2014/1/21 Michal Privoznik <mprivozn@redhat.com>:
On 20.01.2014 15:04, Yuto KAWAMURA wrote:
2014/1/16 Michal Privoznik <mprivozn@redhat.com>:
On 15.01.2014 18:06, Yuto KAWAMURA(kawamuray) wrote:
From: "Yuto KAWAMURA(kawamuray)" <kawamuray.dadada@gmail.com>
Introduce Wireshark dissector plugin which adds support to Wireshark for dissecting libvirt RPC protocol. Added following files to build Wireshark dissector from libvirt source tree. * tools/wireshark/*: Source tree of Wireshark dissector plugin.
Added followings to configure.ac or Makefile.am. configure.ac * --with-wireshark-dissector: Enable support for building Wireshark dissector. * --with-ws-plugindir: Specify wireshark plugin directory that dissector will installed. * Added tools/wireshark/{Makefile,src/Makefile} to AC_CONFIG_FILES. Makefile.am * Added tools/wireshark/ to SUBDIR. --- .gitignore | 2 + Makefile.am | 3 +- cfg.mk | 8 +- configure.ac | 72 ++- tools/wireshark/Makefile.am | 22 + tools/wireshark/README.md | 31 + tools/wireshark/src/Makefile.am | 42 ++ tools/wireshark/src/packet-libvirt.c | 512 ++++++++++++++++ tools/wireshark/src/packet-libvirt.h | 128 ++++ tools/wireshark/util/genxdrstub.pl | 1011 +++++++++++++++++++++++++++++++ tools/wireshark/util/make-dissector-reg | 198 ++++++ 11 files changed, 2023 insertions(+), 6 deletions(-) create mode 100644 tools/wireshark/Makefile.am create mode 100644 tools/wireshark/README.md create mode 100644 tools/wireshark/src/Makefile.am create mode 100644 tools/wireshark/src/packet-libvirt.c create mode 100644 tools/wireshark/src/packet-libvirt.h create mode 100755 tools/wireshark/util/genxdrstub.pl create mode 100755 tools/wireshark/util/make-dissector-reg
diff --git a/tools/wireshark/src/packet-libvirt.c b/tools/wireshark/src/packet-libvirt.c new file mode 100644 index 0000000..2d0350c --- /dev/null +++ b/tools/wireshark/src/packet-libvirt.c
+static void +dissect_libvirt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) +{ + goffset offset; + guint32 prog, proc, type, serial, status; + const value_string *vs; + + col_set_str(pinfo->cinfo, COL_PROTOCOL, "Libvirt"); + col_clear(pinfo->cinfo, COL_INFO); + + offset = 4; /* End of length field */ + prog = tvb_get_ntohl(tvb, offset); offset += 4; + offset += 4; /* Ignore version header field */ + proc = tvb_get_ntohl(tvb, offset); offset += 4; + type = tvb_get_ntohl(tvb, offset); offset += 4; + serial = tvb_get_ntohl(tvb, offset); offset += 4; + status = tvb_get_ntohl(tvb, offset); offset += 4; + + col_add_fstr(pinfo->cinfo, COL_INFO, "Prog=%s", + val_to_str(prog, program_strings, "%x")); + + vs = get_program_data(prog, VIR_PROGRAM_PROCSTRINGS); + if (vs == NULL) { + col_append_fstr(pinfo->cinfo, COL_INFO, " Proc=%u", proc); + } else { + col_append_fstr(pinfo->cinfo, COL_INFO, " Proc=%s", val_to_str(proc, vs, "%d")); + } + + col_append_fstr(pinfo->cinfo, COL_INFO, " Type=%s Serial=%u Status=%s", + val_to_str(type, type_strings, "%d"), serial, + val_to_str(status, status_strings, "%d")); + + if (tree) { + gint hf_proc; + proto_item *ti; + proto_tree *libvirt_tree; + + ti = proto_tree_add_item(tree, proto_libvirt, tvb, 0, tvb_length(tvb), ENC_NA); + libvirt_tree = proto_item_add_subtree(ti, ett_libvirt); + + offset = 0; + proto_tree_add_item(libvirt_tree, hf_libvirt_length, tvb, offset, 4, ENC_NA); offset += 4; + proto_tree_add_item(libvirt_tree, hf_libvirt_program, tvb, offset, 4, ENC_NA); offset += 4; + proto_tree_add_item(libvirt_tree, hf_libvirt_version, tvb, offset, 4, ENC_NA); offset += 4; + + hf_proc = *(int *)get_program_data(prog, VIR_PROGRAM_PROCHFVAR);
There's a possible NULL dereference here. get_program might return NULL in case @prog is not one of REMOTE, QEMU, LXC, KEEPALIVE. This can possibly happen and it did for me indeed:
Program terminated with signal 11, Segmentation fault. #0 0x00007fac1cc60a86 in dissect_libvirt_message (tvb=0x387acc0, pinfo=0x7fffb9a03100, tree=0x3883090) at packet-libvirt.c:396 396 hf_proc = *(int *)get_program_data(prog, VIR_PROGRAM_PROCHFVAR); (gdb) bt #0 0x00007fac1cc60a86 in dissect_libvirt_message (tvb=0x387acc0, pinfo=0x7fffb9a03100, tree=0x3883090) at packet-libvirt.c:396 #1 0x00000034469198fe in tcp_dissect_pdus () from /usr/lib64/libwireshark.so.3 #2 0x00007fac1cc60c0c in dissect_libvirt (tvb=0x3879aa0, pinfo=0x7fffb9a03100, tree=0x3883090) at packet-libvirt.c:424 #3 0x00000034462dff54 in ?? () from /usr/lib64/libwireshark.so.3 #4 0x00000034462e0608 in ?? () from /usr/lib64/libwireshark.so.3 #5 0x00000034462e0e0c in ?? () from /usr/lib64/libwireshark.so.3 #6 0x00000034462e0e67 in dissector_try_uint () from /usr/lib64/libwireshark.so.3 ...
