nano: Security fix for CVE-2024-5742

Upstream-Status: Backport from [https://git.savannah.gnu.org/cgit/nano.git/commit/?id=5e7a3c2e7e118c7f12d5dfda9f9140f638976aa2]

CVE's Fixed:
CVE-2024-5742 nano: running `chmod` and `chown` on the filename allows malicious user to replace the emergency file with a malicious symlink to a root-owned file

Signed-off-by: Siddharth Doshi <sdoshi@mvista.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

2 files changed, 103 insertions, 1 deletions

diff --git a/meta-oe/recipes-support/nano/files/CVE-2024-5742.patch b/meta-oe/recipes-support/nano/files/CVE-2024-5742.patch
new file mode 100644
index 0000000000..64a395f2d2
--- /dev/null
+++ b/meta-oe/recipes-support/nano/files/CVE-2024-5742.patch
@@ -0,0 +1,100 @@
+From 5e7a3c2e7e118c7f12d5dfda9f9140f638976aa2 Mon Sep 17 00:00:00 2001
+From: Benno Schulenberg <bensberg@telfort.nl>
+Date: Sun, 28 Apr 2024 10:51:52 +0200
+Subject: files: run `chmod` and `chown` on the descriptor, not on the filename
+
+This closes a window of opportunity where the emergency file could be
+replaced by a malicious symlink.
+
+The issue was reported by `MartinJM` and `InvisibleMeerkat`.
+
+Problem existed since version 2.2.0, commit 123110c5, when chmodding
+and chowning of the emergency .save file was added.
+
+Upstream-Status: Backport from [https://git.savannah.gnu.org/cgit/nano.git/commit/?id=5e7a3c2e7e118c7f12d5dfda9f9140f638976aa2]
+CVE: CVE-2024-5742
+Signed-off-by: Siddharth Doshi <sdoshi@mvista.com>
+---
+ src/definitions.h |  2 +-
+ src/files.c       | 13 ++++++++++++-
+ src/nano.c        | 12 +-----------
+ 3 files changed, 14 insertions(+), 13 deletions(-)
+
+diff --git a/src/definitions.h b/src/definitions.h
+index 2bdc782..e9d0de3 100644
+--- a/src/definitions.h
++++ b/src/definitions.h
+@@ -277,7 +277,7 @@ typedef enum {
+ } message_type;
+ 
+ typedef enum {
+-       OVERWRITE, APPEND, PREPEND
++       OVERWRITE, APPEND, PREPEND, EMERGENCY
+ } kind_of_writing_type;
+ 
+ typedef enum {
+diff --git a/src/files.c b/src/files.c
+index 62cc8f2..c5527a6 100644
+--- a/src/files.c
++++ b/src/files.c
+@@ -1760,6 +1760,8 @@ bool write_file(const char *name, FILE *thefile, bool normal,
+ #endif
+        char *realname = real_dir_from_tilde(name);
+                /* The filename after tilde expansion. */
++       int fd = 0;
++               /* The descriptor that is assigned when opening the file. */
+        char *tempname = NULL;
+                /* The name of the temporary file we use when prepending. */
+        linestruct *line = openfile->filetop;
+@@ -1843,7 +1845,6 @@ bool write_file(const char *name, FILE *thefile, bool normal,
+         * For an emergency file, access is restricted to just the owner. */
+        if (thefile == NULL) {
+                mode_t permissions = (normal ? RW_FOR_ALL : S_IRUSR|S_IWUSR);
+-               int fd;
+ 
+ #ifndef NANO_TINY
+                block_sigwinch(TRUE);
+@@ -1970,6 +1971,16 @@ bool write_file(const char *name, FILE *thefile, bool normal,
+                }
+ #endif
+ 
++#if !defined(NANO_TINY) && defined(HAVE_CHMOD) && defined(HAVE_CHOWN)
++       /* Change permissions and owner of an emergency save file to the values
++        * of the original file, but ignore any failure as we are in a hurry. */
++       if (method == EMERGENCY && fd && openfile->statinfo) {
++               IGNORE_CALL_RESULT(fchmod(fd, openfile->statinfo->st_mode));
++               IGNORE_CALL_RESULT(fchown(fd, openfile->statinfo->st_uid,
++                                                                                       openfile->statinfo->st_gid));
++       }
++#endif
++
+        if (fclose(thefile) != 0) {
+                statusline(ALERT, _("Error writing %s: %s"), realname, strerror(errno));
+ 
+diff --git a/src/nano.c b/src/nano.c
+index 04ecdbb..2ce3462 100644
+--- a/src/nano.c
++++ b/src/nano.c
+@@ -337,18 +337,8 @@ void emergency_save(const char *filename)
+ 
+        if (*targetname == '\0')
+                fprintf(stderr, _("\nToo many .save files\n"));
+-       else if (write_file(targetname, NULL, SPECIAL, OVERWRITE, NONOTES)) {
++       else if (write_file(targetname, NULL, SPECIAL, EMERGENCY, NONOTES))
+                fprintf(stderr, _("\nBuffer written to %s\n"), targetname);
+-#ifndef NANO_TINY
+-               /* Try to chmod/chown the saved file to the values of the original file,
+-                * but ignore any failure as we are in a hurry to get out. */
+-               if (openfile->statinfo) {
+-                       IGNORE_CALL_RESULT(chmod(targetname, openfile->statinfo->st_mode));
+-                       IGNORE_CALL_RESULT(chown(targetname, openfile->statinfo->st_uid,
+-                                                                                                       openfile->statinfo->st_gid));
+-               }
+-#endif
+-       }
+ 
+        free(targetname);
+        free(plainname);
+-- 
+2.35.7
+
diff --git a/meta-oe/recipes-support/nano/nano_6.2.bb b/meta-oe/recipes-support/nano/nano_6.2.bb
index 0be022467b..10e74869c1 100644
--- a/meta-oe/recipes-support/nano/nano_6.2.bb
+++ b/meta-oe/recipes-support/nano/nano_6.2.bb
@@ -12,7 +12,9 @@ RDEPENDS:${PN} = "ncurses-terminfo-base"
 
 PV_MAJOR = "${@d.getVar('PV').split('.')[0]}"
 
-SRC_URI = "https://nano-editor.org/dist/v${PV_MAJOR}/nano-${PV}.tar.xz"
+SRC_URI = "https://nano-editor.org/dist/v${PV_MAJOR}/nano-${PV}.tar.xz \
+           file://CVE-2024-5742.patch \
+          "
 SRC_URI[sha256sum] = "2bca1804bead6aaf4ad791f756e4749bb55ed860eec105a97fba864bc6a77cb3"
 
 UPSTREAM_CHECK_URI = "https://ftp.gnu.org/gnu/nano"