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bpf: handle pseudo BPF_LD_IMM64 insn

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eBPF programs passed from userspace are using pseudo BPF_LD_IMM64 instructions
to refer to process-local map_fd. Scan the program for such instructions and
if FDs are valid, convert them to 'struct bpf_map' pointers which will be used
by verifier to check access to maps in bpf_map_lookup/update() calls.
If program passes verifier, convert pseudo BPF_LD_IMM64 into generic by dropping
BPF_PSEUDO_MAP_FD flag.

Note that eBPF interpreter is generic and knows nothing about pseudo insns.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
2014-09-26 00:17:04 -07:00
committed by David S. Miller
parent cbd3570086
commit 0246e64d9a
2 changed files with 153 additions and 0 deletions
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6
include/linux/filter.h
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@@ -145,6 +145,12 @@ struct bpf_prog_aux;
.off = 0, \
.imm = ((__u64) (IMM)) >> 32 })
#define BPF_PSEUDO_MAP_FD 1
/* pseudo BPF_LD_IMM64 insn used to refer to process-local map_fd */
#define BPF_LD_MAP_FD(DST, MAP_FD) \
BPF_LD_IMM64_RAW(DST, BPF_PSEUDO_MAP_FD, MAP_FD)
/* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */
#define BPF_MOV64_RAW(TYPE, DST, SRC, IMM) \