| Message ID | 1452621307-2213-1-git-send-email-rabin@rab.in (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jan 12, 2016 at 06:55:07PM +0100, Rabin Vincent wrote: > On ARM64, a BUG() is triggered in the eBPF JIT if a filter with a > constant shift that can't be encoded in the immediate field of the > UBFM/SBFM instructions is passed to the JIT. Since these shifts > amounts, which are negative or >= regsize, are invalid, reject then in > the eBPF verifier and the classic BPF filter checker, for all > architectures. > > Signed-off-by: Rabin Vincent <rabin@rab.in> > --- > kernel/bpf/verifier.c | 10 ++++++++++ > net/core/filter.c | 5 +++++ > 2 files changed, 15 insertions(+) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index a7945d10b378..3643df0dfaa9 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -1121,6 +1121,16 @@ static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn) > return -EINVAL; > } > > + if ((opcode == BPF_LSH || opcode == BPF_RSH) && Missing check for opcode == BPF_ARSH Otherwise looks good. Thank you for fixing this! > @@ -777,6 +777,11 @@ static int bpf_check_classic(const struct sock_filter *filter, > if (ftest->k == 0) > return -EINVAL; > break; > + case BPF_ALU | BPF_LSH | BPF_K: > + case BPF_ALU | BPF_RSH | BPF_K: here it's good. ARSH is eBPF only.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a7945d10b378..3643df0dfaa9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1121,6 +1121,16 @@ static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn) return -EINVAL; } + if ((opcode == BPF_LSH || opcode == BPF_RSH) && + BPF_SRC(insn->code) == BPF_K) { + int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; + + if (insn->imm < 0 || insn->imm >= size) { + verbose("invalid shift %d\n", insn->imm); + return -EINVAL; + } + } + /* pattern match 'bpf_add Rx, imm' instruction */ if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && regs[insn->dst_reg].type == FRAME_PTR && diff --git a/net/core/filter.c b/net/core/filter.c index 672eefbfbe99..37157c4c1a78 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -777,6 +777,11 @@ static int bpf_check_classic(const struct sock_filter *filter, if (ftest->k == 0) return -EINVAL; break; + case BPF_ALU | BPF_LSH | BPF_K: + case BPF_ALU | BPF_RSH | BPF_K: + if (ftest->k >= 32) + return -EINVAL; + break; case BPF_LD | BPF_MEM: case BPF_LDX | BPF_MEM: case BPF_ST:
On ARM64, a BUG() is triggered in the eBPF JIT if a filter with a constant shift that can't be encoded in the immediate field of the UBFM/SBFM instructions is passed to the JIT. Since these shifts amounts, which are negative or >= regsize, are invalid, reject then in the eBPF verifier and the classic BPF filter checker, for all architectures. Signed-off-by: Rabin Vincent <rabin@rab.in> --- kernel/bpf/verifier.c | 10 ++++++++++ net/core/filter.c | 5 +++++ 2 files changed, 15 insertions(+)