user/sven/linux.git/kernel/audit.c, branch v3.12.34

CAPABILITIES: remove undefined caps from all processes

2014-09-17T14:55:03Z

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: Jiri Slaby

net: Use netlink_ns_capable to verify the permisions of netlink messages

2014-06-23T08:27:57Z

[ Upstream commit 90f62cf30a78721641e08737bda787552428061e ] It is possible by passing a netlink socket to a more privileged executable and then to fool that executable into writing to the socket data that happens to be valid netlink message to do something that privileged executable did not intend to do. To keep this from happening replace bare capable and ns_capable calls with netlink_capable, netlink_net_calls and netlink_ns_capable calls. Which act the same as the previous calls except they verify that the opener of the socket had the desired permissions as well. Reported-by: Andy Lutomirski Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby

audit: convert PPIDs to the inital PID namespace.

2014-05-29T09:38:07Z

commit c92cdeb45eea38515e82187f48c2e4f435fb4e25 upstream. sys_getppid() returns the parent pid of the current process in its own pid namespace. Since audit filters are based in the init pid namespace, a process could avoid a filter or trigger an unintended one by being in an alternate pid namespace or log meaningless information. Switch to task_ppid_nr() for PPIDs to anchor all audit filters in the init_pid_ns. (informed by ebiederman's 6c621b7e) Cc: Eric W. Biederman Signed-off-by: Richard Guy Briggs Signed-off-by: Jiri Slaby

audit: restore order of tty and ses fields in log output

2014-05-23T07:39:14Z

commit 2f2ad1013322c8f6c40fc6dafdbd32442fa730ad upstream. When being refactored from audit_log_start() to audit_log_task_info(), in commit e23eb920 the tty and ses fields in the log output got transposed. Restore to original order to avoid breaking search tools. Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Jiri Slaby

audit: reset audit backlog wait time after error recovery

2014-02-13T21:50:10Z

commit e789e561a50de0aaa8c695662d97aaa5eac9d55f upstream. When the audit queue overflows and times out (audit_backlog_wait_time), the audit queue overflow timeout is set to zero. Once the audit queue overflow timeout condition recovers, the timeout should be reset to the original value. See also: https://lkml.org/lkml/2013/9/2/473 Signed-off-by: Luiz Capitulino Signed-off-by: Dan Duval Signed-off-by: Chuck Anderson Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Greg Kroah-Hartman

audit: log the audit_names record type

2013-12-04T19:05:39Z

commit d3aea84a4ace5ff9ce7fb7714cee07bebef681c2 upstream. ...to make it clear what the intent behind each record's operation was. In many cases you can infer this, based on the context of the syscall and the result. In other cases it's not so obvious. For instance, in the case where you have a file being renamed over another, you'll have two different records with the same filename but different inode info. By logging this information we can clearly tell which one was created and which was deleted. This fixes what was broken in commit bfcec708. Commit 79f6530c should also be backported to stable v3.7+. Signed-off-by: Jeff Layton Signed-off-by: Eric Paris Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Greg Kroah-Hartman

audit: fix info leak in AUDIT_GET requests

2013-12-04T19:05:39Z

commit 64fbff9ae0a0a843365d922e0057fc785f23f0e3 upstream. We leak 4 bytes of kernel stack in response to an AUDIT_GET request as we miss to initialize the mask member of status_set. Fix that. Cc: Al Viro Cc: Eric Paris Signed-off-by: Mathias Krause Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Greg Kroah-Hartman

audit: use nlmsg_len() to get message payload length

2013-12-04T19:05:39Z

commit 4d8fe7376a12bf4524783dd95cbc00f1fece6232 upstream. Using the nlmsg_len member of the netlink header to test if the message is valid is wrong as it includes the size of the netlink header itself. Thereby allowing to send short netlink messages that pass those checks. Use nlmsg_len() instead to test for the right message length. The result of nlmsg_len() is guaranteed to be non-negative as the netlink message already passed the checks of nlmsg_ok(). Also switch to min_t() to please checkpatch.pl. Cc: Al Viro Cc: Eric Paris Signed-off-by: Mathias Krause Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Greg Kroah-Hartman

audit: printk USER_AVC messages when audit isn't enabled

2013-12-04T19:05:39Z

commit 0868a5e150bc4c47e7a003367cd755811eb41e0b upstream. When the audit=1 kernel parameter is absent and auditd is not running, AUDIT_USER_AVC messages are being silently discarded. AUDIT_USER_AVC messages should be sent to userspace using printk(), as mentioned in the commit message of 4a4cd633 ("AUDIT: Optimise the audit-disabled case for discarding user messages"). When audit_enabled is 0, audit_receive_msg() discards all user messages except for AUDIT_USER_AVC messages. However, audit_log_common_recv_msg() refuses to allocate an audit_buffer if audit_enabled is 0. The fix is to special case AUDIT_USER_AVC messages in both functions. It looks like commit 50397bd1 ("[AUDIT] clean up audit_receive_msg()") introduced this bug. Signed-off-by: Tyler Hicks Cc: Al Viro Cc: Eric Paris Cc: linux-audit@redhat.com Acked-by: Kees Cook Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Greg Kroah-Hartman

audit: fix endless wait in audit_log_start()

2013-09-25T00:00:26Z

After commit 829199197a43 ("kernel/audit.c: avoid negative sleep durations") audit emitters will block forever if userspace daemon cannot handle backlog. After the timeout the waiting loop turns into busy loop and runs until daemon dies or returns back to work. This is a minimal patch for that bug. Signed-off-by: Konstantin Khlebnikov Cc: Luiz Capitulino Cc: Richard Guy Briggs Cc: Eric Paris Cc: Chuck Anderson Cc: Dan Duval Cc: Dave Kleikamp Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds