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Message-Id: <1475476886-26232-2-git-send-email-elena.reshetova@intel.com>
Date: Mon, 3 Oct 2016 09:41:14 +0300
From: Elena Reshetova <elena.reshetova@...el.com>
To: kernel-hardening@...ts.openwall.com
Cc: keescook@...omium.org,
Elena Reshetova <elena.reshetova@...el.com>,
Hans Liljestrand <ishkamiel@...il.com>,
David Windsor <dwindsor@...il.com>
Subject: [RFC PATCH 01/13] Add architecture independent hardened atomic base
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 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-2016-3135 - Netfilter xt_alloc_table_info integer overflow
CVE-2016-0728 - Keyring refcount overflow
CVE-2014-2851 - Group_info refcount overflow
CVE-2010-2959 - CAN integer overflow vulnerability,
related post: https://jon.oberheide.org/blog/2010/09/10/linux-kernel-can-slub-overflow/
And a relatively fresh exploit example:
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>
---
include/asm-generic/atomic-long.h | 166 +++++++++++++++++++++++++++-----------
include/asm-generic/atomic.h | 9 +++
include/asm-generic/atomic64.h | 13 +++
include/asm-generic/bug.h | 4 +
include/asm-generic/local.h | 15 ++++
include/linux/atomic.h | 14 ++++
include/linux/types.h | 17 ++++
kernel/panic.c | 12 +++
security/Kconfig | 15 ++++
9 files changed, 219 insertions(+), 46 deletions(-)
diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h
index 288cc9e..e74ca86 100644
--- a/include/asm-generic/atomic-long.h
+++ b/include/asm-generic/atomic-long.h
@@ -22,6 +22,12 @@
typedef atomic64_t atomic_long_t;
+#ifdef CONFIG_HARDENED_ATOMIC
+typedef atomic64_wrap_t atomic_long_wrap_t;
+#else
+typedef atomic64_t atomic_long_wrap_t;
+#endif
+
#define ATOMIC_LONG_INIT(i) ATOMIC64_INIT(i)
#define ATOMIC_LONG_PFX(x) atomic64 ## x
@@ -29,51 +35,61 @@ typedef atomic64_t atomic_long_t;
typedef atomic_t atomic_long_t;
+#ifdef CONFIG_HARDENED_ATOMIC
+typedef atomic_wrap_t atomic_long_wrap_t;
+#else
+typedef atomic_t atomic_long_wrap_t;
+#endif
+
#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(,_wrap)
+ATOMIC_LONG_READ_OP(_acquire,)
#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(,_wrap)
+ATOMIC_LONG_SET_OP(_release,)
#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,,_wrap)
+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,,_wrap) todo: check if this is really not needed
+ATOMIC_LONG_ADD_SUB_OP(sub, _relaxed,)
+ATOMIC_LONG_ADD_SUB_OP(sub, _acquire,)
+ATOMIC_LONG_ADD_SUB_OP(sub, _release,)
#undef ATOMIC_LONG_ADD_SUB_OP
@@ -98,6 +114,11 @@ ATOMIC_LONG_ADD_SUB_OP(sub, _release)
#define atomic_long_xchg(v, new) \
(ATOMIC_LONG_PFX(_xchg)((ATOMIC_LONG_PFX(_t) *)(v), (new)))
+#ifdef CONFIG_HARDENED_ATOMIC
+#define atomic_long_xchg_wrap(v, new) \
+ (ATOMIC_LONG_PFX(_xchg_wrap)((ATOMIC_LONG_PFX(_wrap_t) *)(v), (new)))
+#endif
+
static __always_inline void atomic_long_inc(atomic_long_t *l)
{
ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l;
@@ -105,6 +126,15 @@ static __always_inline void atomic_long_inc(atomic_long_t *l)
ATOMIC_LONG_PFX(_inc)(v);
}
+#ifdef CONFIG_HARDENED_ATOMIC
+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);
+}
+#endif
+
static __always_inline void atomic_long_dec(atomic_long_t *l)
{
ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l;
@@ -112,6 +142,15 @@ static __always_inline void atomic_long_dec(atomic_long_t *l)
ATOMIC_LONG_PFX(_dec)(v);
}
+#ifdef CONFIG_HARDENED_ATOMIC
+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);
+}
+#endif
+
#define ATOMIC_LONG_FETCH_OP(op, mo) \
static inline long \
atomic_long_fetch_##op##mo(long i, atomic_long_t *l) \
@@ -168,21 +207,23 @@ 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(add,_wrap)
+ATOMIC_LONG_OP(sub,)
+ATOMIC_LONG_OP(sub,_wrap)
+ATOMIC_LONG_OP(and,)
+ATOMIC_LONG_OP(or,)
+ATOMIC_LONG_OP(xor,)
+ATOMIC_LONG_OP(andnot,)
#undef ATOMIC_LONG_OP
