Backport upstream fix to help address CVE-2024-42472 in flatpak
Resolves: RHEL-56457
This commit is contained in:
parent
392e4f825d
commit
3a5f57ba0b
128
0001-Add-bind-fd-and-ro-bind-fd-to-let-you-bind-a-O_PATH-.patch
Normal file
128
0001-Add-bind-fd-and-ro-bind-fd-to-let-you-bind-a-O_PATH-.patch
Normal file
@ -0,0 +1,128 @@
|
||||
From 52d5f7c3ba5c8e10b3a992304fd28cd4d18caeeb Mon Sep 17 00:00:00 2001
|
||||
From: Alexander Larsson <alexl@redhat.com>
|
||||
Date: Tue, 18 Jun 2024 10:20:36 +0200
|
||||
Subject: [PATCH] Add --bind-fd and --ro-bind-fd to let you bind a O_PATH fd.
|
||||
|
||||
This is useful for example if you for some reason don't have the real
|
||||
path. It is also a way to make bind-mounts race-free (i.e. to have the
|
||||
mount actually be the thing you wanted to be mounted, avoiding issues
|
||||
where some other process replaces the target in parallel with the bwrap
|
||||
launch.
|
||||
|
||||
Unfortunately due to some technical details we can't actually directly
|
||||
mount the dirfd, as they come from different user namespace which is not
|
||||
permitted, but at least we can delay resolving the fd to a path as much as
|
||||
possible, and then validate after mount that we actually mounted the right
|
||||
thing.
|
||||
|
||||
Signed-off-by: Alexander Larsson <alexl@redhat.com>
|
||||
(cherry picked from commit a253257cd298892da43e15201d83f9a02c9b58b5)
|
||||
[kalev: Backport to 0.4.x]
|
||||
Signed-off-by: Kalev Lember <klember@redhat.com>
|
||||
---
|
||||
bubblewrap.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
|
||||
tests/test-run.sh | 7 ++++++-
|
||||
2 files changed, 56 insertions(+), 1 deletion(-)
|
||||
|
||||
diff --git a/bubblewrap.c b/bubblewrap.c
|
||||
index b3d52bc..38b3646 100644
|
||||
--- a/bubblewrap.c
|
||||
+++ b/bubblewrap.c
|
||||
@@ -250,6 +250,8 @@ usage (int ecode, FILE *out)
|
||||
" --dev-bind-try SRC DEST Equal to --dev-bind but ignores non-existent SRC\n"
|
||||
" --ro-bind SRC DEST Bind mount the host path SRC readonly on DEST\n"
|
||||
" --ro-bind-try SRC DEST Equal to --ro-bind but ignores non-existent SRC\n"
|
||||
+ " --bind-fd FD DEST Bind open directory or path fd on DEST\n"
|
||||
+ " --ro-bind-fd FD DEST Bind open directory or path fd read-only on DEST\n"
|
||||
" --remount-ro DEST Remount DEST as readonly; does not recursively remount\n"
|
||||
" --exec-label LABEL Exec label for the sandbox\n"
|
||||
" --file-label LABEL File label for temporary sandbox content\n"
|
||||
@@ -1111,6 +1113,30 @@ setup_newroot (bool unshare_pid,
|
||||
(op->type == SETUP_RO_BIND_MOUNT ? BIND_READONLY : 0) |
|
||||
(op->type == SETUP_DEV_BIND_MOUNT ? BIND_DEVICES : 0),
|
||||
source, dest);
|
||||
+
|
||||
+ if (op->fd >= 0)
|
||||
+ {
|
||||
+ struct stat fd_st, mount_st;
|
||||
+
|
||||
+ /* When using bind-fd, there is a race condition between resolving the fd as a magic symlink
|
||||
+ * and mounting it, where someone could replace what is at the symlink target. Ideally
|
||||
+ * we would not even resolve the symlink and directly bind-mount from the fd, but unfortunately
|
||||
+ * we can't do that, because its not permitted to bind mount a fd from another user namespace.
