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sock: ulimit on MSG_ZEROCOPY pages

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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 789f90fcf6 ("perf_counter: per user mlock gift")

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2017-08-03 16:29:43 -04:00 committed by David S. Miller
parent 4ab6c99d99
commit a91dbff551
3 changed files with 55 additions and 1 deletions
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3
include/linux/sched/user.h
View File

@ -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
};

5
include/linux/skbuff.h
View File

@ -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))

48
net/core/skbuff.c
View File

@ -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