user/sven/linux.git/kernel/capability.c, branch v3.14.42

CAPABILITIES: remove undefined caps from all processes

2014-09-17T16:19:09Z

commit 7d8b6c63751cfbbe5eef81a48c22978b3407a3ad upstream. This is effectively a revert of 7b9a7ec565505699f503b4fcf61500dceb36e744 plus fixing it a different way... We found, when trying to run an application from an application which had dropped privs that the kernel does security checks on undefined capability bits. This was ESPECIALLY difficult to debug as those undefined bits are hidden from /proc/$PID/status. Consider a root application which drops all capabilities from ALL 4 capability sets. We assume, since the application is going to set eff/perm/inh from an array that it will clear not only the defined caps less than CAP_LAST_CAP, but also the higher 28ish bits which are undefined future capabilities. The BSET gets cleared differently. Instead it is cleared one bit at a time. The problem here is that in security/commoncap.c::cap_task_prctl() we actually check the validity of a capability being read. So any task which attempts to 'read all things set in bset' followed by 'unset all things set in bset' will not even attempt to unset the undefined bits higher than CAP_LAST_CAP. So the 'parent' will look something like: CapInh: 0000000000000000 CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: ffffffc000000000 All of this 'should' be fine. Given that these are undefined bits that aren't supposed to have anything to do with permissions. But they do... So lets now consider a task which cleared the eff/perm/inh completely and cleared all of the valid caps in the bset (but not the invalid caps it couldn't read out of the kernel). We know that this is exactly what the libcap-ng library does and what the go capabilities library does. They both leave you in that above situation if you try to clear all of you capapabilities from all 4 sets. If that root task calls execve() the child task will pick up all caps not blocked by the bset. The bset however does not block bits higher than CAP_LAST_CAP. So now the child task has bits in eff which are not in the parent. These are 'meaningless' undefined bits, but still bits which the parent doesn't have. The problem is now in cred_cap_issubset() (or any operation which does a subset test) as the child, while a subset for valid cap bits, is not a subset for invalid cap bits! So now we set durring commit creds that the child is not dumpable. Given it is 'more priv' than its parent. It also means the parent cannot ptrace the child and other stupidity. The solution here: 1) stop hiding capability bits in status This makes debugging easier! 2) stop giving any task undefined capability bits. it's simple, it you don't put those invalid bits in CAP_FULL_SET you won't get them in init and you won't get them in any other task either. This fixes the cap_issubset() tests and resulting fallout (which made the init task in a docker container untraceable among other things) 3) mask out undefined bits when sys_capset() is called as it might use ~0, ~0 to denote 'all capabilities' for backward/forward compatibility. This lets 'capsh --caps="all=eip" -- -c /bin/bash' run. 4) mask out undefined bit when we read a file capability off of disk as again likely all bits are set in the xattr for forward/backward compatibility. This lets 'setcap all+pe /bin/bash; /bin/bash' run Signed-off-by: Eric Paris Reviewed-by: Kees Cook Cc: Andrew Vagin Cc: Andrew G. Morgan Cc: Serge E. Hallyn Cc: Kees Cook Cc: Steve Grubb Cc: Dan Walsh Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

fs,userns: Change inode_capable to capable_wrt_inode_uidgid

2014-06-16T20:40:32Z

commit 23adbe12ef7d3d4195e80800ab36b37bee28cd03 upstream. The kernel has no concept of capabilities with respect to inodes; inodes exist independently of namespaces. For example, inode_capable(inode, CAP_LINUX_IMMUTABLE) would be nonsense. This patch changes inode_capable to check for uid and gid mappings and renames it to capable_wrt_inode_uidgid, which should make it more obvious what it does. Fixes CVE-2014-4014. Cc: Theodore Ts'o Cc: Serge Hallyn Cc: "Eric W. Biederman" Cc: Dave Chinner Signed-off-by: Andy Lutomirski Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

audit: Simplify and correct audit_log_capset

2014-01-14T03:26:48Z

- Always report the current process as capset now always only works on the current process. This prevents reporting 0 or a random pid in a random pid namespace. - Don't bother to pass the pid as is available. Signed-off-by: "Eric W. Biederman" (cherry picked from commit bcc85f0af31af123e32858069eb2ad8f39f90e67) (cherry picked from commit f911cac4556a7a23e0b3ea850233d13b32328692) Signed-off-by: Richard Guy Briggs [eparis: fix build error when audit disabled] Signed-off-by: Eric Paris

