On Mon, Mar 18, 2019 at 6:35 PM Eric Dumazet edumazet@google.com wrote:
On Mon, Mar 18, 2019 at 10:18 AM Andrey Konovalov andreyknvl@google.com wrote:
This patch is a part of a series that extends arm64 kernel ABI to allow to pass tagged user pointers (with the top byte set to something else other than 0x00) as syscall arguments.
tcp_zerocopy_receive() uses provided user pointers for vma lookups, which can only by done with untagged pointers.
Untag user pointers in this function.
Signed-off-by: Andrey Konovalov andreyknvl@google.com
net/ipv4/tcp.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 6baa6dc1b13b..e76beb5ff1ff 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1749,7 +1749,7 @@ EXPORT_SYMBOL(tcp_mmap); static int tcp_zerocopy_receive(struct sock *sk, struct tcp_zerocopy_receive *zc) {
unsigned long address = (unsigned long)zc->address;
unsigned long address; const skb_frag_t *frags = NULL; u32 length = 0, seq, offset; struct vm_area_struct *vma;@@ -1758,7 +1758,12 @@ static int tcp_zerocopy_receive(struct sock *sk, int inq; int ret;
if (address & (PAGE_SIZE - 1) || address != zc->address)
address = (unsigned long)untagged_addr(zc->address);/* The second test in this if detects if the u64->unsigned long* conversion had any truncated bits.*/if (address & (PAGE_SIZE - 1) || address != untagged_addr(zc->address)) return -EINVAL; if (sk->sk_state == TCP_LISTEN)This is quite ugly, the comment does not really help nor belong to this patch.
What about using untagged_addr() only once ?
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 6baa6dc1b13b0b94b1da238668b93e167cf444fe..855a1f68c1ea9b0d07a92bd7f5e7c24840a99d3d 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1761,6 +1761,8 @@ static int tcp_zerocopy_receive(struct sock *sk, if (address & (PAGE_SIZE - 1) || address != zc->address) return -EINVAL;
address = untagged_addr(address);if (sk->sk_state == TCP_LISTEN) return -ENOTCONN;
Looks good, will do it like this in the next version. Thanks!