From: Lukas Sismis <lsismis@oisf.net>
Date: Fri, 31 Mar 2023 12:31:59 +0000 (+0200)
Subject: bpf: refactor the BPF code and postpone querying of the engine mode
X-Git-Tag: suricata-7.0.0-rc2~304
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5a6d5702a48288c70d9a0787cd6fd685964079b4;p=thirdparty%2Fsuricata.git

bpf: refactor the BPF code and postpone querying of the engine mode

BPF codebase queried engine mode earlier than it was determined from
the configuration file/command line. As a result it used the default (IDS)
mode where it could've been configured later on to the IPS mode.
This could lead into an undefined behavior as some Suricata modules behave
according to the engine mode.

PF-Ring, Netmap and AF-Packet all shared almost identical code for
determining the engine mode. It was put into one common function.
Omitted the usage of SCStrdup function in PF-Ring module as it is
uppercased during thread initialization phase.

Ticket: #5957
---

diff --git a/src/runmode-af-packet.c b/src/runmode-af-packet.c
index 6b0e974bb1..6f3d77adff 100644
--- a/src/runmode-af-packet.c
+++ b/src/runmode-af-packet.c
@@ -57,6 +57,7 @@
 #include "util-byte.h"
 
 #include "source-af-packet.h"
+#include "util-bpf.h"
 
 extern intmax_t max_pending_packets;
 
@@ -205,7 +206,6 @@ static void *ParseAFPConfig(const char *iface)
     const char *copymodestr;
     intmax_t value;
     int boolval;
-    const char *bpf_filter = NULL;
     const char *out_iface = NULL;
     int cluster_type = PACKET_FANOUT_HASH;
     const char *ebpf_file = NULL;
@@ -244,14 +244,6 @@ static void *ParseAFPConfig(const char *iface)
     aconf->ebpf_t_config.cpus_count = UtilCpuGetNumProcessorsConfigured();
 #endif
 
-    if (ConfGet("bpf-filter", &bpf_filter) == 1) {
-        if (strlen(bpf_filter) > 0) {
-            aconf->bpf_filter = bpf_filter;
-            SCLogConfig(
-                    "%s: using command-line provided bpf filter '%s'", iface, aconf->bpf_filter);
-        }
-    }
-
     /* Find initial node */
     af_packet_node = ConfGetNode("af-packet");
     if (af_packet_node == NULL) {
@@ -435,16 +427,7 @@ static void *ParseAFPConfig(const char *iface)
                 iface);
     }
 
-    /*load af_packet bpf filter*/
-    /* command line value has precedence */
-    if (ConfGet("bpf-filter", &bpf_filter) != 1) {
-        if (ConfGetChildValueWithDefault(if_root, if_default, "bpf-filter", &bpf_filter) == 1) {
-            if (strlen(bpf_filter) > 0) {
-                aconf->bpf_filter = bpf_filter;
-                SCLogConfig("%s: bpf filter %s", iface, aconf->bpf_filter);
-            }
-        }
-    }
+    ConfSetBPFFilter(if_root, if_default, iface, &aconf->bpf_filter);
 
     if (ConfGetChildValueWithDefault(if_root, if_default, "ebpf-lb-file", &ebpf_file) != 1) {
         aconf->ebpf_lb_file = NULL;
diff --git a/src/runmode-netmap.c b/src/runmode-netmap.c
index 7649e3fc0f..b961bb5713 100644
--- a/src/runmode-netmap.c
+++ b/src/runmode-netmap.c
@@ -48,6 +48,7 @@
 #include "source-netmap.h"
 #include "util-conf.h"
 #include "suricata.h"
+#include "util-bpf.h"
 
 extern intmax_t max_pending_packets;
 
@@ -205,14 +206,6 @@ static int ParseNetmapSettings(NetmapIfaceSettings *ns, const char *iface,
         ns->real = true;
     }
 
