* [PATCH 0/2] Fix mmap_base entropy for >31 bits. @ 2016-02-04 22:06 Daniel Cashman 2016-02-04 22:06 ` [PATCH 1/2] drivers: char: random: Add get_random_long() Daniel Cashman 2016-02-04 22:29 ` [PATCH 0/2] Fix mmap_base entropy for >31 bits Kees Cook 0 siblings, 2 replies; 7+ messages in thread From: Daniel Cashman @ 2016-02-04 22:06 UTC (permalink / raw) To: linux-kernel Cc: linux, akpm, keescook, tytso, arnd, gregkh, catalin.marinas, will.deacon, ralf, benh, paulus, mpe, davem, tglx, mingo, hpa, x86, viro, nnk, jeffv, salyzyn, Daniel Cashman Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the ability to choose from a range of values to use for entropy count in generating the random offset to the mmap_base address. The maximum value on this range was set to 32 bits for 64-bit x86 systems, but this value could be increased further, requiring more than the 32 bits of randomness provided by get_random_int(), as is already possible for arm64. Add a new function: get_random_long() which more naturally fits with the mmap usage of get_random_int() but operates exactly the same as get_random_int(). Also, fix the shifting constant in mmap_rnd() to be an unsigned long so that values greater than 31 bits generate an appropriate mask without overflow. This is especially important on x86, as its shift instruction uses a 5-bit mask for the shift operand, which meant that any value for mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base randomization. Finally, replace calls to get_random_int() with get_random_long() where appropriate. Daniel Cashman (2): drivers: char: random: Add get_random_long(). use get_random_long(). arch/arm/mm/mmap.c | 2 +- arch/arm64/mm/mmap.c | 4 ++-- arch/mips/mm/mmap.c | 4 ++-- arch/powerpc/kernel/process.c | 4 ++-- arch/powerpc/mm/mmap.c | 4 ++-- arch/sparc/kernel/sys_sparc_64.c | 2 +- arch/x86/mm/mmap.c | 6 +++--- drivers/char/random.c | 22 ++++++++++++++++++++++ fs/binfmt_elf.c | 2 +- include/linux/random.h | 1 + 10 files changed, 37 insertions(+), 14 deletions(-) -- 2.7.0.rc3.207.g0ac5344 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 1/2] drivers: char: random: Add get_random_long(). 2016-02-04 22:06 [PATCH 0/2] Fix mmap_base entropy for >31 bits Daniel Cashman @ 2016-02-04 22:06 ` Daniel Cashman 2016-02-04 22:06 ` [PATCH 2/2] use get_random_long() Daniel Cashman 2016-02-04 22:29 ` [PATCH 0/2] Fix mmap_base entropy for >31 bits Kees Cook 1 sibling, 1 reply; 7+ messages in thread From: Daniel Cashman @ 2016-02-04 22:06 UTC (permalink / raw) To: linux-kernel Cc: linux, akpm, keescook, tytso, arnd, gregkh, catalin.marinas, will.deacon, ralf, benh, paulus, mpe, davem, tglx, mingo, hpa, x86, viro, nnk, jeffv, salyzyn, Daniel Cashman Signed-off-by: Daniel Cashman <dcashman@android.com> --- drivers/char/random.c | 22 ++++++++++++++++++++++ include/linux/random.h | 1 + 2 files changed, 23 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index d0da5d8..b583e53 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1819,6 +1819,28 @@ unsigned int get_random_int(void) EXPORT_SYMBOL(get_random_int); /* + * Same as get_random_int(), but returns unsigned long. + */ +unsigned long get_random_long(void) +{ + __u32 *hash; + unsigned long ret; + + if (arch_get_random_long(&ret)) + return ret; + + hash = get_cpu_var(get_random_int_hash); + + hash[0] += current->pid + jiffies + random_get_entropy(); + md5_transform(hash, random_int_secret); + ret = *(unsigned long *)hash; + put_cpu_var(get_random_int_hash); + + return ret; +} +EXPORT_SYMBOL(get_random_long); + +/* * randomize_range() returns a start address such that * * [...... <range> .....] diff --git a/include/linux/random.h b/include/linux/random.h index a75840c..9c29122 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -34,6 +34,7 @@ extern const struct file_operations random_fops, urandom_fops; #endif unsigned int get_random_int(void); +unsigned long get_random_long(void); unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len); u32 prandom_u32(void); -- 2.7.0.rc3.207.g0ac5344 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH 2/2] use get_random_long(). 