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2013-03-26yama: Better permission check for ptracemeEric W. Biederman
Change the permission check for yama_ptrace_ptracee to the standard ptrace permission check, testing if the traceer has CAP_SYS_PTRACE in the tracees user namespace. Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-12-17Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull user namespace changes from Eric Biederman: "While small this set of changes is very significant with respect to containers in general and user namespaces in particular. The user space interface is now complete. This set of changes adds support for unprivileged users to create user namespaces and as a user namespace root to create other namespaces. The tyranny of supporting suid root preventing unprivileged users from using cool new kernel features is broken. This set of changes completes the work on setns, adding support for the pid, user, mount namespaces. This set of changes includes a bunch of basic pid namespace cleanups/simplifications. Of particular significance is the rework of the pid namespace cleanup so it no longer requires sending out tendrils into all kinds of unexpected cleanup paths for operation. At least one case of broken error handling is fixed by this cleanup. The files under /proc/<pid>/ns/ have been converted from regular files to magic symlinks which prevents incorrect caching by the VFS, ensuring the files always refer to the namespace the process is currently using and ensuring that the ptrace_mayaccess permission checks are always applied. The files under /proc/<pid>/ns/ have been given stable inode numbers so it is now possible to see if different processes share the same namespaces. Through the David Miller's net tree are changes to relax many of the permission checks in the networking stack to allowing the user namespace root to usefully use the networking stack. Similar changes for the mount namespace and the pid namespace are coming through my tree. Two small changes to add user namespace support were commited here adn in David Miller's -net tree so that I could complete the work on the /proc/<pid>/ns/ files in this tree. Work remains to make it safe to build user namespaces and 9p, afs, ceph, cifs, coda, gfs2, ncpfs, nfs, nfsd, ocfs2, and xfs so the Kconfig guard remains in place preventing that user namespaces from being built when any of those filesystems are enabled. Future design work remains to allow root users outside of the initial user namespace to mount more than just /proc and /sys." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (38 commits) proc: Usable inode numbers for the namespace file descriptors. proc: Fix the namespace inode permission checks. proc: Generalize proc inode allocation userns: Allow unprivilged mounts of proc and sysfs userns: For /proc/self/{uid,gid}_map derive the lower userns from the struct file procfs: Print task uids and gids in the userns that opened the proc file userns: Implement unshare of the user namespace userns: Implent proc namespace operations userns: Kill task_user_ns userns: Make create_new_namespaces take a user_ns parameter userns: Allow unprivileged use of setns. userns: Allow unprivileged users to create new namespaces userns: Allow setting a userns mapping to your current uid. userns: Allow chown and setgid preservation userns: Allow unprivileged users to create user namespaces. userns: Ignore suid and sgid on binaries if the uid or gid can not be mapped userns: fix return value on mntns_install() failure vfs: Allow unprivileged manipulation of the mount namespace. vfs: Only support slave subtrees across different user namespaces vfs: Add a user namespace reference from struct mnt_namespace ...
2012-11-20Yama: remove locking from delete pathKees Cook
Instead of locking the list during a delete, mark entries as invalid and trigger a workqueue to clean them up. This lets us easily handle task_free from interrupt context. Signed-off-by: Kees Cook <keescook@chromium.org>
2012-11-20Yama: add RCU to drop read lockingKees Cook
Stop using spinlocks in the read path. Add RCU list to handle the readers. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: John Johansen <john.johansen@canonical.com>
2012-11-20userns: Kill task_user_nsEric W. Biederman
The task_user_ns function hides the fact that it is getting the user namespace from struct cred on the task. struct cred may go away as soon as the rcu lock is released. This leads to a race where we can dereference a stale user namespace pointer. To make it obvious a struct cred is involved kill task_user_ns. To kill the race modify the users of task_user_ns to only reference the user namespace while the rcu lock is held. Cc: Kees Cook <keescook@chromium.org> Cc: James Morris <james.l.morris@oracle.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-09-28Merge tag 'v3.6-rc7' into nextJames Morris
Linux 3.6-rc7 Requested by David Howells so he can merge his key susbsystem work into my tree with requisite -linus changesets.
2012-09-08Yama: handle 32-bit userspace prctlKees Cook
When running a 64-bit kernel and receiving prctls from a 32-bit userspace, the "-1" used as an unsigned long will end up being misdetected. The kernel is looking for 0xffffffffffffffff instead of 0xffffffff. Since prctl lacks a distinct compat interface, Yama needs to handle this translation itself. As such, support either value as meaning PR_SET_PTRACER_ANY, to avoid breaking the ABI for 64-bit. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: John Johansen <john.johansen@canonical.com> Cc: stable@vger.kernel.org Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-09-05security: allow Yama to be unconditionally stackedKees Cook
Unconditionally call Yama when CONFIG_SECURITY_YAMA_STACKED is selected, no matter what LSM module is primary. Ubuntu and Chrome OS already carry patches to do this, and Fedora has voiced interest in doing this as well. Instead of having multiple distributions (or LSM authors) carrying these patches, just allow Yama to be called unconditionally when selected by the new CONFIG. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: Eric Paris <eparis@redhat.com> Acked-by: John Johansen <john.johansen@canonical.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-08-17Yama: access task_struct->comm directlyKees Cook
The core ptrace access checking routine holds a task lock, and when reporting a failure, Yama takes a separate task lock. To avoid a potential deadlock with two ptracers taking the opposite locks, do not use get_task_comm() and just use ->comm directly since accuracy is not important for the report. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Suggested-by: Oleg Nesterov <oleg@redhat.com> CC: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: John Johansen <john.johansen@canonical.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-08-10Yama: higher restrictions should block PTRACE_TRACEMEKees Cook
The higher ptrace restriction levels should be blocking even PTRACE_TRACEME requests. The comments in the LSM documentation are misleading about when the checks happen (the parent does not go through security_ptrace_access_check() on a PTRACE_TRACEME call). Signed-off-by: Kees Cook <keescook@chromium.org> Cc: stable@vger.kernel.org # 3.5.x and later Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-05-15Yama: replace capable() with ns_capable()Kees Cook
When checking capabilities, the question we want to be asking is "does current() have the capability in the child's namespace?" Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-04-23Yama: remove an unused variableDan Carpenter
GCC complains that we don't use "one" any more after 389da25f93 "Yama: add additional ptrace scopes". security/yama/yama_lsm.c:322:12: warning: ?one? defined but not used [-Wunused-variable] Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-04-19Yama: add additional ptrace scopesKees Cook
This expands the available Yama ptrace restrictions to include two more modes. Mode 2 requires CAP_SYS_PTRACE for PTRACE_ATTACH, and mode 3 completely disables PTRACE_ATTACH (and locks the sysctl). Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-02-16Yama: add PR_SET_PTRACER_ANYKees Cook
For a process to entirely disable Yama ptrace restrictions, it can use the special PR_SET_PTRACER_ANY pid to indicate that any otherwise allowed process may ptrace it. This is stronger than calling PR_SET_PTRACER with pid "1" because it includes processes in external pid namespaces. This is currently needed by the Chrome renderer, since its crash handler (Breakpad) runs external to the renderer's pid namespace. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <jmorris@namei.org>
2012-02-10security: Yama LSMKees Cook
This adds the Yama Linux Security Module to collect DAC security improvements (specifically just ptrace restrictions for now) that have existed in various forms over the years and have been carried outside the mainline kernel by other Linux distributions like Openwall and grsecurity. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: John Johansen <john.johansen@canonical.com> Signed-off-by: James Morris <jmorris@namei.org>