Re: [PATCH] memcg: enable accounting in keyctl subsys

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, May 23, 2022 at 12:45:09PM +0300, Vasily Averin wrote:
> On 7/19/21 11:17, Yutian Yang wrote:
> > This patch enables accounting for key objects and auth record objects.
> > Allocation of the objects are triggerable by syscalls from userspace.
> > 
> > We have written a PoC to show that the missing-charging objects lead to
> > breaking memcg limits. The PoC program takes around 2.2GB unaccounted
> > memory, while it is charged for only 24MB memory usage. We evaluate the
> > PoC on QEMU x86_64 v5.2.90 + Linux kernel v5.10.19 + Debian buster. All
> > the limitations including ulimits and sysctl variables are set as default.
> > Specifically, we set kernel.keys.maxbytes = 20000 and 
> > kernel.keys.maxkeys = 200.
> > 
> > /*------------------------- POC code ----------------------------*/
> [skipped]
> > /*-------------------------- end --------------------------------*/
> 
> I experimented with "keyctl request2 user debug: X:Y Z" inside the container
> and found that the problem is still relevant and the proposed patch solves it
> correctly.
> 
> I didn't find any complaints about this patch, could someone explain why
> it wasn't applied? If no one objects, I'd like to push it.
> 
> > Signed-off-by: Yutian Yang <nglaive@gmail.com>
> Reviewed-by: Vasily Averin <vvs@openvz.org>
> 
> Thank you,
> 	Vasily Averin
> 
> PS. Should I perhaps resend it?
> 
> > ---
> >  security/keys/key.c              | 4 ++--
> >  security/keys/request_key_auth.c | 4 ++--
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/security/keys/key.c b/security/keys/key.c
> > index e282c6179..925d85c2e 100644
> > --- a/security/keys/key.c
> > +++ b/security/keys/key.c
> > @@ -279,7 +279,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
> >  		goto no_memory_2;
> >  
> >  	key->index_key.desc_len = desclen;
> > -	key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
> > +	key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL_ACCOUNT);
> >  	if (!key->index_key.description)
> >  		goto no_memory_3;
> >  	key->index_key.type = type;
> > @@ -1198,7 +1198,7 @@ void __init key_init(void)
> >  {
> >  	/* allocate a slab in which we can store keys */
> >  	key_jar = kmem_cache_create("key_jar", sizeof(struct key),
> > -			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
> > +			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
> >  
> >  	/* add the special key types */
> >  	list_add_tail(&key_type_keyring.link, &key_types_list);
> > diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
> > index 41e973500..ed50a100a 100644
> > --- a/security/keys/request_key_auth.c
> > +++ b/security/keys/request_key_auth.c
> > @@ -171,10 +171,10 @@ struct key *request_key_auth_new(struct key *target, const char *op,
> >  	kenter("%d,", target->serial);
> >  
> >  	/* allocate a auth record */
> > -	rka = kzalloc(sizeof(*rka), GFP_KERNEL);
> > +	rka = kzalloc(sizeof(*rka), GFP_KERNEL_ACCOUNT);
> >  	if (!rka)
> >  		goto error;
> > -	rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
> > +	rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL_ACCOUNT);
> >  	if (!rka->callout_info)
> >  		goto error_free_rka;
> >  	rka->callout_len = callout_len;
> 


Acked-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko