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Groups > linux.kernel > #1235079
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 3.10 01/56] unshare: Unsharing a thread does not require unsharing a vm |
| Date | 2015-09-29 15:50 +0200 |
| Message-ID | <qe3s8-85D-43@gated-at.bofh.it> (permalink) |
| References | <qe3s5-85D-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Eric W. Biederman" <ebiederm@xmission.com>
commit 12c641ab8270f787dfcce08b5f20ce8b65008096 upstream.
In the logic in the initial commit of unshare made creating a new
thread group for a process, contingent upon creating a new memory
address space for that process. That is wrong. Two separate
processes in different thread groups can share a memory address space
and clone allows creation of such proceses.
This is significant because it was observed that mm_users > 1 does not
mean that a process is multi-threaded, as reading /proc/PID/maps
temporarily increments mm_users, which allows other processes to
(accidentally) interfere with unshare() calls.
Correct the check in check_unshare_flags() to test for
!thread_group_empty() for CLONE_THREAD, CLONE_SIGHAND, and CLONE_VM.
For sighand->count > 1 for CLONE_SIGHAND and CLONE_VM.
For !current_is_single_threaded instead of mm_users > 1 for CLONE_VM.
By using the correct checks in unshare this removes the possibility of
an accidental denial of service attack.
Additionally using the correct checks in unshare ensures that only an
explicit unshare(CLONE_VM) can possibly trigger the slow path of
current_is_single_threaded(). As an explict unshare(CLONE_VM) is
pointless it is not expected there are many applications that make
that call.
Fixes: b2e0d98705e60e45bbb3c0032c48824ad7ae0704 userns: Implement unshare of the user namespace
Reported-by: Ricky Zhou <rickyz@chromium.org>
Reported-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/fork.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1760,13 +1760,21 @@ static int check_unshare_flags(unsigned
CLONE_NEWUSER|CLONE_NEWPID))
return -EINVAL;
/*
- * Not implemented, but pretend it works if there is nothing to
- * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
- * needs to unshare vm.
+ * Not implemented, but pretend it works if there is nothing
+ * to unshare. Note that unsharing the address space or the
+ * signal handlers also need to unshare the signal queues (aka
+ * CLONE_THREAD).
*/
if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
- /* FIXME: get_task_mm() increments ->mm_users */
- if (atomic_read(¤t->mm->mm_users) > 1)
+ if (!thread_group_empty(current))
+ return -EINVAL;
+ }
+ if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
+ if (atomic_read(¤t->sighand->count) > 1)
+ return -EINVAL;
+ }
+ if (unshare_flags & CLONE_VM) {
+ if (!current_is_single_threaded())
return -EINVAL;
}
@@ -1840,16 +1848,16 @@ SYSCALL_DEFINE1(unshare, unsigned long,
if (unshare_flags & CLONE_NEWPID)
unshare_flags |= CLONE_THREAD;
/*
- * If unsharing a thread from a thread group, must also unshare vm.
- */
- if (unshare_flags & CLONE_THREAD)
- unshare_flags |= CLONE_VM;
- /*
* If unsharing vm, must also unshare signal handlers.
*/
if (unshare_flags & CLONE_VM)
unshare_flags |= CLONE_SIGHAND;
/*
+ * If unsharing a signal handlers, must also unshare the signal queues.
+ */
+ if (unshare_flags & CLONE_SIGHAND)
+ unshare_flags |= CLONE_THREAD;
+ /*
* If unsharing namespace, must also unshare filesystem information.
*/
if (unshare_flags & CLONE_NEWNS)
--
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[PATCH 3.10 00/56] 3.10.90-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 15:50 +0200
[PATCH 3.10 01/56] unshare: Unsharing a thread does not require unsharing a vm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 15:50 +0200
[PATCH 3.10 04/56] mac80211: enable assoc check for mesh interfaces Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 15:50 +0200
[PATCH 3.10 02/56] rtlwifi: rtl8192cu: Add new device ID Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 15:50 +0200
[PATCH 3.10 17/56] NFS: nfs_set_pgio_error sometimes misses errors Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 15:50 +0200
[PATCH 3.10 25/56] IB/uverbs: reject invalid or unknown opcodes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 15:50 +0200
[PATCH 3.10 40/56] net: Fix skb csum races when peeking Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 43/56] isdn/gigaset: reset tty->receive_room when attaching ser_gigaset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 55/56] vfs: Remove incorrect debugging WARN in prepend_path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 29/56] stmmac: fix check for phydev being open Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
Re: [PATCH 3.10 29/56] stmmac: fix check for phydev being open Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-09-30 13:30 +0200
[PATCH 3.10 49/56] ip6_gre: release cached dst on tunnel removal Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 27/56] IB/mlx4: Forbid using sysfs to change RoCE pkeys Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 31/56] sctp: fix ASCONF list handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 41/56] net: Fix skb_set_peeked use-after-free bug Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 32/56] vhost/scsi: potential memory corruption Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 30/56] hfs,hfsplus: cache pages correctly between bnode_create and bnode_free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 35/56] net/tipc: initialize security state for new connection socket Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 52/56] net/ipv6: Correct PIM6 mrt_lock handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 50/56] usbnet: Get EVENT_NO_RUNTIME_PM bit before it is cleared Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 44/56] ipv6: lock socket in ip6_datagram_connect() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 42/56] bridge: mdb: fix double add notification Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 33/56] x86: bpf_jit: fix compilation of large bpf programs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 37/56] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 45/56] bonding: fix destruction of bond with devices different from arphrd_ether Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 53/56] sctp: fix race on protocol/netns initialization Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 47/56] netlink: dont hold mutex in rcu callback when releasing mmapd ring Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 36/56] bridge: mdb: zero out the local br_ip variable before use Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 48/56] rds: fix an integer overflow test in rds_info_getsockopt() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
Re: [PATCH 3.10 08/56] Input: synaptics - fix handling of disabling gesture mode Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-09-29 16:00 +0200
Re: [PATCH 3.10 08/56] Input: synaptics - fix handling of disabling gesture mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:20 +0200
[PATCH 3.10 56/56] Revert "iio: bmg160: IIO_BUFFER and IIO_TRIGGERED_BUFFER are required" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 38/56] net: call rcu_read_lock early in process_backlog Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 54/56] fib_rules: fix fib rule dumps across multiple skbs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 46/56] inet: frags: fix defragmented packets IP header for af_packet Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 34/56] ipv6: Make MLD packets to only be processed locally Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 51/56] ipv6: fix exthdrs offload registration in out_rt path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 39/56] net: Clone skb before setting peeked flag Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:00 +0200
[PATCH 3.10 03/56] tg3: Fix temperature reporting Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 22/56] md/raid10: always set reshape_safe when initializing reshape_position. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 18/56] parisc: Filter out spurious interrupts in PA-RISC irq handler Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 13/56] Add radeon suspend/resume quirk for HP Compaq dc5750. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 16/56] NFSv4: dont set SETATTR for O_RDONLY|O_EXCL Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 20/56] fs: if a coredump already exists, unlink and recreate with O_EXCL Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 08/56] Input: synaptics - fix handling of disabling gesture mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 06/56] arm64: compat: fix vfp save/restore across signal handlers in big-endian Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 21/56] mmc: core: fix race condition in mmc_wait_data_done Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 24/56] hfs: fix B-tree corruption after insertion at position 0 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 19/56] vmscan: fix increasing nr_isolated incurred by putback unevictable pages Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 12/56] powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 11/56] powerpc/mm: Fix pte_pagesize_index() crash on 4K w/64K hash Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 07/56] arm64: head.S: initialise mdcr_el2 in el2_setup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
[PATCH 3.10 26/56] IB/uverbs: Fix race between ib_uverbs_open and remove_one Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-29 16:10 +0200
Re: [PATCH 3.10 00/56] 3.10.90-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2015-09-29 19:00 +0200
Re: [PATCH 3.10 00/56] 3.10.90-stable review Guenter Roeck <linux@roeck-us.net> - 2015-09-29 23:20 +0200
Re: [PATCH 3.10 00/56] 3.10.90-stable review Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2015-09-30 07:50 +0200
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