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bpf: recognize 64bit immediate loads as consts 

When running as parser interpret BPF_LD | BPF_IMM | BPF_DW
instructions as loading CONST_IMM with the value stored
in imm.  The verifier will continue not recognizing those
due to concerns about search space/program complexity
increase.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Jakub Kicinski 2016-09-21 11:43:59 +01:00 committed by David S. Miller
parent 13a27dfc66
commit 6b17387307
1 changed files with 12 additions and 2 deletions
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14
kernel/bpf/verifier.c
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@ -1769,9 +1769,19 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
if (err)
return err;
if (insn->src_reg == 0)
/* generic move 64-bit immediate into a register */
if (insn->src_reg == 0) {
/* generic move 64-bit immediate into a register,
* only analyzer needs to collect the ld_imm value.
*/
u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
if (!env->analyzer_ops)
return 0;
regs[insn->dst_reg].type = CONST_IMM;
regs[insn->dst_reg].imm = imm;
return 0;
}
/* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);