Date: Sat, 08 Dec 2007 09:26:35 +1300 From: Matthew Luckie <mluckie@cs.waikato.ac.nz> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/118486: [patch][bpf] change BPF filters without discarding buffered packets Message-ID: <E1J0jmN-000GpX-OS@sorcerer.cs.waikato.ac.nz> Resent-Message-ID: <200712072110.lB7LA2pW017913@freefall.freebsd.org>
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>Number: 118486
>Category: kern
>Synopsis: [patch][bpf] change BPF filters without discarding buffered packets
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Fri Dec 07 21:10:01 UTC 2007
>Closed-Date:
>Last-Modified:
>Originator: Matthew Luckie
>Release: FreeBSD 6.2-STABLE i386
>Organization:
>Environment:
System: FreeBSD sorcerer.cs.waikato.ac.nz 6.2-STABLE FreeBSD 6.2-STABLE #0: Mon May 14 13:25:05 NZST 2007 root@sorcerer.cs.waikato.ac.nz:/usr/obj/usr/src/sys/SMP i386
>Description:
BIOCSETF and BIOCSETWF call reset_d which discards any packets
currently in the hold buffer and resets the packet rx count.
The patch below adds BIOCSETFNR, an ioctl that swaps the BPF filter
without resetting the hold buffer and without resetting the packet rx
counts, which is handy when the application wants to adjust its filter
program but without discarding whatever the system might have
buffered.
I've also changed BIOCSETWF to map to the new function. I don't see
the rationale in having BIOCSETWF mucking with the receive stats and
hold buffer.
>How-To-Repeat:
>Fix:
Patch against -HEAD below.
--- bpf-setfnr.patch begins here ---
--- sys/net/bpf.c.orig Mon Nov 19 16:09:09 2007
+++ sys/net/bpf.c Sat Nov 24 12:14:23 2007
@@ -112,7 +112,8 @@
u_int, void (*)(const void *, void *, size_t),
struct timeval *);
static void reset_d(struct bpf_d *);
-static int bpf_setf(struct bpf_d *, struct bpf_program *, u_long cmd);
+static int bpf_setf(struct bpf_d *, struct bpf_program *);
+static int bpf_setfnr(struct bpf_d *, struct bpf_program *, u_long);
static int bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
static int bpf_setdlt(struct bpf_d *, u_int);
static void filt_bpfdetach(struct knote *);
@@ -681,7 +682,6 @@
static void
reset_d(struct bpf_d *d)
{
-
mtx_assert(&d->bd_mtx, MA_OWNED);
if (d->bd_hbuf) {
/* Free the hold buffer. */
@@ -699,8 +699,9 @@
* FIONREAD Check for read packet available.
* SIOCGIFADDR Get interface address - convenient hook to driver.
* BIOCGBLEN Get buffer len [for read()].
- * BIOCSETF Set ethernet read filter.
- * BIOCSETWF Set ethernet write filter.
+ * BIOCSETF Set read filter.
+ * BIOCSETFNR Set read filter without resetting descriptor.
+ * BIOCSETWF Set write filter.
* BIOCFLUSH Flush read packet buffer.
* BIOCPROMISC Put interface into promiscuous mode.
* BIOCGDLT Get link layer type.
@@ -823,8 +824,12 @@
* Set link layer read filter.
*/
case BIOCSETF:
+ error = bpf_setf(d, (struct bpf_program *)addr);
+ break;
+
+ case BIOCSETFNR:
case BIOCSETWF:
- error = bpf_setf(d, (struct bpf_program *)addr, cmd);
+ error = bpf_setfnr(d, (struct bpf_program *)addr, cmd);
break;
/*
@@ -1060,39 +1065,24 @@
* free it and replace it. Returns EINVAL for bogus requests.