-    const char *bpf_filter = NULL;
-    if (ConfGet("bpf-filter", &bpf_filter) == 1) {
-        if (strlen(bpf_filter) > 0) {
-            ns->bpf_filter = bpf_filter;
-            SCLogInfo("%s: using command-line provided bpf filter '%s'", iface, ns->bpf_filter);
-        }
-    }
-
     if (if_root == NULL && if_default == NULL) {
         SCLogInfo("%s: unable to find netmap config for interface \"%s\" or \"default\", using "
                   "default values",
@@ -242,16 +235,7 @@ static int ParseNetmapSettings(NetmapIfaceSettings *ns, const char *iface,
         }
     }
 
-    /* load netmap bpf filter */
-    /* command line value has precedence */
-    if (ns->bpf_filter == NULL) {
-        if (ConfGetChildValueWithDefault(if_root, if_default, "bpf-filter", &bpf_filter) == 1) {
-            if (strlen(bpf_filter) > 0) {
-                ns->bpf_filter = bpf_filter;
-                SCLogInfo("%s: using bpf filter %s", iface, ns->bpf_filter);
-            }
-        }
-    }
+    ConfSetBPFFilter(if_root, if_default, iface, &ns->bpf_filter);
 
     int boolval = 0;
     (void)ConfGetChildValueBoolWithDefault(if_root, if_default, "disable-promisc", (int *)&boolval);
diff --git a/src/runmode-pfring.c b/src/runmode-pfring.c
index c7ab688958..2de535fc27 100644
--- a/src/runmode-pfring.c
+++ b/src/runmode-pfring.c
@@ -21,7 +21,8 @@
 #include "conf.h"
 #include "runmodes.h"
 #include "source-pfring.h"
-
+#include "suricata.h"
+#include "util-bpf.h"
 #include "util-debug.h"
 #include "util-time.h"
 #include "util-cpu.h"
@@ -70,9 +71,6 @@ static void PfringDerefConfig(void *conf)
 {
     PfringIfaceConfig *pfp = (PfringIfaceConfig *)conf;
     if (SC_ATOMIC_SUB(pfp->ref, 1) == 1) {
-        if (pfp->bpf_filter) {
-            SCFree(pfp->bpf_filter);
-        }
         SCFree(pfp);
     }
 }
@@ -201,7 +199,6 @@ static void *ParsePfringConfig(const char *iface)
     const char *tmpctype = NULL;
     cluster_type default_ctype = CLUSTER_FLOW;
     int getctype = 0;
-    const char *bpf_filter = NULL;
     int bool_val;
 
     if (unlikely(pfconf == NULL)) {
@@ -312,30 +309,10 @@ static void *ParsePfringConfig(const char *iface)
         }
     }
 
-    /*load pfring bpf filter*/
-    /* command line value has precedence */
-    if (ConfGet("bpf-filter", &bpf_filter) == 1) {
-        if (strlen(bpf_filter) > 0) {
-            pfconf->bpf_filter = SCStrdup(bpf_filter);
-            if (unlikely(pfconf->bpf_filter == NULL)) {
-                SCLogError("Can't allocate BPF filter string");
-            } else {
-                SCLogDebug("Going to use command-line provided bpf filter %s",
-                           pfconf->bpf_filter);
-            }
-        }
-    } else {
-        if (ConfGetChildValueWithDefault(if_root, if_default, "bpf-filter", &bpf_filter) == 1) {
-            if (strlen(bpf_filter) > 0) {
-                pfconf->bpf_filter = SCStrdup(bpf_filter);
-                if (unlikely(pfconf->bpf_filter == NULL)) {
-                    SCLogError("Can't allocate BPF filter string");
-                } else {
-                    SCLogDebug("Going to use bpf filter %s",
-                               pfconf->bpf_filter);
-                }
-            }
-        }
+    ConfSetBPFFilter(if_root, if_default, pfconf->iface, &pfconf->bpf_filter);
+
+    if (EngineModeIsIPS()) {
+        FatalError("IPS mode not supported in PF_RING.");
     }
 
     if (ConfGet("pfring.cluster-type", &tmpctype) == 1) {
diff --git a/src/source-pfring.h b/src/source-pfring.h
index 163568a9e0..6b170ee78d 100644
--- a/src/source-pfring.h
+++ b/src/source-pfring.h
@@ -44,7 +44,7 @@ typedef struct PfringIfaceConfig_
     /* number of threads */
     int threads;
 
