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Message-ID: <CAEXv5_gvcpY0K3MeJUVHo4199X=9=UnH7UDttresd_eBrVFi7g@mail.gmail.com>
Date: Thu, 10 Nov 2016 15:41:19 -0500
From: David Windsor <dwindsor@...il.com>
To: Elena Reshetova <elena.reshetova@...el.com>
Cc: kernel-hardening@...ts.openwall.com, Kees Cook <keescook@...omium.org>,
arnd@...db.de, tglx@...utronix.de, mingo@...hat.com, h.peter.anvin@...el.com,
peterz@...radead.org, will.deacon@....com,
Hans Liljestrand <ishkamiel@...il.com>
Subject: Re: [RFC v4 PATCH 01/13] Add architecture independent hardened atomic base
The work done by this series adds overflow protection to existing
kernel atomic_t users.
In the initial upstream submission, do we want to include my series
which extends HARDENED_ATOMIC protection to cover additional kernel
reference counters, which are currently integers (and thus
unprotected):
* struct fs_struct.users
* struct tty_port.count
* struct tty_ldisc_ops.refcount
* struct pipe_inode_info.{readers|writers|files|waiting_writers}
* struct kmem_cache.refcount
I can see arguments both for and against including new HARDENED_ATOMIC
users in the initial upstream RFC. Personally, I think it might be
more appropriate to add new HARDENED_ATOMIC users in subsequent RFCs,
after the original feature is merged.
In case folks are interested, I submitted this as an RFC, which can be
found here: http://www.openwall.com/lists/kernel-hardening/2016/10/29/1
The code itself can be found here:
https://github.com/ereshetova/linux-stable/tree/hardened_atomic_next_expanded
Thanks,
David
On Thu, Nov 10, 2016 at 3:24 PM, Elena Reshetova
<elena.reshetova@...el.com> wrote:
> This series brings the PaX/Grsecurity PAX_REFCOUNT [1]
> feature support to the upstream kernel. All credit for the
> feature goes to the feature authors.
>
> The copyright for the original PAX_REFCOUNT code:
> - all REFCOUNT code in general: PaX Team <pageexec@...email.hu>
> - various false positive fixes: Mathias Krause <minipli@...glemail.com>
>
> The name of the upstream feature is HARDENED_ATOMIC
> and it is configured using CONFIG_HARDENED_ATOMIC and
> HAVE_ARCH_HARDENED_ATOMIC.
>
> This series only adds x86 support; other architectures are expected
> to add similar support gradually.
>
> Feature Summary
> ---------------
> The primary goal of KSPP is to provide protection against classes
> of vulnerabilities. One such class of vulnerabilities, known as
> use-after-free bugs, frequently results when reference counters
> guarding shared kernel objects are overflowed. The existence of
> a kernel path in which a reference counter is incremented more
> than it is decremented can lead to wrapping. This buggy path can be
> executed until INT_MAX/LONG_MAX is reached, at which point further
> increments will cause the counter to wrap to 0. At this point, the
> kernel will erroneously mark the object as not in use, resulting in
> a multitude of undesirable cases: releasing the object to other users,
> freeing the object while it still has legitimate users, or other
> undefined conditions. The above scenario is known as a use-after-free
> bug.
>
> HARDENED_ATOMIC provides mandatory protection against kernel
> reference counter overflows. In Linux, reference counters
> are implemented using the atomic_t and atomic_long_t types.
> HARDENED_ATOMIC modifies the functions dealing with these types
> such that when INT_MAX/LONG_MAX is reached, the atomic variables
> remain saturated at these maximum values, rather than wrapping.
>
> There are several non-reference counter users of atomic_t and
> atomic_long_t (the fact that these types are being so widely
> misused is not addressed by this series). These users, typically
> statistical counters, are not concerned with whether the values of
> these types wrap, and therefore can dispense with the added performance
> penalty incurred from protecting against overflows. New types have
> been introduced for these users: atomic_wrap_t and atomic_long_wrap_t.
> Functions for manipulating these types have been added as well.
>
> Note that the protection provided by HARDENED_ATOMIC is not "opt-in":
> since atomic_t is so widely misused, it must be protected as-is.
> HARDENED_ATOMIC protects all users of atomic_t and atomic_long_t
> against overflow. New users wishing to use atomic types, but not
> needing protection against overflows, should use the new types
> introduced by this series: atomic_wrap_t and atomic_long_wrap_t.
>
> Bugs Prevented
> --------------
> HARDENED_ATOMIC would directly mitigate these Linux kernel bugs:
>
> CVE-2014-2851 - Group_info refcount overflow.
> Exploit: https://www.exploit-db.com/exploits/32926/
>
> CVE-2016-0728 - Keyring refcount overflow.
> Exploit: https://www.exploit-db.com/exploits/39277/
>
> CVE-2016-4558 - BPF reference count mishandling.
> Explot: https://www.exploit-db.com/exploits/39773/
>
> [1] https://forums.grsecurity.net/viewtopic.php?f=7&t=4173
>
> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
> Signed-off-by: David Windsor <dwindsor@...il.com>
> ---
> Documentation/security/hardened-atomic.txt | 146 ++++++++++++++++++++++++
> arch/alpha/include/asm/local.h | 2 +
> arch/m32r/include/asm/local.h | 2 +
> arch/mips/include/asm/local.h | 2 +
> arch/powerpc/include/asm/local.h | 2 +
> arch/x86/include/asm/local.h | 2 +
> include/asm-generic/atomic-long.h | 165 ++++++++++++++++++++--------
> include/asm-generic/atomic.h | 4 +
> include/asm-generic/atomic64.h | 2 +
> include/asm-generic/atomic64_wrap.h | 123 +++++++++++++++++++++
> include/asm-generic/atomic_wrap.h | 114 +++++++++++++++++++
> include/asm-generic/bug.h | 7 ++
> include/asm-generic/local.h | 3 +
> include/asm-generic/local_wrap.h | 63 +++++++++++
> include/linux/atomic.h | 171 +++++++++++++++++++++++++++--
> include/linux/types.h | 4 +
> kernel/panic.c | 11 ++
> kernel/trace/ring_buffer.c | 3 +-
> security/Kconfig | 20 ++++
> 19 files changed, 789 insertions(+), 57 deletions(-)
> create mode 100644 Documentation/security/hardened-atomic.txt
> create mode 100644 include/asm-generic/atomic64_wrap.h
> create mode 100644 include/asm-generic/atomic_wrap.h
> create mode 100644 include/asm-generic/local_wrap.h
>
> diff --git a/Documentation/security/hardened-atomic.txt b/Documentation/security/hardened-atomic.txt
> new file mode 100644
> index 0000000..de41be1
> --- /dev/null
> +++ b/Documentation/security/hardened-atomic.txt
> @@ -0,0 +1,146 @@
> +=====================
> +KSPP: HARDENED_ATOMIC
> +=====================
> +
> +Risks/Vulnerabilities Addressed
> +===============================
> +
> +The Linux Kernel Self Protection Project (KSPP) was created with a mandate
> +to eliminate classes of kernel bugs. The class of vulnerabilities addressed
> +by HARDENED_ATOMIC is known as use-after-free vulnerabilities.
> +
> +HARDENED_ATOMIC is based off of work done by the PaX Team [1]. The feature
> +on which HARDENED_ATOMIC is based is called PAX_REFCOUNT in the original
> +PaX patch.
> +
> +Use-after-free Vulnerabilities
> +------------------------------
> +Use-after-free vulnerabilities are aptly named: they are classes of bugs in
> +which an attacker is able to gain control of a piece of memory after it has
> +already been freed and use this memory for nefarious purposes: introducing
> +malicious code into the address space of an existing process, redirecting
> +the flow of execution, etc.
