<p>laforge <strong>merged</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/osmo-mgw/+/15242">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Jenkins Builder: Verified
laforge: Looks good to me, approved
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">fix crashes: don't assert on incoming RTP packet size<br><br>Remove various OSMO_ASSERT() on size of incoming packets. Doing an assert on<br>incoming data is a DoS attack vector, absolute no-go. Instead, return -EINVAL<br>and keep running.<br><br>Change some return values to be able to distinguish successful operation from<br>invalid RTP sizes. In rtp_data_net(), make sure to return negative if the RTP<br>packet was invalid.<br><br>Some of the error return codes implemented here will only be used in upcoming<br>patch Iba115a0b1d74e7cefba5dcdd777e98ddea9eba8c.<br><br>Change-Id: I6bc6ee950ce07bcc2c585c30fad02b81153bdde2<br>---<br>M src/libosmo-mgcp/mgcp_network.c<br>1 file changed, 32 insertions(+), 10 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/src/libosmo-mgcp/mgcp_network.c b/src/libosmo-mgcp/mgcp_network.c</span><br><span>index bb29d2b..e163d23 100644</span><br><span>--- a/src/libosmo-mgcp/mgcp_network.c</span><br><span>+++ b/src/libosmo-mgcp/mgcp_network.c</span><br><span>@@ -475,7 +475,9 @@</span><br><span> uint8_t pt_in;</span><br><span> int pt_out;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- OSMO_ASSERT(len >= sizeof(struct rtp_hdr));</span><br><span style="color: hsl(120, 100%, 40%);">+ if (len < sizeof(struct rtp_hdr))</span><br><span style="color: hsl(120, 100%, 40%);">+ return -EINVAL;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> rtp_hdr = (struct rtp_hdr *)data;</span><br><span> </span><br><span> pt_in = rtp_hdr->payload_type;</span><br><span>@@ -640,8 +642,9 @@</span><br><span> /* There are different dialects used to format and transfer voice data. When</span><br><span> * the receiving end expects GSM-HR data to be formated after RFC 5993, this</span><br><span> * function is used to convert between RFC 5993 and TS 101318, which we normally</span><br><span style="color: hsl(0, 100%, 40%);">- * use. */</span><br><span style="color: hsl(0, 100%, 40%);">-static void rfc5993_hr_convert(struct mgcp_endpoint *endp, char *data, int *len)</span><br><span style="color: hsl(120, 100%, 40%);">+ * use.</span><br><span style="color: hsl(120, 100%, 40%);">+ * Return 0 on sucess, negative on errors like invalid data length. */</span><br><span style="color: hsl(120, 100%, 40%);">+static int rfc5993_hr_convert(struct mgcp_endpoint *endp, char *data, int *len)</span><br><span> {</span><br><span> /* NOTE: *data has an overall length of RTP_BUF_SIZE, so there is</span><br><span> * plenty of space available to store the slightly larger, converted</span><br><span>@@ -649,7 +652,12 @@</span><br><span> </span><br><span> struct rtp_hdr *rtp_hdr;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- OSMO_ASSERT(*len >= sizeof(struct rtp_hdr));</span><br><span style="color: hsl(120, 100%, 40%);">+ if (*len < sizeof(struct rtp_hdr)) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPENDP(endp, DRTP, LOGL_ERROR, "AMR RTP packet too short (%d < %zu)\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ *len, sizeof(struct rtp_hdr));</span><br><span style="color: hsl(120, 100%, 40%);">+ return -EINVAL;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> rtp_hdr = (struct rtp_hdr *)data;</span><br><span> </span><br><span> if (*len == GSM_HR_BYTES + sizeof(struct rtp_hdr)) {</span><br><span>@@ -667,7 +675,9 @@</span><br><span> * packet. This is not supported yet. */</span><br><span> LOGPENDP(endp, DRTP, LOGL_ERROR,</span><br><span> "cannot figure out how to convert RTP packet\n");</span><br><span style="color: hsl(120, 100%, 40%);">+ return -ENOTSUP;</span><br><span> }</span><br><span style="color: hsl(120, 100%, 40%);">+ return 0;</span><br><span> }</span><br><span> </span><br><span> /* For