+++ /dev/null
-From 5506202b83e65b844309093e712b5b507eb1e403 Mon Sep 17 00:00:00 2001
-From: Jann Horn <jannh@google.com>
-Date: Tue, 13 Nov 2018 07:42:38 +0000
-Subject: [PATCH 09/11] userns: also map extents in the reverse map to kernel
- IDs
-
-BugLink: https://launchpad.net/bugs/1801924
-
-The current logic first clones the extent array and sorts both copies, then
-maps the lower IDs of the forward mapping into the lower namespace, but
-doesn't map the lower IDs of the reverse mapping.
-
-This means that code in a nested user namespace with >5 extents will see
-incorrect IDs. It also breaks some access checks, like
-inode_owner_or_capable() and privileged_wrt_inode_uidgid(), so a process
-can incorrectly appear to be capable relative to an inode.
-
-To fix it, we have to make sure that the "lower_first" members of extents
-in both arrays are translated; and we have to make sure that the reverse
-map is sorted *after* the translation (since otherwise the translation can
-break the sorting).
-
-This is CVE-2018-18955.
-
-Fixes: 6397fac4915a ("userns: bump idmap limits to 340")
-Cc: stable@vger.kernel.org
-Signed-off-by: Jann Horn <jannh@google.com>
-Tested-by: Eric W. Biederman <ebiederm@xmission.com>
-Reviewed-by: Eric W. Biederman <ebiederm@xmission.com>
-Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
-
-CVE-2018-18955
-
-(cherry picked from commit d2f007dbe7e4c9583eea6eb04d60001e85c6f1bd)
-Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
-Acked-by: Colin King <colin.king@canonical.com>
-Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
-Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
----
- kernel/user_namespace.c | 12 ++++++++----
- 1 file changed, 8 insertions(+), 4 deletions(-)
-
-diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
-index 08d638386b83..12de8c144db9 100644
---- a/kernel/user_namespace.c
-+++ b/kernel/user_namespace.c
-@@ -983,10 +983,6 @@ static ssize_t map_write(struct file *file, const char __user *buf,
- if (!new_idmap_permitted(file, ns, cap_setid, &new_map))
- goto out;
-
-- ret = sort_idmaps(&new_map);
-- if (ret < 0)
-- goto out;
--
- ret = -EPERM;
- /* Map the lower ids from the parent user namespace to the
- * kernel global id space.
-@@ -1013,6 +1009,14 @@ static ssize_t map_write(struct file *file, const char __user *buf,
- e->lower_first = lower_first;
- }
-
-+ /*
-+ * If we want to use binary search for lookup, this clones the extent
-+ * array and sorts both copies.
-+ */
-+ ret = sort_idmaps(&new_map);
-+ if (ret < 0)
-+ goto out;
-+
- /* Install the map */
- if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) {
- memcpy(map->extent, new_map.extent,
---
-2.11.0
-
+++ /dev/null
-From 3918a0379c7d37ce5d348ec6c2439d744a92a1f8 Mon Sep 17 00:00:00 2001
-From: "Eric W. Biederman" <ebiederm@xmission.com>
-Date: Tue, 13 Nov 2018 07:44:37 +0000
-Subject: [PATCH 10/11] mount: Retest MNT_LOCKED in do_umount
-
-BugLink: https://launchpad.net/bugs/1789161
-
-It was recently pointed out that the one instance of testing MNT_LOCKED
-outside of the namespace_sem is in ksys_umount.
-
-Fix that by adding a test inside of do_umount with namespace_sem and
-the mount_lock held. As it helps to fail fails the existing test is
-maintained with an additional comment pointing out that it may be racy
-because the locks are not held.