@@ -193,6 +234,13 @@ static inline int atomic_long_sub_and_test(long i, atomic_long_t *l)
return ATOMIC_LONG_PFX(_sub_and_test)(i, v);
}
+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(atomic_long_t *l)
{
ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l;
@@ -214,22 +262,23 @@ 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) \
+#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,,_wrap)
+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,)
#undef ATOMIC_LONG_INC_DEC_OP
@@ -243,4 +292,29 @@ static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u)
#define atomic_long_inc_not_zero(l) \
ATOMIC_LONG_PFX(_inc_not_zero)((ATOMIC_LONG_PFX(_t) *)(l))
+#ifndef CONFIG_HARDENED_ATOMIC
+#define atomic_read_wrap(v) atomic_read(v)
+#define atomic_set_wrap(v, i) atomic_set((v), (i))
+#define atomic_add_wrap(i, v) atomic_add((i), (v))
+#define atomic_add_unless_wrap(v, i, j) atomic_add_unless((v), (i), (j))
+#define atomic_sub_wrap(i, v) atomic_sub((i), (v))
+#define atomic_inc_wrap(v) atomic_inc(v)
+#define atomic_inc_and_test_wrap(v) atomic_inc_and_test(v)
+#define atomic_inc_return_wrap(v) atomic_inc_return(v)
+#define atomic_add_return_wrap(i, v) atomic_add_return((i), (v))
+#define atomic_dec_wrap(v) atomic_dec(v)
+#define atomic_cmpxchg_wrap(v, o, n) atomic_cmpxchg((v), (o), (n))
+#define atomic_xchg_wrap(v, i) atomic_xchg((v), (i))
+#define atomic_long_read_wrap(v) atomic_long_read(v)
+#define atomic_long_set_wrap(v, i) atomic_long_set((v), (i))
+#define atomic_long_add_wrap(i, v) atomic_long_add((i), (v))
+#define atomic_long_sub_wrap(i, v) atomic_long_sub((i), (v))
+#define atomic_long_inc_wrap(v) atomic_long_inc(v)
+#define atomic_long_add_return_wrap(i, v) atomic_long_add_return((i), (v))
+#define atomic_long_inc_return_wrap(v) atomic_long_inc_return(v)
+#define atomic_long_sub_and_test_wrap(v) atomic_long_sub_and_test(v)
+#define atomic_long_dec_wrap(v) atomic_long_dec(v)
+#define atomic_long_xchg_wrap(v, i) atomic_long_xchg((v), (i))
+#endif /* CONFIG_HARDENED_ATOMIC */
+
#endif /* _ASM_GENERIC_ATOMIC_LONG_H */
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index 9ed8b98..159e749 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -232,4 +232,13 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
return c;
}
+static inline int __atomic_add_unless_wrap(atomic_t *v, int a, int u)
+{
+ int c, old;
+ c = atomic_read_wrap(v);
+ while (c != u && (old = atomic_cmpxchg_wrap(v, c, c + a)) != c)
+ c = old;
+ return c;
+}
+
#endif /* __ASM_GENERIC_ATOMIC_H */
diff --git a/include/asm-generic/atomic64.h b/include/asm-generic/atomic64.h
index dad68bf..4987419 100644
--- a/include/asm-generic/atomic64.h
+++ b/include/asm-generic/atomic64.h
@@ -16,6 +16,8 @@ typedef struct {
long long counter;
} atomic64_t;
+typedef atomic64_t atomic64_wrap_t;
+
#define ATOMIC64_INIT(i) { (i) }
extern long long atomic64_read(const atomic64_t *v);
@@ -62,4 +64,15 @@ 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)
+#define atomic64_read_wrap(v) atomic64_read(v)
+#define atomic64_set_wrap(v, i) atomic64_set((v), (i))
+#define atomic64_add_wrap(a, v) atomic64_add((a), (v))
+#define atomic64_add_return_wrap(a, v) atomic64_add_return((a), (v))
+#define atomic64_sub_wrap(a, v) atomic64_sub((a), (v))
+#define atomic64_inc_wrap(v) atomic64_inc(v)
+#define atomic64_inc_return_wrap(v) atomic64_inc_return(v)
+#define atomic64_dec_wrap(v) atomic64_dec(v)
+#define atomic64_cmpxchg_wrap(v, o, n) atomic64_cmpxchg((v), (o), (n))
+#define atomic64_xchg_wrap(v, n) atomic64_xchg((v), (n))
+
#endif /* _ASM_GENERIC_ATOMIC64_H */
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 6f96247..9428d60 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -215,6 +215,10 @@ 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_refcount_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..a98ad1d 100644
--- a/include/asm-generic/local.h