> +
> +While use-after-free vulnerabilities can arise in a variety of situations,
> +the use case addressed by HARDENED_ATOMIC is that of referenced counted
> +objects. The kernel can only safely free these objects when all existing
> +users of these objects are finished using them. This necessitates the
> +introduction of some sort of accounting system to keep track of current
> +users of kernel objects. Reference counters and get()/put() APIs are the
> +means typically chosen to do this: calls to get() increment the reference
> +counter, put() decrments it. When the value of the reference counter
> +becomes some sentinel (typically 0), the kernel can safely free the counted
> +object.
> +
> +Problems arise when the reference counter gets overflowed. If the reference
> +counter is represented with a signed integer type, overflowing the reference
> +counter causes it to go from INT_MAX to INT_MIN, then approach 0. Depending
> +on the logic, the transition to INT_MIN may be enough to trigger the bug,
> +but when the reference counter becomes 0, the kernel will free the
> +underlying object guarded by the reference counter while it still has valid
> +users.
> +
> +
> +HARDENED_ATOMIC Design
> +======================
> +
> +HARDENED_ATOMIC provides its protections by modifying the data type used in
> +the Linux kernel to implement reference counters: atomic_t. atomic_t is a
> +type that contains an integer type, used for counting. HARDENED_ATOMIC
> +modifies atomic_t and its associated API so that the integer type contained
> +inside of atomic_t cannot be overflowed.
> +
> +A key point to remember about HARDENED_ATOMIC is that, once enabled, it
> +protects all users of atomic_t without any additional code changes. The
> +protection provided by HARDENED_ATOMIC is not “opt-in”: since atomic_t is so
> +widely misused, it must be protected as-is. HARDENED_ATOMIC protects all
> +users of atomic_t and atomic_long_t against overflow. New users wishing to
> +use atomic types, but not needing protection against overflows, should use
> +the new types introduced by this series: atomic_wrap_t and
> +atomic_long_wrap_t.
> +
> +Detect/Mitigate
> +---------------
> +The mechanism of HARDENED_ATOMIC can be viewed as a bipartite process:
> +detection of an overflow and mitigating the effects of the overflow, either
> +by not performing or performing, then reversing, the operation that caused
> +the overflow.
> +
> +Overflow detection is architecture-specific. Details of the approach used to
> +detect overflows on each architecture can be found in the PAX_REFCOUNT
> +documentation. [1]
> +
> +Once an overflow has been detected, HARDENED_ATOMIC mitigates the overflow
> +by either reverting the operation or simply not writing the result of the
> +operation to memory.
> +
> +
> +HARDENED_ATOMIC Implementation
> +==============================
> +
> +As mentioned above, HARDENED_ATOMIC modifies the atomic_t API to provide its
> +protections. Following is a description of the functions that have been
> +modified.
> +
> +Benchmarks show that no measurable performance difference occurs when
> +HARDENED_ATOMIC is enabled.
> +
> +First, the type atomic_wrap_t needs to be defined for those kernel users who
> +want an atomic type that may be allowed to overflow/wrap (e.g. statistical
> +counters). Otherwise, the built-in protections (and associated costs) for
> +atomic_t would erroneously apply to these non-reference counter users of
> +atomic_t:
> +
> + * include/linux/types.h: define atomic_wrap_t and atomic64_wrap_t
> +
> +Next, we define the mechanism for reporting an overflow of a protected
> +atomic type:
> +
> + * kernel/panic.c: void hardened_atomic_overflow(struct pt_regs)
> +
> +The following functions are an extension of the atomic_t API, supporting
> +this new “wrappable” type:
> +
> + * static inline int atomic_read_wrap()
> + * static inline void atomic_set_wrap()
> + * static inline void atomic_inc_wrap()
> + * static inline void atomic_dec_wrap()
> + * static inline void atomic_add_wrap()
> + * static inline long atomic_inc_return_wrap()
> +
> +Departures from Original PaX Implementation
> +-------------------------------------------
> +While HARDENED_ATOMIC is based largely upon the work done by PaX in their
> +original PAX_REFCOUNT patchset, HARDENED_ATOMIC does in fact have a few
> +minor differences. We will be posting them here as final decisions are made
> +regarding how certain core protections are implemented.
> +
> +x86 Race Condition
> +------------------
> +In the original implementation of PAX_REFCOUNT, a known race condition
> +exists when performing atomic add operations. The crux of the problem lies
> +in the fact that, on x86, there is no way to know a priori whether a
> +prospective atomic operation will result in an overflow. To detect an
> +overflow, PAX_REFCOUNT had to perform an operation then check if the
> +operation caused an overflow.
> +
> +Therefore, there exists a set of conditions in which, given the correct
> +timing of threads, an overflowed counter could be visible to a processor.
> +If multiple threads execute in such a way so that one thread overflows the
> +counter with an addition operation, while a second thread executes another
> +addition operation on the same counter before the first thread is able to
> +revert the previously executed addition operation (by executing a
> +subtraction operation of the same (or greater) magnitude), the counter will
> +have been incremented to a value greater than INT_MAX. At this point, the
> +protection provided by PAX_REFCOUNT has been bypassed, as further increments
> +to the counter will not be detected by the processor’s overflow detection
> +mechanism.
> +
> +Note that only SMP systems are vulnerable to this race condition.
> +
> +The likelihood of an attacker being able to exploit this race was
> +sufficiently insignificant such that fixing the race would be
> +counterproductive.
> +
> +[1] https://pax.grsecurity.net
> +[2] https://forums.grsecurity.net/viewtopic.php?f=7&t=4173
> diff --git a/arch/alpha/include/asm/local.h b/arch/alpha/include/asm/local.h
> index 9c94b84..c5503ea 100644
> --- a/arch/alpha/include/asm/local.h
> +++ b/arch/alpha/include/asm/local.h
> @@ -9,6 +9,8 @@ typedef struct
> atomic_long_t a;
> } local_t;
>
> +#include <asm-generic/local_wrap.h>
> +
> #define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
> #define local_read(l) atomic_long_read(&(l)->a)
> #define local_set(l,i) atomic_long_set(&(l)->a, (i))
> diff --git a/arch/m32r/include/asm/local.h b/arch/m32r/include/asm/local.h
> index 4045db3..6f294ac 100644
> --- a/arch/m32r/include/asm/local.h
> +++ b/arch/m32r/include/asm/local.h
> @@ -26,6 +26,8 @@
> */
> typedef struct { volatile int counter; } local_t;
>
> +#include <asm-generic/local_wrap.h>
> +
> #define LOCAL_INIT(i) { (i) }
>
> /**
> diff --git a/arch/mips/include/asm/local.h b/arch/mips/include/asm/local.h
> index 8feaed6..52e6d03 100644
> --- a/arch/mips/include/asm/local.h
> +++ b/arch/mips/include/asm/local.h
> @@ -13,6 +13,8 @@ typedef struct
> atomic_long_t a;
> } local_t;
>
> +#include <asm-generic/local_wrap.h>
> +
> #define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
>
> #define local_read(l) atomic_long_read(&(l)->a)
> diff --git a/arch/powerpc/include/asm/local.h b/arch/powerpc/include/asm/local.h
> index b8da913..961a91d 100644
> --- a/arch/powerpc/include/asm/local.h
> +++ b/arch/powerpc/include/asm/local.h
> @@ -9,6 +9,8 @@ typedef struct
> atomic_long_t a;
> } local_t;
>
> +#include <asm-generic/local_wrap.h>
> +
> #define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
>
> #define local_read(l) atomic_long_read(&(l)->a)
> diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h
> index 7511978..b6ab86c 100644
> --- a/arch/x86/include/asm/local.h
> +++ b/arch/x86/include/asm/local.h
> @@ -10,6 +10,8 @@ typedef struct {
> atomic_long_t a;
> } local_t;
>
> +#include <asm-generic/local_wrap.h>
> +
> #define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
>
> #define local_read(l) atomic_long_read(&(l)->a)
> diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h
> index 288cc9e..91d1deb 100644
> --- a/include/asm-generic/atomic-long.h
> +++ b/include/asm-generic/atomic-long.h
> @@ -9,6 +9,7 @@
> */
>
> #include <asm/types.h>
> +#include <asm-generic/atomic_wrap.h>
>
> /*
> * Suppport for atomic_long_t
> @@ -21,6 +22,7 @@
> #if BITS_PER_LONG == 64
>
> typedef atomic64_t atomic_long_t;
> +typedef atomic64_wrap_t atomic_long_wrap_t;
>
> #define ATOMIC_LONG_INIT(i) ATOMIC64_INIT(i)
> #define ATOMIC_LONG_PFX(x) atomic64 ## x
> @@ -28,52 +30,60 @@ typedef atomic64_t atomic_long_t;
> #else
>
> typedef atomic_t atomic_long_t;
> +typedef atomic_wrap_t atomic_long_wrap_t;
>
> #define ATOMIC_LONG_INIT(i) ATOMIC_INIT(i)
> #define ATOMIC_LONG_PFX(x) atomic ## x
>
> #endif
>
> -#define ATOMIC_LONG_READ_OP(mo) \
> -static inline long atomic_long_read##mo(const atomic_long_t *l) \
> +#define ATOMIC_LONG_READ_OP(mo, suffix) \
> +static inline long atomic_long_read##mo##suffix(const atomic_long##suffix##_t *l)\
> { \
> - ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
> + ATOMIC_LONG_PFX(suffix##_t) *v = (ATOMIC_LONG_PFX(suffix##_t) *)l;\
> \
> - return (long)ATOMIC_LONG_PFX(_read##mo)(v); \
> + return (long)ATOMIC_LONG_PFX(_read##mo##suffix)(v); \
> }
> -ATOMIC_LONG_READ_OP()
> -ATOMIC_LONG_READ_OP(_acquire)
> +ATOMIC_LONG_READ_OP(,)
> +ATOMIC_LONG_READ_OP(_acquire,)
> +
> +ATOMIC_LONG_READ_OP(,_wrap)
>
> #undef ATOMIC_LONG_READ_OP
>
> -#define ATOMIC_LONG_SET_OP(mo) \
> -static inline void atomic_long_set##mo(atomic_long_t *l, long i) \
> +#define ATOMIC_LONG_SET_OP(mo, suffix) \
> +static inline void atomic_long_set##mo##suffix(atomic_long##suffix##_t *l, long i)\
> { \
> - ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
> + ATOMIC_LONG_PFX(suffix##_t) *v = (ATOMIC_LONG_PFX(suffix##_t) *)l;\
> \
> - ATOMIC_LONG_PFX(_set##mo)(v, i); \
> + ATOMIC_LONG_PFX(_set##mo##suffix)(v, i); \
> }
> -ATOMIC_LONG_SET_OP()
> -ATOMIC_LONG_SET_OP(_release)
> +ATOMIC_LONG_SET_OP(,)
> +ATOMIC_LONG_SET_OP(_release,)
> +
> +ATOMIC_LONG_SET_OP(,_wrap)
>
> #undef ATOMIC_LONG_SET_OP
>
> -#define ATOMIC_LONG_ADD_SUB_OP(op, mo) \
> +#define ATOMIC_LONG_ADD_SUB_OP(op, mo, suffix) \
> static inline long \
> -atomic_long_##op##_return##mo(long i, atomic_long_t *l) \
> +atomic_long_##op##_return##mo##suffix(long i, atomic_long##suffix##_t *l)\
> { \
> - ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
> + ATOMIC_LONG_PFX(suffix##_t) *v = (ATOMIC_LONG_PFX(suffix##_t) *)l;\
> \
> - return (long)ATOMIC_LONG_PFX(_##op##_return##mo)(i, v); \
> + return (long)ATOMIC_LONG_PFX(_##op##_return##mo##suffix)(i, v);\
> }
> -ATOMIC_LONG_ADD_SUB_OP(add,)
> -ATOMIC_LONG_ADD_SUB_OP(add, _relaxed)
> -ATOMIC_LONG_ADD_SUB_OP(add, _acquire)
> -ATOMIC_LONG_ADD_SUB_OP(add, _release)
> -ATOMIC_LONG_ADD_SUB_OP(sub,)
> -ATOMIC_LONG_ADD_SUB_OP(sub, _relaxed)
> -ATOMIC_LONG_ADD_SUB_OP(sub, _acquire)
> -ATOMIC_LONG_ADD_SUB_OP(sub, _release)
> +ATOMIC_LONG_ADD_SUB_OP(add,,)
> +ATOMIC_LONG_ADD_SUB_OP(add, _relaxed,)
> +ATOMIC_LONG_ADD_SUB_OP(add, _acquire,)
> +ATOMIC_LONG_ADD_SUB_OP(add, _release,)
> +ATOMIC_LONG_ADD_SUB_OP(sub,,)
> +ATOMIC_LONG_ADD_SUB_OP(sub, _relaxed,)
> +ATOMIC_LONG_ADD_SUB_OP(sub, _acquire,)
> +ATOMIC_LONG_ADD_SUB_OP(sub, _release,)
> +
> +ATOMIC_LONG_ADD_SUB_OP(add,,_wrap)
> +ATOMIC_LONG_ADD_SUB_OP(sub,,_wrap)
>
> #undef ATOMIC_LONG_ADD_SUB_OP
>
> @@ -89,6 +99,9 @@ ATOMIC_LONG_ADD_SUB_OP(sub, _release)
> #define atomic_long_cmpxchg(l, old, new) \
> (ATOMIC_LONG_PFX(_cmpxchg)((ATOMIC_LONG_PFX(_t) *)(l), (old), (new)))
>
> +#define atomic_long_cmpxchg_wrap(l, old, new) \
> + (ATOMIC_LONG_PFX(_cmpxchg_wrap)((ATOMIC_LONG_PFX(_wrap_t) *)(l), (old), (new)))
> +
> #define atomic_long_xchg_relaxed(v, new) \
> (ATOMIC_LONG_PFX(_xchg_relaxed)((ATOMIC_LONG_PFX(_t) *)(v), (new)))
> #define atomic_long_xchg_acquire(v, new) \
> @@ -98,6 +111,9 @@ ATOMIC_LONG_ADD_SUB_OP(sub, _release)
> #define atomic_long_xchg(v, new) \
> (ATOMIC_LONG_PFX(_xchg)((ATOMIC_LONG_PFX(_t) *)(v), (new)))
>
> +#define atomic_long_xchg_wrap(v, new) \
> + (ATOMIC_LONG_PFX(_xchg_wrap)((ATOMIC_LONG_PFX(_wrap_t) *)(v), (new)))
> +
> static __always_inline void atomic_long_inc(atomic_long_t *l)
> {
> ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l;
> @@ -105,6 +121,13 @@ static __always_inline void atomic_long_inc(atomic_long_t *l)
> ATOMIC_LONG_PFX(_inc)(v);
> }
>
> +static __always_inline void atomic_long_inc_wrap(atomic_long_wrap_t *l)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + ATOMIC_LONG_PFX(_inc_wrap)(v);
> +}
> +
> static __always_inline void atomic_long_dec(atomic_long_t *l)
> {
> ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l;
> @@ -112,6 +135,13 @@ static __always_inline void atomic_long_dec(atomic_long_t *l)
> ATOMIC_LONG_PFX(_dec)(v);
> }
>
> +static __always_inline void atomic_long_dec_wrap(atomic_long_wrap_t *l)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + ATOMIC_LONG_PFX(_dec_wrap)(v);
> +}
> +
> #define ATOMIC_LONG_FETCH_OP(op, mo) \
> static inline long \
> atomic_long_fetch_##op##mo(long i, atomic_long_t *l) \
> @@ -168,21 +198,24 @@ ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _release)
>
> #undef ATOMIC_LONG_FETCH_INC_DEC_OP
>
> -#define ATOMIC_LONG_OP(op) \
> +#define ATOMIC_LONG_OP(op, suffix) \
> static __always_inline void \
> -atomic_long_##op(long i, atomic_long_t *l) \
> +atomic_long_##op##suffix(long i, atomic_long##suffix##_t *l) \
> { \
> - ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
> + ATOMIC_LONG_PFX(suffix##_t) *v = (ATOMIC_LONG_PFX(suffix##_t) *)l;\
> \
> - ATOMIC_LONG_PFX(_##op)(i, v); \
> + ATOMIC_LONG_PFX(_##op##suffix)(i, v); \
> }
>
> -ATOMIC_LONG_OP(add)
> -ATOMIC_LONG_OP(sub)
> -ATOMIC_LONG_OP(and)
> -ATOMIC_LONG_OP(andnot)
> -ATOMIC_LONG_OP(or)
> -ATOMIC_LONG_OP(xor)
> +ATOMIC_LONG_OP(add,)
> +ATOMIC_LONG_OP(sub,)
> +ATOMIC_LONG_OP(and,)
> +ATOMIC_LONG_OP(or,)
> +ATOMIC_LONG_OP(xor,)
> +ATOMIC_LONG_OP(andnot,)
> +
> +ATOMIC_LONG_OP(add,_wrap)
> +ATOMIC_LONG_OP(sub,_wrap)
>
> #undef ATOMIC_LONG_OP
>
> @@ -214,22 +247,53 @@ static inline int atomic_long_add_negative(long i, atomic_long_t *l)
> return ATOMIC_LONG_PFX(_add_negative)(i, v);
> }
>
> -#define ATOMIC_LONG_INC_DEC_OP(op, mo) \
> +static inline int atomic_long_sub_and_test_wrap(long i, atomic_long_wrap_t *l)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + return ATOMIC_LONG_PFX(_sub_and_test_wrap)(i, v);
> +}
> +
> +static inline int atomic_long_dec_and_test_wrap(atomic_long_wrap_t *l)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + return ATOMIC_LONG_PFX(_dec_and_test_wrap)(v);
> +}
> +
> +static inline int atomic_long_inc_and_test_wrap(atomic_long_wrap_t *l)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + return ATOMIC_LONG_PFX(_inc_and_test_wrap)(v);
> +}
> +
> +static inline int atomic_long_add_negative_wrap(long i, atomic_long_wrap_t *l)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + return ATOMIC_LONG_PFX(_add_negative_wrap)(i, v);
> +}
> +
> +#define ATOMIC_LONG_INC_DEC_OP(op, mo, suffix) \
> static inline long \
> -atomic_long_##op##_return##mo(atomic_long_t *l) \
> +atomic_long_##op##_return##mo##suffix(atomic_long##suffix##_t *l) \
> { \
> - ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
> + ATOMIC_LONG_PFX(suffix##_t) *v = (ATOMIC_LONG_PFX(suffix##_t) *)l;\
> \
> - return (long)ATOMIC_LONG_PFX(_##op##_return##mo)(v); \
> + return (long)ATOMIC_LONG_PFX(_##op##_return##mo##suffix)(v); \
> }
> -ATOMIC_LONG_INC_DEC_OP(inc,)
> -ATOMIC_LONG_INC_DEC_OP(inc, _relaxed)
> -ATOMIC_LONG_INC_DEC_OP(inc, _acquire)
> -ATOMIC_LONG_INC_DEC_OP(inc, _release)
> -ATOMIC_LONG_INC_DEC_OP(dec,)
> -ATOMIC_LONG_INC_DEC_OP(dec, _relaxed)
> -ATOMIC_LONG_INC_DEC_OP(dec, _acquire)
> -ATOMIC_LONG_INC_DEC_OP(dec, _release)
> +ATOMIC_LONG_INC_DEC_OP(inc,,)
> +ATOMIC_LONG_INC_DEC_OP(inc, _relaxed,)
> +ATOMIC_LONG_INC_DEC_OP(inc, _acquire,)
> +ATOMIC_LONG_INC_DEC_OP(inc, _release,)
> +ATOMIC_LONG_INC_DEC_OP(dec,,)
> +ATOMIC_LONG_INC_DEC_OP(dec, _relaxed,)
> +ATOMIC_LONG_INC_DEC_OP(dec, _acquire,)
> +ATOMIC_LONG_INC_DEC_OP(dec, _release,)
> +
> +ATOMIC_LONG_INC_DEC_OP(inc,,_wrap)
> +ATOMIC_LONG_INC_DEC_OP(dec,,_wrap)
>
> #undef ATOMIC_LONG_INC_DEC_OP
>
> @@ -240,7 +304,16 @@ static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u)
> return (long)ATOMIC_LONG_PFX(_add_unless)(v, a, u);
> }
>
> +static inline long atomic_long_add_unless_wrap(atomic_long_wrap_t *l, long a, long u)
> +{
> + ATOMIC_LONG_PFX(_wrap_t) *v = (ATOMIC_LONG_PFX(_wrap_t) *)l;
> +
> + return (long)ATOMIC_LONG_PFX(_add_unless_wrap)(v, a, u);
> +}
> +
> #define atomic_long_inc_not_zero(l) \
> ATOMIC_LONG_PFX(_inc_not_zero)((ATOMIC_LONG_PFX(_t) *)(l))
>
> +#include <asm-generic/atomic_wrap.h>
> +
> #endif /* _ASM_GENERIC_ATOMIC_LONG_H */
> diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
> index 9ed8b98..90c8017 100644
> --- a/include/asm-generic/atomic.h
> +++ b/include/asm-generic/atomic.h
> @@ -223,6 +223,8 @@ static inline void atomic_dec(atomic_t *v)
> #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
> #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
>
> +#endif /* CONFIG_HARDENED_ATOMIC */
> +
> static inline int __atomic_add_unless(atomic_t *v, int a, int u)
> {
> int c, old;
> @@ -232,4 +234,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
> return c;
> }
>
> +#include <asm-generic/atomic_wrap.h>
> +
> #endif /* __ASM_GENERIC_ATOMIC_H */
> diff --git a/include/asm-generic/atomic64.h b/include/asm-generic/atomic64.h
> index dad68bf..2a60cd4 100644
> --- a/include/asm-generic/atomic64.h
> +++ b/include/asm-generic/atomic64.h
> @@ -62,4 +62,6 @@ extern int atomic64_add_unless(atomic64_t *v, long long a, long long u);
> #define atomic64_dec_and_test(v) (atomic64_dec_return((v)) == 0)
> #define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1LL, 0LL)
>
> +#include <asm-generic/atomic64_wrap.h>
> +
> #endif /* _ASM_GENERIC_ATOMIC64_H */
> diff --git a/include/asm-generic/atomic64_wrap.h b/include/asm-generic/atomic64_wrap.h
> new file mode 100644
> index 0000000..2e29cf3
> --- /dev/null
> +++ b/include/asm-generic/atomic64_wrap.h
> @@ -0,0 +1,123 @@
> +#ifndef _ASM_GENERIC_ATOMIC64_WRAP_H
> +#define _ASM_GENERIC_ATOMIC64_WRAP_H
> +
> +#ifndef CONFIG_HARDENED_ATOMIC
> +
> +#ifndef atomic64_wrap_t
> +#define atomic64_wrap_t atomic64_wrap_t
> +typedef struct {
> + long counter;
> +} atomic64_wrap_t;
> +#endif
> +
> +/*
> + * CONFIG_HARDENED_ATOMIC requires a non-generic implementation of ATOMIC64.
> + * This only serves to make the wrap-functions available when HARDENED_ATOMIC is
> + * either unimplemented or unset.
> + */
> +
> +static inline long long atomic64_read_wrap(const atomic64_wrap_t *v)
> +{
> + return atomic64_read((atomic64_t *) v);
> +}
> +#define atomic64_read_wrap atomic64_read_wrap
> +
> +static inline void atomic64_set_wrap(atomic64_wrap_t *v, long long i)
> +{
> + atomic64_set((atomic64_t *) v, i);
> +}
> +#define atomic64_set_wrap atomic64_set_wrap
> +
> +static inline void atomic64_add_wrap(long long a, atomic64_wrap_t *v)
> +{
> + atomic64_add(a, (atomic64_t *) v);
> +}
> +#define atomic64_add_wrap atomic64_add_wrap
> +
> +static inline long long atomic64_add_return_wrap(long long a, atomic64_wrap_t *v)
> +{
> + return atomic64_add_return(a, (atomic64_t *) v);
> +}
> +#define atomic64_add_return_wrap atomic64_add_return_wrap
> +
> +static inline void atomic64_sub_wrap(long long a, atomic64_wrap_t *v)
> +{
> + atomic64_sub(a, (atomic64_t *) v);
> +}
> +#define atomic64_sub_wrap atomic64_sub_wrap
> +
> +static inline long long atomic64_sub_return_wrap(long long a, atomic64_wrap_t *v)
> +{
> + return atomic64_sub_return(a, (atomic64_t *) v);
> +}
> +#define atomic64_sub_return_wrap atomic64_sub_return_wrap
> +
> +static inline long long atomic64_sub_and_test_wrap(long long a, atomic64_wrap_t *v)
> +{
> + return atomic64_sub_and_test(a, (atomic64_t *) v);
> +}
> +#define atomic64_sub_and_test_wrap atomic64_sub_and_test_wrap
> +
> +static inline void atomic64_inc_wrap(atomic64_wrap_t *v)
> +{
> + atomic64_inc((atomic64_t *) v);
> +}
> +#define atomic64_inc_wrap atomic64_inc_wrap
> +
> +static inline long long atomic64_inc_return_wrap(atomic64_wrap_t *v)
> +{
> + return atomic64_inc_return((atomic64_t *) v);
> +}
> +#define atomic64_inc_return_wrap atomic64_inc_return_wrap
> +
> +static inline long long atomic64_inc_and_test_wrap(atomic64_wrap_t *v)
> +{
> + return atomic64_inc_and_test((atomic64_t *) v);
> +}
> +#define atomic64_inc_and_test_wrap atomic64_inc_and_test_wrap
> +
> +static inline void atomic64_dec_wrap(atomic64_wrap_t *v)
> +{
> + atomic64_dec((atomic64_t *) v);
> +}
> +#define atomic64_dec_wrap atomic64_dec_wrap
> +
> +static inline long long atomic64_dec_return_wrap(atomic64_wrap_t *v)
> +{
> + return atomic64_dec_return((atomic64_t *) v);
> +}
> +#define atomic64_dec_return_wrap atomic64_dec_return_wrap
> +
> +static inline long long atomic64_dec_and_test_wrap(atomic64_wrap_t *v)
> +{
> + return atomic64_dec_and_test((atomic64_t *) v);
> +}
> +#define atomic64_dec_and_test_wrap atomic64_dec_and_test_wrap
> +
> +static inline long long atomic64_cmpxchg_wrap(atomic64_wrap_t *v, long long o, long long n)
> +{
> + return atomic64_cmpxchg((atomic64_t *) v, o, n);
> +}
> +#define atomic64_cmpxchg_wrap atomic64_cmpxchg_wrap
> +
> +static inline long long atomic64_xchg_wrap(atomic64_wrap_t *v, long long n)
> +{
> + return atomic64_xchg((atomic64_t *) v, n);
> +}
> +#define atomic64_xchg_wrap atomic64_xchg_wrap
> +
> +static inline bool atomic64_add_negative_wrap(long i, atomic64_wrap_t *v)
> +{
> + return atomic64_add_negative(i, (atomic64_t *) v);
> +}
> +#define atomic64_add_negative_wrap atomic64_add_negative_wrap
> +
> +static inline bool atomic64_add_unless_wrap(atomic64_wrap_t *v, long a, long u)
> +{
> + return atomic64_add_unless((atomic64_t *) v, a, u);
> +}
> +#define atomic64_add_unless_wrap atomic64_add_unless_wrap
> +
> +#endif /* CONFIG_HARDENED_ATOMIC */
> +
> +#endif /* _ASM_GENERIC_ATOMIC64_WRAP_H */
> diff --git a/include/asm-generic/atomic_wrap.h b/include/asm-generic/atomic_wrap.h
> new file mode 100644
> index 0000000..8cd0137
> --- /dev/null
> +++ b/include/asm-generic/atomic_wrap.h
> @@ -0,0 +1,114 @@
> +#ifndef _LINUX_ATOMIC_WRAP_H
> +#define _LINUX_ATOMIC_WRAP_H
> +
> +#ifndef CONFIG_HARDENED_ATOMIC
> +
> +#include <asm/atomic.h>
> +
> +#ifndef atomic_read_wrap
> +#define atomic_read_wrap(v) READ_ONCE((v)->counter)
> +#endif
> +#ifndef atomic_set_wrap
> +#define atomic_set_wrap(v, i) WRITE_ONCE(((v)->counter), (i))
> +#endif
> +
> +#ifndef atomic_inc_return_wrap
> +static inline int atomic_inc_return_wrap(atomic_wrap_t *v)
> +{
> + return atomic_inc_return((atomic_t *) v);
> +}
> +#define atomic_inc_return_wrap atomic_inc_return_wrap
> +#endif
> +
> +#ifndef atomic_dec_return_wrap
> +static inline int atomic_dec_return_wrap(atomic_wrap_t *v)
> +{
> + return atomic_dec_return((atomic_t *) v);
> +}
> +#define atomic_dec_return_wrap atomic_dec_return_wrap
> +#endif
> +
> +#ifndef atomic_add_return_wrap
> +static inline int atomic_add_return_wrap(int i, atomic_wrap_t *v)
> +{
> + return atomic_add_return(i, (atomic_t *) v);
> +}
> +#define atomic_add_return_wrap atomic_add_return_wrap
> +#endif
> +
> +#ifndef atomic_sub_return_wrap
> +static inline int atomic_sub_return_wrap(int i, atomic_wrap_t *v)
> +{
> + return atomic_sub_return(i, (atomic_t *) v);
> +}
> +#define atomic_sub_return_wrap atomic_sub_return_wrap
> +#endif
> +
> +#ifndef atomic_xchg_wrap
> +#define atomic_xchg_wrap(ptr, v) (xchg(&(ptr)->counter, (v)))
> +#endif
> +#ifndef atomic_cmpxchg_wrap
> +#define atomic_cmpxchg_wrap(v, o, n) atomic_cmpxchg(((atomic_t *) v), (o), (n))
> +#endif
> +
> +#ifndef atomic_add_negative_wrap
> +static inline int atomic_add_negative_wrap(int i, atomic_wrap_t *v)
> +{
> + return atomic_add_return_wrap(i, v) < 0;
> +}
> +#define atomic_add_negative_wrap atomic_add_negative_wrap
> +#endif
> +
> +#ifndef atomic_add_wrap
> +static inline void atomic_add_wrap(int i, atomic_wrap_t *v)
> +{
> + atomic_add_return_wrap(i, v);
> +}
> +#define atomic_add_wrap atomic_add_wrap
> +#endif
> +
> +#ifndef atomic_sub_wrap
> +static inline void atomic_sub_wrap(int i, atomic_wrap_t *v)
> +{
> + atomic_sub_return_wrap(i, v);
> +}
> +#define atomic_sub_wrap atomic_sub_wrap
> +#endif
> +
> +#ifndef atomic_inc_wrap
> +static inline void atomic_inc_wrap(atomic_wrap_t *v)
> +{
> + atomic_add_return_wrap(1, v);
> +}
> +#define atomic_inc_wrap atomic_inc_wrap
> +#endif
> +
> +#ifndef atomic_dec_wrap
> +static inline void atomic_dec_wrap(atomic_wrap_t *v)
> +{
> + atomic_sub_return_wrap(1, v);
> +}
> +#define atomic_dec_wrap atomic_dec_wrap
> +#endif
> +
> +#ifndef atomic_sub_and_test_wrap
> +#define atomic_sub_and_test_wrap(i, v) (atomic_sub_return_wrap((i), (v)) == 0)
> +#endif
> +#ifndef atomic_dec_and_test_wrap
> +#define atomic_dec_and_test_wrap(v) (atomic_dec_return_wrap(v) == 0)
> +#endif
> +#ifndef atomic_inc_and_test_wrap
> +#define atomic_inc_and_test_wrap(v) (atomic_inc_return_wrap(v) == 0)
> +#endif
> +
> +#ifndef atomic_add_unless_wrap
> +static inline int atomic_add_unless_wrap(atomic_wrap_t *v, int a, int u)
> +{
> + return __atomic_add_unless((atomic_t *) v, a, u);
> +}
> +#define atomic_add_unless_wrap atomic_add_unless_wrap
> +#endif
> +
> +#endif /* CONFIG_HARDENED_ATOMIC */
> +
> +#endif /* _LINUX_ATOMIC_WRAP_H */
> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> index 6f96247..20ce604 100644
> --- a/include/asm-generic/bug.h
> +++ b/include/asm-generic/bug.h
> @@ -215,6 +215,13 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
> # define WARN_ON_SMP(x) ({0;})
> #endif
>
> +#ifdef CONFIG_HARDENED_ATOMIC
> +void hardened_atomic_overflow(struct pt_regs *regs);
> +#else
> +static inline void hardened_atomic_overflow(struct pt_regs *regs){
> +}
> +#endif
> +
> #endif /* __ASSEMBLY__ */
>
> #endif
> diff --git a/include/asm-generic/local.h b/include/asm-generic/local.h
> index 9ceb03b..75e5554 100644
> --- a/include/asm-generic/local.h
> +++ b/include/asm-generic/local.h
> @@ -39,6 +39,7 @@ typedef struct
> #define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
> #define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
> #define local_inc_return(l) atomic_long_inc_return(&(l)->a)
> +#define local_dec_return(l) atomic_long_dec_return(&(l)->a)
>
> #define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n))
> #define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
> @@ -52,4 +53,6 @@ typedef struct
> #define __local_add(i,l) local_set((l), local_read(l) + (i))
> #define __local_sub(i,l) local_set((l), local_read(l) - (i))
>
> +#include <asm-generic/local_wrap.h>
> +
> #endif /* _ASM_GENERIC_LOCAL_H */
> diff --git a/include/asm-generic/local_wrap.h b/include/asm-generic/local_wrap.h
> new file mode 100644
> index 0000000..53c7a82
> --- /dev/null
> +++ b/include/asm-generic/local_wrap.h
> @@ -0,0 +1,63 @@
> +#ifndef _LINUX_LOCAL_H
> +#define _LINUX_LOCAL_H
> +
> +#include <asm/local.h>
> +
> +/*
> + * A signed long type for operations which are atomic for a single CPU. Usually
> + * used in combination with per-cpu variables. This is a safeguard header that
> + * ensures that local_wrap_* is available regardless of whether platform support
> + * for HARDENED_ATOMIC is available.
> + */
> +
> +#ifdef CONFIG_HARDENED_ATOMIC
> +typedef struct {
> + atomic_long_wrap_t a;
> +} local_wrap_t;
> +#else
> +typedef struct {
> + atomic_long_t a;
> +} local_wrap_t;
> +#endif /* CONFIG_HARDENED_ATOMIC */
> +
> +#ifdef CONFIG_HARDENED_ATOMIC
> +
> +#define local_read_wrap(l) atomic_long_read_wrap(&(l)->a)
> +#define local_set_wrap(l,i) atomic_long_set_wrap((&(l)->a),(i))
> +#define local_inc_wrap(l) atomic_long_inc_wrap(&(l)->a)
> +#define local_inc_return_wrap(l) atomic_long_return_wrap(&(l)->a)
> +#define local_inc_and_test_wrap(l) atomic_long_inc_and_test_wrap(&(l)->a)
> +#define local_dec_wrap(l) atomic_long_dec_wrap(&(l)->a)
> +#define local_dec_return_wrap(l) atomic_long_dec_return_wrap(&(l)->a)
> +#define local_dec_and_test_wrap(l) atomic_long_dec_and_test_wrap(&(l)->a)
> +#define local_add_wrap(i,l) atomic_long_add_wrap((i),(&(l)->a))
> +#define local_add_return_wrap(i, l) atomic_long_add_return_wrap((i), (&(l)->a))
> +#define local_sub_wrap(i,l) atomic_long_sub_wrap((i),(&(l)->a))
> +#define local_sub_return_wrap(i, l) atomic_long_sub_return_wrap((i), (&(l)->a))
> +#define local_sub_and_test_wrap(i, l) atomic_long_sub_and_test_wrap((i), (&(l)->a))
> +#define local_cmpxchg_wrap(l, o, n) atomic_long_cmpxchg_wrap((&(l)->a), (o), (n))
> +#define local_add_unless_wrap(l, _a, u) atomic_long_add_unless_wrap((&(l)->a), (_a), (u))
> +#define local_add_negative_wrap(i, l) atomic_long_add_negative_wrap((i), (&(l)->a))
> +
> +#else /* CONFIG_HARDENED_ATOMIC */
> +
> +#define local_read_wrap(l) local_read((local_t *) l)
> +#define local_set_wrap(l,i) local_set(((local_t *) l),(i))
> +#define local_inc_wrap(l) local_inc((local_t *) l)
> +#define local_inc_return_wrap(l) local_inc_return((local_t *) l)
> +#define local_inc_and_test_wrap(l) local_inc_and_test((local_t *) l)
> +#define local_dec_wrap(l) local_dec((local_t *) l)
> +#define local_dec_return_wrap(l) local_dec_return((local_t *) l)
> +#define local_dec_and_test_wrap(l) local_dec_and_test((local_t *) l)
> +#define local_add_wrap(i,l) local_add((i),((local_t *) l))
> +#define local_add_return_wrap(i, l) local_add_return((i), ((local_t *) l))
> +#define local_sub_wrap(i,l) local_sub((i),((local_t *) l))
> +#define local_sub_return_wrap(i, l) local_sub_return((i), ((local_t *) l))
> +#define local_sub_and_test_wrap(i, l) local_sub_and_test((i), ((local_t *) l))
> +#define local_cmpxchg_wrap(l, o, n) local_cmpxchg(((local_t *) l), (o), (n))
> +#define local_add_unless_wrap(l, _a, u) local_add_unless(((local_t *) l), (_a), (u))
> +#define local_add_negative_wrap(i, l) local_add_negative((i), ((local_t *) l))
> +
> +#endif /* CONFIG_HARDENED_ATOMIC */
> +
> +#endif /* _LINUX_LOCAL_H */
> diff --git a/include/linux/atomic.h b/include/linux/atomic.h
> index e71835b..dd05ca5 100644
> --- a/include/linux/atomic.h
> +++ b/include/linux/atomic.h
> @@ -40,28 +40,40 @@
> * variants
> */
> #ifndef __atomic_op_acquire
> -#define __atomic_op_acquire(op, args...) \