2016-02-04 22:06 ` [PATCH 1/2] drivers: char: random: Add get_random_long() Daniel Cashman @ 2016-02-04 22:06 ` Daniel Cashman 2016-02-04 22:38 ` Kees Cook 0 siblings, 1 reply; 7+ messages in thread From: Daniel Cashman @ 2016-02-04 22:06 UTC (permalink / raw) To: linux-kernel Cc: linux, akpm, keescook, tytso, arnd, gregkh, catalin.marinas, will.deacon, ralf, benh, paulus, mpe, davem, tglx, mingo, hpa, x86, viro, nnk, jeffv, salyzyn, Daniel Cashman Replace calls to get_random_int() followed by a cast to (unsigned long) with calls to get_random_long(). Also address shifting bug which, in case of x86 removed entropy mask for mmap_rnd_bits values > 31 bits. Signed-off-by: Daniel Cashman <dcashman@android.com> --- arch/arm/mm/mmap.c | 2 +- arch/arm64/mm/mmap.c | 4 ++-- arch/mips/mm/mmap.c | 4 ++-- arch/powerpc/kernel/process.c | 4 ++-- arch/powerpc/mm/mmap.c | 4 ++-- arch/sparc/kernel/sys_sparc_64.c | 2 +- arch/x86/mm/mmap.c | 6 +++--- fs/binfmt_elf.c | 2 +- 8 files changed, 14 insertions(+), 14 deletions(-) diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index 4b4058d..66353ca 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -173,7 +173,7 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); return rnd << PAGE_SHIFT; } diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 4c893b5..232f787 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -53,10 +53,10 @@ unsigned long arch_mmap_rnd(void) #ifdef CONFIG_COMPAT if (test_thread_flag(TIF_32BIT)) - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1); + rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); else #endif - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); return rnd << PAGE_SHIFT; } diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index 5c81fdd..3530376 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -146,7 +146,7 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; - rnd = (unsigned long)get_random_int(); + rnd = get_random_long(); rnd <<= PAGE_SHIFT; if (TASK_IS_32BIT_ADDR) rnd &= 0xfffffful; @@ -174,7 +174,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) static inline unsigned long brk_rnd(void) { - unsigned long rnd = get_random_int(); + unsigned long rnd = get_random_long(); rnd = rnd << PAGE_SHIFT; /* 8MB for 32bit, 256MB for 64bit */ diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index dccc87e..3c5736e 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1768,9 +1768,9 @@ static inline unsigned long brk_rnd(void) /* 8MB for 32bit, 1GB for 64bit */ if (is_32bit_task()) - rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT))); + rnd = (get_random_long() % (1UL<<(23-PAGE_SHIFT))); else - rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT))); + rnd = (get_random_long() % (1UL<<(30-PAGE_SHIFT))); return rnd << PAGE_SHIFT; } diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c index 0f0502e..4087705 100644 --- a/arch/powerpc/mm/mmap.c +++ b/arch/powerpc/mm/mmap.c @@ -59,9 +59,9 @@ unsigned long arch_mmap_rnd(void) /* 8MB for 32bit, 1GB for 64bit */ if (is_32bit_task()) - rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT)); + rnd = get_random_long() % (1<<(23-PAGE_SHIFT)); else - rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT)); + rnd = get_random_long() % (1UL<<(30-PAGE_SHIFT)); return rnd << PAGE_SHIFT; } diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c index c690c8e..b489e97 100644 --- a/arch/sparc/kernel/sys_sparc_64.c +++ b/arch/sparc/kernel/sys_sparc_64.c @@ -264,7 +264,7 @@ static unsigned long mmap_rnd(void) unsigned long rnd = 0UL; if (current->flags & PF_RANDOMIZE) { - unsigned long val = get_random_int(); + unsigned long val = get_random_long(); if (test_thread_flag(TIF_32BIT)) rnd = (val % (1UL << (23UL-PAGE_SHIFT))); else diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 96bd1e2..72bb52f 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -71,12 +71,12 @@ unsigned long arch_mmap_rnd(void) if (mmap_is_ia32()) #ifdef CONFIG_COMPAT - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1); + rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); #else - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); #endif else - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); return rnd << PAGE_SHIFT; } diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 051ea48..7d914c6 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -653,7 +653,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top) if ((current->flags & PF_RANDOMIZE) && !(current->personality & ADDR_NO_RANDOMIZE)) { - random_variable = (unsigned long) get_random_int(); + random_variable = get_random_long(); random_variable &= STACK_RND_MASK; random_variable <<= PAGE_SHIFT; } -- 2.7.0.rc3.207.g0ac5344 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] use get_random_long(). 2016-02-04 22:06 ` [PATCH 2/2] use get_random_long() Daniel Cashman @ 2016-02-04 22:38 ` Kees Cook 0 siblings, 0 replies; 7+ messages in thread From: Kees Cook @ 2016-02-04 22:38 UTC (permalink / raw) To: Daniel Cashman, Andrew Morton, Theodore Ts'o Cc: LKML, Russell King - ARM Linux, Arnd Bergmann, Greg KH, Catalin Marinas, Will Deacon, Ralf Baechle, benh@kernel.crashing.org, Paul Mackerras, Michael Ellerman, David S. Miller, Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86@kernel.org, Al Viro, Nick Kralevich, Jeffrey Vander Stoep, Mark Salyzyn On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <dcashman@android.com> wrote: > Replace calls to get_random_int() followed by a cast to (unsigned long) > with calls to get_random_long(). Also address shifting bug which, in > case of x86 removed entropy mask for mmap_rnd_bits values > 31 bits. I wonder if randomize_range() should be using get_random_long()? Right now, a large range would get truncated: unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len) { unsigned long range = end - len - start; if (end <= start + len) return 0; return PAGE_ALIGN(get_random_int() % range + start); } For example, randomize_range(0, 0x7ffffffff000, 4096) will never return 0x700000000000... no current callers use a >MAX_UINT range, so nothing is bugged now, but it seems like we should fix this too (separately)? -Kees > > Signed-off-by: Daniel Cashman <dcashman@android.com> > --- > arch/arm/mm/mmap.c | 2 +- > arch/arm64/mm/mmap.c | 4 ++-- > arch/mips/mm/mmap.c | 4 ++-- > arch/powerpc/kernel/process.c | 4 ++-- > arch/powerpc/mm/mmap.c | 4 ++-- > arch/sparc/kernel/sys_sparc_64.c | 2 +- > arch/x86/mm/mmap.c | 6 +++--- > fs/binfmt_elf.c | 2 +- > 8 files changed, 14 insertions(+), 14 deletions(-) > > diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c > index 4b4058d..66353ca 100644 > --- a/arch/arm/mm/mmap.c > +++ b/arch/arm/mm/mmap.c > @@ -173,7 +173,7 @@ unsigned long arch_mmap_rnd(void) > { > unsigned long rnd; > > - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); > + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); > > return rnd << PAGE_SHIFT; > } > diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c > index 4c893b5..232f787 100644 > --- a/arch/arm64/mm/mmap.c > +++ b/arch/arm64/mm/mmap.c > @@ -53,10 +53,10 @@ unsigned long arch_mmap_rnd(void) > > #ifdef CONFIG_COMPAT > if (test_thread_flag(TIF_32BIT)) > - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1); > + rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); > else > #endif > - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); > + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); > return rnd << PAGE_SHIFT; > } > > diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c > index 5c81fdd..3530376 100644 > --- a/arch/mips/mm/mmap.c > +++ b/arch/mips/mm/mmap.c > @@ -146,7 +146,7 @@ unsigned long arch_mmap_rnd(void) > { > unsigned long rnd; > > - rnd = (unsigned long)get_random_int(); > + rnd = get_random_long(); > rnd <<= PAGE_SHIFT; > if (TASK_IS_32BIT_ADDR) > rnd &= 0xfffffful; > @@ -174,7 +174,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) > > static inline unsigned long brk_rnd(void) > { > - unsigned long rnd = get_random_int(); > + unsigned long rnd = get_random_long(); > > rnd = rnd << PAGE_SHIFT; > /* 8MB for 32bit, 256MB for 64bit */ > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c > index dccc87e..3c5736e 100644 > --- a/arch/powerpc/kernel/process.c > +++ b/arch/powerpc/kernel/process.c > @@ -1768,9 +1768,9 @@ static inline unsigned long brk_rnd(void) > > /* 8MB for 32bit, 1GB for 64bit */ > if (is_32bit_task()) > - rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT))); > + rnd = (get_random_long() % (1UL<<(23-PAGE_SHIFT))); > else > - rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT))); > + rnd = (get_random_long() % (1UL<<(30-PAGE_SHIFT))); > > return rnd << PAGE_SHIFT; > } > diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c > index 0f0502e..4087705 100644 > --- a/arch/powerpc/mm/mmap.c > +++ b/arch/powerpc/mm/mmap.c > @@ -59,9 +59,9 @@ unsigned long arch_mmap_rnd(void) > > /* 8MB for 32bit, 1GB for 64bit */ > if (is_32bit_task()) > - rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT)); > + rnd = get_random_long() % (1<<(23-PAGE_SHIFT)); > else > - rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT)); > + rnd = get_random_long() % (1UL<<(30-PAGE_SHIFT)); > > return rnd << PAGE_SHIFT; > } > diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c > index c690c8e..b489e97 100644 > --- a/arch/sparc/kernel/sys_sparc_64.c > +++ b/arch/sparc/kernel/sys_sparc_64.c > @@ -264,7 +264,7 @@ static unsigned long mmap_rnd(void) > unsigned long rnd = 0UL; > > if (current->flags & PF_RANDOMIZE) { > - unsigned long val = get_random_int(); > + unsigned long val = get_random_long(); > if (test_thread_flag(TIF_32BIT)) > rnd = (val % (1UL << (23UL-PAGE_SHIFT))); > else > diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c > index 96bd1e2..72bb52f 100644 > --- a/arch/x86/mm/mmap.c > +++ b/arch/x86/mm/mmap.c > @@ -71,12 +71,12 @@ unsigned long arch_mmap_rnd(void) > > if (mmap_is_ia32()) > #ifdef CONFIG_COMPAT > - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1); > + rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); > #else > - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); > + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); > #endif > else > - rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1); > + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); > > return rnd << PAGE_SHIFT; > } > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index 051ea48..7d914c6 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -653,7 +653,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top) > > if ((current->flags & PF_RANDOMIZE) && > !(current->personality & ADDR_NO_RANDOMIZE)) { > - random_variable = (unsigned long) get_random_int(); > + random_variable = get_random_long(); > random_variable &= STACK_RND_MASK; > random_variable <<= PAGE_SHIFT; > } > -- > 2.7.0.rc3.207.g0ac5344 > -- Kees Cook Chrome OS & Brillo Security ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 0/2] Fix mmap_base entropy for >31 bits. 2016-02-04 22:06 [PATCH 0/2] Fix mmap_base entropy for >31 bits Daniel Cashman 2016-02-04 22:06 ` [PATCH 1/2] drivers: char: random: Add get_random_long() Daniel Cashman @ 2016-02-04 22:29 ` Kees Cook 2016-02-24 20:40 ` Daniel Cashman 1 sibling, 1 reply; 7+ messages in thread From: Kees Cook @ 2016-02-04 22:29 UTC (permalink / raw) To: Daniel Cashman, Andrew Morton Cc: LKML, Russell King - ARM Linux, Theodore Ts'o, Arnd Bergmann, Greg KH, Catalin Marinas, Will Deacon, Ralf Baechle, benh@kernel.crashing.org, Paul Mackerras, Michael Ellerman, David S. Miller, Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86@kernel.org, Al Viro, Nick Kralevich, Jeffrey Vander Stoep, Mark Salyzyn On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <dcashman@android.com> wrote: > Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the > ability to choose from a range of values