*/
static int
-bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
+bpf_setf(struct bpf_d *d, struct bpf_program *fp)
{
struct bpf_insn *fcode, *old;
- u_int wfilter, flen, size;
+ u_int flen, size;
#ifdef BPF_JITTER
- bpf_jit_filter *ofunc;
+ bpf_jit_filter *ofunc, *nfunc;
#endif
- if (cmd == BIOCSETWF) {
- old = d->bd_wfilter;
- wfilter = 1;
-#ifdef BPF_JITTER
- ofunc = NULL;
-#endif
- } else {
- wfilter = 0;
- old = d->bd_rfilter;
-#ifdef BPF_JITTER
- ofunc = d->bd_bfilter;
-#endif
- }
if (fp->bf_insns == NULL) {
if (fp->bf_len != 0)
return (EINVAL);
BPFD_LOCK(d);
- if (wfilter)
- d->bd_wfilter = NULL;
- else {
- d->bd_rfilter = NULL;
+ old = d->bd_rfilter;
+ d->bd_rfilter = NULL;
#ifdef BPF_JITTER
- d->bd_bfilter = NULL;
+ ofunc = d->bd_bfilter;
+ d->bd_bfilter = NULL;
#endif
- }
reset_d(d);
BPFD_UNLOCK(d);
if (old != NULL)
@@ -1111,15 +1101,16 @@
fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
bpf_validate(fcode, (int)flen)) {
+#ifdef BPF_JITTER
+ nfunc = bpf_jitter(fcode, flen);
+#endif
BPFD_LOCK(d);
- if (wfilter)
- d->bd_wfilter = fcode;
- else {
- d->bd_rfilter = fcode;
+ old = d->bd_rfilter;
+ d->bd_rfilter = fcode;
#ifdef BPF_JITTER
- d->bd_bfilter = bpf_jitter(fcode, flen);
+ ofunc = d->bd_bfilter;
+ d->bd_bfilter = nfunc;
#endif
- }
reset_d(d);
BPFD_UNLOCK(d);
if (old != NULL)
@@ -1128,11 +1119,70 @@
if (ofunc != NULL)
bpf_destroy_jit_filter(ofunc);
#endif
-
return (0);
}
free((caddr_t)fcode, M_BPF);
return (EINVAL);
+}
+
+static int
+bpf_setfnr(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
+{
+ struct bpf_insn *fcode, *old;
+ u_int flen, size;
+#ifdef BPF_JITTER
+ bpf_jit_filter *ofunc, *nfunc;
+#endif
+
+ if (fp->bf_insns != NULL) {
+ flen = fp->bf_len;
+ if (flen > bpf_maxinsns)
+ return (EINVAL);
+
+ size = flen * sizeof(*fp->bf_insns);
+ fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
+ if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) != 0 ||
+ bpf_validate(fcode, (int)flen) == 0) {
+ free((caddr_t)fcode, M_BPF);
+ return (EINVAL);
+ }
+#ifdef BPF_JITTER
+ if (cmd == BIOCSETFNR)
+ nfunc = bpf_jitter(fcode, flen);
+ else
+ nfunc = NULL;
+#endif
+ } else {
+ if (fp->bf_len != 0)
+ return (EINVAL);
+ fcode = NULL;
+#ifdef BPF_JITTER
+ nfunc = NULL;
+#endif
+ }
+
+ BPFD_LOCK(d);
+ if (cmd == BIOCSETFNR) {
+ old = d->bd_rfilter;
+ d->bd_rfilter = fcode;
+#ifdef BPF_JITTER
+ ofunc = d->bd_bfilter;
+ d->bd_bfilter = nfunc;
+#endif
+ } else {
+ old = d->bd_wfilter;
+ d->bd_wfilter = fcode;
+ }
+ BPFD_UNLOCK(d);
+
+ if (old != NULL)
+ free((caddr_t)old, M_BPF);
+#ifdef BPF_JITTER
+ if (ofunc != NULL)
+ bpf_destroy_jit_filter(ofunc);
+#endif
+
+ return (0);
}
/*
--- sys/net/bpf.h.orig Mon Nov 19 16:09:17 2007
+++ sys/net/bpf.h Mon Nov 19 16:09:58 2007
@@ -116,6 +116,7 @@
#define BIOCLOCK _IO('B', 122)
#define BIOCSETWF _IOW('B',123, struct bpf_program)
#define BIOCFEEDBACK _IOW('B',124, u_int)
+#define BIOCSETFNR _IOW('B',125, struct bpf_program)
/* Obsolete */
#define BIOCGSEESENT BIOCGDIRECTION
--- share/man/man4/bpf.4.orig Fri Nov 23 09:39:01 2007
+++ share/man/man4/bpf.4 Fri Nov 23 09:57:33 2007
@@ -230,6 +230,7 @@
which must respond to messages in real time.
The default for a new file is off.
.It Dv BIOCSETF
+.It Dv BIOCSETFNR
.Pq Li "struct bpf_program"
Sets the read filter program used by the kernel to discard uninteresting
packets.
@@ -249,12 +250,21 @@
is given by the
.Li bf_len
field.
-Also, the actions of
-.Dv BIOCFLUSH
-are performed.
See section
.Sx "FILTER MACHINE"
for an explanation of the filter language.
+.Pp
+The only difference between
+.Dv BIOCSETF
+and
+.Dv BIOCSETFNR
+is
+.Dv BIOCSETF
+performs the actions of
+.Dv BIOCFLUSH
+while
+.Dv BIOCSETFNR
+does not.
.It Dv BIOCSETWF
.Pq Li "struct bpf_program"
Sets the write filter program used by the kernel to control what type of
--- bpf-setfnr.patch ends here ---
>Release-Note:
>Audit-Trail:
>Unformatted:
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