+++ b/include/asm-generic/local.h
@@ -23,24 +23,39 @@ typedef struct
atomic_long_t a;
} local_t;
+typedef struct {
+ atomic_long_wrap_t a;
+} local_wrap_t;
+
#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
#define local_read(l) atomic_long_read(&(l)->a)
+#define local_read_wrap(l) atomic_long_read_wrap(&(l)->a)
#define local_set(l,i) atomic_long_set((&(l)->a),(i))
+#define local_set_wrap(l,i) atomic_long_set_wrap((&(l)->a),(i))
#define local_inc(l) atomic_long_inc(&(l)->a)
+#define local_inc_wrap(l) atomic_long_inc_wrap(&(l)->a)
#define local_dec(l) atomic_long_dec(&(l)->a)
+#define local_dec_wrap(l) atomic_long_dec_wrap(&(l)->a)
#define local_add(i,l) atomic_long_add((i),(&(l)->a))
+#define local_add_wrap(i,l) atomic_long_add_wrap((i),(&(l)->a))
#define local_sub(i,l) atomic_long_sub((i),(&(l)->a))
+#define local_sub_wrap(i,l) atomic_long_sub_wrap((i),(&(l)->a))
#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
+#define local_sub_and_test_wrap(i, l) atomic_long_sub_and_test_wrap((i), (&(l)->a))
#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
+#define local_add_return_wrap(i, l) atomic_long_add_return_wrap((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)
+/* verify that below function is needed */
+#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_cmpxchg_wrap(l, o, n) atomic_long_cmpxchg_wrap((&(l)->a), (o), (n))
#define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index e71835b..b5817c8 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -507,6 +507,20 @@ static inline int atomic_add_unless(atomic_t *v, int a, int u)
}
/**
+ * atomic_add_unless_wrap - add unless the number is already a given value
+ * @v: pointer of type atomic_wrap_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as @v was not already @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+static inline int atomic_add_unless_wrap(atomic_wrap_t *v, int a, int u)
+{
+ return __atomic_add_unless_wrap(v, a, u) != u;
+}
+
+/**
* atomic_inc_not_zero - increment unless the number is zero
* @v: pointer of type atomic_t
*
diff --git a/include/linux/types.h b/include/linux/types.h
index baf7183..b47a7f8 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -175,10 +175,27 @@ typedef struct {
int counter;
} atomic_t;
+#ifdef CONFIG_HARDENED_ATOMIC
+typedef struct {
+ int counter;
+} atomic_wrap_t;
+#else
+typedef atomic_t atomic_wrap_t;
+#endif
+
#ifdef CONFIG_64BIT
typedef struct {
long counter;
} atomic64_t;
+
+#ifdef CONFIG_HARDENED_ATOMIC
+typedef struct {
+ long counter;
+} atomic64_wrap_t;
+#else
+typedef atomic64_t atomic64_wrap_t;
+#endif
+
#endif
struct list_head {
diff --git a/kernel/panic.c b/kernel/panic.c
index e6480e2..66b0154 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -616,3 +616,15 @@ static int __init oops_setup(char *s)
return 0;
}
early_param("oops", oops_setup);
+
+#ifdef CONFIG_HARDENED_ATOMIC
+void hardened_atomic_refcount_overflow(struct pt_regs *regs)
+{
+ printk(KERN_EMERG "HARDENED_ATOMIC: refcount 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()));
+ print_symbol(KERN_EMERG "HARDENED_ATOMIC: refcount overflow occurred at: %s\n", instruction_pointer(regs));
+ BUG();
+}
+#endif
diff --git a/security/Kconfig b/security/Kconfig
index 118f454..dc39f7e 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -158,6 +158,21 @@ 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 additional checks on counter overflows for atomic_t
+
+config HARDENED_ATOMIC
+ bool "Prevent reference counter overflow in atomic_t"
+ depends on HAVE_ARCH_HARDENED_ATOMIC
+ help
+ This option prevents reference counters in atomic_t from
+ overflow. This allows to avoid the
+ situation when counter overflow leads to an exploitable
+ use-after-free situation.
+
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig
--
2.7.4
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