Merge tag 'xfs-for-linus-v3.12-rc1' of git://oss.sgi.com/xfs/xfs

2013-09-09T18:19:09Z

Pull xfs updates from Ben Myers: "For 3.12-rc1 there are a number of bugfixes in addition to work to ease usage of shared code between libxfs and the kernel, the rest of the work to enable project and group quotas to be used simultaneously, performance optimisations in the log and the CIL, directory entry file type support, fixes for log space reservations, some spelling/grammar cleanups, and the addition of user namespace support. - introduce readahead to log recovery - add directory entry file type support - fix a number of spelling errors in comments - introduce new Q_XGETQSTATV quotactl for project quotas - add USER_NS support - log space reservation rework - CIL optimisations - kernel/userspace libxfs rework" * tag 'xfs-for-linus-v3.12-rc1' of git://oss.sgi.com/xfs/xfs: (112 commits) xfs: XFS_MOUNT_QUOTA_ALL needed by userspace xfs: dtype changed xfs_dir2_sfe_put_ino to xfs_dir3_sfe_put_ino Fix wrong flag ASSERT in xfs_attr_shortform_getvalue xfs: finish removing IOP_* macros. xfs: inode log reservations are too small xfs: check correct status variable for xfs_inobt_get_rec() call xfs: inode buffers may not be valid during recovery readahead xfs: check LSN ordering for v5 superblocks during recovery xfs: btree block LSN escaping to disk uninitialised XFS: Assertion failed: first <= last && last < BBTOB(bp->b_length), file: fs/xfs/xfs_trans_buf.c, line: 568 xfs: fix bad dquot buffer size in log recovery readahead xfs: don't account buffer cancellation during log recovery readahead xfs: check for underflow in xfs_iformat_fork() xfs: xfs_dir3_sfe_put_ino can be static xfs: introduce object readahead to log recovery xfs: Simplify xfs_ail_min() with list_first_entry_or_null() xfs: Register hotcpu notifier after initialization xfs: add xfs sb v4 support for dirent filetype field xfs: Add write support for dirent filetype field xfs: Add read-only support for dirent filetype field ...

userns: Kill nsown_capable it makes the wrong thing easy

2013-08-31T06:44:11Z

nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and CAP_SETGID. For the existing users it doesn't noticably simplify things and from the suggested patches I have seen it encourages people to do the wrong thing. So remove nsown_capable. Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman"

xfs: ioctl check for capabilities in the current user namespace

2013-08-15T19:19:25Z

Use inode_capable() to check if SUID|SGID bits should be cleared to match similar check in inode_change_ok(). The check for CAP_LINUX_IMMUTABLE was not modified since all other file systems also check against init_user_ns rather than current_user_ns. Only allow changing of projid from init_user_ns. Reviewed-by: Dave Chinner Reviewed-by: Gao feng Signed-off-by: Dwight Engen Signed-off-by: Ben Myers

Add file_ns_capable() helper function for open-time capability checking

2013-04-14T17:06:31Z

Nothing is using it yet, but this will allow us to delay the open-time checks to use time, without breaking the normal UNIX permission semantics where permissions are determined by the opener (and the file descriptor can then be passed to a different process, or the process can drop capabilities). Signed-off-by: Linus Torvalds

userns: Teach inode_capable to understand inodes whose uids map to other namespaces.

2012-05-15T21:59:24Z

Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

userns: Replace the hard to write inode_userns with inode_capable.

2012-04-08T00:02:46Z

This represents a change in strategy of how to handle user namespaces. Instead of tagging everything explicitly with a user namespace and bulking up all of the comparisons of uids and gids in the kernel, all uids and gids in use will have a mapping to a flat kuid and kgid spaces respectively. This allows much more of the existing logic to be preserved and in general allows for faster code. In this new and improved world we allow someone to utiliize capabilities over an inode if the inodes owner mapps into the capabilities holders user namespace and the user has capabilities in their user namespace. Which is simple and efficient. Moving the fs uid comparisons to be comparisons in a flat kuid space follows in later patches, something that is only significant if you are using user namespaces. Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call"

2012-01-17T18:19:41Z

This reverts commit d2a7009f0bb03fa22ad08dd25472efa0568126b9. J. R. Okajima explains: "After this commit, I am afraid access(2) on NFS may not work correctly. The scenario based upon my guess. - access(2) overrides the credentials. - calls inode_permission() -- ... -- generic_permission() -- ns_capable(). - while the old ns_capable() calls security_capable(current_cred()), the new ns_capable() calls has_ns_capability(current) -- security_capable(__task_cred(t)). current_cred() returns current->cred which is effective (overridden) credentials, but __task_cred(current) returns current->real_cred (the NFSD's credential). And the overridden credentials by access(2) lost." Requested-by: J. R. Okajima Acked-by: Eric Paris Signed-off-by: Linus Torvalds