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-rw-r--r--debian/patches/bugfix/all/ovl-fail-on-invalid-uid-gid-mapping-at-copy-up.patch49
1 files changed, 49 insertions, 0 deletions
diff --git a/debian/patches/bugfix/all/ovl-fail-on-invalid-uid-gid-mapping-at-copy-up.patch b/debian/patches/bugfix/all/ovl-fail-on-invalid-uid-gid-mapping-at-copy-up.patch
new file mode 100644
index 000000000..368787579
--- /dev/null
+++ b/debian/patches/bugfix/all/ovl-fail-on-invalid-uid-gid-mapping-at-copy-up.patch
@@ -0,0 +1,49 @@
+From: Miklos Szeredi <mszeredi@redhat.com>
+Date: Tue, 24 Jan 2023 16:41:18 +0100
+Subject: ovl: fail on invalid uid/gid mapping at copy up
+Origin: https://git.kernel.org/linus/4f11ada10d0ad3fd53e2bd67806351de63a4f9c3
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2023-0386
+
+If st_uid/st_gid doesn't have a mapping in the mounter's user_ns, then
+copy-up should fail, just like it would fail if the mounter task was doing
+the copy using "cp -a".
+
+There's a corner case where the "cp -a" would succeed but copy up fail: if
+there's a mapping of the invalid uid/gid (65534 by default) in the user
+namespace. This is because stat(2) will return this value if the mapping
+doesn't exist in the current user_ns and "cp -a" will in turn be able to
+create a file with this uid/gid.
+
+This behavior would be inconsistent with POSIX ACL's, which return -1 for
+invalid uid/gid which result in a failed copy.
+
+For consistency and simplicity fail the copy of the st_uid/st_gid are
+invalid.
+
+Fixes: 459c7c565ac3 ("ovl: unprivieged mounts")
+Cc: <stable@vger.kernel.org> # v5.11
+Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
+Reviewed-by: Christian Brauner <brauner@kernel.org>
+Reviewed-by: Seth Forshee <sforshee@kernel.org>
+---
+ fs/overlayfs/copy_up.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
+index 140f2742074d..c14e90764e35 100644
+--- a/fs/overlayfs/copy_up.c
++++ b/fs/overlayfs/copy_up.c
+@@ -1011,6 +1011,10 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
+ if (err)
+ return err;
+
++ if (!kuid_has_mapping(current_user_ns(), ctx.stat.uid) ||
++ !kgid_has_mapping(current_user_ns(), ctx.stat.gid))
++ return -EOVERFLOW;
++
+ ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags);
+
+ if (parent) {
+--
+2.40.1
+