Commit 69c4e8ad authored by Edward Cree's avatar Edward Cree Committed by David S. Miller

selftests/bpf: variable offset negative tests

Variable ctx accesses and stack accesses aren't allowed, because we can't
 determine what type of value will be read.
Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f999d64c
...@@ -5980,6 +5980,47 @@ static struct bpf_test tests[] = { ...@@ -5980,6 +5980,47 @@ static struct bpf_test tests[] = {
.errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.", .errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.",
.result = REJECT, .result = REJECT,
}, },
{
"variable-offset ctx access",
.insns = {
/* Get an unknown value */
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
/* Make it small and 4-byte aligned */
BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
/* add it to skb. We now have either &skb->len or
* &skb->pkt_type, but we don't know which
*/
BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2),
/* dereference it */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0),
BPF_EXIT_INSN(),
},
.errstr = "variable ctx access var_off=(0x0; 0x4)",
.result = REJECT,
.prog_type = BPF_PROG_TYPE_LWT_IN,
},
{
"variable-offset stack access",
.insns = {
/* Fill the top 8 bytes of the stack */
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
/* Get an unknown value */
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
/* Make it small and 4-byte aligned */
BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8),
/* add it to fp. We now have either fp-4 or fp-8, but
* we don't know which
*/
BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
/* dereference it */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
BPF_EXIT_INSN(),
},
.errstr = "variable stack access var_off=(0xfffffffffffffff8; 0x4)",
.result = REJECT,
.prog_type = BPF_PROG_TYPE_LWT_IN,
},
}; };
static int probe_filter_length(const struct bpf_insn *fp) static int probe_filter_length(const struct bpf_insn *fp)
......
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