exim/backport-bug3099-Fix-MIME-parsing-of-filenames-specified-using-multiple-parameters.patch
zhangxianting 434d0f9b40 Fix CVE-2024-39929
(cherry picked from commit a228892f677978b06ffad8b1963a093b9aeb2413)
2024-09-04 09:36:23 +08:00

160 lines
5.4 KiB
Diff

From 6ce5c70cff8989418e05d01fd2a57703007a6357 Mon Sep 17 00:00:00 2001
From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Mon, 1 Jul 2024 19:35:12 +0100
Subject: [PATCH] Fix MIME parsing of filenames specified using multiple
parameters. Bug 3099
---
doc/ChangeLog | 3 +++
doc/spec.txt | 10 +++++-----
src/mime.c | 51 +++++++++++++++++++++++++++++----------------------
3 files changed, 37 insertions(+), 27 deletions(-)
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 3e6da91..095bdb4 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -148,6 +148,9 @@ JH/32 Fix CHUNKING for a second message on a connection when the first was
JH/33 Fis ${srs_encode ...} to handle an empty sender address, now returning
an empty address. Previously the expansion returned an error.
+JH/34 Bug 3099: fix parsing of MIME filenames split over multiple paramemters.
+ Previously the $mime_filename variable would have an incorrect value.
+
HS/01 Bug 2855: Handle a v4mapped sender address given us by a frontending
proxy. Previously these were misparsed, leading to paniclog entries.
diff --git a/doc/spec.txt b/doc/spec.txt
index ddadcaf..9128166 100644
--- a/doc/spec.txt
+++ b/doc/spec.txt
@@ -32165,13 +32165,13 @@ The right hand side is expanded before use. After expansion, the value can be:
the default path is then used.
The decode condition normally succeeds. It is only false for syntax errors or
-unusual circumstances such as memory shortages. You can easily decode a file
-with its original, proposed filename using
+errors or unusual circumstances such as memory shortages.
-decode = $mime_filename
+The variable &$mime_filename$& will have the suggested name for the file.
+Note however that this might contain anything, and is very difficult
+to safely use as all or even part of the filename.
-However, you should keep in mind that $mime_filename might contain anything. If
-you place files outside of the default path, they are not automatically
+If you place files outside of the default path, they are not
unlinked.
For RFC822 attachments (these are messages attached to messages, with a
diff --git a/src/mime.c b/src/mime.c
index c192199..e7af413 100644
--- a/src/mime.c
+++ b/src/mime.c
@@ -586,10 +586,10 @@ while(1)
while (*p)
{
- DEBUG(D_acl) debug_printf_indent("MIME: considering paramlist '%s'\n", p);
+ DEBUG(D_acl)
+ debug_printf_indent("MIME: considering paramlist '%s'\n", p);
- if ( !mime_filename
- && strncmpic(CUS"content-disposition:", header, 20) == 0
+ if ( strncmpic(CUS"content-disposition:", header, 20) == 0
&& strncmpic(CUS"filename*", p, 9) == 0
)
{ /* RFC 2231 filename */
@@ -603,11 +603,12 @@ while(1)
if (q && *q)
{
- uschar * temp_string, * err_msg;
+ uschar * temp_string, * err_msg, * fname = q;
int slen;
/* build up an un-decoded filename over successive
filename*= parameters (for use when 2047 decode fails) */
+/*XXX could grow a gstring here */
mime_fname_rfc2231 = string_sprintf("%#s%s",
mime_fname_rfc2231, q);
@@ -622,26 +623,32 @@ while(1)
/* look for a ' in the "filename" */
while(*s != '\'' && *s) s++; /* s is 1st ' or NUL */
- if ((size = s-q) > 0)
- mime_filename_charset = string_copyn(q, size);
+ if (*s) /* there was a ' */
+ {
+ if ((size = s-q) > 0)
+ mime_filename_charset = string_copyn(q, size);
- if (*(p = s)) p++;
- while(*p == '\'') p++; /* p is after 2nd ' */
+ if (*(fname = s)) fname++;
+ while(*fname == '\'') fname++; /* fname is after 2nd ' */
+ }
}
- else
- p = q;
- DEBUG(D_acl) debug_printf_indent("MIME: charset %s fname '%s'\n",
- mime_filename_charset ? mime_filename_charset : US"<NULL>", p);
+ DEBUG(D_acl)
+ debug_printf_indent("MIME: charset %s fname '%s'\n",
+ mime_filename_charset ? mime_filename_charset : US"<NULL>",
+ fname);
- temp_string = rfc2231_to_2047(p, mime_filename_charset, &slen);
- DEBUG(D_acl) debug_printf_indent("MIME: 2047-name %s\n", temp_string);
+ temp_string = rfc2231_to_2047(fname, mime_filename_charset,
+ &slen);
+ DEBUG(D_acl)
+ debug_printf_indent("MIME: 2047-name %s\n", temp_string);
temp_string = rfc2047_decode(temp_string, FALSE, NULL, ' ',
- NULL, &err_msg);
- DEBUG(D_acl) debug_printf_indent("MIME: plain-name %s\n", temp_string);
+ NULL, &err_msg);
+ DEBUG(D_acl)
+ debug_printf_indent("MIME: plain-name %s\n", temp_string);
- if (!temp_string || (size = Ustrlen(temp_string)) == slen)
+ if (!temp_string || (size = Ustrlen(temp_string)) == slen)
decoding_failed = TRUE;
else
/* build up a decoded filename over successive
@@ -650,9 +657,9 @@ while(1)
mime_filename = mime_fname = mime_fname
? string_sprintf("%s%s", mime_fname, temp_string)
: temp_string;
- }
- }
- }
+ } /*!decoding_failed*/
+ } /*q*/
+ } /*2231 filename*/
else
/* look for interesting parameters */
@@ -681,7 +688,7 @@ while(1)
/* There is something, but not one of our interesting parameters.
- Advance past the next semicolon */
+ Advance past the next semicolon */
p = mime_next_semicolon(p);
if (*p) p++;
} /* param scan on line */
@@ -799,5 +806,5 @@ return rc;
#endif /*WITH_CONTENT_SCAN*/
-/* vi: sw ai sw=2
+/* vi: aw ai sw=2
*/
--
2.33.0