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Bug#1035351: marked as done (unblock: ncurses/6.4-4)

Your message dated Sun, 7 May 2023 21:26:27 +0200
with message-id <e670d99b-beed-9d74-4594-79a03ece28f0@debian.org>
and subject line Re: Bug#1035351: [pre-approval] unblock: ncurses/6.4-3
has caused the Debian Bug report #1035351,
regarding unblock: ncurses/6.4-4
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
1035351: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1035351
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: release.debian.org
Severity: normal
User: release.debian.org@packages.debian.org
Usertags: unblock
Tags: d-i
X-Debbugs-Cc: ncurses@packages.debian.org, debian-boot@lists.debian.org
Control: affects -1 + src:ncurses

I would like to address CVE-2023-29491[1] aka bug #1034372[2] in
Bookworm.

[ Reason ]
Various memory corruption bugs exist when loading specifically crafted
terminfo database files.  This is a security problem in programs running
with elevated privileges, as users are allowed to provide their own
terminfo files under ${HOME}/.terminfo or via the TERMINFO or
TERMINFO_DIRS environment variables.

Backporting the upstream fixes seems to be too risky this late in the
release process, but via a configure option it is possible to prevent
setuid/setgid programs from loading custom terminfo files supplied by
the user, after which the bugs are no longer security relevant.

[ Impact ]
Local users could try privilege escalations in setuid/setgid programs
linked to the tinfo library.  How easily those can be achieved probably
depends on the program.

[ Tests ]
No automatic tests exist.  I have manually verified that programs can no
longer use custom terminfo files if their effective UID or GID differs
from the real one.  Also I have verified that the terminfo database in
the ncurses-{base,term} packages is unchanged from 6.4-2.

[ Risks ]
Users who are relying on their own terminfo files under
${HOME}/.terminfo can no longer use them in setuid/setgid programs and
will have to work around that, e.g. by changing their TERM variable,
using a different terminal emulator or asking their sysadmin for help.

On my systems I did not find any setuid binaries linked to the tinfo
library, but some setgid games in the bsdgames package.

[ Checklist ]
  [x] all changes are documented in the d/changelog
  [x] I reviewed all changes and I approve them
  [x] attach debdiff against the package in testing

I have slightly edited the debdiff to exclude spurious changes to the
debian/lib{32,64}tinfo6.symbols files, as these are just symlinks to
libtinfo6.symbols.  See devscripts bug #773762[3].

[ Other info ]
Since ncurses produces udebs, I have CC'ed debian-boot and tagged the
bug accordingly.  There should be no effect on the installer, as I would
expect it to run all programs as root.

Thanks for consideration.

Cheers,
       Sven


1. https://security-tracker.debian.org/tracker/CVE-2023-29491
2. https://bugs.debian.org/1034372
3. https://bugs.debian.org/773762


diff -Nru ncurses-6.4/debian/changelog ncurses-6.4/debian/changelog
--- ncurses-6.4/debian/changelog	2023-01-25 21:21:49.000000000 +0100
+++ ncurses-6.4/debian/changelog	2023-05-01 17:57:51.000000000 +0200
@@ -1,3 +1,21 @@
+ncurses (6.4-3) unstable; urgency=medium
+
+  * Configure with "--disable-root-environ" to disallow loading of
+    custom terminfo entries in setuid/setgid programs, mitigating the
+    impact of CVE-2023-29491 (see #1034372).
+    - Update the symbols files for the newly exported symbol
+      _nc_env_access.
+    - New patch fix-configure-root-args-option.diff cherry-picked from
+      the 20230415 patchlevel, fixing a copy/paste error which caused
+      the "--disable-root-environ" configure option to pick up code
+      meant to be used by the "--disable-root-args" option instead.
+    - New patch debian-env-access.diff, changing the behavior of the
+      "--disable-root-environ" configure option to not restrict programs
+      run by the superuser, equivalent to the "--disable-setuid-environ"
+      option introduced in the 20230423 patchlevel.
+
+ -- Sven Joachim <svenjoac@gmx.de>  Mon, 01 May 2023 17:57:51 +0200
+
 ncurses (6.4-2) unstable; urgency=medium