-
-Cc: stable@vger.kernel.org
-Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
-Fixes: 5ff9d8a65ce8 ("vfs: Lock in place mounts from more privileged users")
-Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
-(cherry picked from commit 25d202ed820ee347edec0bf3bf553544556bf64b)
-Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
-Acked-by: Colin King <colin.king@canonical.com>
-Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
-Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
----
- fs/namespace.c | 10 ++++++++--
- 1 file changed, 8 insertions(+), 2 deletions(-)
-
-diff --git a/fs/namespace.c b/fs/namespace.c
-index 570c9672ac9f..dcf107925150 100644
---- a/fs/namespace.c
-+++ b/fs/namespace.c
-@@ -1609,8 +1609,13 @@ static int do_umount(struct mount *mnt, int flags)
-
- namespace_lock();
- lock_mount_hash();
-- event++;
-
-+ /* Recheck MNT_LOCKED with the locks held */
-+ retval = -EINVAL;
-+ if (mnt->mnt.mnt_flags & MNT_LOCKED)
-+ goto out;
-+
-+ event++;
- if (flags & MNT_DETACH) {
- if (!list_empty(&mnt->mnt_list))
- umount_tree(mnt, UMOUNT_PROPAGATE);
-@@ -1624,6 +1629,7 @@ static int do_umount(struct mount *mnt, int flags)
- retval = 0;
- }
- }
-+out:
- unlock_mount_hash();
- namespace_unlock();
- return retval;
-@@ -1714,7 +1720,7 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
- goto dput_and_out;
- if (!check_mnt(mnt))
- goto dput_and_out;
-- if (mnt->mnt.mnt_flags & MNT_LOCKED)
-+ if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
- goto dput_and_out;
- retval = -EPERM;
- if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
---
-2.11.0
-
+++ /dev/null
-From 37b0e20be5149d5dc049e2aed3e8b03589a6ffa0 Mon Sep 17 00:00:00 2001
-From: "Eric W. Biederman" <ebiederm@xmission.com>
-Date: Tue, 13 Nov 2018 07:44:38 +0000
-Subject: [PATCH 11/11] mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED
- mounts
-
-BugLink: https://launchpad.net/bugs/1789161
-
-Jonathan Calmels from NVIDIA reported that he's able to bypass the
-mount visibility security check in place in the Linux kernel by using
-a combination of the unbindable property along with the private mount
-propagation option to allow a unprivileged user to see a path which
-was purposefully hidden by the root user.
-
-Reproducer:
- # Hide a path to all users using a tmpfs
- root@castiana:~# mount -t tmpfs tmpfs /sys/devices/
- root@castiana:~#
-
- # As an unprivileged user, unshare user namespace and mount namespace
- stgraber@castiana:~$ unshare -U -m -r
-
- # Confirm the path is still not accessible
- root@castiana:~# ls /sys/devices/
-
- # Make /sys recursively unbindable and private
- root@castiana:~# mount --make-runbindable /sys
- root@castiana:~# mount --make-private /sys
-
- # Recursively bind-mount the rest of /sys over to /mnnt
- root@castiana:~# mount --rbind /sys/ /mnt
-
- # Access our hidden /sys/device as an unprivileged user
- root@castiana:~# ls /mnt/devices/
- breakpoint cpu cstate_core cstate_pkg i915 intel_pt isa kprobe
- LNXSYSTM:00 msr pci0000:00 platform pnp0 power software system
- tracepoint uncore_arb uncore_cbox_0 uncore_cbox_1 uprobe virtual
-
-Solve this by teaching copy_tree to fail if a mount turns out to be
-both unbindable and locked.
-
-Cc: stable@vger.kernel.org
-Fixes: 5ff9d8a65ce8 ("vfs: Lock in place mounts from more privileged users")
-Reported-by: Jonathan Calmels <jcalmels@nvidia.com>
-Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
-(cherry picked from commit df7342b240185d58d3d9665c0bbf0a0f5570ec29)
-Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
-Acked-by: Colin King <colin.king@canonical.com>
-Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
-Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
----
- fs/namespace.c | 10 ++++++++--
- 1 file changed, 8 insertions(+), 2 deletions(-)
-
-diff --git a/fs/namespace.c b/fs/namespace.c
-index dcf107925150..91a3040f0cd0 100644
---- a/fs/namespace.c
-+++ b/fs/namespace.c
-@@ -1798,8 +1798,14 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
- for (s = r; s; s = next_mnt(s, r)) {
- if (!(flag & CL_COPY_UNBINDABLE) &&
- IS_MNT_UNBINDABLE(s)) {
-- s = skip_mnt_tree(s);
-- continue;
-+ if (s->mnt.mnt_flags & MNT_LOCKED) {
-+ /* Both unbindable and locked. */
-+ q = ERR_PTR(-EPERM);
-+ goto out;
-+ } else {
-+ s = skip_mnt_tree(s);
-+ continue;
-+ }
- }
- if (!(flag & CL_COPY_MNT_NS_FILE) &&
- is_mnt_ns_file(s->mnt.mnt_root)) {
---
-2.11.0
-
projects / pve-kernel.git / commitdiff