Gitweb:
https://git.exim.org/exim.git/commitdiff/2ff143741c68ad7fb8544f3238016b3d9227f3c1
Commit: 2ff143741c68ad7fb8544f3238016b3d9227f3c1
Parent: 3bf3a99e444713b1b4070b8d12811741ed69258b
Author: Jeremy Harris <jgh146exb@???>
AuthorDate: Tue Nov 10 21:10:56 2020 +0000
Committer: Jeremy Harris <jgh146exb@???>
CommitDate: Tue Nov 10 21:26:09 2020 +0000
More taint discussion in docs
---
doc/doc-docbook/spec.xfpt | 57 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 52 insertions(+), 5 deletions(-)
diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 7f9f426..f09e025 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -1394,9 +1394,22 @@ Again, cutthrough delivery counts as a verification.
.next
Individual routers can be explicitly skipped when running the routers to
check an address given in the SMTP EXPN command (see the &%expn%& option).
+
.next
If the &%domains%& option is set, the domain of the address must be in the set
of domains that it defines.
+.new
+.cindex "tainted data" "de-tainting"
+A match verifies the variable &$domain$& (which carries tainted data)
+and assigns an untainted value to the &$domain_data$& variable.
+Such an untainted value is often needed in the transport.
+For specifics of the matching operation and the resulting untainted value,
+refer to section &<<SECTdomainlist>>&.
+
+When an untainted value is wanted, use this option
+rather than the generic &%condition%& option.
+.wen
+
.next
.vindex "&$local_part_prefix$&"
.vindex "&$local_part_prefix_v$&"
@@ -1405,13 +1418,26 @@ of domains that it defines.
.vindex "&$local_part_suffix_v$&"
.cindex affix "router precondition"
If the &%local_parts%& option is set, the local part of the address must be in
-the set of local parts that it defines. If &%local_part_prefix%& or
+the set of local parts that it defines.
+.new
+A match verifies the variable &$local_part$& (which carries tainted data)
+and assigns an untainted value to the &$local_part_data$& variable.
+Such an untainted value is often needed in the transport.
+For specifics of the matching operation and the resulting untainted value,
+refer to section &<<SECTlocparlis>>&.
+
+When an untainted value is wanted, use this option
+rather than the generic &%condition%& option.
+.wen
+
+If &%local_part_prefix%& or
&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
part before this check. If you want to do precondition tests on local parts
that include affixes, you can do so by using a &%condition%& option (see below)
that uses the variables &$local_part$&, &$local_part_prefix$&,
&$local_part_prefix_v$&, &$local_part_suffix$&
and &$local_part_suffix_v$& as necessary.
+
.next
.vindex "&$local_user_uid$&"
.vindex "&$local_user_gid$&"
@@ -1421,23 +1447,37 @@ an account on the local host. If this check succeeds, the uid and gid of the
local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
user's home directory is placed in &$home$&; these values can be used in the
remaining preconditions.
+
.next
If the &%router_home_directory%& option is set, it is expanded at this point,
because it overrides the value of &$home$&. If this expansion were left till
later, the value of &$home$& as set by &%check_local_user%& would be used in
subsequent tests. Having two different values of &$home$& in the same router
could lead to confusion.
+
.next
If the &%senders%& option is set, the envelope sender address must be in the
set of addresses that it defines.
+
.next
If the &%require_files%& option is set, the existence or non-existence of
specified files is tested.
+
.next
.cindex "customizing" "precondition"
If the &%condition%& option is set, it is evaluated and tested. This option
uses an expanded string to allow you to set up your own custom preconditions.
Expanded strings are described in chapter &<<CHAPexpand>>&.
+
+.new
+Note that while using
+this option for address matching technically works,
+it does not set any de-tainted values.
+Such values are often needed, either for router-specific options or
+for transport options.
+Using the &%domains%& and &%local_parts%& options is usually the most
+convenient way to obtain them.
+.wen
.endlist
@@ -8428,7 +8468,10 @@ will store a result in the &$host_data$& variable.
A &%local_parts%& router option or &%local_parts%& ACL condition
will store a result in the &$local_part_data$& variable.
.vitem domains
+.new
A &%domains%& router option or &%domains%& ACL condition
+will store a result in the &$domain_data$& variable
+.wen
.vitem senders
A &%senders%& router option or &%senders%& ACL condition
will store a result in the &$sender_data$& variable.
@@ -9513,7 +9556,9 @@ reasons,
.cindex "tainted data" definition
.cindex expansion "tainted data"
and expansion of data deriving from the sender (&"tainted data"&)
-is not permitted.
+.new
+is not permitted (including acessing a file using a tainted name).
+.wen
.new
Common ways of obtaining untainted equivalents of variables with
@@ -18960,7 +19005,8 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence.
If this option is set, the router is skipped unless the current domain matches
the list. If the match is achieved by means of a file lookup, the data that the
lookup returned for the domain is placed in &$domain_data$& for use in string
-expansions of the driver's private options. See section &<<SECTrouprecon>>& for
+expansions of the driver's private options and in the transport.
+See section &<<SECTrouprecon>>& for
a list of the order in which preconditions are evaluated.
@@ -19323,12 +19369,13 @@ section &<<SECTlocparlis>>& for a discussion of local part lists. Because the
string is expanded, it is possible to make it depend on the domain, for
example:
.code
-local_parts = dbm;/usr/local/specials/$domain
+local_parts = dbm;/usr/local/specials/$domain_data
.endd
.vindex "&$local_part_data$&"
If the match is achieved by a lookup, the data that the lookup returned
for the local part is placed in the variable &$local_part_data$& for use in
-expansions of the router's private options. You might use this option, for
+expansions of the router's private options or in the transport.
+You might use this option, for
example, if you have a large number of local virtual domains, and you want to
send all postmaster mail to the same place without having to set up an alias in
each virtual domain:
