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Commit a91dbff5 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

sock: ulimit on MSG_ZEROCOPY pages 



Bound the number of pages that a user may pin.

Follow the lead of perf tools to maintain a per-user bound on memory
locked pages commit 789f90fc ("perf_counter: per user mlock gift")

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4ab6c99d

include/linux/sched/user.h

+2 −1
Original line number Diff line number Diff line
@@ -36,7 +36,8 @@ struct user_struct { 
	struct hlist_node uidhash_node;

	kuid_t uid;



#if defined(CONFIG_PERF_EVENTS) || defined(CONFIG_BPF_SYSCALL)

#if defined(CONFIG_PERF_EVENTS) || defined(CONFIG_BPF_SYSCALL) || \

    defined(CONFIG_NET)

	atomic_long_t locked_vm;

#endif

};

include/linux/skbuff.h

+5 −0
Original line number Diff line number Diff line
@@ -457,6 +457,11 @@ struct ubuf_info { 
		};

	};

	atomic_t refcnt;



	struct mmpin {

		struct user_struct *user;

		unsigned int num_pg;

	} mmp;

};



#define skb_uarg(SKB)	((struct ubuf_info *)(skb_shinfo(SKB)->destructor_arg))

net/core/skbuff.c

+48 −0
Original line number Diff line number Diff line
@@ -897,6 +897,44 @@ struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src) 
}

EXPORT_SYMBOL_GPL(skb_morph);



static int mm_account_pinned_pages(struct mmpin *mmp, size_t size)

{

	unsigned long max_pg, num_pg, new_pg, old_pg;

	struct user_struct *user;



	if (capable(CAP_IPC_LOCK) || !size)

		return 0;



	num_pg = (size >> PAGE_SHIFT) + 2;	/* worst case */

	max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	user = mmp->user ? : current_user();



	do {

		old_pg = atomic_long_read(&user->locked_vm);

		new_pg = old_pg + num_pg;

		if (new_pg > max_pg)

			return -ENOBUFS;

	} while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=

		 old_pg);



	if (!mmp->user) {

		mmp->user = get_uid(user);

		mmp->num_pg = num_pg;

	} else {

		mmp->num_pg += num_pg;

	}



	return 0;

}



static void mm_unaccount_pinned_pages(struct mmpin *mmp)

{

	if (mmp->user) {

		atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);

		free_uid(mmp->user);

	}

}



struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)

{

	struct ubuf_info *uarg;
@@ -913,6 +951,12 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size) 


	BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));

	uarg = (void *)skb->cb;

	uarg->mmp.user = NULL;



	if (mm_account_pinned_pages(&uarg->mmp, size)) {

		kfree_skb(skb);

		return NULL;

	}



	uarg->callback = sock_zerocopy_callback;

	uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
@@ -956,6 +1000,8 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size, 


		next = (u32)atomic_read(&sk->sk_zckey);

		if ((u32)(uarg->id + uarg->len) == next) {

			if (mm_account_pinned_pages(&uarg->mmp, size))

				return NULL;

			uarg->len++;

			uarg->bytelen = bytelen;

			atomic_set(&sk->sk_zckey, ++next);
@@ -1038,6 +1084,8 @@ EXPORT_SYMBOL_GPL(sock_zerocopy_callback); 
void sock_zerocopy_put(struct ubuf_info *uarg)

{

	if (uarg && atomic_dec_and_test(&uarg->refcnt)) {

		mm_unaccount_pinned_pages(&uarg->mmp);



		if (uarg->callback)

			uarg->callback(uarg, uarg->zerocopy);

		else