to use for entropy count in > generating the random offset to the mmap_base address. The > maximum value on this range was set to 32 bits for 64-bit x86 systems, > but this value could be increased further, requiring more than the 32 > bits of randomness provided by get_random_int(), as is already possible > for arm64. Add a new function: get_random_long() which more naturally > fits with the mmap usage of get_random_int() but operates exactly the > same as get_random_int(). > > Also, fix the shifting constant in mmap_rnd() to be an unsigned long so > that values greater than 31 bits generate an appropriate mask without > overflow. This is especially important on x86, as its shift instruction > uses a 5-bit mask for the shift operand, which meant that any value for > mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base > randomization. > > Finally, replace calls to get_random_int() with get_random_long() where > appropriate. > > Daniel Cashman (2): > drivers: char: random: Add get_random_long(). > use get_random_long(). > > arch/arm/mm/mmap.c | 2 +- > arch/arm64/mm/mmap.c | 4 ++-- > arch/mips/mm/mmap.c | 4 ++-- > arch/powerpc/kernel/process.c | 4 ++-- > arch/powerpc/mm/mmap.c | 4 ++-- > arch/sparc/kernel/sys_sparc_64.c | 2 +- > arch/x86/mm/mmap.c | 6 +++--- > drivers/char/random.c | 22 ++++++++++++++++++++++ > fs/binfmt_elf.c | 2 +- > include/linux/random.h | 1 + > 10 files changed, 37 insertions(+), 14 deletions(-) Thanks for fixing this! Acked-by: Kees Cook <keescook@chromium.org> -Kees -- Kees Cook Chrome OS & Brillo Security ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 0/2] Fix mmap_base entropy for >31 bits. 2016-02-04 22:29 ` [PATCH 0/2] Fix mmap_base entropy for >31 bits Kees Cook @ 2016-02-24 20:40 ` Daniel Cashman 2016-02-24 21:50 ` Kees Cook 0 siblings, 1 reply; 7+ messages in thread From: Daniel Cashman @ 2016-02-24 20:40 UTC (permalink / raw) To: Kees Cook, Andrew Morton Cc: LKML, Russell King - ARM Linux, Theodore Ts'o, Arnd Bergmann, Greg KH, Catalin Marinas, Will Deacon, Ralf Baechle, benh@kernel.crashing.org, Paul Mackerras, Michael Ellerman, David S. Miller, Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86@kernel.org, Al Viro, Nick Kralevich, Jeffrey Vander Stoep, Mark Salyzyn On 02/04/2016 02:29 PM, Kees Cook wrote: > On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <dcashman@android.com> wrote: >> Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the >> ability to choose from a range of values to use for entropy count in >> generating the random offset to the mmap_base address. The >> maximum value on this range was set to 32 bits for 64-bit x86 systems, >> but this value could be increased further, requiring more than the 32 >> bits of randomness provided by get_random_int(), as is already possible >> for arm64. Add a new function: get_random_long() which more naturally >> fits with the mmap usage of get_random_int() but operates exactly the >> same as get_random_int(). >> >> Also, fix the shifting constant in mmap_rnd() to be an unsigned long so >> that values greater than 31 bits generate an appropriate mask without >> overflow. This is especially important on x86, as its shift instruction >> uses a 5-bit mask for the shift operand, which meant that any value for >> mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base >> randomization. >> >> Finally, replace calls to get_random_int() with get_random_long() where >> appropriate. >> >> Daniel Cashman (2): >> drivers: char: random: Add get_random_long(). >> use get_random_long(). >> >> arch/arm/mm/mmap.c | 2 +- >> arch/arm64/mm/mmap.c | 4 ++-- >> arch/mips/mm/mmap.c | 4 ++-- >> arch/powerpc/kernel/process.c | 4 ++-- >> arch/powerpc/mm/mmap.c | 4 ++-- >> arch/sparc/kernel/sys_sparc_64.c | 2 +- >> arch/x86/mm/mmap.c | 6 +++--- >> drivers/char/random.c | 22 ++++++++++++++++++++++ >> fs/binfmt_elf.c | 2 +- >> include/linux/random.h | 1 + >> 10 files changed, 37 insertions(+), 14 deletions(-) > > Thanks for fixing this! > > Acked-by: Kees Cook <keescook@chromium.org> > > -Kees > This has now been in linux-next for awhile. Could we please submit this for the 4.5 rc window so that it fixes the issue in the final 4.5 release? Sorry if this is a protocol breach, but I'm not sure what the best way is for me to indicate that this is a "fix" that should go out in the same release as the original feature. Thank You, Dan ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 0/2] Fix mmap_base entropy for >31 bits. 2016-02-24 20:40 ` Daniel Cashman @ 2016-02-24 21:50 ` Kees Cook 0 siblings, 0 replies; 7+ messages in thread From: Kees Cook @ 2016-02-24 21:50 UTC (permalink / raw) To: Andrew Morton Cc: Daniel Cashman, LKML, Russell King - ARM Linux, Theodore Ts'o, Arnd Bergmann, Greg KH, Catalin Marinas, Will Deacon, Ralf Baechle, benh@kernel.crashing.org, Paul Mackerras, Michael Ellerman, David S. Miller, Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86@kernel.org, Al Viro, Nick Kralevich, Jeffrey Vander Stoep, Mark Salyzyn On Wed, Feb 24, 2016 at 12:40 PM, Daniel Cashman <dcashman@android.com> wrote: > On 02/04/2016 02:29 PM, Kees Cook wrote: >> On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <dcashman@android.com> wrote: >>> Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the >>> ability to choose from a range of values to use for entropy count in >>> generating the random offset to the mmap_base address. The >>> maximum value on this range was set to 32 bits for 64-bit x86 systems, >>> but this value could be increased further, requiring more than the 32 >>> bits of randomness provided by get_random_int(), as is already possible >>> for arm64. Add a new function: get_random_long() which more naturally >>> fits with the mmap usage of get_random_int() but operates exactly the >>> same as get_random_int(). >>> >>> Also, fix the shifting constant in mmap_rnd() to be an unsigned long so >>> that values greater than 31 bits generate an appropriate mask without >>> overflow. This is especially important on x86, as its shift instruction >>> uses a 5-bit mask for the shift operand, which meant that any value for >>> mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base >>> randomization. >>> >>> Finally, replace calls to get_random_int() with get_random_long() where >>> appropriate. >>> >>> Daniel Cashman (2): >>> drivers: char: random: Add get_random_long(). >>> use get_random_long(). >>> >>> arch/arm/mm/mmap.c | 2 +- >>> arch/arm64/mm/mmap.c | 4 ++-- >>> arch/mips/mm/mmap.c | 4 ++-- >>> arch/powerpc/kernel/process.c | 4 ++-- >>> arch/powerpc/mm/mmap.c | 4 ++-- >>> arch/sparc/kernel/sys_sparc_64.c | 2 +- >>> arch/x86/mm/mmap.c | 6 +++--- >>> drivers/char/random.c | 22 ++++++++++++++++++++++ >>> fs/binfmt_elf.c | 2 +- >>> include/linux/random.h | 1 + >>> 10 files changed, 37 insertions(+), 14 deletions(-) >> >> Thanks for fixing this! >> >> Acked-by: Kees Cook <keescook@chromium.org> >> >> -Kees >> > > This has now been in linux-next for awhile. Could we please submit this > for the 4.5 rc window so that it fixes the issue in the final 4.5 > release? Sorry if this is a protocol breach, but I'm not sure what the > best way is for me to indicate that this is a "fix" that should go out > in the same release as the original feature. Yes please! :) Andrew, can you push these for 4.5? Best to keep the feature from releasing broken. Thanks! -Kees -- Kees Cook Chrome OS & Brillo Security ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2016-02-24 21:50 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2016-02-04 22:06 [PATCH 0/2] Fix mmap_base entropy for >31 bits Daniel Cashman 2016-02-04 22:06 ` [PATCH 1/2] drivers: char: random: Add get_random_long() Daniel Cashman 2016-02-04 22:06 ` [PATCH 2/2] use get_random_long() Daniel Cashman 2016-02-04 22:38 ` Kees Cook 2016-02-04 22:29 ` [PATCH 0/2] Fix mmap_base entropy for >31 bits Kees Cook 2016-02-24 20:40 ` Daniel Cashman 2016-02-24 21:50 ` Kees Cook
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).