| Message ID | 80e79c47dc7c5ee3572034a1d69bb724fbed2ecb.1552929301.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: untag user pointers passed to the kernel | expand |
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;
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!
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 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(-)