The Samba-Bugzilla – Attachment 17600 Details for
Bug 15203
CVE-2022-42898 [SECURITY] krb5_pac_parse() buffer parsing vulnerability
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Nico's version of Joseph's patch for Heimdal
CVE-2022-42898-heimdal-nico.patch (text/plain), 34.06 KB, created by
nico
on 2022-10-25 06:15:31 UTC
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Description:
Nico's version of Joseph's patch for Heimdal
Filename:
MIME Type:
Creator:
nico
Created:
2022-10-25 06:15:31 UTC
Size:
34.06 KB
patch
obsolete
>commit 3ae96e8aeb02ab2cf4ab388fd6174d5a95a96c45 >Author: Joseph Sutton <josephsutton@catalyst.net.nz> >Date: Fri Oct 14 16:45:37 2022 +1300 > > krb5: CVE-2022-42898 PAC parse integer overflows > > Catch overflows that result from adding PAC_INFO_BUFFER_SIZE. > > Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=15203 > > Heavily edited by committer Nico Williams <nico@twosigma.com>, original by > Joseph Sutton <josephsutton@catalyst.net.nz>. > > Signed-off-by: Nico Williams <nico@twosigma.com> > >diff --git a/lib/krb5/pac.c b/lib/krb5/pac.c >index 122120c10..54bc2b971 100644 >--- a/lib/krb5/pac.c >+++ b/lib/krb5/pac.c >@@ -37,19 +37,34 @@ > #include <wind.h> > #include <assert.h> > >+/* >+ * https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-pac/3341cfa2-6ef5-42e0-b7bc-4544884bf399 >+ */ > struct PAC_INFO_BUFFER { >- uint32_t type; >- uint32_t buffersize; >- uint32_t offset_hi; >- uint32_t offset_lo; >+ uint32_t type; /* ULONG ulType in the original */ >+ uint32_t buffersize; /* ULONG cbBufferSize in the original */ >+ uint64_t offset; /* ULONG64 Offset in the original >+ * this being the offset from the beginning of the >+ * struct PACTYPE to the beginning of the buffer >+ * containing data of type ulType >+ */ > }; > >+/* >+ * https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-pac/6655b92f-ab06-490b-845d-037e6987275f >+ */ > struct PACTYPE { >- uint32_t numbuffers; >- uint32_t version; >- struct PAC_INFO_BUFFER buffers[1]; >+ uint32_t numbuffers; /* named cBuffers of type ULONG in the original */ >+ uint32_t version; /* Named Version of type ULONG in the original */ >+ struct PAC_INFO_BUFFER buffers[1]; /* an ellipsis (...) in the original */ > }; > >+/* >+ * A PAC starts with a PACTYPE header structure that is followed by an array of >+ * numbuffers PAC_INFO_BUFFER structures, each of which points to a buffer >+ * beyond the last PAC_INFO_BUFFER structures. >+ */ >+ > struct krb5_pac_data { > struct PACTYPE *pac; > krb5_data data; >@@ -133,6 +148,60 @@ struct heim_type_data pac_object = { > NULL > }; > >+/* >+ * Returns the size of the PACTYPE header + the PAC_INFO_BUFFER array. This is >+ * also the end of the whole thing, and any offsets to buffers from >+ * thePAC_INFO_BUFFER[] entries have to be beyond it. >+ */ >+static krb5_error_code >+pac_header_size(krb5_context context, uint32_t num_buffers, uint32_t *result) >+{ >+ krb5_error_code ret; >+ uint32_t header_size; >+ >+ /* Guard against integer overflow */ >+ if (num_buffers > UINT32_MAX / PAC_INFO_BUFFER_SIZE) { >+ ret = EOVERFLOW; >+ krb5_set_error_message(context, ret, "PAC has too many buffers"); >+ return ret; >+ } >+ header_size = PAC_INFO_BUFFER_SIZE * num_buffers; >+ >+ /* Guard against integer overflow */ >+ if (header_size > UINT32_MAX - PACTYPE_SIZE) { >+ ret = EOVERFLOW; >+ krb5_set_error_message(context, ret, "PAC has too many buffers"); >+ return ret; >+ } >+ header_size += PACTYPE_SIZE; >+ >+ *result = header_size; >+ >+ return 0; >+} >+ >+/* Output `size' + `addend' + padding for alignment if it doesn't overflow */ >+static krb5_error_code >+pac_aligned_size(krb5_context context, >+ uint32_t size, >+ uint32_t addend, >+ uint32_t *aligned_size) >+{ >+ krb5_error_code ret; >+ >+ if (size > UINT32_MAX - addend || >+ (size + addend) > UINT32_MAX - (PAC_ALIGNMENT - 1)) { >+ ret = EOVERFLOW; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ return ret; >+ } >+ size += addend; >+ size += PAC_ALIGNMENT - 1; >+ size &= ~(PAC_ALIGNMENT - 1); >+ *aligned_size = size; >+ return 0; >+} >+ > /* > * HMAC-MD5 checksum over any key (needed for the PAC routines) > */ >@@ -184,165 +253,164 @@ KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL > krb5_pac_parse(krb5_context context, const void *ptr, size_t len, > krb5_pac *pac) > { >- krb5_error_code ret; >+ krb5_error_code ret = 0; > krb5_pac p; > krb5_storage *sp = NULL; >- uint32_t i, tmp, tmp2, header_end; >+ uint32_t i, num_buffers, version, header_size; >+ uint32_t prev_start = 0; >+ uint32_t prev_end = 0; > >+ *pac = NULL; > p = _heim_alloc_object(&pac_object, sizeof(*p)); >- if (p == NULL) { >- ret = krb5_enomem(context); >- goto out; >- } >- >- sp = krb5_storage_from_readonly_mem(ptr, len); >- if (sp == NULL) { >+ if (p) >+ sp = krb5_storage_from_readonly_mem(ptr, len); >+ if (sp == NULL) > ret = krb5_enomem(context); >- goto out; >- } >- krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE); >- >- CHECK(ret, krb5_ret_uint32(sp, &tmp), out); >- CHECK(ret, krb5_ret_uint32(sp, &tmp2), out); >- if (tmp < 1) { >- ret = EINVAL; /* Too few buffers */ >- krb5_set_error_message(context, ret, N_("PAC has too few buffers", "")); >- goto out; >+ if (ret == 0) { >+ krb5_storage_set_flags(sp, KRB5_STORAGE_BYTEORDER_LE); >+ ret = krb5_ret_uint32(sp, &num_buffers); > } >- if (tmp2 != 0) { >- ret = EINVAL; /* Wrong version */ >- krb5_set_error_message(context, ret, >+ if (ret == 0) >+ ret = krb5_ret_uint32(sp, &version); >+ if (ret == 0 && num_buffers < 1) >+ krb5_set_error_message(context, ret = EINVAL, >+ N_("PAC has too few buffers", "")); >+ if (ret == 0 && num_buffers > 1000) >+ krb5_set_error_message(context, ret = EINVAL, >+ N_("PAC has too many buffers", "")); >+ if (ret == 0 && version != 0) >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC has wrong version %d", ""), >- (int)tmp2); >- goto out; >- } >- >- p->pac = calloc(1, >- sizeof(*p->pac) + (sizeof(p->pac->buffers[0]) * (tmp - 1))); >- if (p->pac == NULL) { >+ (int)version); >+ if (ret == 0) >+ ret = pac_header_size(context, num_buffers, &header_size); >+ if (ret == 0 && header_size > len) >+ krb5_set_error_message(context, ret = EOVERFLOW, >+ N_("PAC encoding invalid, would overflow buffers", "")); >+ if (ret == 0) >+ p->pac = calloc(1, header_size); >+ if (p->pac == NULL) > ret = krb5_enomem(context); >- goto out; >- } > >- p->pac->numbuffers = tmp; >- p->pac->version = tmp2; >- >- header_end = PACTYPE_SIZE + (PAC_INFO_BUFFER_SIZE * p->pac->numbuffers); >- if (header_end > len) { >- ret = EINVAL; >- goto out; >+ if (ret == 0) { >+ p->pac->numbuffers = num_buffers; >+ p->pac->version = version; > } > >- for (i = 0; i < p->pac->numbuffers; i++) { >- CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].type), out); >- CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].buffersize), out); >- CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].offset_lo), out); >- CHECK(ret, krb5_ret_uint32(sp, &p->pac->buffers[i].offset_hi), out); >+ for (i = 0; ret == 0 && i < p->pac->numbuffers; i++) { >+ ret = krb5_ret_uint32(sp, &p->pac->buffers[i].type); >+ if (ret == 0) >+ ret = krb5_ret_uint32(sp, &p->pac->buffers[i].buffersize); >+ if (ret == 0) >+ ret = krb5_ret_uint64(sp, &p->pac->buffers[i].offset); >+ if (ret) >+ break; > >- /* consistency checks */ >- if (p->pac->buffers[i].offset_lo & (PAC_ALIGNMENT - 1)) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >+ /* Consistency checks (we don't check for wasted space) */ >+ if (p->pac->buffers[i].offset & (PAC_ALIGNMENT - 1)) { >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC out of alignment", "")); >- goto out; >+ break; > } >- if (p->pac->buffers[i].offset_hi) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >- N_("PAC high offset set", "")); >- goto out; >- } >- if (p->pac->buffers[i].offset_lo > len) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >- N_("PAC offset overflow", "")); >- goto out; >+ if (p->pac->buffers[i].offset > len || >+ p->pac->buffers[i].buffersize > len || >+ len - p->pac->buffers[i].offset < p->pac->buffers[i].buffersize) { >+ krb5_set_error_message(context, ret = EOVERFLOW, >+ N_("PAC buffer overflow", "")); >+ break; > } >- if (p->pac->buffers[i].offset_lo < header_end) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >+ if (p->pac->buffers[i].offset < header_size) { >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC offset inside header: %lu %lu", ""), >- (unsigned long)p->pac->buffers[i].offset_lo, >- (unsigned long)header_end); >- goto out; >- } >- if (p->pac->buffers[i].buffersize > len - p->pac->buffers[i].offset_lo){ >- ret = EINVAL; >- krb5_set_error_message(context, ret, N_("PAC length overflow", "")); >- goto out; >+ (unsigned long)p->pac->buffers[i].offset, >+ (unsigned long)header_size); >+ break; > } > >- /* let save pointer to data we need later */ >- if (p->pac->buffers[i].type == PAC_SERVER_CHECKSUM) { >- if (p->server_checksum) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >+ /* >+ * We'd like to check for non-overlapping of buffers, but the buffers >+ * need not be in the same order as the PAC_INFO_BUFFER[] entries >+ * pointing to them! To fully check for overlap we'd have to have an >+ * O(N^2) loop after we parse all the PAC_INFO_BUFFER[]. >+ * >+ * But we can check that each buffer does not overlap the previous >+ * buffer. >+ */ >+ if (prev_start) { >+ if (p->pac->buffers[i].offset >= prev_start && >+ p->pac->buffers[i].offset < prev_end) { >+ krb5_set_error_message(context, ret = EINVAL, >+ N_("PAC overlap", "")); >+ break; >+ } >+ if (p->pac->buffers[i].offset < prev_start && >+ p->pac->buffers[i].offset + >+ p->pac->buffers[i].buffersize > prev_start) { >+ krb5_set_error_message(context, ret = EINVAL, >+ N_("PAC overlap", "")); >+ break; >+ } >+ } >+ prev_start = p->pac->buffers[i].offset; >+ prev_end = p->pac->buffers[i].offset + p->pac->buffers[i].buffersize; >+ >+ /* Let's save pointers to buffers we'll need later */ >+ switch (p->pac->buffers[i].type) { >+ case PAC_SERVER_CHECKSUM: >+ if (p->server_checksum) >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC has multiple server checksums", "")); >- goto out; >- } >- p->server_checksum = &p->pac->buffers[i]; >- } else if (p->pac->buffers[i].type == PAC_PRIVSVR_CHECKSUM) { >- if (p->privsvr_checksum) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >- N_("PAC has multiple KDC checksums", "")); >- goto out; >- } >- p->privsvr_checksum = &p->pac->buffers[i]; >- } else if (p->pac->buffers[i].type == PAC_LOGON_NAME) { >- if (p->logon_name) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >- N_("PAC has multiple logon names", "")); >- goto out; >- } >- p->logon_name = &p->pac->buffers[i]; >- } else if (p->pac->buffers[i].type == PAC_UPN_DNS_INFO) { >- if (p->upn_dns_info) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >+ else >+ p->server_checksum = &p->pac->buffers[i]; >+ break; >+ case PAC_PRIVSVR_CHECKSUM: >+ if (p->privsvr_checksum) >+ krb5_set_error_message(context, ret = EINVAL, >+ N_("PAC has multiple KDC checksums", "")); >+ else >+ p->privsvr_checksum = &p->pac->buffers[i]; >+ break; >+ case PAC_LOGON_NAME: >+ if (p->logon_name) >+ krb5_set_error_message(context, ret = EINVAL, >+ N_("PAC has multiple logon names", "")); >+ else >+ p->logon_name = &p->pac->buffers[i]; >+ break; >+ case PAC_UPN_DNS_INFO: >+ if (p->upn_dns_info) >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC has multiple UPN DNS info buffers", "")); >- goto out; >- } >- p->upn_dns_info = &p->pac->buffers[i]; >- } else if (p->pac->buffers[i].type == PAC_TICKET_CHECKSUM) { >- if (p->ticket_checksum) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >+ else >+ p->upn_dns_info = &p->pac->buffers[i]; >+ break; >+ case PAC_TICKET_CHECKSUM: >+ if (p->ticket_checksum) >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC has multiple ticket checksums", "")); >- goto out; >- } >- p->ticket_checksum = &p->pac->buffers[i]; >- } else if (p->pac->buffers[i].type == PAC_ATTRIBUTES_INFO) { >- if (p->attributes_info) { >- ret = EINVAL; >- krb5_set_error_message(context, ret, >+ else >+ p->ticket_checksum = &p->pac->buffers[i]; >+ break; >+ case PAC_ATTRIBUTES_INFO: >+ if (p->attributes_info) >+ krb5_set_error_message(context, ret = EINVAL, > N_("PAC has multiple attributes info buffers", "")); >- goto out; >- } >- p->attributes_info = &p->pac->buffers[i]; >- } >+ else >+ p->attributes_info = &p->pac->buffers[i]; >+ break; >+ default: break; >+ } > } > >- ret = krb5_data_copy(&p->data, ptr, len); >- if (ret) >- goto out; >- >- krb5_storage_free(sp); >- >- *pac = p; >- return 0; >- >-out: >- if (sp) >- krb5_storage_free(sp); >- if (p) { >- if (p->pac) >- free(p->pac); >- krb5_pac_free(context, p); >+ if (ret == 0) >+ ret = krb5_data_copy(&p->data, ptr, len); >+ if (ret == 0) { >+ *pac = p; >+ p = NULL; > } >- *pac = NULL; >- >+ if (sp) >+ krb5_storage_free(sp); >+ krb5_pac_free(context, p); > return ret; > } > >@@ -369,77 +437,111 @@ krb5_pac_init(krb5_context context, krb5_pac *pac) > krb5_pac_free(context, p); > return krb5_enomem(context); > } >+ memset(p->data.data, 0, p->data.length); > > *pac = p; > return 0; > } > >+/** >+ * Add a PAC buffer `nd' of type `type' to the pac `p'. >+ * >+ * @param context >+ * @param p >+ * @param type >+ * @param nd >+ * >+ * @return 0 on success or a Kerberos or system error. >+ */ > KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL > krb5_pac_add_buffer(krb5_context context, krb5_pac p, >- uint32_t type, const krb5_data *data) >+ uint32_t type, const krb5_data *nd) > { > krb5_error_code ret; > void *ptr; >- size_t len, offset, header_end, old_end; >+ size_t old_len = p->data.length; >+ uint32_t len, offset, header_size; > uint32_t i; >+ uint32_t num_buffers; > >- assert(data->data != NULL); >+ assert(nd->data != NULL); > >- len = p->pac->numbuffers; >+ num_buffers = p->pac->numbuffers; >+ ret = pac_header_size(context, num_buffers + 1, &header_size); >+ if (ret) >+ return ret; > >- ptr = realloc(p->pac, >- sizeof(*p->pac) + (sizeof(p->pac->buffers[0]) * len)); >+ ptr = realloc(p->pac, header_size); > if (ptr == NULL) > return krb5_enomem(context); > > p->pac = ptr; >+ p->pac->buffers[num_buffers].type = 0; >+ p->pac->buffers[num_buffers].buffersize = 0; >+ p->pac->buffers[num_buffers].offset = 0; > >- for (i = 0; i < len; i++) >- p->pac->buffers[i].offset_lo += PAC_INFO_BUFFER_SIZE; >- >- offset = p->data.length + PAC_INFO_BUFFER_SIZE; >- >- p->pac->buffers[len].type = type; >- p->pac->buffers[len].buffersize = data->length; >- p->pac->buffers[len].offset_lo = offset; >- p->pac->buffers[len].offset_hi = 0; >- >- old_end = p->data.length; >- len = p->data.length + data->length + PAC_INFO_BUFFER_SIZE; >- if (len < p->data.length) { >- krb5_set_error_message(context, EINVAL, "integer overrun"); >- return EINVAL; >+ /* >+ * Check that we can adjust all the buffer offsets in the existing >+ * PAC_INFO_BUFFERs, since changing the size of PAC_INFO_BUFFER[] means >+ * changing the offsets of buffers following that array. >+ * >+ * We don't adjust them until we can't fail. >+ */ >+ for (i = 0; i < num_buffers; i++) { >+ if (p->pac->buffers[i].offset > UINT32_MAX - PAC_INFO_BUFFER_SIZE) { >+ krb5_set_error_message(context, ret = EOVERFLOW, >+ "too many / too large PAC buffers"); >+ return ret; >+ } > } > >- /* align to PAC_ALIGNMENT */ >- len = ((len + PAC_ALIGNMENT - 1) / PAC_ALIGNMENT) * PAC_ALIGNMENT; >+ /* >+ * The new buffer's offset must be past the end of the buffers we have >+ * (p->data), which is the sum of the header and p->data.length. >+ */ > >+ /* Set offset = p->data.length + PAC_INFO_BUFFER_SIZE + alignment */ >+ ret = pac_aligned_size(context, p->data.length, PAC_INFO_BUFFER_SIZE, &offset); >+ if (ret == 0) >+ /* Set the new length = offset + nd->length + alignment */ >+ ret = pac_aligned_size(context, offset, nd->length, &len); >+ if (ret) { >+ krb5_set_error_message(context, ret, "PAC buffer too large"); >+ return ret; >+ } > ret = krb5_data_realloc(&p->data, len); > if (ret) { > krb5_set_error_message(context, ret, N_("malloc: out of memory", "")); > return ret; > } > >+ /* Zero out the new allocation to zero out any padding */ >+ memset((char *)p->data.data + old_len, 0, len - old_len); >+ >+ p->pac->buffers[num_buffers].type = type; >+ p->pac->buffers[num_buffers].buffersize = nd->length; >+ p->pac->buffers[num_buffers].offset = offset; >+ >+ /* Adjust all the buffer offsets in the existing PAC_INFO_BUFFERs now */ >+ for (i = 0; i < num_buffers; i++) >+ p->pac->buffers[i].offset += PAC_INFO_BUFFER_SIZE; >+ > /* >- * make place for new PAC INFO BUFFER header >+ * Make place for new PAC INFO BUFFER header > */ >- header_end = PACTYPE_SIZE + (PAC_INFO_BUFFER_SIZE * p->pac->numbuffers); >- memmove((unsigned char *)p->data.data + header_end + PAC_INFO_BUFFER_SIZE, >- (unsigned char *)p->data.data + header_end , >- old_end - header_end); >- memset((unsigned char *)p->data.data + header_end, 0, PAC_INFO_BUFFER_SIZE); >+ header_size -= PAC_INFO_BUFFER_SIZE; >+ memmove((unsigned char *)p->data.data + header_size + PAC_INFO_BUFFER_SIZE, >+ (unsigned char *)p->data.data + header_size , >+ old_len - header_size); >+ /* Clear the space where we would put the new PAC_INFO_BUFFER[] element */ >+ memset((unsigned char *)p->data.data + header_size, 0, >+ PAC_INFO_BUFFER_SIZE); > > /* >- * copy in new data part >+ * Copy in new data part > */ >- >- memcpy((unsigned char *)p->data.data + offset, >- data->data, data->length); >- memset((unsigned char *)p->data.data + offset + data->length, >- 0, p->data.length - offset - data->length); >- >+ memcpy((unsigned char *)p->data.data + offset, nd->data, nd->length); > p->pac->numbuffers += 1; >- > return 0; > } > >@@ -451,8 +553,8 @@ krb5_pac_add_buffer(krb5_context context, krb5_pac p, > * @param type type of buffer to get > * @param data return data, free with krb5_data_free(). > * >- * @return Returns 0 to indicate success. Otherwise an kerberos et >- * error code is returned, see krb5_get_error_message(). >+ * @return Returns 0 to indicate success, ENOENT to indicate that a buffer of >+ * the given type was not found, or a Kerberos or system error code. > * > * @ingroup krb5_pac > */ >@@ -465,21 +567,19 @@ krb5_pac_get_buffer(krb5_context context, krb5_const_pac p, > uint32_t i; > > for (i = 0; i < p->pac->numbuffers; i++) { >- const size_t len = p->pac->buffers[i].buffersize; >- const size_t offset = p->pac->buffers[i].offset_lo; >+ size_t len = p->pac->buffers[i].buffersize; >+ size_t offset = p->pac->buffers[i].offset; > > if (p->pac->buffers[i].type != type) > continue; > >- if (data) { >- ret = krb5_data_copy(data, (unsigned char *)p->data.data + offset, len); >- if (ret) { >- krb5_set_error_message(context, ret, N_("malloc: out of memory", "")); >- return ret; >- } >- } >+ if (!data) >+ return 0; > >- return 0; >+ ret = krb5_data_copy(data, (unsigned char *)p->data.data + offset, len); >+ if (ret) >+ krb5_set_error_message(context, ret, N_("malloc: out of memory", "")); >+ return ret; > } > krb5_set_error_message(context, ENOENT, "No PAC buffer of type %lu was found", > (unsigned long)type); >@@ -578,7 +678,7 @@ verify_checksum(krb5_context context, > > memset(&cksum, 0, sizeof(cksum)); > >- sp = krb5_storage_from_mem((char *)data->data + sig->offset_lo, >+ sp = krb5_storage_from_mem((char *)data->data + sig->offset, > sig->buffersize); > if (sp == NULL) > return krb5_enomem(context); >@@ -738,7 +838,7 @@ parse_upn_dns_info(krb5_context context, > *canon_princ = NULL; > krb5_data_zero(sid); > >- sp = krb5_storage_from_readonly_mem((const char *)data->data + upndnsinfo->offset_lo, >+ sp = krb5_storage_from_readonly_mem((const char *)data->data + upndnsinfo->offset, > upndnsinfo->buffersize); > if (sp == NULL) > return krb5_enomem(context); >@@ -940,7 +1040,7 @@ verify_logonname(krb5_context context, > char *principal_string = NULL; > char *logon_string = NULL; > >- sp = krb5_storage_from_readonly_mem((const char *)data->data + logon_name->offset_lo, >+ sp = krb5_storage_from_readonly_mem((const char *)data->data + logon_name->offset, > logon_name->buffersize); > if (sp == NULL) > return krb5_enomem(context); >@@ -1160,7 +1260,7 @@ parse_attributes_info(krb5_context context, > > *pac_attributes = 0; > >- sp = krb5_storage_from_readonly_mem((const char *)data->data + attributes_info->offset_lo, >+ sp = krb5_storage_from_readonly_mem((const char *)data->data + attributes_info->offset, > attributes_info->buffersize); > if (sp == NULL) > return krb5_enomem(context); >@@ -1284,11 +1384,11 @@ krb5_pac_verify(krb5_context context, > if (ret) > return ret; > >- memset((char *)copy->data + pac->server_checksum->offset_lo + 4, >+ memset((char *)copy->data + pac->server_checksum->offset + 4, > 0, > pac->server_checksum->buffersize - 4); > >- memset((char *)copy->data + pac->privsvr_checksum->offset_lo + 4, >+ memset((char *)copy->data + pac->privsvr_checksum->offset + 4, > 0, > pac->privsvr_checksum->buffersize - 4); > >@@ -1308,7 +1408,7 @@ krb5_pac_verify(krb5_context context, > pac->privsvr_checksum, > &pac->data, > (char *)pac->data.data >- + pac->server_checksum->offset_lo + 4, >+ + pac->server_checksum->offset + 4, > pac->server_checksum->buffersize - 4, > privsvr); > if (ret) >@@ -1428,8 +1528,8 @@ _krb5_pac_sign(krb5_context context, > size_t server_size, priv_size; > uint32_t server_offset = 0, priv_offset = 0, ticket_offset = 0; > uint32_t server_cksumtype = 0, priv_cksumtype = 0; >- int num = 0; >- size_t i, sz; >+ uint32_t num = 0; >+ uint32_t i, sz; > krb5_data logon, d; > krb5_data upn_dns_info; > krb5_data attributes_info; >@@ -1439,6 +1539,13 @@ _krb5_pac_sign(krb5_context context, > krb5_data_zero(&upn_dns_info); > krb5_data_zero(&attributes_info); > >+ /* >+ * Set convenience buffer pointers. >+ * >+ * This could really stand to be moved to krb5_pac_add_buffer() and/or >+ * utility function, so that when this function gets called they must >+ * already have been set. >+ */ > for (i = 0; i < p->pac->numbuffers; i++) { > if (p->pac->buffers[i].type == PAC_SERVER_CHECKSUM) { > if (p->server_checksum == NULL) { >@@ -1503,6 +1610,7 @@ _krb5_pac_sign(krb5_context context, > } > } > >+ /* Count missing-but-necessary buffers */ > if (p->logon_name == NULL) > num++; > if (p->server_checksum == NULL) >@@ -1516,45 +1624,53 @@ _krb5_pac_sign(krb5_context context, > if (pac_attributes && p->attributes_info == NULL) > num++; > >+ /* Allocate any missing-but-necessary buffers */ > if (num) { > void *ptr; >+ uint32_t old_len, len; > >- ptr = realloc(p->pac, sizeof(*p->pac) + (sizeof(p->pac->buffers[0]) * (p->pac->numbuffers + num - 1))); >+ if (p->pac->numbuffers > UINT32_MAX - num) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } >+ ret = pac_header_size(context, p->pac->numbuffers, &old_len); >+ if (ret == 0) >+ ret = pac_header_size(context, p->pac->numbuffers + num, &len); >+ if (ret) >+ goto out; >+ >+ ptr = realloc(p->pac, len); > if (ptr == NULL) { > ret = krb5_enomem(context); > goto out; > } >- >+ memset((char *)ptr + old_len, 0, len - old_len); > p->pac = ptr; > >+ > if (p->logon_name == NULL) { > p->logon_name = &p->pac->buffers[p->pac->numbuffers++]; >- memset(p->logon_name, 0, sizeof(*p->logon_name)); > p->logon_name->type = PAC_LOGON_NAME; > } > if (p->server_checksum == NULL) { > p->server_checksum = &p->pac->buffers[p->pac->numbuffers++]; >- memset(p->server_checksum, 0, sizeof(*p->server_checksum)); > p->server_checksum->type = PAC_SERVER_CHECKSUM; > } > if (p->privsvr_checksum == NULL) { > p->privsvr_checksum = &p->pac->buffers[p->pac->numbuffers++]; >- memset(p->privsvr_checksum, 0, sizeof(*p->privsvr_checksum)); > p->privsvr_checksum->type = PAC_PRIVSVR_CHECKSUM; > } > if ((upn_princ || canon_princ) && p->upn_dns_info == NULL) { > p->upn_dns_info = &p->pac->buffers[p->pac->numbuffers++]; >- memset(p->upn_dns_info, 0, sizeof(*p->upn_dns_info)); > p->upn_dns_info->type = PAC_UPN_DNS_INFO; > } > if (p->ticket_sign_data.length != 0 && p->ticket_checksum == NULL) { > p->ticket_checksum = &p->pac->buffers[p->pac->numbuffers++]; >- memset(p->ticket_checksum, 0, sizeof(*p->ticket_checksum)); > p->ticket_checksum->type = PAC_TICKET_CHECKSUM; > } > if (pac_attributes && p->attributes_info == NULL) { > p->attributes_info = &p->pac->buffers[p->pac->numbuffers++]; >- memset(p->attributes_info, 0, sizeof(*p->attributes_info)); > p->attributes_info->type = PAC_ATTRIBUTES_INFO; > } > } >@@ -1599,11 +1715,36 @@ _krb5_pac_sign(krb5_context context, > > krb5_storage_set_flags(spdata, KRB5_STORAGE_BYTEORDER_LE); > >+ /* `sp' has the header, `spdata' has the buffers */ > CHECK(ret, krb5_store_uint32(sp, p->pac->numbuffers), out); > CHECK(ret, krb5_store_uint32(sp, p->pac->version), out); > >- end = PACTYPE_SIZE + (PAC_INFO_BUFFER_SIZE * p->pac->numbuffers); >+ ret = pac_header_size(context, p->pac->numbuffers, &end); >+ if (ret) >+ goto out; > >+ /* >+ * For each buffer we write its contents to `spdata' and then append the >+ * PAC_INFO_BUFFER for that buffer into the header in `sp'. The logical >+ * end of the whole thing is kept in `end', which functions as the offset >+ * to write in the buffer's PAC_INFO_BUFFER, then we update it at the >+ * bottom so that the next buffer can be written there. >+ * >+ * TODO? Maybe rewrite all of this so that: >+ * >+ * - we use krb5_pac_add_buffer() to add the buffers we produce >+ * - we use the krb5_data of the concatenated buffers that's maintained by >+ * krb5_pac_add_buffer() so we don't need `spdata' here >+ * >+ * We do way too much here, and that makes this code hard to read. Plus we >+ * throw away all the work done in krb5_pac_add_buffer(). On the other >+ * hand, krb5_pac_add_buffer() has to loop over all the buffers, so if we >+ * call krb5_pac_add_buffer() here in a loop, we'll be accidentally >+ * quadratic, but we only need to loop over adding the buffers we add, >+ * which is very few, so not quite quadratic. We should also cap the >+ * number of buffers we're willing to accept in a PAC we parse to something >+ * reasonable, like a few tens. >+ */ > for (i = 0; i < p->pac->numbuffers; i++) { > uint32_t len; > size_t sret; >@@ -1612,26 +1753,66 @@ _krb5_pac_sign(krb5_context context, > /* store data */ > > if (p->pac->buffers[i].type == PAC_SERVER_CHECKSUM) { >+ if (server_size > UINT32_MAX - 4) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > len = server_size + 4; >+ if (end > UINT32_MAX - 4) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > server_offset = end + 4; > CHECK(ret, krb5_store_uint32(spdata, server_cksumtype), out); > CHECK(ret, fill_zeros(context, spdata, server_size), out); > } else if (p->pac->buffers[i].type == PAC_PRIVSVR_CHECKSUM) { >+ if (priv_size > UINT32_MAX - 4) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > len = priv_size + 4; >+ if (end > UINT32_MAX - 4) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > priv_offset = end + 4; > CHECK(ret, krb5_store_uint32(spdata, priv_cksumtype), out); > CHECK(ret, fill_zeros(context, spdata, priv_size), out); > if (rodc_id != 0) { >+ if (len > UINT32_MAX - sizeof(rodc_id)) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > len += sizeof(rodc_id); > CHECK(ret, fill_zeros(context, spdata, sizeof(rodc_id)), out); > } > } else if (p->ticket_sign_data.length != 0 && > p->pac->buffers[i].type == PAC_TICKET_CHECKSUM) { >+ if (priv_size > UINT32_MAX - 4) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > len = priv_size + 4; >+ if (end > UINT32_MAX - 4) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > ticket_offset = end + 4; > CHECK(ret, krb5_store_uint32(spdata, priv_cksumtype), out); > CHECK(ret, fill_zeros(context, spdata, priv_size), out); > if (rodc_id != 0) { >+ if (len > UINT32_MAX - sizeof(rodc_id)) { >+ ret = EINVAL; >+ krb5_set_error_message(context, ret, "integer overrun"); >+ goto out; >+ } > len += sizeof(rodc_id); > CHECK(ret, krb5_store_uint16(spdata, rodc_id), out); > } >@@ -1657,7 +1838,7 @@ _krb5_pac_sign(krb5_context context, > } > } else { > len = p->pac->buffers[i].buffersize; >- ptr = (char *)p->data.data + p->pac->buffers[i].offset_lo; >+ ptr = (char *)p->data.data + p->pac->buffers[i].offset; > > sret = krb5_storage_write(spdata, ptr, len); > if (sret != len) { >@@ -1670,18 +1851,17 @@ _krb5_pac_sign(krb5_context context, > /* write header */ > CHECK(ret, krb5_store_uint32(sp, p->pac->buffers[i].type), out); > CHECK(ret, krb5_store_uint32(sp, len), out); >- CHECK(ret, krb5_store_uint32(sp, end), out); >- CHECK(ret, krb5_store_uint32(sp, 0), out); >+ CHECK(ret, krb5_store_uint64(sp, end), out); /* offset */ > > /* advance data endpointer and align */ > { >- int32_t e; >+ uint32_t e; > >- end += len; >- e = ((end + PAC_ALIGNMENT - 1) / PAC_ALIGNMENT) * PAC_ALIGNMENT; >- if ((int32_t)end != e) { >- CHECK(ret, fill_zeros(context, spdata, e - end), out); >- } >+ ret = pac_aligned_size(context, end, len, &e); >+ if (ret == 0 && end + len != e) >+ ret = fill_zeros(context, spdata, e - (end + len)); >+ if (ret) >+ goto out; > end = e; > } > >@@ -1785,7 +1965,7 @@ krb5_pac_get_kdc_checksum_info(krb5_context context, > return KRB5KDC_ERR_BADOPTION; > } > >- sp = krb5_storage_from_mem((char *)pac->data.data + sig->offset_lo, >+ sp = krb5_storage_from_mem((char *)pac->data.data + sig->offset, > sig->buffersize); > if (sp == NULL) > return krb5_enomem(context); >diff --git a/lib/krb5/test_pac.c b/lib/krb5/test_pac.c >index 51b4fff16..70da1cb62 100644 >--- a/lib/krb5/test_pac.c >+++ b/lib/krb5/test_pac.c >@@ -838,6 +838,7 @@ check_ticket_signature(krb5_context context, > krb5_crypto crypto; > krb5_data data, orig_pac_ad; > Ticket ticket; >+ AuthorizationDataElement ad; > EncTicketPart et; > krb5_principal client; > krb5_pac pac; >@@ -889,8 +890,10 @@ check_ticket_signature(krb5_context context, > heim_assert(rodc_id == tkt->rodc_id, "Wrong RODCIdentifier"); > > /* Try to resign the PAC */ >- orig_pac_ad = et.authorization_data->val[0].ad_data; >- et.authorization_data->val[0].ad_data.data = NULL; >+ ret = copy_AuthorizationDataElement(&et.authorization_data->val[0], &ad); >+ if (ret) >+ t_err(context, tkt->name, "remove_AuthorizationData", ret); >+ orig_pac_ad = ad.ad_data; > > ret = remove_AuthorizationData(et.authorization_data, 0); > if (ret) >@@ -905,6 +908,8 @@ check_ticket_signature(krb5_context context, > heim_assert(krb5_data_cmp(&et.authorization_data->val[0].ad_data, > &orig_pac_ad) == 0, "PACs differ"); > >+ free_AuthorizationDataElement(&ad); >+ > /* Sign and verify a clean PAC */ > krb5_pac_free(context, pac); > ret = krb5_pac_init(context, &pac); >@@ -958,6 +963,7 @@ main(int argc, char **argv) > krb5_pac pac; > krb5_data data; > krb5_principal p, p2; >+ unsigned char bad_pac[sizeof(saved_pac)]; > > ret = krb5_init_context(&context); > if (ret) >@@ -970,6 +976,44 @@ main(int argc, char **argv) > if (ret) > krb5_err(context, 1, ret, "krb5_parse_name"); > >+ /* Attempt to parse a truncated PAC */ >+ ret = krb5_pac_parse(context, saved_pac, sizeof(saved_pac) >> 1, &pac); >+ if (ret == 0) >+ krb5_err(context, 1, ret, "krb5_pac_parse parsed a short PAC"); >+ >+ /* Attempt to parse a PAC with a buffer claiming too large a length */ >+ memcpy(bad_pac, saved_pac, sizeof(saved_pac)); >+ bad_pac[13] += 1; >+ >+ ret = krb5_pac_parse(context, bad_pac, sizeof(saved_pac), &pac); >+ if (ret == 0) >+ krb5_err(context, 1, ret, "krb5_pac_parse parsed a malicious PAC"); >+ >+ /* Attempt to parse a PAC with a buffer offset too far in */ >+ memcpy(bad_pac, saved_pac, sizeof(saved_pac)); >+ bad_pac[16] += 1; >+ >+ ret = krb5_pac_parse(context, bad_pac, sizeof(saved_pac), &pac); >+ if (ret == 0) >+ krb5_err(context, 1, ret, "krb5_pac_parse parsed a malicious PAC"); >+ >+ /* Attempt to parse a PAC with a buffer offset too far back */ >+ memcpy(bad_pac, saved_pac, sizeof(saved_pac)); >+ bad_pac[16] -= 1; >+ >+ ret = krb5_pac_parse(context, bad_pac, sizeof(saved_pac), &pac); >+ if (ret == 0) >+ krb5_err(context, 1, ret, "krb5_pac_parse parsed a malicious PAC"); >+ >+ /* Attempt to parse a PAC with an incorrect buffer count */ >+ memcpy(bad_pac, saved_pac, sizeof(saved_pac)); >+ bad_pac[0] += 1; >+ >+ ret = krb5_pac_parse(context, bad_pac, sizeof(saved_pac), &pac); >+ if (ret == 0) >+ krb5_err(context, 1, ret, "krb5_pac_parse parsed a malicious PAC"); >+ >+ /* Parse a well-formed PAC */ > ret = krb5_pac_parse(context, saved_pac, sizeof(saved_pac), &pac); > if (ret) > krb5_err(context, 1, ret, "krb5_pac_parse");
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