linux/security/smack, branch v4.2

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

2015-07-03T22:20:57Z

Pull user namespace updates from Eric Biederman: "Long ago and far away when user namespaces where young it was realized that allowing fresh mounts of proc and sysfs with only user namespace permissions could violate the basic rule that only root gets to decide if proc or sysfs should be mounted at all. Some hacks were put in place to reduce the worst of the damage could be done, and the common sense rule was adopted that fresh mounts of proc and sysfs should allow no more than bind mounts of proc and sysfs. Unfortunately that rule has not been fully enforced. There are two kinds of gaps in that enforcement. Only filesystems mounted on empty directories of proc and sysfs should be ignored but the test for empty directories was insufficient. So in my tree directories on proc, sysctl and sysfs that will always be empty are created specially. Every other technique is imperfect as an ordinary directory can have entries added even after a readdir returns and shows that the directory is empty. Special creation of directories for mount points makes the code in the kernel a smidge clearer about it's purpose. I asked container developers from the various container projects to help test this and no holes were found in the set of mount points on proc and sysfs that are created specially. This set of changes also starts enforcing the mount flags of fresh mounts of proc and sysfs are consistent with the existing mount of proc and sysfs. I expected this to be the boring part of the work but unfortunately unprivileged userspace winds up mounting fresh copies of proc and sysfs with noexec and nosuid clear when root set those flags on the previous mount of proc and sysfs. So for now only the atime, read-only and nodev attributes which userspace happens to keep consistent are enforced. Dealing with the noexec and nosuid attributes remains for another time. This set of changes also addresses an issue with how open file descriptors from /proc//ns/* are displayed. Recently readlink of /proc//fd has been triggering a WARN_ON that has not been meaningful since it was added (as all of the code in the kernel was converted) and is not now actively wrong. There is also a short list of issues that have not been fixed yet that I will mention briefly. It is possible to rename a directory from below to above a bind mount. At which point any directory pointers below the renamed directory can be walked up to the root directory of the filesystem. With user namespaces enabled a bind mount of the bind mount can be created allowing the user to pick a directory whose children they can rename to outside of the bind mount. This is challenging to fix and doubly so because all obvious solutions must touch code that is in the performance part of pathname resolution. As mentioned above there is also a question of how to ensure that developers by accident or with purpose do not introduce exectuable files on sysfs and proc and in doing so introduce security regressions in the current userspace that will not be immediately obvious and as such are likely to require breaking userspace in painful ways once they are recognized" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: vfs: Remove incorrect debugging WARN in prepend_path mnt: Update fs_fully_visible to test for permanently empty directories sysfs: Create mountpoints with sysfs_create_mount_point sysfs: Add support for permanently empty directories to serve as mount points. kernfs: Add support for always empty directories. proc: Allow creating permanently empty directories that serve as mount points sysctl: Allow creating permanently empty directories that serve as mountpoints. fs: Add helper functions for permanently empty directories. vfs: Ignore unlocked mounts in fs_fully_visible mnt: Modify fs_fully_visible to deal with locked ro nodev and atime mnt: Refactor the logic for mounting sysfs and proc in a user namespace

sysfs: Create mountpoints with sysfs_create_mount_point

2015-07-01T15:36:47Z

This allows for better documentation in the code and it allows for a simpler and fully correct version of fs_fully_visible to be written. The mount points converted and their filesystems are: /sys/hypervisor/s390/ s390_hypfs /sys/kernel/config/ configfs /sys/kernel/debug/ debugfs /sys/firmware/efi/efivars/ efivarfs /sys/fs/fuse/connections/ fusectl /sys/fs/pstore/ pstore /sys/kernel/tracing/ tracefs /sys/fs/cgroup/ cgroup /sys/kernel/security/ securityfs /sys/fs/selinux/ selinuxfs /sys/fs/smackfs/ smackfs Cc: stable@vger.kernel.org Acked-by: Greg Kroah-Hartman Signed-off-by: "Eric W. Biederman"

Smack: freeing an error pointer in smk_write_revoke_subj()

2015-06-12T18:59:11Z

This code used to rely on the fact that kfree(NULL) was a no-op, but then we changed smk_parse_smack() to return error pointers on failure instead of NULL. Calling kfree() on an error pointer will oops. I have re-arranged things a bit so that we only free things if they have been allocated. Fixes: e774ad683f42 ('smack: pass error code through pointers') Signed-off-by: Dan Carpenter

Smack: allow multiple labels in onlycap

2015-06-02T18:53:42Z

Smack onlycap allows limiting of CAP_MAC_ADMIN and CAP_MAC_OVERRIDE to processes running with the configured label. But having single privileged label is not enough in some real use cases. On a complex system like Tizen, there maybe few programs that need to configure Smack policy in run-time and running them all with a single label is not always practical. This patch extends onlycap feature for multiple labels. They are configured in the same smackfs "onlycap" interface, separated by spaces. Signed-off-by: Rafal Krypa

