116 lines
3.6 KiB
Diff
116 lines
3.6 KiB
Diff
From: Antonio Torres <antorres@redhat.com>
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Date: Fri, 09 Dec 2022
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Subject: Fix crash on unknown option in EAP-SIM
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When an EAP-SIM supplicant sends an unknown SIM option, the server will try to
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look that option up in the internal dictionaries. This lookup will fail, but the
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SIM code will not check for that failure. Instead, it will dereference a NULL
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pointer, and cause the server to crash.
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Backport of:
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https://github.com/FreeRADIUS/freeradius-server/commit/f1cdbb33ec61c4a64a
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https://github.com/FreeRADIUS/freeradius-server/commit/71128cac3ee236a88a05cc7bddd43e43a88a3089
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Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2151704
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Signed-off-by: Antonio Torres <antorres@redhat.com>
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---
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diff --git a/src/modules/rlm_eap/libeap/eapsimlib.c b/src/modules/rlm_eap/libeap/eapsimlib.c
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index cf1e8a7dd92..e438a844eab 100644
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--- a/src/modules/rlm_eap/libeap/eapsimlib.c
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+++ b/src/modules/rlm_eap/libeap/eapsimlib.c
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@@ -307,42 +307,77 @@ int unmap_eapsim_basictypes(RADIUS_PACKET *r,
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newvp->vp_length = 1;
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fr_pair_add(&(r->vps), newvp);
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+ /*
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+ * EAP-SIM has a 1 octet of subtype, and 2 octets
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+ * reserved.
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+ */
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attr += 3;
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attrlen -= 3;
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- /* now, loop processing each attribute that we find */
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- while(attrlen > 0) {
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+ /*
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+ * Loop over each attribute. The format is:
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+ *
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+ * 1 octet of type
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+ * 1 octet of length (value 1..255)
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+ * ((4 * length) - 2) octets of data.
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+ */
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+ while (attrlen > 0) {
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uint8_t *p;
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- if(attrlen < 2) {
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+ if (attrlen < 2) {
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fr_strerror_printf("EAP-Sim attribute %d too short: %d < 2", es_attribute_count, attrlen);
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return 0;
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}
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+ if (!attr[1]) {
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+ fr_strerror_printf("EAP-Sim attribute %d (no.%d) has no data", attr[0],
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+ es_attribute_count);
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+ return 0;
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+ }
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+
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eapsim_attribute = attr[0];
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eapsim_len = attr[1] * 4;
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+ /*
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+ * The length includes the 2-byte header.
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+ */
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if (eapsim_len > attrlen) {
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fr_strerror_printf("EAP-Sim attribute %d (no.%d) has length longer than data (%d > %d)",
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eapsim_attribute, es_attribute_count, eapsim_len, attrlen);
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return 0;
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}
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- if(eapsim_len > MAX_STRING_LEN) {
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- eapsim_len = MAX_STRING_LEN;
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- }
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- if (eapsim_len < 2) {
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- fr_strerror_printf("EAP-Sim attribute %d (no.%d) has length too small", eapsim_attribute,
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- es_attribute_count);
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- return 0;
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- }
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+ newvp = fr_pair_afrom_num(r, eapsim_attribute + PW_EAP_SIM_BASE, 0);
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+ if (!newvp) {
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+ /*
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+ * RFC 4186 Section 8.1 says 0..127 are
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+ * "non-skippable". If one such
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+ * attribute is found and we don't
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+ * understand it, the server has to send:
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+ *
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+ * EAP-Request/SIM/Notification packet with an
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+ * (AT_NOTIFICATION code, which implies general failure ("General
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+ * failure after authentication" (0), or "General failure" (16384),
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+ * depending on the phase of the exchange), which terminates the
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+ * authentication exchange.
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+ */
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+ if (eapsim_attribute <= 127) {
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+ fr_strerror_printf("Unknown mandatory attribute %d, failing",
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+ eapsim_attribute);
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+ return 0;
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+ }
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- newvp = fr_pair_afrom_num(r, eapsim_attribute+PW_EAP_SIM_BASE, 0);
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- newvp->vp_length = eapsim_len-2;
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- newvp->vp_octets = p = talloc_array(newvp, uint8_t, newvp->vp_length);
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- memcpy(p, &attr[2], eapsim_len-2);
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- fr_pair_add(&(r->vps), newvp);
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- newvp = NULL;
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+ } else {
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+ /*
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+ * It's known, ccount for header, and
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+ * copy the value over.
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+ */
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+ newvp->vp_length = eapsim_len - 2;
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+
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+ newvp->vp_octets = p = talloc_array(newvp, uint8_t, newvp->vp_length);
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+ memcpy(p, &attr[2], newvp->vp_length);
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+ fr_pair_add(&(r->vps), newvp);
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+ }
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/* advance pointers, decrement length */
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attr += eapsim_len;
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