svcrpc: fix potential GSSX_ACCEPT_SEC_CONTEXT decoding failures
In an environment where the KDC is running Active Directory, the exported composite name field returned in the context could be large enough to span a page boundary. Attaching a scratch buffer to the decoding xdr_stream helps deal with those cases. The case where we saw this was actually due to behavior that's been fixed in newer gss-proxy versions, but we're fixing it here too. Signed-off-by: Scott Mayhew <smayhew@redhat.com> Cc: stable@vger.kernel.org Reviewed-by: Simo Sorce <simo@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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@ -793,20 +793,26 @@ int gssx_dec_accept_sec_context(struct rpc_rqst *rqstp,
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{
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{
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u32 value_follows;
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u32 value_follows;
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int err;
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int err;
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struct page *scratch;
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scratch = alloc_page(GFP_KERNEL);
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if (!scratch)
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return -ENOMEM;
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xdr_set_scratch_buffer(xdr, page_address(scratch), PAGE_SIZE);
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/* res->status */
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/* res->status */
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err = gssx_dec_status(xdr, &res->status);
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err = gssx_dec_status(xdr, &res->status);
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if (err)
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if (err)
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return err;
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goto out_free;
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/* res->context_handle */
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/* res->context_handle */
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err = gssx_dec_bool(xdr, &value_follows);
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err = gssx_dec_bool(xdr, &value_follows);
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if (err)
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if (err)
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return err;
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goto out_free;
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if (value_follows) {
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if (value_follows) {
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err = gssx_dec_ctx(xdr, res->context_handle);
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err = gssx_dec_ctx(xdr, res->context_handle);
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if (err)
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if (err)
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return err;
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goto out_free;
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} else {
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} else {
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res->context_handle = NULL;
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res->context_handle = NULL;
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}
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}
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@ -814,11 +820,11 @@ int gssx_dec_accept_sec_context(struct rpc_rqst *rqstp,
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/* res->output_token */
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/* res->output_token */
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err = gssx_dec_bool(xdr, &value_follows);
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err = gssx_dec_bool(xdr, &value_follows);
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if (err)
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if (err)
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return err;
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goto out_free;
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if (value_follows) {
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if (value_follows) {
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err = gssx_dec_buffer(xdr, res->output_token);
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err = gssx_dec_buffer(xdr, res->output_token);
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if (err)
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if (err)
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return err;
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goto out_free;
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} else {
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} else {
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res->output_token = NULL;
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res->output_token = NULL;
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}
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}
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@ -826,14 +832,17 @@ int gssx_dec_accept_sec_context(struct rpc_rqst *rqstp,
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/* res->delegated_cred_handle */
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/* res->delegated_cred_handle */
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err = gssx_dec_bool(xdr, &value_follows);
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err = gssx_dec_bool(xdr, &value_follows);
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if (err)
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if (err)
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return err;
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goto out_free;
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if (value_follows) {
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if (value_follows) {
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/* we do not support upcall servers sending this data. */
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/* we do not support upcall servers sending this data. */
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return -EINVAL;
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err = -EINVAL;
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goto out_free;
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}
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}
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/* res->options */
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/* res->options */
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err = gssx_dec_option_array(xdr, &res->options);
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err = gssx_dec_option_array(xdr, &res->options);
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out_free:
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__free_page(scratch);
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return err;
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return err;
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}
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}
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