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 789f90fcf6b0 ("perf_counter: per user mlock gift")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index dcee0f6..42b62c71 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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