-    char *bpf_filter;
+    const char *bpf_filter;
 
     ChecksumValidationMode checksum_mode;
     SC_ATOMIC_DECLARE(unsigned int, ref);
diff --git a/src/suricata.c b/src/suricata.c
index a8f3f84109..29494f8ebf 100644
--- a/src/suricata.c
+++ b/src/suricata.c
@@ -141,6 +141,7 @@
 #include "util-running-modes.h"
 #include "util-signal.h"
 #include "util-time.h"
+#include "util-validate.h"
 
 /*
  * we put this here, because we only use it here in main.
@@ -456,15 +457,9 @@ static int SetBpfString(int argc, char *argv[])
     if (bpf_len == 0)
         return TM_ECODE_OK;
 
-    if (EngineModeIsIPS()) {
-        SCLogError("BPF filter not available in IPS mode."
-                   " Use firewall filtering if possible.");
-        return TM_ECODE_FAILED;
-    }
-
     bpf_filter = SCMalloc(bpf_len);
     if (unlikely(bpf_filter == NULL))
-        return TM_ECODE_OK;
+        return TM_ECODE_FAILED;
     memset(bpf_filter, 0x00, bpf_len);
 
     tmpindex = optind;
@@ -502,11 +497,6 @@ static void SetBpfStringFromFile(char *filename)
     FILE *fp = NULL;
     size_t nm = 0;
 
-    if (EngineModeIsIPS()) {
-        FatalError("BPF filter not available in IPS mode."
-                   " Use firewall filtering if possible.");
-    }
-
     fp = fopen(filename, "r");
     if (fp == NULL) {
         SCLogError("Failed to open file %s", filename);
diff --git a/src/util-bpf.c b/src/util-bpf.c
index b57dd0f512..443b311c60 100644
--- a/src/util-bpf.c
+++ b/src/util-bpf.c
@@ -24,6 +24,31 @@
 #include "suricata-common.h"
 #include "util-bpf.h"
 #include "threads.h"
+#include "conf.h"
+#include "util-debug.h"
+
+void ConfSetBPFFilter(
+        ConfNode *if_root, ConfNode *if_default, const char *iface, const char **bpf_filter)
+{
+    if (*bpf_filter != NULL) {
+        SCLogInfo("BPF filter already configured");
+        return;
+    }
+
+    /* command line value has precedence */
+    if (ConfGet("bpf-filter", bpf_filter) == 1) {
+        if (strlen(*bpf_filter) > 0) {
+            SCLogConfig("%s: using command-line provided bpf filter '%s'", iface, *bpf_filter);
+        }
+    } else if (ConfGetChildValueWithDefault(if_root, if_default, "bpf-filter", bpf_filter) ==
+               1) { // reading from a file
+        if (strlen(*bpf_filter) > 0) {
+            SCLogConfig("%s: using file provided bpf filter %s", iface, *bpf_filter);
+        }
+    } else {
+        SCLogDebug("No BPF filter found, skipping");
+    }
+}
 
 #if !defined __OpenBSD__
 
diff --git a/src/util-bpf.h b/src/util-bpf.h
index f38d31d5ba..341c158453 100644
--- a/src/util-bpf.h
+++ b/src/util-bpf.h
@@ -24,6 +24,11 @@
 #ifndef __UTIL_BPF_H__
 #define __UTIL_BPF_H__
 
+#include "conf.h"
+
+void ConfSetBPFFilter(
+        ConfNode *if_root, ConfNode *if_default, const char *iface, const char **bpf_filter);
+
 #if !defined __OpenBSD__
 
 int SCBPFCompile(int snaplen_arg, int linktype_arg, struct bpf_program *program,