|
||||
+ * So, we resolve, mount and then compare fstat+stat to detect the race. */
|
||||
+
|
||||
+ if (fstat(op->fd, &fd_st) != 0)
|
||||
+ die_with_error("Can't stat fd %d", op->fd);
|
||||
+ if (lstat(dest, &mount_st) != 0)
|
||||
+ die_with_error("Can't stat mount at %s", dest);
|
||||
+
|
||||
+ if (fd_st.st_ino != mount_st.st_ino ||
|
||||
+ fd_st.st_dev != mount_st.st_dev)
|
||||
+ die_with_error("Race condition binding dirfd");
|
||||
+
|
||||
+ close(op->fd);
|
||||
+ op->fd = -1;
|
||||
+ }
|
||||
+
|
||||
break;
|
||||
|
||||
case SETUP_REMOUNT_RO_NO_RECURSIVE:
|
||||
@@ -1648,6 +1674,30 @@ parse_args_recurse (int *argcp,
|
||||
if (strcmp(arg, "--dev-bind-try") == 0)
|
||||
op->flags = ALLOW_NOTEXIST;
|
||||
|
||||
+ argv += 2;
|
||||
+ argc -= 2;
|
||||
+ }
|
||||
+ else if (strcmp (arg, "--bind-fd") == 0 ||
|
||||
+ strcmp (arg, "--ro-bind-fd") == 0)
|
||||
+ {
|
||||
+ int src_fd;
|
||||
+ char *endptr;
|
||||
+
|
||||
+ if (argc < 3)
|
||||
+ die ("--bind-fd takes two arguments");
|
||||
+
|
||||
+ src_fd = strtol (argv[1], &endptr, 10);
|
||||
+ if (argv[1][0] == 0 || endptr[0] != 0 || src_fd < 0)
|
||||
+ die ("Invalid fd: %s", argv[1]);
|
||||
+
|
||||
+ if (strcmp(arg, "--ro-bind-fd") == 0)
|
||||
+ op = setup_op_new (SETUP_RO_BIND_MOUNT);
|
||||
+ else
|
||||
+ op = setup_op_new (SETUP_BIND_MOUNT);
|
||||
+ op->source = xasprintf ("/proc/self/fd/%d", src_fd);
|
||||
+ op->fd = src_fd;
|
||||
+ op->dest = argv[2];
|
||||
+
|
||||
argv += 2;
|
||||
argc -= 2;
|
||||
}
|
||||
diff --git a/tests/test-run.sh b/tests/test-run.sh
|
||||
index 702c480..ce1eaf6 100755
|
||||
--- a/tests/test-run.sh
|
||||
+++ b/tests/test-run.sh
|
||||
@@ -80,7 +80,7 @@ if ! $RUN true; then
|
||||
skip Seems like bwrap is not working at all. Maybe setuid is not working
|
||||
fi
|
||||
|
||||
-echo "1..49"
|
||||
+echo "1..50"
|
||||
|
||||
# Test help
|
||||
${BWRAP} --help > help.txt
|
||||
@@ -382,5 +382,10 @@ else
|
||||
echo "ok - Test --pidns"
|
||||
fi
|
||||
|
||||
+echo "foobar" > file-data
|
||||
+$RUN --proc /proc --dev /dev --bind / / --bind-fd 100 /tmp cat /tmp/file-data 100< . > stdout
|
||||
+assert_file_has_content stdout foobar
|
||||
+
|
||||
+echo "ok - bind-fd"
|
||||
|
||||
echo "ok - End of test"
|
||||
--
|
||||
2.46.0
|
||||
|
@ -1,12 +1,13 @@
|
||||
Name: bubblewrap
|
||||
Version: 0.4.0
|
||||
Release: 1%{?dist}
|
||||
Release: 2%{?dist}
|
||||
Summary: Core execution tool for unprivileged containers
|
||||
|
||||
License: LGPLv2+
|
||||
#VCS: git:https://github.com/projectatomic/bubblewrap
|
||||
URL: https://github.com/projectatomic/bubblewrap
|
||||
Source0: https://github.com/projectatomic/bubblewrap/releases/download/v%{version}/bubblewrap-%{version}.tar.xz
|
||||
Patch0: 0001-Add-bind-fd-and-ro-bind-fd-to-let-you-bind-a-O_PATH-.patch
|
||||
|
||||
BuildRequires: autoconf automake libtool
|
||||
BuildRequires: gcc
|
||||
@ -21,7 +22,7 @@ containers that works as a setuid binary on kernels without
|
||||
user namespaces.
|
||||
|
||||
%prep
|
||||
%autosetup
|
||||
%autosetup -p1
|
||||
|
||||
%build
|
||||
if ! test -x configure; then NOCONFIGURE=1 ./autogen.sh; fi
|
||||
@ -45,6 +46,9 @@ find %{buildroot} -name '*.la' -delete -print
|
||||
%{_mandir}/man1/*
|
||||
|
||||
%changelog
|
||||
* Fri Aug 30 2024 Kalev Lember <klember@redhat.com> - 0.4.0-2
|
||||
- Backport upstream fix to help address CVE-2024-42472 in flatpak
|
||||
|
||||
* Thu Jan 09 2020 David King <dking@redhat.com> - 0.4.0-1
|
||||
- Rebase to 0.4.0 (#1788067)
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user