Smack: fix seq operations in smackfs

2015-06-02T18:53:23Z

Use proper RCU functions and read locking in smackfs seq_operations. Smack gets away with not using proper RCU functions in smackfs, because it never removes entries from these lists. But now one list will be needed (with interface in smackfs) that will have both elements added and removed to it. This change will also help any future changes implementing removal of unneeded entries from other Smack lists. The patch also fixes handling of pos argument in smk_seq_start and smk_seq_next. This fixes a bug in case when smackfs is read with a small buffer: Kernel panic - not syncing: Kernel mode fault at addr 0xfa0000011b CPU: 0 PID: 1292 Comm: dd Not tainted 4.1.0-rc1-00012-g98179b8 #13 Stack: 00000003 0000000d 7ff39e48 7f69fd00 7ff39ce0 601ae4b0 7ff39d50 600e587b 00000010 6039f690 7f69fd40 00612003 Call Trace: [<601ae4b0>] load2_seq_show+0x19/0x1d [<600e587b>] seq_read+0x168/0x331 [<600c5943>] __vfs_read+0x21/0x101 [<601a595e>] ? security_file_permission+0xf8/0x105 [<600c5ec6>] ? rw_verify_area+0x86/0xe2 [<600c5fc3>] vfs_read+0xa1/0x14c [<600c68e2>] SyS_read+0x57/0xa0 [<6001da60>] handle_syscall+0x60/0x80 [<6003087d>] userspace+0x442/0x548 [<6001aa77>] ? interrupt_end+0x0/0x80 [<6001daae>] ? copy_chunk_to_user+0x0/0x2b [<6002cb6b>] ? save_registers+0x1f/0x39 [<60032ef7>] ? arch_prctl+0xf5/0x170 [<6001a92d>] fork_handler+0x85/0x87 Signed-off-by: Rafal Krypa

smack: pass error code through pointers

2015-05-15T15:36:03Z

This patch makes the following functions to use ERR_PTR() and related macros to pass the appropriate error code through returned pointers: smk_parse_smack() smk_import_entry() smk_fetch() It also makes all the other functions that use them to handle the error cases properly. This ways correct error codes from places where they happened can be propagated to the user space if necessary. Doing this it fixes a bug in onlycap and unconfined files handling. Previously their content was cleared on any error from smk_import_entry/smk_parse_smack, be it EINVAL (as originally intended) or ENOMEM. Right now it only reacts on EINVAL passing other codes properly to userspace. Comments have been updated accordingly. Signed-off-by: Lukasz Pawelczyk

Smack: ignore private inode for smack_file_receive

2015-05-15T15:35:50Z

The dmabuf fd can be shared between processes via unix domain socket. The file of dmabuf fd is came from anon_inode. The inode has no set and get xattr operations, so it can not be shared between processes with smack. This patch fixes just to ignore private inode including anon_inode for smack_file_receive. Signed-off-by: Seung-Woo Kim

LSM: Switch to lists of hooks

2015-05-12T05:00:41Z

Instead of using a vector of security operations with explicit, special case stacking of the capability and yama hooks use lists of hooks with capability and yama hooks included as appropriate. The security_operations structure is no longer required. Instead, there is a union of the function pointers that allows all the hooks lists to use a common mechanism for list management while retaining typing. Each module supplies an array describing the hooks it provides instead of a sparsely populated security_operations structure. The description includes the element that gets put on the hook list, avoiding the issues surrounding individual element allocation. The method for registering security modules is changed to reflect the information available. The method for removing a module, currently only used by SELinux, has also changed. It should be generic now, however if there are potential race conditions based on ordering of hook removal that needs to be addressed by the calling module. The security hooks are called from the lists and the first failure is returned. Signed-off-by: Casey Schaufler Acked-by: John Johansen Acked-by: Kees Cook Acked-by: Paul Moore Acked-by: Stephen Smalley Acked-by: Tetsuo Handa Signed-off-by: James Morris

LSM: Add security module hook list heads

2015-05-12T05:00:36Z

Add a list header for each security hook. They aren't used until later in the patch series. They are grouped together in a structure so that there doesn't need to be an external address for each. Macro-ize the initialization of the security_operations for each security module in anticipation of changing out the security_operations structure. Signed-off-by: Casey Schaufler Acked-by: John Johansen Acked-by: Kees Cook Acked-by: Paul Moore Acked-by: Stephen Smalley Acked-by: Tetsuo Handa Signed-off-by: James Morris

LSM: Split security.h

2015-05-12T05:00:16Z

The security.h header file serves two purposes, interfaces for users of the security modules and interfaces for security modules. Users of the security modules don't need to know about what's in the security_operations structure, so pull it out into it's own header, lsm_hooks.h Signed-off-by: Casey Schaufler Acked-by: John Johansen Acked-by: Kees Cook Acked-by: Paul Moore Acked-by: Stephen Smalley Acked-by: Tetsuo Handa Signed-off-by: James Morris