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SubjectRe: [PATCH 8/9] keys: Network namespace domain tag [ver #4]
On Wed, Jun 19, 2019 at 12:49 PM David Howells <dhowells@redhat.com> wrote:
>
> Create key domain tags for network namespaces and make it possible to
> automatically tag keys that are used by networked services (e.g. AF_RXRPC,
> AFS, DNS) with the default network namespace if not set by the caller.
>
> This allows keys with the same description but in different namespaces to
> coexist within a keyring.
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: netdev@vger.kernel.org
> cc: linux-nfs@vger.kernel.org
> cc: linux-cifs@vger.kernel.org
> cc: linux-afs@lists.infradead.org
> ---

> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index 711b161505ac..076a75c73c9e 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -38,9 +38,16 @@ EXPORT_SYMBOL_GPL(net_namespace_list);
> DECLARE_RWSEM(net_rwsem);
> EXPORT_SYMBOL_GPL(net_rwsem);
>
> +#ifdef CONFIG_KEYS
> +static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
> +#endif
> +
> struct net init_net = {
> .count = REFCOUNT_INIT(1),
> .dev_base_head = LIST_HEAD_INIT(init_net.dev_base_head),
> +#ifdef CONFIG_KEYS
> + .key_domain = &init_net_key_domain,
> +#endif
> };
> EXPORT_SYMBOL(init_net);
>
> @@ -386,10 +393,21 @@ static struct net *net_alloc(void)
> if (!net)
> goto out_free;
>
> +#ifdef CONFIG_KEYS
> + net->key_domain = kzalloc(sizeof(struct key_tag), GFP_KERNEL);
> + if (!net->key_domain)
> + goto out_free_2;
> + refcount_set(&net->key_domain->usage, 1);
> +#endif
> +
> rcu_assign_pointer(net->gen, ng);
> out:
> return net;
>
> +#ifdef CONFIG_KEYS
> +out_free_2:
> + kmem_cache_free(net_cachep, net);

needs
net = NULL;

to signal failure

> +#endif
> out_free:
> kfree(ng);
> goto out;

Reported-by: syzbot <syzkaller@googlegroups.com>

BUG: KASAN: use-after-free in atomic_set
include/asm-generic/atomic-instrumented.h:44 [inline]
BUG: KASAN: use-after-free in refcount_set include/linux/refcount.h:32 [inline]
BUG: KASAN: use-after-free in copy_net_ns+0x1e8/0x431
net/core/net_namespace.c:466
Write of size 4 at addr ffff88809c9de080 by task syz-executor.1/12624

CPU: 1 PID: 12624 Comm: syz-executor.1 Not tainted 5.2.0-rc6-next-20190626 #23
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
__kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
kasan_report+0x12/0x17 mm/kasan/common.c:614
check_memory_region_inline mm/kasan/generic.c:185 [inline]
check_memory_region+0x123/0x190 mm/kasan/generic.c:191
kasan_check_write+0x14/0x20 mm/kasan/common.c:100
atomic_set include/asm-generic/atomic-instrumented.h:44 [inline]
refcount_set include/linux/refcount.h:32 [inline]
copy_net_ns+0x1e8/0x431 net/core/net_namespace.c:466
create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
ksys_unshare+0x444/0x980 kernel/fork.c:2828
__do_sys_unshare kernel/fork.c:2896 [inline]
__se_sys_unshare kernel/fork.c:2894 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:2894
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459519
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2202261c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f2202261c90 RCX: 0000000000459519
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f22022626d4
R13: 00000000004c8a2c R14: 00000000004df7d0 R15: 0000000000000006

Allocated by task 12624:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
slab_post_alloc_hook mm/slab.h:520 [inline]
slab_alloc mm/slab.c:3320 [inline]
kmem_cache_alloc+0x121/0x710 mm/slab.c:3484
kmem_cache_zalloc include/linux/slab.h:737 [inline]
net_alloc net/core/net_namespace.c:410 [inline]
copy_net_ns+0xf1/0x431 net/core/net_namespace.c:461
create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
ksys_unshare+0x444/0x980 kernel/fork.c:2828
__do_sys_unshare kernel/fork.c:2896 [inline]
__se_sys_unshare kernel/fork.c:2894 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:2894
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 12624:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
__cache_free mm/slab.c:3426 [inline]
kmem_cache_free+0x86/0x320 mm/slab.c:3694
net_alloc net/core/net_namespace.c:427 [inline]
copy_net_ns+0x3b1/0x431 net/core/net_namespace.c:461
create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
ksys_unshare+0x444/0x980 kernel/fork.c:2828
__do_sys_unshare kernel/fork.c:2896 [inline]
__se_sys_unshare kernel/fork.c:2894 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:2894
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe

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