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authorDaniel Borkmann <daniel@iogearbox.net>2016-05-18 14:14:28 +0200
committerDavid S. Miller <davem@davemloft.net>2016-05-20 11:18:21 -0700
commitb7552e1bccbe3da9c8e7386c6188e8ea4667c8e7 (patch)
treeb688a09ce700098d34a06040dba03406feb0e439 /kernel/bpf
parent09ec8e7fb6bcb351bbded18a571ea037504bb3a6 (diff)
downloadlinux-sh-b7552e1bccbe3da9c8e7386c6188e8ea4667c8e7.tar.gz
bpf: rather use get_random_int for randomizations
Start address randomization and blinding in BPF currently use prandom_u32(). prandom_u32() values are not exposed to unpriviledged user space to my knowledge, but given other kernel facilities such as ASLR, stack canaries, etc make use of stronger get_random_int(), we better make use of it here as well given blinding requests successively new random values. get_random_int() has minimal entropy pool depletion, is not cryptographically secure, but doesn't need to be for our use cases here. Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/core.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index f1e8a0def99b..b94a36550591 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -231,7 +231,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
hdr->pages = size / PAGE_SIZE;
hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),
PAGE_SIZE - sizeof(*hdr));
- start = (prandom_u32() % hole) & ~(alignment - 1);
+ start = (get_random_int() % hole) & ~(alignment - 1);
/* Leave a random number of instructions before BPF code. */
*image_ptr = &hdr->image[start];
@@ -251,7 +251,7 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from,
struct bpf_insn *to_buff)
{
struct bpf_insn *to = to_buff;
- u32 imm_rnd = prandom_u32();
+ u32 imm_rnd = get_random_int();
s16 off;
BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG);