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authorLinus Torvalds <torvalds@linux-foundation.org>2018-11-10 13:27:58 -0600
committerLinus Torvalds <torvalds@linux-foundation.org>2018-11-10 13:27:58 -0600
commit1de4f2ef216dade3b5bd5f5247c4c750a953f51c (patch)
tree7be22ffabcb98c2aeeb0df644a32a06328154c2f
parenta1aa42f1d8c00a0767afee28d17caafd2a4dd8ff (diff)
parent9c8e0a1b683525464a2abe9fb4b54404a50ed2b4 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull namespace fixes from Eric Biederman: "I believe all of these are simple obviously correct bug fixes. These fall into two groups: - Fixing the implementation of MNT_LOCKED which prevents lesser privileged users from seeing unders mounts created by more privileged users. - Fixing the extended uid and group mapping in user namespaces. As well as ensuring the code looks correct I have spot tested these changes as well and in my testing the fixes are working" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: mount: Prevent MNT_DETACH from disconnecting locked mounts mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts mount: Retest MNT_LOCKED in do_umount userns: also map extents in the reverse map to kernel IDs
-rw-r--r--fs/namespace.c22
-rw-r--r--kernel/user_namespace.c12
2 files changed, 25 insertions, 9 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 98d27da43304..74f64294a410 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1540,8 +1540,13 @@ 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);
@@ -1555,6 +1560,7 @@ static int do_umount(struct mount *mnt, int flags)
retval = 0;
}
}
+out:
unlock_mount_hash();
namespace_unlock();
return retval;
@@ -1645,7 +1651,7 @@ int ksys_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))
@@ -1728,8 +1734,14 @@ 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)) {
@@ -1782,7 +1794,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
{
namespace_lock();
lock_mount_hash();
- umount_tree(real_mount(mnt), UMOUNT_SYNC);
+ umount_tree(real_mount(mnt), 0);
unlock_mount_hash();
namespace_unlock();
}
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index e5222b5fb4fe..923414a246e9 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -974,10 +974,6 @@ 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.
@@ -1004,6 +1000,14 @@ 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,