commit 44a62f58613f26f5cba82e9fa1e3d6f83124c550
Author: Jeremy Harris <jgh146exb@wizmail.org>
Date:   Wed Aug 11 13:08:43 2021 +0100

    DKIM: fix verify under TLS & chunking, with pipelined next command
    
    Cherry-picked from: b367453a08

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 3e93f653f..136363b51 100644
--- doc/ChangeLog
+++ doc/ChangeLog
@@ -231,6 +231,11 @@ JH/57 Fix control=fakreject for a custom message containing tainted data.
       Previously this resulted in a log complaint, due to a re-expansion present
       since fakereject was originally introduced.
 
+JH/59 DKIM: Fix small-message verification under TLS with chunking. If a
+      pipelined SMTP command followed the BDAT LAST then it would be
+      incorrrectly treated as part of the message body, causing a verification
+      fail.
+
 
 Exim version 4.94
 -----------------
diff --git a/src/src/dkim.c b/src/src/dkim.c
index 92adb3589..b376aa240 100644
--- src/dkim.c
+++ src/dkim.c
@@ -127,8 +127,9 @@ dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing);
 dkim_collect_input = dkim_verify_ctx ? DKIM_MAX_SIGNATURES : 0;
 dkim_collect_error = NULL;
 
-/* Start feed up with any cached data */
-receive_get_cache();
+/* Start feed up with any cached data, but limited to message data */
+receive_get_cache(chunking_state == CHUNKING_LAST
+		  ? chunking_data_left : GETC_BUFFER_UNLIMITED);
 
 store_pool = dkim_verify_oldpool;
 }
diff --git a/src/src/functions.h b/src/src/functions.h
index e22fd4f99..c450536a2 100644
--- src/functions.h
+++ src/functions.h
@@ -64,7 +64,7 @@ extern int     tls_ferror(void);
 extern void    tls_free_cert(void **);
 extern int     tls_getc(unsigned);
 extern uschar *tls_getbuf(unsigned *);
-extern void    tls_get_cache(void);
+extern void    tls_get_cache(unsigned);
 extern BOOL    tls_import_cert(const uschar *, void **);
 extern int     tls_read(void *, uschar *, size_t);
 extern int     tls_server_start(const uschar *, uschar **);
@@ -481,7 +481,7 @@ extern BOOL    smtp_get_interface(uschar *, int, address_item *,
 extern BOOL    smtp_get_port(uschar *, address_item *, int *, uschar *);
 extern int     smtp_getc(unsigned);
 extern uschar *smtp_getbuf(unsigned *);
-extern void    smtp_get_cache(void);
+extern void    smtp_get_cache(unsigned);
 extern int     smtp_handle_acl_fail(int, int, uschar *, uschar *);
 extern void    smtp_log_no_mail(void);
 extern void    smtp_message_code(uschar **, int *, uschar **, uschar **, BOOL);
diff --git a/src/src/globals.c b/src/src/globals.c
index fcb9cc0b5..c89cf6304 100644
--- src/globals.c
+++ src/globals.c
@@ -168,7 +168,7 @@ uschar * (*lwr_receive_getbuf)(unsigned *) = NULL;
 int (*lwr_receive_ungetc)(int) = stdin_ungetc;
 int (*receive_getc)(unsigned)  = stdin_getc;
 uschar * (*receive_getbuf)(unsigned *)  = NULL;
-void (*receive_get_cache)(void)= NULL;
+void (*receive_get_cache)(unsigned)     = NULL;
 int (*receive_ungetc)(int)     = stdin_ungetc;
 int (*receive_feof)(void)      = stdin_feof;
 int (*receive_ferror)(void)    = stdin_ferror;
diff --git a/src/src/globals.h b/src/src/globals.h
index bb811553c..f615a29ad 100644
--- src/globals.h
+++ src/globals.h
@@ -156,7 +156,7 @@ extern uschar * (*lwr_receive_getbuf)(unsigned *);
 extern int (*lwr_receive_ungetc)(int);
 extern int (*receive_getc)(unsigned);
 extern uschar * (*receive_getbuf)(unsigned *);
-extern void (*receive_get_cache)(void);
+extern void (*receive_get_cache)(unsigned);
 extern int (*receive_ungetc)(int);
 extern int (*receive_feof)(void);
 extern int (*receive_ferror)(void);
diff --git a/src/src/smtp_in.c b/src/src/smtp_in.c
index 17d17beb9..fc5328478 100644
--- src/smtp_in.c
+++ src/smtp_in.c
@@ -583,10 +583,12 @@ return buf;
 }
 
 void
-smtp_get_cache(void)
+smtp_get_cache(unsigned lim)
 {
 #ifndef DISABLE_DKIM
 int n = smtp_inend - smtp_inptr;
+if (n > lim)
+  n = lim;
 if (n > 0)
   dkim_exim_verify_feed(smtp_inptr, n);
 #endif
@@ -661,7 +663,9 @@ for(;;)
   if (chunking_state == CHUNKING_LAST)
     {
 #ifndef DISABLE_DKIM
+    dkim_collect_input = dkim_save;
     dkim_exim_verify_feed(NULL, 0);	/* notify EOD */
+    dkim_collect_input = 0;
 #endif
     return EOD;
     }
diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index 6ee603595..17081c821 100644
--- src/tls-gnu.c
+++ src/tls-gnu.c
@@ -3267,11 +3267,13 @@ return buf;
 
 
 void
-tls_get_cache()
+tls_get_cache(unsigned lim)
 {
 #ifndef DISABLE_DKIM
 exim_gnutls_state_st * state = &state_server;
 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
+if (n > lim)
+  n = lim;
 if (n > 0)
   dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
 #endif
diff --git a/src/src/tls-openssl.c b/src/src/tls-openssl.c
index 499384b50..55b4162f8 100644
--- src/tls-openssl.c
+++ src/tls-openssl.c
@@ -3566,10 +3566,12 @@ return buf;
 
 
 void
-tls_get_cache()
+tls_get_cache(unsigned lim)
 {
 #ifndef DISABLE_DKIM
 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
+if (n > lim)
+  n = lim;
 if (n > 0)
   dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
 #endif