user/sven/linux.git/include/linux/mount.h, branch v4.13.14

randstruct: Mark various structs for randomization

2017-06-30T19:00:51Z

This marks many critical kernel structures for randomization. These are structures that have been targeted in the past in security exploits, or contain functions pointers, pointers to function pointer tables, lists, workqueues, ref-counters, credentials, permissions, or are otherwise sensitive. This initial list was extracted from Brad Spengler/PaX Team's code in the last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Left out of this list is task_struct, which requires special handling and will be covered in a subsequent patch. Signed-off-by: Kees Cook

fs: Better permission checking for submounts

2017-02-01T15:36:12Z

To support unprivileged users mounting filesystems two permission checks have to be performed: a test to see if the user allowed to create a mount in the mount namespace, and a test to see if the user is allowed to access the specified filesystem. The automount case is special in that mounting the original filesystem grants permission to mount the sub-filesystems, to any user who happens to stumble across the their mountpoint and satisfies the ordinary filesystem permission checks. Attempting to handle the automount case by using override_creds almost works. It preserves the idea that permission to mount the original filesystem is permission to mount the sub-filesystem. Unfortunately using override_creds messes up the filesystems ordinary permission checks. Solve this by being explicit that a mount is a submount by introducing vfs_submount, and using it where appropriate. vfs_submount uses a new mount internal mount flags MS_SUBMOUNT, to let sget and friends know that a mount is a submount so they can take appropriate action. sget and sget_userns are modified to not perform any permission checks on submounts. follow_automount is modified to stop using override_creds as that has proven problemantic. do_mount is modified to always remove the new MS_SUBMOUNT flag so that we know userspace will never by able to specify it. autofs4 is modified to stop using current_real_cred that was put in there to handle the previous version of submount permission checking. cifs is modified to pass the mountpoint all of the way down to vfs_submount. debugfs is modified to pass the mountpoint all of the way down to trace_automount by adding a new parameter. To make this change easier a new typedef debugfs_automount_t is introduced to capture the type of the debugfs automount function. Cc: stable@vger.kernel.org Fixes: 069d5ac9ae0d ("autofs: Fix automounts by using current_real_cred()->uid") Fixes: aeaa4a79ff6a ("fs: Call d_automount with the filesystems creds") Reviewed-by: Trond Myklebust Reviewed-by: Seth Forshee Signed-off-by: "Eric W. Biederman"

Merge branch 'work.autofs' into for-linus

2016-12-16T21:34:52Z

Signed-off-by: Al Viro

namespace.c: constify struct path passed to a bunch of primitives

2016-12-06T00:03:12Z

Signed-off-by: Al Viro

vfs: add path_is_mountpoint() helper

2016-12-04T01:51:35Z

d_mountpoint() can only be used reliably to establish if a dentry is not mounted in any namespace. It isn't aware of the possibility there may be multiple mounts using a given dentry that may be in a different namespace. Add helper functions, path_is_mountpoint(), that checks if a struct path is a mountpoint for this case. Link: http://lkml.kernel.org/r/20161011053358.27645.9729.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro

mnt: Add a per mount namespace limit on the number of mounts

2016-09-30T17:46:48Z

CAI Qian pointed out that the semantics of shared subtrees make it possible to create an exponentially increasing number of mounts in a mount namespace. mkdir /tmp/1 /tmp/2 mount --make-rshared / for i in $(seq 1 20) ; do mount --bind /tmp/1 /tmp/2 ; done Will create create 2^20 or 1048576 mounts, which is a practical problem as some people have managed to hit this by accident. As such CVE-2016-6213 was assigned. Ian Kent described the situation for autofs users as follows: > The number of mounts for direct mount maps is usually not very large because of > the way they are implemented, large direct mount maps can have performance > problems. There can be anywhere from a few (likely case a few hundred) to less > than 10000, plus mounts that have been triggered and not yet expired. > > Indirect mounts have one autofs mount at the root plus the number of mounts that > have been triggered and not yet expired. > > The number of autofs indirect map entries can range from a few to the common > case of several thousand and in rare cases up to between 30000 and 50000. I've > not heard of people with maps larger than 50000 entries. > > The larger the number of map entries the greater the possibility for a large > number of active mounts so it's not hard to expect cases of a 1000 or somewhat > more active mounts. So I am setting the default number of mounts allowed per mount namespace at 100,000. This is more than enough for any use case I know of, but small enough to quickly stop an exponential increase in mounts. Which should be perfect to catch misconfigurations and malfunctioning programs. For anyone who needs a higher limit this can be changed by writing to the new /proc/sys/fs/mount-max sysctl. Tested-by: CAI Qian Signed-off-by: "Eric W. Biederman"

fs: Treat foreign mounts as nosuid

2016-06-24T15:40:41Z

If a process gets access to a mount from a different user namespace, that process should not be able to take advantage of setuid files or selinux entrypoints from that filesystem. Prevent this by treating mounts from other mount namespaces and those not owned by current_user_ns() or an ancestor as nosuid. This will make it safer to allow more complex filesystems to be mounted in non-root user namespaces. This does not remove the need for MNT_LOCK_NOSUID. The setuid, setgid, and file capability bits can no longer be abused if code in a user namespace were to clear nosuid on an untrusted filesystem, but this patch, by itself, is insufficient to protect the system from abuse of files that, when execed, would increase MAC privilege. As a more concrete explanation, any task that can manipulate a vfsmount associated with a given user namespace already has capabilities in that namespace and all of its descendents. If they can cause a malicious setuid, setgid, or file-caps executable to appear in that mount, then that executable will only allow them to elevate privileges in exactly the set of namespaces in which they are already privileges. On the other hand, if they can cause a malicious executable to appear with a dangerous MAC label, running it could change the caller's security context in a way that should not have been possible, even inside the namespace in which the task is confined. As a hardening measure, this would have made CVE-2014-5207 much more difficult to exploit. Signed-off-by: Andy Lutomirski Signed-off-by: Seth Forshee Acked-by: James Morris Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2015-04-18T15:20:31Z

Pull usernamespace mount fixes from Eric Biederman: "Way back in October Andrey Vagin reported that umount(MNT_DETACH) could be used to defeat MNT_LOCKED. As I worked to fix this I discovered that combined with mount propagation and an appropriate selection of shared subtrees a reference to a directory on an unmounted filesystem is not necessary. That MNT_DETACH is allowed in user namespace in a form that can break MNT_LOCKED comes from my early misunderstanding what MNT_DETACH does. To avoid breaking existing userspace the conflict between MNT_DETACH and MNT_LOCKED is fixed by leaving mounts that are locked to their parents in the mount hash table until the last reference goes away. While investigating this issue I also found an issue with __detach_mounts. The code was unnecessarily and incorrectly triggering mount propagation. Resulting in too many mounts going away when a directory is deleted, and too many cpu cycles are burned while doing that. Looking some more I realized that __detach_mounts by only keeping mounts connected that were MNT_LOCKED it had the potential to still leak information so I tweaked the code to keep everything locked together that possibly could be. This code was almost ready last cycle but Al invented fs_pin which slightly simplifies this code but required rewrites and retesting, and I have not been in top form for a while so it took me a while to get all of that done. Similiarly this pull request is late because I have been feeling absolutely miserable all week. The issue of being able to escape a bind mount has not yet been addressed, as the fixes are not yet mature" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: mnt: Update detach_mounts to leave mounts connected mnt: Fix the error check in __detach_mounts mnt: Honor MNT_LOCKED when detaching mounts fs_pin: Allow for the possibility that m_list or s_list go unused. mnt: Factor umount_mnt from umount_tree mnt: Factor out unhash_mnt from detach_mnt and umount_tree mnt: Fail collect_mounts when applied to unmounted mounts mnt: Don't propagate unmounts to locked mounts mnt: On an unmount propagate clearing of MNT_LOCKED mnt: Delay removal from the mount hash. mnt: Add MNT_UMOUNT flag mnt: In umount_tree reuse mnt_list instead of mnt_hash mnt: Don't propagate umounts in __detach_mounts mnt: Improve the umount_tree flags mnt: Use hlist_move_list in namespace_unlock

init: export name_to_dev_t and mark name argument as const

2015-04-15T16:10:18Z

DM will switch its device lookup code to using name_to_dev_t() so it must be exported. Also, the @name argument should be marked const. Signed-off-by: Dan Ehrenberg Signed-off-by: Mike Snitzer

mnt: Add MNT_UMOUNT flag

2015-04-03T01:34:18Z

In some instances it is necessary to know if the the unmounting process has begun on a mount. Add MNT_UMOUNT to make that reliably testable. This fix gets used in fixing locked mounts in MNT_DETACH Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman"