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author | Dan Williams <dan.j.williams@intel.com> | 2018-01-29 17:02:49 -0800 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2018-03-19 18:58:40 +0000 |
commit | 68f7d993a826bc3f8542b61ca85673eb15e43b86 (patch) | |
tree | fa7b73d6a2e52e6773f2af9f6e21f4e1f48c028e | |
parent | db24e93e36ab2d3591bfd6008b37a5c82a91610c (diff) | |
download | linux-stable-68f7d993a826bc3f8542b61ca85673eb15e43b86.tar.gz linux-stable-68f7d993a826bc3f8542b61ca85673eb15e43b86.tar.bz2 linux-stable-68f7d993a826bc3f8542b61ca85673eb15e43b86.zip |
x86/uaccess: Use __uaccess_begin_nospec() and uaccess_try_nospec
commit 304ec1b050310548db33063e567123fae8fd0301 upstream.
Quoting Linus:
I do think that it would be a good idea to very expressly document
the fact that it's not that the user access itself is unsafe. I do
agree that things like "get_user()" want to be protected, but not
because of any direct bugs or problems with get_user() and friends,
but simply because get_user() is an excellent source of a pointer
that is obviously controlled from a potentially attacking user
space. So it's a prime candidate for then finding _subsequent_
accesses that can then be used to perturb the cache.
__uaccess_begin_nospec() covers __get_user() and copy_from_iter() where the
limit check is far away from the user pointer de-reference. In those cases
a barrier_nospec() prevents speculation with a potential pointer to
privileged memory. uaccess_try_nospec covers get_user_try.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>
Cc: kernel-hardening@lists.openwall.com
Cc: gregkh@linuxfoundation.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: alan@linux.intel.com
Link: https://lkml.kernel.org/r/151727416953.33451.10508284228526170604.stgit@dwillia2-desk3.amr.corp.intel.com
[bwh: Backported to 3.2:
- There's no SMAP support, so use barrier_nospec() directly instead of
__uaccess_begin_nospec()
- Convert several more functions to use barrier_nospec(), that are just
wrappers in mainline
- There's no 'case 8' in __copy_to_user_inatomic()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r-- | arch/x86/include/asm/uaccess.h | 3 | ||||
-rw-r--r-- | arch/x86/include/asm/uaccess_32.h | 12 | ||||
-rw-r--r-- | arch/x86/include/asm/uaccess_64.h | 22 | ||||
-rw-r--r-- | arch/x86/lib/usercopy_32.c | 5 |
4 files changed, 37 insertions, 5 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index d74bf3a41706..7dd47ba20f75 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -423,6 +423,7 @@ do { \ ({ \ int __gu_err; \ unsigned long __gu_val; \ + barrier_nospec(); \ __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ __gu_err; \ @@ -529,7 +530,7 @@ struct __large_struct { unsigned long buf[100]; }; * get_user_ex(...); * } get_user_catch(err) */ -#define get_user_try uaccess_try +#define get_user_try uaccess_try_nospec #define get_user_catch(err) uaccess_catch(err) #define get_user_ex(x, ptr) do { \ diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h index 566e803cc602..b6f5617e8d27 100644 --- a/arch/x86/include/asm/uaccess_32.h +++ b/arch/x86/include/asm/uaccess_32.h @@ -48,14 +48,17 @@ __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) switch (n) { case 1: + barrier_nospec(); __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1); return ret; case 2: + barrier_nospec(); __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2); return ret; case 4: + barrier_nospec(); __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4); return ret; @@ -98,12 +101,15 @@ __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n) switch (n) { case 1: + barrier_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); return ret; case 2: + barrier_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); return ret; case 4: + barrier_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); return ret; } @@ -142,12 +148,15 @@ __copy_from_user(void *to, const void __user *from, unsigned long n) switch (n) { case 1: + barrier_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); return ret; case 2: + barrier_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); return ret; case 4: + barrier_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); return ret; } @@ -164,12 +173,15 @@ static __always_inline unsigned long __copy_from_user_nocache(void *to, switch (n) { case 1: + barrier_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); return ret; case 2: + barrier_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); return ret; case 4: + barrier_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); return ret; } diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 31fed191a41e..dda633ca71fa 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -75,19 +75,28 @@ int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size) if (!__builtin_constant_p(size)) return copy_user_generic(dst, (__force void *)src, size); switch (size) { - case 1:__get_user_asm(*(u8 *)dst, (u8 __user *)src, + case 1: + barrier_nospec(); + __get_user_asm(*(u8 *)dst, (u8 __user *)src, ret, "b", "b", "=q", 1); return ret; - case 2:__get_user_asm(*(u16 *)dst, (u16 __user *)src, + case 2: + barrier_nospec(); + __get_user_asm(*(u16 *)dst, (u16 __user *)src, ret, "w", "w", "=r", 2); return ret; - case 4:__get_user_asm(*(u32 *)dst, (u32 __user *)src, + case 4: + barrier_nospec(); + __get_user_asm(*(u32 *)dst, (u32 __user *)src, ret, "l", "k", "=r", 4); return ret; - case 8:__get_user_asm(*(u64 *)dst, (u64 __user *)src, + case 8: + barrier_nospec(); + __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 8); return ret; case 10: + barrier_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 10); if (unlikely(ret)) @@ -97,6 +106,7 @@ int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size) ret, "w", "w", "=r", 2); return ret; case 16: + barrier_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 16); if (unlikely(ret)) @@ -179,6 +189,7 @@ int __copy_in_user(void __user *dst, const void __user *src, unsigned size) switch (size) { case 1: { u8 tmp; + barrier_nospec(); __get_user_asm(tmp, (u8 __user *)src, ret, "b", "b", "=q", 1); if (likely(!ret)) @@ -188,6 +199,7 @@ int __copy_in_user(void __user *dst, const void __user *src, unsigned size) } case 2: { u16 tmp; + barrier_nospec(); __get_user_asm(tmp, (u16 __user *)src, ret, "w", "w", "=r", 2); if (likely(!ret)) @@ -198,6 +210,7 @@ int __copy_in_user(void __user *dst, const void __user *src, unsigned size) case 4: { u32 tmp; + barrier_nospec(); __get_user_asm(tmp, (u32 __user *)src, ret, "l", "k", "=r", 4); if (likely(!ret)) @@ -207,6 +220,7 @@ int __copy_in_user(void __user *dst, const void __user *src, unsigned size) } case 8: { u64 tmp; + barrier_nospec(); __get_user_asm(tmp, (u64 __user *)src, ret, "q", "", "=r", 8); if (likely(!ret)) diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c index e218d5df85ff..0462f6531ed6 100644 --- a/arch/x86/lib/usercopy_32.c +++ b/arch/x86/lib/usercopy_32.c @@ -774,6 +774,7 @@ survive: return n; } #endif + barrier_nospec(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else @@ -785,6 +786,7 @@ EXPORT_SYMBOL(__copy_to_user_ll); unsigned long __copy_from_user_ll(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); if (movsl_is_ok(to, from, n)) __copy_user_zeroing(to, from, n); else @@ -796,6 +798,7 @@ EXPORT_SYMBOL(__copy_from_user_ll); unsigned long __copy_from_user_ll_nozero(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else @@ -808,6 +811,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nozero); unsigned long __copy_from_user_ll_nocache(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_zeroing_intel_nocache(to, from, n); @@ -823,6 +827,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nocache); unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_intel_nocache(to, from, n); |