Commit 617aebe6 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'usercopy-v4.16-rc1' of git://

Pull hardened usercopy whitelisting from Kees Cook:
 "Currently, hardened usercopy performs dynamic bounds checking on slab
  cache objects. This is good, but still leaves a lot of kernel memory
  available to be copied to/from userspace in the face of bugs.

  To further restrict what memory is available for copying, this creates
  a way to whitelist specific areas of a given slab cache object for
  copying to/from userspace, allowing much finer granularity of access

  Slab caches that are never exposed to userspace can declare no
  whitelist for their objects, thereby keeping them unavailable to
  userspace via dynamic copy operations. (Note, an implicit form of
  whitelisting is the use of constant sizes in usercopy operations and
  get_user()/put_user(); these bypass all hardened usercopy checks since
  these sizes cannot change at runtime.)

  This new check is WARN-by-default, so any mistakes can be found over
  the next several releases without breaking anyone's system.

  The series has roughly the following sections:
   - remove %p and improve reporting with offset
   - prepare infrastructure and whitelist kmalloc
   - update VFS subsystem with whitelists
   - update SCSI subsystem with whitelists
   - update network subsystem with whitelists
   - update process memory with whitelists
   - update per-architecture thread_struct with whitelists
   - update KVM with whitelists and fix ioctl bug
   - mark all other allocations as not whitelisted
   - update lkdtm for more sensible test overage"

* tag 'usercopy-v4.16-rc1' of git:// (38 commits)
  lkdtm: Update usercopy tests for whitelisting
  usercopy: Restrict non-usercopy caches to size 0
  kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl
  kvm: whitelist struct kvm_vcpu_arch
  arm: Implement thread_struct whitelist for hardened usercopy
  arm64: Implement thread_struct whitelist for hardened usercopy
  x86: Implement thread_struct whitelist for hardened usercopy
  fork: Provide usercopy whitelisting for task_struct
  fork: Define usercopy region in thread_stack slab caches
  fork: Define usercopy region in mm_struct slab caches
  net: Restrict unwhitelisted proto caches to size 0
  sctp: Copy struct sctp_sock.autoclose to userspace using put_user()
  sctp: Define usercopy region in SCTP proto slab cache
  caif: Define usercopy region in caif proto slab cache
  ip: Define usercopy region in IP proto slab cache
  net: Define usercopy region in struct proto slab cache
  scsi: Define usercopy region in scsi_sense_cache slab cache
  cifs: Define usercopy region in cifs_request slab cache
  vxfs: Define usercopy region in vxfs_inode slab cache
  ufs: Define usercopy region in ufs_inode_cache slab cache
parents 0771ad44 e47e3118
......@@ -1272,6 +1272,8 @@ struct proto rawv6_prot = {
.hash = raw_hash_sk,
.unhash = raw_unhash_sk,
.obj_size = sizeof(struct raw6_sock),
.useroffset = offsetof(struct raw6_sock, filter),
.usersize = sizeof_field(struct raw6_sock, filter),
.h.raw_hash = &raw_v6_hashinfo,
.compat_setsockopt = compat_rawv6_setsockopt,
......@@ -5053,7 +5053,7 @@ static int sctp_getsockopt_autoclose(struct sock *sk, int len, char __user *optv
len = sizeof(int);
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval, &sctp_sk(sk)->autoclose, len))
if (put_user(sctp_sk(sk)->autoclose, (int __user *)optval))
return -EFAULT;
return 0;
......@@ -8552,6 +8552,10 @@ struct proto sctp_prot = {
.unhash = sctp_unhash,
.get_port = sctp_get_port,
.obj_size = sizeof(struct sctp_sock),
.useroffset = offsetof(struct sctp_sock, subscribe),
.usersize = offsetof(struct sctp_sock, initmsg) -
offsetof(struct sctp_sock, subscribe) +
sizeof_field(struct sctp_sock, initmsg),
.sysctl_mem = sysctl_sctp_mem,
.sysctl_rmem = sysctl_sctp_rmem,
.sysctl_wmem = sysctl_sctp_wmem,
......@@ -8591,6 +8595,10 @@ struct proto sctpv6_prot = {
.unhash = sctp_unhash,
.get_port = sctp_get_port,
.obj_size = sizeof(struct sctp6_sock),
.useroffset = offsetof(struct sctp6_sock, sctp.subscribe),
.usersize = offsetof(struct sctp6_sock, sctp.initmsg) -
offsetof(struct sctp6_sock, sctp.subscribe) +
sizeof_field(struct sctp6_sock, sctp.initmsg),
.sysctl_mem = sysctl_sctp_mem,
.sysctl_rmem = sysctl_sctp_rmem,
.sysctl_wmem = sysctl_sctp_wmem,
......@@ -164,6 +164,20 @@ config HARDENED_USERCOPY
or are part of the kernel text. This kills entire classes
of heap overflow exploits and similar kernel memory exposures.
bool "Allow usercopy whitelist violations to fallback to object size"
default y
This is a temporary option that allows missing usercopy whitelists
to be discovered via a WARN() to the kernel log, instead of
rejecting the copy, falling back to non-whitelisted hardened
usercopy that checks the slab allocation size instead of the
whitelist size. This option will be removed once it seems like
all missing usercopy whitelists have been identified and fixed.
Booting with "slab_common.usercopy_fallback=Y/N" can change
this setting.
bool "Refuse to copy allocations that span multiple pages"
......@@ -138,6 +138,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
if (func->bind == STB_WEAK)
......@@ -4019,8 +4019,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
/* A kmem cache lets us meet the alignment requirements of fx_save. */
if (!vcpu_align)
vcpu_align = __alignof__(struct kvm_vcpu);
kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
kvm_vcpu_cache =
kmem_cache_create_usercopy("kvm_vcpu", vcpu_size, vcpu_align,
offsetof(struct kvm_vcpu, arch),
sizeof_field(struct kvm_vcpu, arch),
if (!kvm_vcpu_cache) {
r = -ENOMEM;
goto out_free_3;
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