linux-stable.git/security, branch v3.16.53

KPTI: Rename to PAGE_TABLE_ISOLATION

2018-01-09T00:35:20+00:00

This renames CONFIG_KAISER to CONFIG_PAGE_TABLE_ISOLATION.

Signed-off-by: Kees Cook 
Signed-off-by: Greg Kroah-Hartman 
[bwh: Backported to 3.16]
Signed-off-by: Ben Hutchings

x86/kaiser: Reenable PARAVIRT

2018-01-09T00:35:19+00:00

Now that the required bits have been addressed, reenable
PARAVIRT.

Signed-off-by: Borislav Petkov 
Signed-off-by: Greg Kroah-Hartman 
Cc: Hugh Dickins 
Signed-off-by: Ben Hutchings

KAISER: Kernel Address Isolation

2018-01-09T00:35:13+00:00

This patch introduces our implementation of KAISER (Kernel Address Isolation to
have Side-channels Efficiently Removed), a kernel isolation technique to close
hardware side channels on kernel address information.

More information about the patch can be found on:

        https://github.com/IAIK/KAISER

From: Richard Fellner 
From: Daniel Gruss 
Subject: [RFC, PATCH] x86_64: KAISER - do not map kernel in user mode
Date: Thu, 4 May 2017 14:26:50 +0200
Link: http://marc.info/?l=linux-kernel&m=149390087310405&w=2
Kaiser-4.10-SHA1: c4b1831d44c6144d3762ccc72f0c4e71a0c713e5

To: 
To: 
Cc: 
Cc: 
Cc: Michael Schwarz 
Cc: Richard Fellner 
Cc: Ingo Molnar 
Cc: 
Cc: 

After several recent works [1,2,3] KASLR on x86_64 was basically
considered dead by many researchers. We have been working on an
efficient but effective fix for this problem and found that not mapping
the kernel space when running in user mode is the solution to this
problem [4] (the corresponding paper [5] will be presented at ESSoS17).

With this RFC patch we allow anybody to configure their kernel with the
flag CONFIG_KAISER to add our defense mechanism.

If there are any questions we would love to answer them.
We also appreciate any comments!

Cheers,
Daniel (+ the KAISER team from Graz University of Technology)

[1] http://www.ieee-security.org/TC/SP2013/papers/4977a191.pdf
[2] https://www.blackhat.com/docs/us-16/materials/us-16-Fogh-Using-Undocumented-CPU-Behaviour-To-See-Into-Kernel-Mode-And-Break-KASLR-In-The-Process.pdf
[3] https://www.blackhat.com/docs/us-16/materials/us-16-Jang-Breaking-Kernel-Address-Space-Layout-Randomization-KASLR-With-Intel-TSX.pdf
[4] https://github.com/IAIK/KAISER
[5] https://gruss.cc/files/kaiser.pdf

(cherry picked from Change-Id: I0eb000c33290af01fc4454ca0c701d00f1d30b1d)

Conflicts:
arch/x86/entry/entry_64.S (not in this tree)
arch/x86/kernel/entry_64.S (patched instead of that)
arch/x86/entry/entry_64_compat.S (not in this tree)
arch/x86/ia32/ia32entry.S (patched instead of that)
arch/x86/include/asm/hw_irq.h
arch/x86/include/asm/pgtable_types.h
arch/x86/include/asm/processor.h
arch/x86/kernel/irqinit.c
arch/x86/kernel/process.c
arch/x86/mm/Makefile
arch/x86/mm/pgtable.c
init/main.c

Signed-off-by: Hugh Dickins 
[bwh: Folded in the follow-up patches from Hugh:
 - kaiser: merged update
 - kaiser: do not set _PAGE_NX on pgd_none
 - kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE
 - kaiser: fix build and FIXME in alloc_ldt_struct()
 - kaiser: KAISER depends on SMP
 - kaiser: fix regs to do_nmi() ifndef CONFIG_KAISER
 - kaiser: fix perf crashes
 - kaiser: ENOMEM if kaiser_pagetable_walk() NULL
 - kaiser: tidied up asm/kaiser.h somewhat
 - kaiser: tidied up kaiser_add/remove_mapping slightly
 - kaiser: kaiser_remove_mapping() move along the pgd
 - kaiser: align addition to x86/mm/Makefile
 - kaiser: cleanups while trying for gold link
 - kaiser: name that 0x1000 KAISER_SHADOW_PGD_OFFSET
 - kaiser: delete KAISER_REAL_SWITCH option
 - kaiser: vmstat show NR_KAISERTABLE as nr_overhead
 - kaiser: enhanced by kernel and user PCIDs
 - kaiser: load_new_mm_cr3() let SWITCH_USER_CR3 flush user
 - kaiser: PCID 0 for kernel and 128 for user
 - kaiser: x86_cr3_pcid_noflush and x86_cr3_pcid_user
 - kaiser: paranoid_entry pass cr3 need to paranoid_exit
 - kaiser: _pgd_alloc() without __GFP_REPEAT to avoid stalls
 - kaiser: fix unlikely error in alloc_ldt_struct()
 - kaiser: drop is_atomic arg to kaiser_pagetable_walk()
 Backported to 3.16:
 - Add missing #include in arch/x86/mm/kaiser.c
 - Use variable PEBS buffer size since we have "perf/x86/intel: Use PAGE_SIZE
   for PEBS buffer size on Core2"
 - Renumber X86_FEATURE_INVPCID_SINGLE to avoid collision
 - Adjust context]
Signed-off-by: Ben Hutchings

KEYS: add missing permission check for request_key() destination

2018-01-01T20:52:12+00:00

commit 4dca6ea1d9432052afb06baf2e3ae78188a4410b upstream.

When the request_key() syscall is not passed a destination keyring, it
links the requested key (if constructed) into the "default" request-key
keyring.  This should require Write permission to the keyring.  However,
there is actually no permission check.

This can be abused to add keys to any keyring to which only Search
permission is granted.  This is because Search permission allows joining
the keyring.  keyctl_set_reqkey_keyring(KEY_REQKEY_DEFL_SESSION_KEYRING)
then will set the default request-key keyring to the session keyring.
Then, request_key() can be used to add keys to the keyring.

Both negatively and positively instantiated keys can be added using this
method.  Adding negative keys is trivial.  Adding a positive key is a
bit trickier.  It requires that either /sbin/request-key positively
instantiates the key, or that another thread adds the key to the process
keyring at just the right time, such that request_key() misses it
initially but then finds it in construct_alloc_key().

Fix this bug by checking for Write permission to the keyring in
construct_get_dest_keyring() when the default keyring is being used.

We don't do the permission check for non-default keyrings because that
was already done by the earlier call to lookup_user_key().  Also,
request_key_and_link() is currently passed a 'struct key *' rather than
a key_ref_t, so the "possessed" bit is unavailable.

We also don't do the permission check for the "requestor keyring", to
continue to support the use case described by commit 8bbf4976b59f
("KEYS: Alter use of key instantiation link-to-keyring argument") where
/sbin/request-key recursively calls request_key() to add keys to the
original requestor's destination keyring.  (I don't know of any users
who actually do that, though...)

Fixes: 3e30148c3d52 ("[PATCH] Keys: Make request-key create an authorisation key")
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

security: let security modules use PTRACE_MODE_* with bitmasks

2018-01-01T20:52:10+00:00

commit 3dfb7d8cdbc7ea0c2970450e60818bb3eefbad69 upstream.

It looks like smack and yama weren't aware that the ptrace mode
can have flags ORed into it - PTRACE_MODE_NOAUDIT until now, but
only for /proc/$pid/stat, and with the PTRACE_MODE_*CREDS patch,
all modes have flags ORed into them.

Signed-off-by: Jann Horn 
Acked-by: Kees Cook 
Acked-by: Casey Schaufler 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Cc: James Morris 
Cc: "Serge E. Hallyn" 
Cc: Andy Shevchenko 
Cc: Andy Lutomirski 
Cc: Al Viro 
Cc: "Eric W. Biederman" 
Cc: Willy Tarreau 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

KEYS: trusted: fix writing past end of buffer in trusted_read()

2018-01-01T20:52:03+00:00

commit a3c812f7cfd80cf51e8f5b7034f7418f6beb56c1 upstream.

When calling keyctl_read() on a key of type "trusted", if the
user-supplied buffer was too small, the kernel ignored the buffer length
and just wrote past the end of the buffer, potentially corrupting
userspace memory.  Fix it by instead returning the size required, as per
the documentation for keyctl_read().

