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Commit 0766f788 authored by Emese Revfy's avatar Emese Revfy Committed by Kees Cook
Browse files

latent_entropy: Mark functions with __latent_entropy 



The __latent_entropy gcc attribute can be used only on functions and
variables.  If it is on a function then the plugin will instrument it for
gathering control-flow entropy. If the attribute is on a variable then
the plugin will initialize it with random contents.  The variable must
be an integer, an integer array type or a structure with integer fields.

These specific functions have been selected because they are init
functions (to help gather boot-time entropy), are called at unpredictable
times, or they have variable loops, each of which provide some level of
latent entropy.

Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
[kees: expanded commit message]
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 38addce8

block/blk-softirq.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -18,7 +18,7 @@ static DEFINE_PER_CPU(struct list_head, blk_cpu_done); 
 * Softirq action handler - move entries to local list and loop over them

 * Softirq action handler - move entries to local list and loop over them

 * while passing them to the queue registered handler.

 * while passing them to the queue registered handler.

 */

 */

static void blk_done_softirq(struct softirq_action *h)

static __latent_entropy void blk_done_softirq(struct softirq_action *h)

{

{

	struct list_head *cpu_list, local_list;

	struct list_head *cpu_list, local_list;

drivers/char/random.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -479,8 +479,8 @@ static ssize_t _extract_entropy(struct entropy_store *r, void *buf, 




static void crng_reseed(struct crng_state *crng, struct entropy_store *r);

static void crng_reseed(struct crng_state *crng, struct entropy_store *r);

static void push_to_pool(struct work_struct *work);

static void push_to_pool(struct work_struct *work);

static __u32 input_pool_data[INPUT_POOL_WORDS];

static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;

static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];

static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;





static struct entropy_store input_pool = {

static struct entropy_store input_pool = {

	.poolinfo = &poolinfo_table[0],

	.poolinfo = &poolinfo_table[0],

fs/namespace.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -2759,6 +2759,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) 
	return new_ns;

	return new_ns;

}

}





__latent_entropy

struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,

struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,

		struct user_namespace *user_ns, struct fs_struct *new_fs)

		struct user_namespace *user_ns, struct fs_struct *new_fs)

{

{

include/linux/compiler-gcc.h

+7 −0
Original line number Original line Diff line number Diff line
@@ -188,6 +188,13 @@ 
#endif /* GCC_VERSION >= 40300 */

#endif /* GCC_VERSION >= 40300 */





#if GCC_VERSION >= 40500

#if GCC_VERSION >= 40500



#ifndef __CHECKER__

#ifdef LATENT_ENTROPY_PLUGIN

#define __latent_entropy __attribute__((latent_entropy))

#endif

#endif



/*

/*

 * Mark a position in code as unreachable.  This can be used to

 * Mark a position in code as unreachable.  This can be used to

 * suppress control flow warnings after asm blocks that transfer

 * suppress control flow warnings after asm blocks that transfer

include/linux/compiler.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -406,6 +406,10 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s 
# define __attribute_const__	/* unimplemented */

# define __attribute_const__	/* unimplemented */

#endif

#endif





#ifndef __latent_entropy

# define __latent_entropy

#endif



/*

/*

 * Tell gcc if a function is cold. The compiler will assume any path

 * Tell gcc if a function is cold. The compiler will assume any path

 * directly leading to the call is unlikely.

 * directly leading to the call is unlikely.