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[PATCH v3 23/31] net: Restrict unwhitelisted proto caches to size 0

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Now that protocols have been annotated (the copy of icsk_ca_ops->name
is of an ops field from outside the slab cache):

$ git grep 'copy_.*_user.*sk.*->'
caif/caif_socket.c: copy_from_user(&cf_sk->conn_req.param.data, ov, ol)) {
ipv4/raw.c:   if (copy_from_user(&raw_sk(sk)->filter, optval, optlen))
ipv4/raw.c:       copy_to_user(optval, &raw_sk(sk)->filter, len))
ipv4/tcp.c:       if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
ipv4/tcp.c:       if (copy_to_user(optval, icsk->icsk_ulp_ops->name, len))
ipv6/raw.c:       if (copy_from_user(&raw6_sk(sk)->filter, optval, optlen))
ipv6/raw.c:           if (copy_to_user(optval, &raw6_sk(sk)->filter, len))
sctp/socket.c: if (copy_from_user(&sctp_sk(sk)->subscribe, optval, optlen))
sctp/socket.c: if (copy_to_user(optval, &sctp_sk(sk)->subscribe, len))
sctp/socket.c: if (copy_to_user(optval, &sctp_sk(sk)->initmsg, len))

we can switch the default proto usercopy region to size 0. Any protocols
needing to add whitelisted regions must annotate the fields with the
useroffset and usersize fields of struct proto.

This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 net/core/sock.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 832dfb03102e..84cd0b362a02 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3168,9 +3168,7 @@ int proto_register(struct proto *prot, int alloc_slab)
 		prot->slab = kmem_cache_create_usercopy(prot->name,
 					prot->obj_size, 0,
 					SLAB_HWCACHE_ALIGN | prot->slab_flags,
-					prot->usersize ? prot->useroffset : 0,
-					prot->usersize ? prot->usersize
-						       : prot->obj_size,
+					prot->useroffset, prot->usersize,
 					NULL);
 
 		if (prot->slab == NULL) {
-- 
2.7.4

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[PATCH v3 00/31] Hardened usercopy whitelisting Kees Cook <keescook@chromium.org> - 2017-09-20 22:50 +0200
  [PATCH v3 26/31] fork: Provide usercopy whitelisting for task_struct Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 15/31] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 07/31] ext4: Define usercopy region in ext4_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 29/31] arm: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 25/31] fork: Define usercopy region in thread_stack slab caches Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 02/31] usercopy: Enforce slab cache usercopy region boundaries Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
    Re: [PATCH v3 02/31] usercopy: Enforce slab cache usercopy region  boundaries Christopher Lameter <cl@linux.com> - 2017-09-21 17:30 +0200
  [PATCH v3 23/31] net: Restrict unwhitelisted proto caches to size 0 Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 17/31] scsi: Define usercopy region in scsi_sense_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 19/31] ip: Define usercopy region in IP proto slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 28/31] arm64: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 21/31] sctp: Define usercopy region in SCTP proto slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 31/31] lkdtm: Update usercopy tests for whitelisting Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 01/31] usercopy: Prepare for usercopy whitelisting Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
    Re: [PATCH v3 01/31] usercopy: Prepare for usercopy whitelisting Christopher Lameter <cl@linux.com> - 2017-09-21 17:30 +0200
  [PATCH v3 08/31] ext2: Define usercopy region in ext2_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 18/31] net: Define usercopy region in struct proto slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 24/31] fork: Define usercopy region in mm_struct slab caches Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
  [PATCH v3 04/31] dcache: Define usercopy region in dentry_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:10 +0200
  [PATCH v3 27/31] x86: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-09-20 23:10 +0200
  [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches Kees Cook <keescook@chromium.org> - 2017-09-20 23:10 +0200
    Re: [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy  caches Christopher Lameter <cl@linux.com> - 2017-09-21 17:30 +0200
      Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc  caches as usercopy caches Kees Cook <keescook@chromium.org> - 2017-09-21 17:50 +0200
        Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc  caches as usercopy caches Christopher Lameter <cl@linux.com> - 2017-09-21 18:10 +0200
          Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc  caches as usercopy caches Kees Cook <keescook@chromium.org> - 2017-09-21 20:30 +0200

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