(gdb) p /x VIR_PROGRAM_PROCHFVAR $1 = 0x0 (gdb) p /x prog $2 = 0xd21c44f9
This happened if I used sasl for authentication (auth_tcp="sasl" listen_tcp=1 listen_tls=0)
+ if (hf_proc == -1) { + proto_tree_add_none_format(libvirt_tree, -1, tvb, offset, 4, "Unknown proc: %u", proc); + } else { + proto_tree_add_item(libvirt_tree, hf_proc, tvb, offset, 4, ENC_NA); + } + offset += 4;
I've tried to fixed this by applying: @@ -381,7 +381,7 @@ dissect_libvirt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) val_to_str(status, status_strings, "%d"));
if (tree) { - gint hf_proc; + gint *hf_proc; proto_item *ti; proto_tree *libvirt_tree;
@@ -393,11 +393,11 @@ dissect_libvirt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) proto_tree_add_item(libvirt_tree, hf_libvirt_program, tvb, offset, 4, ENC_NA); offset += 4; proto_tree_add_item(libvirt_tree, hf_libvirt_version, tvb, offset, 4, ENC_NA); offset += 4;
- hf_proc = *(int *)get_program_data(prog, VIR_PROGRAM_PROCHFVAR); - if (hf_proc == -1) { + hf_proc = (int *)get_program_data(prog, VIR_PROGRAM_PROCHFVAR); + if (!hf_proc || *hf_proc == -1) { proto_tree_add_none_format(libvirt_tree, -1, tvb, offset, 4, "Unknown proc: %u", proc); } else { - proto_tree_add_item(libvirt_tree, hf_proc, tvb, offset, 4, ENC_NA); + proto_tree_add_item(libvirt_tree, *hf_proc, tvb, offset, 4, ENC_NA); } offset += 4;
but it worked only partially as then I was seeing this error messages (but no segfault :) ):
12:29:09 Warn Dissector bug, protocol libvirt, in packet 32: proto.c:1854: failed assertion "(guint)hfindex < gpa_hfinfo.len" (Unregistered hf!)
The error message kept repeating over and over again. The rest of the patch looks okay. Once you fix this (sending a follow-up patch is just fine) I'll push this. Thanks for taking care of the dissector!
Michal
Thanks for review Michal. Fix patch for this bug is following. Regoards.
diff --git a/tools/wireshark/src/packet-libvirt.c b/tools/wireshark/src/packet-libvirt.c index 2d0350c..d64ecce 100644 --- a/tools/wireshark/src/packet-libvirt.c +++ b/tools/wireshark/src/packet-libvirt.c @@ -39,6 +39,7 @@ static int proto_libvirt = -1; static int hf_libvirt_length = -1; static int hf_libvirt_program = -1; static int hf_libvirt_version = -1; +static int hf_libvirt_procedure = -1; static int hf_libvirt_type = -1; static int hf_libvirt_serial = -1; static int hf_libvirt_status = -1; @@ -381,7 +382,7 @@ dissect_libvirt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) val_to_str(status, status_strings, "%d"));
if (tree) { - gint hf_proc; + gint *hf_proc; proto_item *ti; proto_tree *libvirt_tree;
@@ -393,11 +394,12 @@ dissect_libvirt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) proto_tree_add_item(libvirt_tree, hf_libvirt_program, tvb, offset, 4, ENC_NA); offset += 4; proto_tree_add_item(libvirt_tree, hf_libvirt_version, tvb, offset, 4, ENC_NA); offset += 4;
- hf_proc = *(int *)get_program_data(prog, VIR_PROGRAM_PROCHFVAR); - if (hf_proc == -1) { - proto_tree_add_none_format(libvirt_tree, -1, tvb, offset, 4, "Unknown proc: %u", proc); + hf_proc = (int *)get_program_data(prog, VIR_PROGRAM_PROCHFVAR); + if (hf_proc != NULL && *hf_proc != -1) { + proto_tree_add_item(libvirt_tree, *hf_proc, tvb, offset, 4, ENC_NA); } else { - proto_tree_add_item(libvirt_tree, hf_proc, tvb, offset, 4, ENC_NA); + /* No string representation, but still useful displaying proc number */ + proto_tree_add_item(libvirt_tree, hf_libvirt_procedure, tvb, offset, 4, ENC_NA); } offset += 4;
@@ -446,6 +448,12 @@ proto_register_libvirt(void) NULL, 0x0, NULL, HFILL} }, + { &hf_libvirt_procedure, + { "procedure", "libvirt.procedure", + FT_INT32, BASE_DEC, + NULL, 0x0, + NULL, HFILL} + }, { &hf_libvirt_type, { "type", "libvirt.type", FT_INT32, BASE_DEC,
Yes, this fixes the problem. ACK. I'm squashing this in and pushing the series. Thanks!
Michal
Thank you Michal. kawamuray