> +#define __atomic_op_acquire(op, args...) __atomic_op_acquire_wrap(op, , args)
> +#endif
> +
> +#ifndef __atomic_op_acquire_wrap
> +#define __atomic_op_acquire_wrap(op, mo, args...) \
> ({ \
> - typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \
> + typeof(op##_relaxed##mo(args)) __ret = op##_relaxed##mo(args); \
> smp_mb__after_atomic(); \
> __ret; \
> })
> #endif
>
> #ifndef __atomic_op_release
> -#define __atomic_op_release(op, args...) \
> +#define __atomic_op_release(op, args...) __atomic_op_release_wrap(op, , args)
> +#endif
> +
> +#ifndef __atomic_op_release_wrap
> +#define __atomic_op_release_wrap(op, mo, args...) \
> ({ \
> smp_mb__before_atomic(); \
> - op##_relaxed(args); \
> + op##_relaxed##mo(args); \
> })
> #endif
>
> #ifndef __atomic_op_fence
> -#define __atomic_op_fence(op, args...) \
> +#define __atomic_op_fence(op, args...) __atomic_op_fence_wrap(op, , args)
> +#endif
> +
> +#ifndef __atomic_op_fence_wrap
> +#define __atomic_op_fence_wrap(op, mo, args...) \
> ({ \
> - typeof(op##_relaxed(args)) __ret; \
> + typeof(op##_relaxed##mo(args)) __ret; \
> smp_mb__before_atomic(); \
> - __ret = op##_relaxed(args); \
> + __ret = op##_relaxed##mo(args); \
> smp_mb__after_atomic(); \
> __ret; \
> })
> @@ -91,6 +103,13 @@
> #endif
> #endif /* atomic_add_return_relaxed */
>
> +#ifndef atomic_add_return_relaxed_wrap
> +#define atomic_add_return_relaxed_wrap atomic_add_return_wrap
> +#else
> +#define atomic_add_return_wrap(...) \
> + __atomic_op_fence_wrap(atomic_add_return, _wrap, __VA_ARGS__)
> +#endif /* atomic_add_return_relaxed_wrap */
> +
> /* atomic_inc_return_relaxed */
> #ifndef atomic_inc_return_relaxed
> #define atomic_inc_return_relaxed atomic_inc_return
> @@ -115,6 +134,13 @@
> #endif
> #endif /* atomic_inc_return_relaxed */
>
> +#ifndef atomic_inc_return_relaxed_wrap
> +#define atomic_inc_return_relaxed_wrap atomic_in_return_wrap
> +#else
> +#define atomic_inc_return_wrap(...) \
> + __atomic_op_fence_wrap(atomic_inc_return, _wrap, __VA_ARGS__)
> +#endif /* atomic_inc_return_relaxed_wrap */
> +
> /* atomic_sub_return_relaxed */
> #ifndef atomic_sub_return_relaxed
> #define atomic_sub_return_relaxed atomic_sub_return
> @@ -139,6 +165,13 @@
> #endif
> #endif /* atomic_sub_return_relaxed */
>
> +#ifndef atomic_sub_return_relaxed_wrap
> +#define atomic_sub_return_relaxed_wrap atomic_sub_return_wrap
> +#else
> +#define atomic_sub_return_wrap(...) \
> + __atomic_op_fence_wrap(atomic_sub_return, _wrap, __VA_ARGS__)
> +#endif /* atomic_sub_return_relaxed_wrap */
> +
> /* atomic_dec_return_relaxed */
> #ifndef atomic_dec_return_relaxed
> #define atomic_dec_return_relaxed atomic_dec_return
> @@ -163,6 +196,12 @@
> #endif
> #endif /* atomic_dec_return_relaxed */
>
> +#ifndef atomic_dec_return_relaxed_wrap
> +#define atomic_dec_return_relaxed_wrap atomic_dec_return_wrap
> +#else
> +#define atomic_dec_return_wrap(...) \
> + __atomic_op_fence_wrap(atomic_dec_return, _wrap, __VA_ARGS__)
> +#endif /* atomic_dec_return_relaxed_wrap */
>
> /* atomic_fetch_add_relaxed */
> #ifndef atomic_fetch_add_relaxed
> @@ -385,20 +424,28 @@
>
> #ifndef atomic_xchg_acquire
> #define atomic_xchg_acquire(...) \
> - __atomic_op_acquire(atomic_xchg, __VA_ARGS__)
> + __atomic_op_acquire(atomic_xchg,, __VA_ARGS__)
> #endif
>
> #ifndef atomic_xchg_release
> #define atomic_xchg_release(...) \
> - __atomic_op_release(atomic_xchg, __VA_ARGS__)
> + __atomic_op_release(atomic_xchg,, __VA_ARGS__)
> #endif
>
> #ifndef atomic_xchg
> #define atomic_xchg(...) \
> - __atomic_op_fence(atomic_xchg, __VA_ARGS__)
> + __atomic_op_fence(atomic_xchg,, __VA_ARGS__)
> #endif
> +
> #endif /* atomic_xchg_relaxed */
>
> +#ifndef atomic_xchg_relaxed_wrap
> +#define atomic_xchg_relaxed_wrap atomic_xchg_wrap
> +#else
> +#define atomic_xchg_wrap(...) \
> + __atomic_op_fence_wrap(atomic_xchg, _wrap, __VA_ARGS__)
> +#endif
> +
> /* atomic_cmpxchg_relaxed */
> #ifndef atomic_cmpxchg_relaxed
> #define atomic_cmpxchg_relaxed atomic_cmpxchg
> @@ -421,8 +468,16 @@
> #define atomic_cmpxchg(...) \
> __atomic_op_fence(atomic_cmpxchg, __VA_ARGS__)
> #endif
> +
> #endif /* atomic_cmpxchg_relaxed */
>
> +#ifndef atomic_cmpxchg_relaxed_wrap
> +#define atomic_cmpxchg_relaxed_wrap atomic_cmpxchg_wrap
> +#else
> +#define atomic_cmpxchg_wrap(...) \
> + __atomic_op_fence_wrap(atomic_cmpxchg, _wrap, __VA_ARGS__)
> +#endif
> +
> /* cmpxchg_relaxed */
> #ifndef cmpxchg_relaxed
> #define cmpxchg_relaxed cmpxchg
> @@ -627,10 +682,75 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> }
> #endif
>
> +#include <asm-generic/atomic_wrap.h>
> +
> #ifdef CONFIG_GENERIC_ATOMIC64
> #include <asm-generic/atomic64.h>
> #endif
>
> +#ifndef CONFIG_HARDENED_ATOMIC
> +
> +#ifndef atomic64_wrap_t
> +#define atomic64_wrap_t atomic64_wrap_t
> +typedef struct {
> + long counter;
> +} atomic64_wrap_t;
> +#endif
> +
> +#ifndef atomic64_read_wrap
> +#define atomic64_read_wrap(v) atomic64_read((atomic64_t *) v)
> +#endif
> +#ifndef atomic64_set_wrap
> +#define atomic64_set_wrap(v, i) atomic64_set((atomic64_t *) v, (i))
> +#endif
> +#ifndef atomic64_inc_wrap
> +#define atomic64_inc_wrap(l) atomic64_inc((atomic64_t *) l)
> +#endif
> +#ifndef atomic64_inc_return_wrap
> +#define atomic64_inc_return_wrap(l) atomic64_inc_return((atomic64_t *) l)
> +#endif
> +#ifndef atomic64_inc_and_test_wrap
> +#define atomic64_inc_and_test_wrap(l) atomic64_inc_and_test((atomic64_t *) l)
> +#endif
> +#ifndef atomic64_dec_wrap
> +#define atomic64_dec_wrap(l) atomic64_dec((atomic64_t *) l)
> +#endif
> +#ifndef atomic64_dec_return_wrap
> +#define atomic64_dec_return_wrap(l)atomic64_dec_return((atomic64_t *) l)
> +#endif
> +#ifndef atomic64_dec_and_test_wrap
> +#define atomic64_dec_and_test_wrap(l) atomic64_dec_and_test((atomic64_t *) l)
> +#endif
> +#ifndef atomic64_add_wrap
> +#define atomic64_add_wrap(i,l) atomic64_add((i),((atomic64_t *) l))
> +#endif
> +#ifndef atomic64_add_return_wrap
> +#define atomic64_add_return_wrap(i, l) atomic64_add_return((i), ((atomic64_t *) l))
> +#endif
> +#ifndef atomic64_sub_wrap
> +#define atomic64_sub_wrap(i,l) atomic64_sub((i),((atomic64_t *) l))
> +#endif
> +#ifndef atomic64_sub_return_wrap
> +#define atomic64_sub_return_wrap(i, l) atomic64_sub_return((i), ((atomic64_t *) l))
> +#endif
> +#ifndef atomic64_sub_and_test_wrap
> +#define atomic64_sub_and_test_wrap(i, l) atomic64_sub_and_test((i), ((atomic64_t *) l))
> +#endif
> +#ifndef atomic64_cmpxchg_wrap
> +#define atomic64_cmpxchg_wrap(l, o, n) atomic64_cmpxchg(((atomic64_t *) l), (o), (n))
> +#endif
> +#ifndef atomic64_xchg_wrap
> +#define atomic64_xchg_wrap(l, n) atomic64_xchg(((atomic64_t *) l), (n))
> +#endif
> +#ifndef atomic64_add_unless_wrap
> +#define atomic64_add_unless_wrap(l, _a, u) atomic64_add_unless(((atomic64_t *) l), (_a), (u))
> +#endif
> +#ifndef atomic64_add_negative_wrap
> +#define atomic64_add_negative_wrap(i, l) atomic64_add_negative((i), ((atomic64_t *) l))
> +#endif
> +
> +#endif /* CONFIG_HARDENED_ATOMIC */
> +
> #ifndef atomic64_read_acquire
> #define atomic64_read_acquire(v) smp_load_acquire(&(v)->counter)
> #endif
> @@ -661,6 +781,12 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> #define atomic64_add_return(...) \
> __atomic_op_fence(atomic64_add_return, __VA_ARGS__)
> #endif
> +
> +#ifndef atomic64_add_return_wrap
> +#define atomic64_add_return_wrap(...) \
> + __atomic_op_fence(atomic64_add_return_wrap, __VA_ARGS__)
> +#endif
> +
> #endif /* atomic64_add_return_relaxed */
>
> /* atomic64_inc_return_relaxed */
> @@ -685,6 +811,11 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> #define atomic64_inc_return(...) \
> __atomic_op_fence(atomic64_inc_return, __VA_ARGS__)
> #endif
> +
> +#ifndef atomic64_inc_return_wrap
> +#define atomic64_inc_return_wrap(...) \
> + __atomic_op_fence(atomic64_inc_return_wrap, __VA_ARGS__)
> +#endif
> #endif /* atomic64_inc_return_relaxed */
>
>
> @@ -710,6 +841,11 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> #define atomic64_sub_return(...) \
> __atomic_op_fence(atomic64_sub_return, __VA_ARGS__)
> #endif
> +
> +#ifndef atomic64_sub_return_wrap
> +#define atomic64_sub_return_wrap(...) \
> + __atomic_op_fence(atomic64_sub_return_wrap, __VA_ARGS__)
> +#endif
> #endif /* atomic64_sub_return_relaxed */
>
> /* atomic64_dec_return_relaxed */
> @@ -734,6 +870,11 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> #define atomic64_dec_return(...) \
> __atomic_op_fence(atomic64_dec_return, __VA_ARGS__)
> #endif
> +
> +#ifndef atomic64_dec_return_wrap
> +#define atomic64_dec_return_wrap(...) \
> + __atomic_op_fence(atomic64_dec_return_wrap, __VA_ARGS__)
> +#endif
> #endif /* atomic64_dec_return_relaxed */
>
>
> @@ -970,6 +1111,11 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> #define atomic64_xchg(...) \
> __atomic_op_fence(atomic64_xchg, __VA_ARGS__)
> #endif
> +
> +#ifndef atomic64_xchg_wrap
> +#define atomic64_xchg_wrap(...) \
> + __atomic_op_fence(atomic64_xchg_wrap, __VA_ARGS__)
> +#endif
> #endif /* atomic64_xchg_relaxed */
>
> /* atomic64_cmpxchg_relaxed */
> @@ -994,6 +1140,11 @@ static inline int atomic_dec_if_positive(atomic_t *v)
> #define atomic64_cmpxchg(...) \
> __atomic_op_fence(atomic64_cmpxchg, __VA_ARGS__)
> #endif
> +
> +#ifndef atomic64_cmpxchg_wrap
> +#define atomic64_cmpxchg_wrap(...) \
> + __atomic_op_fence(atomic64_cmpxchg_wrap, __VA_ARGS__)
> +#endif
> #endif /* atomic64_cmpxchg_relaxed */
>
> #ifndef atomic64_andnot
> diff --git a/include/linux/types.h b/include/linux/types.h
> index baf7183..3f818aa 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -175,6 +175,10 @@ typedef struct {
> int counter;
> } atomic_t;
>
> +typedef struct {
> + int counter;
> +} atomic_wrap_t;
> +
> #ifdef CONFIG_64BIT
> typedef struct {
> long counter;
> diff --git a/kernel/panic.c b/kernel/panic.c
> index e6480e2..cb1d6db 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -616,3 +616,14 @@ static int __init oops_setup(char *s)
> return 0;
> }
> early_param("oops", oops_setup);
> +
> +#ifdef CONFIG_HARDENED_ATOMIC
> +void hardened_atomic_overflow(struct pt_regs *regs)
> +{
> + pr_emerg(KERN_EMERG "HARDENED_ATOMIC: overflow detected in: %s:%d, uid/euid: %u/%u\n",
> + current->comm, task_pid_nr(current),
> + from_kuid_munged(&init_user_ns, current_uid()),
> + from_kuid_munged(&init_user_ns, current_euid()));
> + BUG();
> +}
> +#endif
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 9c14373..f96fa03 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -23,7 +23,8 @@
> #include <linux/list.h>
> #include <linux/cpu.h>
>
> -#include <asm/local.h>
> +#include <linux/local_wrap.h>
> +
>
> static void update_pages_handler(struct work_struct *work);
>
> diff --git a/security/Kconfig b/security/Kconfig
> index 118f454..604bee5 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -158,6 +158,26 @@ config HARDENED_USERCOPY_PAGESPAN
> been removed. This config is intended to be used only while
> trying to find such users.
>
> +config HAVE_ARCH_HARDENED_ATOMIC
> + bool
> + help
> + The architecture supports CONFIG_HARDENED_ATOMIC by
> + providing trapping on atomic_t wraps, with a call to
> + hardened_atomic_overflow().
> +
> +config HARDENED_ATOMIC
> + bool "Prevent reference counter overflow in atomic_t"
> + depends on HAVE_ARCH_HARDENED_ATOMIC
> + depends on !CONFIG_GENERIC_ATOMIC64
> + select BUG
> + help
> + This option catches counter wrapping in atomic_t, which
> + can turn refcounting overflow bugs into resource
> + consumption bugs instead of exploitable use-after-free
> + flaws. This feature has a negligible
> + performance impact and therefore recommended to be turned
> + on for security reasons.
> +
> source security/selinux/Kconfig
> source security/smack/Kconfig
> source security/tomoyo/Kconfig
> --
> 2.7.4
>
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