   * Add Breaks against vim-common (<< 2:9.0.1000-2) to ncurses-base
diff -Nru ncurses-6.4/debian/libtinfo5.symbols ncurses-6.4/debian/libtinfo5.symbols
--- ncurses-6.4/debian/libtinfo5.symbols	2023-01-22 17:54:52.000000000 +0100
+++ ncurses-6.4/debian/libtinfo5.symbols	2023-05-01 11:36:38.000000000 +0200
@@ -95,6 +95,7 @@
  _nc_curr_col@NCURSES_TINFO_5.0.19991023 6
  _nc_curr_line@NCURSES_TINFO_5.0.19991023 6
  _nc_doalloc@NCURSES_TINFO_5.0.19991023 6
+ _nc_env_access@NCURSES_TINFO_5.2.20001021 6.4-3~
  _nc_err_abort@NCURSES_TINFO_5.0.19991023 6
  _nc_fallback@NCURSES_TINFO_5.0.19991023 6
  _nc_find_entry@NCURSES_TINFO_5.0.19991023 6
diff -Nru ncurses-6.4/debian/libtinfo6.symbols ncurses-6.4/debian/libtinfo6.symbols
--- ncurses-6.4/debian/libtinfo6.symbols	2023-01-22 17:54:52.000000000 +0100
+++ ncurses-6.4/debian/libtinfo6.symbols	2023-05-01 11:36:38.000000000 +0200
@@ -94,6 +94,7 @@
  _nc_curr_col@NCURSES6_TINFO_5.0.19991023 6
  _nc_curr_line@NCURSES6_TINFO_5.0.19991023 6
  _nc_doalloc@NCURSES6_TINFO_5.0.19991023 6
+ _nc_env_access@NCURSES6_TINFO_5.2.20001021 6.4-3~
  _nc_err_abort@NCURSES6_TINFO_5.0.19991023 6
  _nc_export_termtype2@NCURSES6_TINFO_6.1.20171230 6.1
  _nc_fallback2@NCURSES6_TINFO_6.1.20171230 6.1
diff -Nru ncurses-6.4/debian/patches/debian-env-access.diff ncurses-6.4/debian/patches/debian-env-access.diff
--- ncurses-6.4/debian/patches/debian-env-access.diff	1970-01-01 01:00:00.000000000 +0100
+++ ncurses-6.4/debian/patches/debian-env-access.diff	2023-05-01 11:31:44.000000000 +0200
@@ -0,0 +1,27 @@
+Author: Sven Joachim <svenjoac@gmx.de>
+Description: Change the --disable-root-environ configure option behavior
+ By default, the --disable-root-environ option forbids program run by
+ the superuser to load custom terminfo entries.  This patch changes
+ that to only restrict programs running with elevated privileges,
+ matching the behavior of the --disable-setuid-environ option
+ introduced in the 20230423 upstream patchlevel.
+Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1034372#29
+Bug: https://lists.gnu.org/archive/html/bug-ncurses/2023-04/msg00018.html
+Forwarded: not-needed
+Last-Update: 2023-05-01
+
+---
+ ncurses/tinfo/access.c |    2 --
+ 1 file changed, 2 deletions(-)
+
+--- a/ncurses/tinfo/access.c
++++ b/ncurses/tinfo/access.c
+@@ -215,8 +215,6 @@ _nc_env_access(void)
+
+     if (is_elevated()) {
+ 	result = FALSE;
+-    } else if ((getuid() == ROOT_UID) || (geteuid() == ROOT_UID)) {
+-	result = FALSE;
+     }
+     return result;
+ }
diff -Nru ncurses-6.4/debian/patches/fix-configure-root-args-option.diff ncurses-6.4/debian/patches/fix-configure-root-args-option.diff
--- ncurses-6.4/debian/patches/fix-configure-root-args-option.diff	1970-01-01 01:00:00.000000000 +0100
+++ ncurses-6.4/debian/patches/fix-configure-root-args-option.diff	2023-05-01 11:31:04.000000000 +0200
@@ -0,0 +1,24 @@
+Author: Sven Joachim <svenjoac@gmx.de>
+Description: Fix copy/paste error in configure.in
+ Fix the --disable-root-access and --disableroot-environ configure
+ options.  Due to a copy/paste error, the latter performs the actions
+ of the former, while the --disable-root-access option has no effect
+ at all.
+Forwarded: https://lists.gnu.org/archive/html/bug-ncurses/2023-04/msg00003.html
+Last-Update: 2023-05-01
+
+---
+ configure.in |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/configure.in
++++ b/configure.in
+@@ -868,7 +868,7 @@ AC_MSG_RESULT($with_root_environ)
+ test "x$with_root_environ" = xyes && AC_DEFINE(USE_ROOT_ENVIRON,1,[Define to 1 if root is allowed to use ncurses environment])
+
+ AC_MSG_CHECKING(if you want to permit setuid programs to access all files)
+-AC_ARG_ENABLE(root-environ,
++AC_ARG_ENABLE(root-access,
+ 	[  --disable-root-access   restrict file-access when running setuid],
+ 	[with_root_access=$enableval],
+ 	[with_root_access=yes])
diff -Nru ncurses-6.4/debian/patches/series ncurses-6.4/debian/patches/series
--- ncurses-6.4/debian/patches/series	2023-01-22 18:31:25.000000000 +0100
+++ ncurses-6.4/debian/patches/series	2023-05-01 11:31:44.000000000 +0200
@@ -3,3 +3,5 @@
 02-debian-xterm.diff
 03-debian-ncursesconfig-omit-L.diff
 fix_crash_on_very_long_tc-use_clause.diff
+fix-configure-root-args-option.diff
+debian-env-access.diff
diff -Nru ncurses-6.4/debian/rules ncurses-6.4/debian/rules
--- ncurses-6.4/debian/rules	2023-01-22 19:46:39.000000000 +0100
+++ ncurses-6.4/debian/rules	2023-05-01 11:36:38.000000000 +0200
@@ -148,6 +148,7 @@
 		--without-progs \
 		$(with_mouse) \
 		--enable-symlinks \
+		--disable-root-environ \
 		--disable-termcap \
 		--with-default-terminfo-dir=/etc/terminfo \
 		--with-terminfo-dirs="/etc/terminfo:/lib/terminfo:/usr/share/terminfo" \

--- End Message ---
--- Begin Message --- 
Hi,

On 07-05-2023 18:36, Sven Joachim wrote:

Control: reopen -1
Control: retitle -1 unblock: ncurses/6.4-4


unblocked and aged.


Thanks, unfortunately this upload uncovered an old but hitherto hidden
bug in the build system that would lead to random build failures after
patching configure.in, see #1035621.  It is only by chance that none of
the three arches where ncurses 6.4-3 FTBFS is a release architecture.
I'm surprised to learn that there's a .pc directory. I thought that during builds quilt wasn't being used and dpkg unpacked the source. I might be wrong, but if not, why is that directory even there? 

Paul

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