AMR RTP two framing modes are defined RFC3267. There is a bandwith</span><br><span>@@ -685,7 +695,11 @@</span><br><span> unsigned int payload_len;</span><br><span> int rc;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- OSMO_ASSERT(*len >= sizeof(struct rtp_hdr));</span><br><span style="color: hsl(120, 100%, 40%);">+ if (*len < sizeof(struct rtp_hdr)) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPENDP(endp, DRTP, LOGL_ERROR, "AMR RTP packet too short (%d < %zu)\n", *len, sizeof(struct rtp_hdr));</span><br><span style="color: hsl(120, 100%, 40%);">+ return -EINVAL;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> rtp_hdr = (struct rtp_hdr *)data;</span><br><span> </span><br><span> payload_len = *len - sizeof(struct rtp_hdr);</span><br><span>@@ -735,18 +749,23 @@</span><br><span> }</span><br><span> </span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">-/* Check if a given RTP with AMR payload for octet-aligned mode */</span><br><span style="color: hsl(0, 100%, 40%);">-static bool amr_oa_check(char *data, int len)</span><br><span style="color: hsl(120, 100%, 40%);">+/* Return whether an RTP packet with AMR payload is in octet-aligned mode.</span><br><span style="color: hsl(120, 100%, 40%);">+ * Return 0 if in bandwidth-efficient mode, 1 for octet-aligned mode, and negative if the RTP data is invalid. */</span><br><span style="color: hsl(120, 100%, 40%);">+static int amr_oa_check(char *data, int len)</span><br><span> {</span><br><span> struct rtp_hdr *rtp_hdr;</span><br><span> unsigned int payload_len;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- OSMO_ASSERT(len >= sizeof(struct rtp_hdr));</span><br><span style="color: hsl(120, 100%, 40%);">+ if (len < sizeof(struct rtp_hdr))</span><br><span style="color: hsl(120, 100%, 40%);">+ return -EINVAL;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> rtp_hdr = (struct rtp_hdr *)data;</span><br><span> </span><br><span> payload_len = len - sizeof(struct rtp_hdr);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (payload_len < sizeof(struct amr_hdr))</span><br><span style="color: hsl(120, 100%, 40%);">+ return -EINVAL;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- return osmo_amr_is_oa(rtp_hdr->data, payload_len);</span><br><span style="color: hsl(120, 100%, 40%);">+ return osmo_amr_is_oa(rtp_hdr->data, payload_len) ? 1 : 0;</span><br><span> }</span><br><span> </span><br><span> /* Forward data to a debug tap. This is debug function that is intended for</span><br><span>@@ -1340,7 +1359,10 @@</span><br><span> * define, then we check if the incoming payload matches that</span><br><span> * expectation. */</span><br><span> if (amr_oa_bwe_convert_indicated(conn_src->end.codec)) {</span><br><span style="color: hsl(0, 100%, 40%);">- if (amr_oa_check(buf, len) != conn_src->end.codec->param.amr_octet_aligned)</span><br><span style="color: hsl(120, 100%, 40%);">+ int oa = amr_oa_check(buf, len);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (oa < 0)</span><br><span style="color: hsl(120, 100%, 40%);">+ return -1;</span><br><span style="color: hsl(120, 100%, 40%);">+ if (((bool)oa) != conn_src->end.codec->param.amr_octet_aligned)</span><br><span> return -1;</span><br><span> }</span><br><span> </span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-mgw/+/15242">change 15242</a>. 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<div style="display:none"> Gerrit-Project: osmo-mgw </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: I6bc6ee950ce07bcc2c585c30fad02b81153bdde2 </div>
<div style="display:none"> Gerrit-Change-Number: 15242 </div>
<div style="display:none"> Gerrit-PatchSet: 3 </div>
<div style="display:none"> Gerrit-Owner: neels <nhofmeyr@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: laforge <laforge@gnumonks.org> </div>
<div style="display:none"> Gerrit-Reviewer: neels <nhofmeyr@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>