We also don't even fill the buffer at all in this case, as this is
slightly easier to implement than doing a short read, and either
behavior appears to be permitted.  It also makes it match the behavior
of the "encrypted" key type.

Fixes: d00a1c72f7f4 ("keys: add new trusted key-type")
Reported-by: Ben Hutchings 
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
Reviewed-by: Mimi Zohar 
Reviewed-by: James Morris 
Signed-off-by: James Morris 
Signed-off-by: Ben Hutchings

KEYS: trusted: sanitize all key material

2018-01-01T20:52:03+00:00

commit ee618b4619b72527aaed765f0f0b74072b281159 upstream.

As the previous patch did for encrypted-keys, zero sensitive any
potentially sensitive data related to the "trusted" key type before it
is freed.  Notably, we were not zeroing the tpm_buf structures in which
the actual key is stored for TPM seal and unseal, nor were we zeroing
the trusted_key_payload in certain error paths.

Cc: Mimi Zohar 
Cc: David Safford 
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
Signed-off-by: James Morris 
[bwh: Backported to 3.16:
 - Drop one unapplicable change
 - Adjust context]
Signed-off-by: Ben Hutchings

KEYS: return full count in keyring_read() if buffer is too small

2018-01-01T20:52:03+00:00

commit 3239b6f29bdfb4b0a2ba59df995fc9e6f4df7f1f upstream.

Commit e645016abc80 ("KEYS: fix writing past end of user-supplied buffer
in keyring_read()") made keyring_read() stop corrupting userspace memory
when the user-supplied buffer is too small.  However it also made the
return value in that case be the short buffer size rather than the size
required, yet keyctl_read() is actually documented to return the size
required.  Therefore, switch it over to the documented behavior.

Note that for now we continue to have it fill the short buffer, since it
did that before (pre-v3.13) and dump_key_tree_aux() in keyutils arguably
relies on it.

Fixes: e645016abc80 ("KEYS: fix writing past end of user-supplied buffer in keyring_read()")
Reported-by: Ben Hutchings 
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
Reviewed-by: James Morris 
Signed-off-by: James Morris 
Signed-off-by: Ben Hutchings

KEYS: encrypted: fix dereference of NULL user_key_payload

2018-01-01T20:51:52+00:00

commit 13923d0865ca96312197962522e88bc0aedccd74 upstream.

A key of type "encrypted" references a "master key" which is used to
encrypt and decrypt the encrypted key's payload.  However, when we
accessed the master key's payload, we failed to handle the case where
the master key has been revoked, which sets the payload pointer to NULL.
Note that request_key() *does* skip revoked keys, but there is still a
window where the key can be revoked before we acquire its semaphore.

Fix it by checking for a NULL payload, treating it like a key which was
already revoked at the time it was requested.

This was an issue for master keys of type "user" only.  Master keys can
also be of type "trusted", but those cannot be revoked.

Fixes: 7e70cb497850 ("keys: add new key-type encrypted")
Reviewed-by: James Morris 
Cc: Mimi Zohar 
Cc: David Safford 
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

lsm: fix smack_inode_removexattr and xattr_getsecurity memleak

2018-01-01T20:51:48+00:00

commit 57e7ba04d422c3d41c8426380303ec9b7533ded9 upstream.

security_inode_getsecurity() provides the text string value
of a security attribute. It does not provide a "secctx".
The code in xattr_getsecurity() that calls security_inode_getsecurity()
and then calls security_release_secctx() happened to work because
SElinux and Smack treat the attribute and the secctx the same way.
It fails for cap_inode_getsecurity(), because that module has no
secctx that ever needs releasing. It turns out that Smack is the
one that's doing things wrong by not allocating memory when instructed
to do so by the "alloc" parameter.

The fix is simple enough. Change the security_release_secctx() to
kfree() because it isn't a secctx being returned by
security_inode_getsecurity(). Change Smack to allocate the string when
told to do so.

Note: this also fixes memory leaks for LSMs which implement
inode_getsecurity but not release_secctx, such as capabilities.

Signed-off-by: Casey Schaufler 
Reported-by: Konstantin Khlebnikov 
Signed-off-by: James Morris 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings