@@ -8355,6 +8355,43 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
} \
} while (0)
+#define SOCK_OPS_GET_SK() \
+ do { \
+ int fullsock_reg = si->dst_reg, reg = BPF_REG_9, jmp = 1; \
+ if (si->dst_reg == reg || si->src_reg == reg) \
+ reg--; \
+ if (si->dst_reg == reg || si->src_reg == reg) \
+ reg--; \
+ if (si->dst_reg == si->src_reg) { \
+ *insn++ = BPF_STX_MEM(BPF_DW, si->src_reg, reg, \
+ offsetof(struct bpf_sock_ops_kern, \
+ temp)); \
+ fullsock_reg = reg; \
+ jmp += 2; \
+ } \
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF( \
+ struct bpf_sock_ops_kern, \
+ is_fullsock), \
+ fullsock_reg, si->src_reg, \
+ offsetof(struct bpf_sock_ops_kern, \
+ is_fullsock)); \
+ *insn++ = BPF_JMP_IMM(BPF_JEQ, fullsock_reg, 0, jmp); \
+ if (si->dst_reg == si->src_reg) \
+ *insn++ = BPF_LDX_MEM(BPF_DW, reg, si->src_reg, \
+ offsetof(struct bpf_sock_ops_kern, \
+ temp)); \
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF( \
+ struct bpf_sock_ops_kern, sk),\
+ si->dst_reg, si->src_reg, \
+ offsetof(struct bpf_sock_ops_kern, sk));\
+ if (si->dst_reg == si->src_reg) { \
+ *insn++ = BPF_JMP_A(1); \
+ *insn++ = BPF_LDX_MEM(BPF_DW, reg, si->src_reg, \
+ offsetof(struct bpf_sock_ops_kern, \
+ temp)); \
+ } \
+ } while (0)
+
#define SOCK_OPS_GET_TCP_SOCK_FIELD(FIELD) \
SOCK_OPS_GET_FIELD(FIELD, FIELD, struct tcp_sock)
@@ -8639,17 +8676,7 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
SOCK_OPS_GET_TCP_SOCK_FIELD(bytes_acked);
break;
case offsetof(struct bpf_sock_ops, sk):
- *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
- struct bpf_sock_ops_kern,
- is_fullsock),
- si->dst_reg, si->src_reg,
- offsetof(struct bpf_sock_ops_kern,
- is_fullsock));
- *insn++ = BPF_JMP_IMM(BPF_JEQ, si->dst_reg, 0, 1);
- *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
- struct bpf_sock_ops_kern, sk),
- si->dst_reg, si->src_reg,
- offsetof(struct bpf_sock_ops_kern, sk));
+ SOCK_OPS_GET_SK();
break;
}
return insn - insn_buf;
Similar to patch ("bpf: sock_ops ctx access may stomp registers") if the src_reg = dst_reg when reading the sk field of a sock_ops struct we generate xlated code, 53: (61) r9 = *(u32 *)(r9 +28) 54: (15) if r9 == 0x0 goto pc+3 56: (79) r9 = *(u64 *)(r9 +0) This stomps on the r9 reg to do the sk_fullsock check and then when reading the skops->sk field instead of the sk pointer we get the sk_fullsock. To fix use similar pattern noted in the previous fix and use the temp field to save/restore a register used to do sk_fullsock check. After the fix the generated xlated code reads, 52: (7b) *(u64 *)(r9 +32) = r8 53: (61) r8 = *(u32 *)(r9 +28) 54: (15) if r9 == 0x0 goto pc+3 55: (79) r8 = *(u64 *)(r9 +32) 56: (79) r9 = *(u64 *)(r9 +0) 57: (05) goto pc+1 58: (79) r8 = *(u64 *)(r9 +32) Here r9 register was in-use so r8 is chosen as the temporary register. In line 52 r8 is saved in temp variable and at line 54 restored in case fullsock != 0. Finally we handle fullsock == 0 case by restoring at line 58. This adds a new macro SOCK_OPS_GET_SK it is almost possible to merge this with SOCK_OPS_GET_FIELD, but I found the extra branch logic a bit more confusing than just adding a new macro despite a bit of duplicating code. Fixes: 1314ef561102e ("bpf: export bpf_sock for BPF_PROG_TYPE_SOCK_OPS prog type") Signed-off-by: John Fastabend <john.fastabend@gmail.com> --- net/core/filter.c | 49 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 11 deletions(-)