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@@ -57,6 +57,7 @@
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#ifdef PPP_FILTER
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#include <pcap.h>
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+#include <pcap-bpf.h>
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/*
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* There have been 3 or 4 different names for this in libpcap CVS, but
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* this seems to be what they have settled on...
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@@ -165,6 +166,13 @@ static int setlogfile __P((char **));
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static int loadplugin __P((char **));
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#endif
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+#ifdef PPP_PRECOMPILED_FILTER
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+#include "pcap_pcc.h"
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+static int setprecompiledpassfilter __P((char **));
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+static int setprecompiledactivefilter __P((char **));
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+#undef PPP_FILTER
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+#endif
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+
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#ifdef PPP_FILTER
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static int setpassfilter __P((char **));
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static int setactivefilter __P((char **));
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@@ -344,6 +352,14 @@ option_t general_options[] = {
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"set filter for active pkts", OPT_PRIO },
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#endif
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+#ifdef PPP_PRECOMPILED_FILTER
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+ { "precompiled-pass-filter", 1, setprecompiledpassfilter,
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+ "set precompiled filter for packets to pass", OPT_PRIO },
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+
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+ { "precompiled-active-filter", 1, setprecompiledactivefilter,
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+ "set precompiled filter for active pkts", OPT_PRIO },
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+#endif
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+
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#ifdef MAXOCTETS
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{ "maxoctets", o_int, &maxoctets,
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"Set connection traffic limit",
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@@ -1493,6 +1509,29 @@ callfile(argv)
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return ok;
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}
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+#ifdef PPP_PRECOMPILED_FILTER
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+/*
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+ * setprecompiledpassfilter - Set the pass filter for packets using a
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+ * precompiled expression
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+ */
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+static int
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+setprecompiledpassfilter(argv)
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+ char **argv;
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+{
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+ return pcap_pre_compiled (*argv, &pass_filter);
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+}
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+
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+/*
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+ * setactivefilter - Set the active filter for packets
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+ */
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+static int
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+setprecompiledactivefilter(argv)
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+ char **argv;
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+{
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+ return pcap_pre_compiled (*argv, &active_filter);
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+}
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+#endif
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+
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#ifdef PPP_FILTER
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/*
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* setpassfilter - Set the pass filter for packets
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--- /dev/null
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+++ b/pppd/pcap_pcc.c
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@@ -0,0 +1,74 @@
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+#include <pcap.h>
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+#include <pcap-bpf.h>
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+#include <stdio.h>
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+#include <stdlib.h>
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+#include <string.h>
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+#include <errno.h>
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+#include "pppd.h"
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+
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+int pcap_pre_compiled (char * fname, struct bpf_program *p)
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+{
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+ char buf[128];
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+ int line = 0, size = 0, index=0, ret=1;
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+ FILE *f = fopen (fname, "r");
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+ if (!f)
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+ {
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+ option_error("error opening precompiled active-filter '%s': %s",
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+ fname, strerror (errno));
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+ return 0;
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+ }
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+ while (fgets (buf, 127, f))
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+ {
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+ line++;
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+ if (*buf == '#')
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+ continue;
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+ if (size)
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+ {
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+ /*
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+ struct bpf_insn {
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+ u_short code;
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+ u_char jt;
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+ u_char jf;
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+ bpf_int32 k;
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+ }
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+ */
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+ struct bpf_insn * insn = & p->bf_insns[index];
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+ unsigned code, jt, jf, k;
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+ if (sscanf (buf, "%u %u %u %u", &code, &jt, &jf, &k) != 4)
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+ {
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+ goto err;
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+ }
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+ insn->code = code;
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+ insn->jt = jt;
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+ insn->jf = jf;
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+ insn->k = k;
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+ index++;
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+ }
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+ else
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+ {
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+ if (sscanf (buf, "%u", &size) != 1)
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+ {
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+ goto err;
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+ }
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+ p->bf_len = size;
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+ p->bf_insns = (struct bpf_insn *)
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+ malloc (size * sizeof (struct bpf_insn));
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+ }
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+ }
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+ if (size != index)
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+ {
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+ option_error("error in precompiled active-filter,"
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+ " expected %d expressions, got %dn",
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+ size, index);
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+ ret = 0;
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+ }
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+ fclose(f);
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+ return ret;
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+
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+err:
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+ option_error("error in precompiled active-filter"
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+ " expression line %s:%d (wrong size)\n",
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+ fname, line);
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+ fclose (f);
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+ return 0;
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+}
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--- /dev/null
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+++ b/pppd/pcap_pcc.h
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@@ -0,0 +1,7 @@
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+#ifndef PCAP_PCC_H
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+#define PCAP_PCC_H
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+
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+#include <pcap.h>
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+
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+int pcap_pre_compiled (char * fname, struct bpf_program *p);
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+#endif /* PCAP_PCC_H */
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