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Diffstat (limited to 'tools/testing/selftests/bpf/verifier/var_off.c')
-rw-r--r--tools/testing/selftests/bpf/verifier/var_off.c343
1 files changed, 343 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/verifier/var_off.c b/tools/testing/selftests/bpf/verifier/var_off.c
new file mode 100644
index 000000000..d37f512fa
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/var_off.c
@@ -0,0 +1,343 @@
+{
+ "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 read, priv vs unpriv",
+ .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 for a stack read */
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .result_unpriv = REJECT,
+ .errstr_unpriv = "R2 variable stack access prohibited for !root",
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+},
+{
+ "variable-offset stack read, uninitialized",
+ .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),
+ 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 for a stack read */
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "invalid variable-offset read from stack R2",
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+ "variable-offset stack write, priv vs unpriv",
+ .insns = {
+ /* Get an unknown value */
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+ /* Make it small and 8-byte aligned */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 8),
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16),
+ /* Add it to fp. We now have either fp-8 or fp-16, but
+ * we don't know which
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it for a stack write */
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ /* Now read from the address we just wrote. This shows
+ * that, after a variable-offset write, a priviledged
+ * program can read the slots that were in the range of
+ * that write (even if the verifier doesn't actually know
+ * if the slot being read was really written to or not.
+ */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ /* Variable stack access is rejected for unprivileged.
+ */
+ .errstr_unpriv = "R2 variable stack access prohibited for !root",
+ .result_unpriv = REJECT,
+ .result = ACCEPT,
+},
+{
+ "variable-offset stack write clobbers spilled regs",
+ .insns = {
+ /* Dummy instruction; needed because we need to patch the next one
+ * and we can't patch the first instruction.
+ */
+ BPF_MOV64_IMM(BPF_REG_6, 0),
+ /* Make R0 a map ptr */
+ BPF_LD_MAP_FD(BPF_REG_0, 0),
+ /* Get an unknown value */
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+ /* Make it small and 8-byte aligned */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 8),
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16),
+ /* Add it to fp. We now have either fp-8 or fp-16, but
+ * we don't know which.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Spill R0(map ptr) into stack */
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
+ /* Dereference the unknown value for a stack write */
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ /* Fill the register back into R2 */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_10, -8),
+ /* Try to dereference R2 for a memory load */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 8),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 1 },
+ /* The unprivileged case is not too interesting; variable
+ * stack access is rejected.
+ */
+ .errstr_unpriv = "R2 variable stack access prohibited for !root",
+ .result_unpriv = REJECT,
+ /* In the priviledged case, dereferencing a spilled-and-then-filled
+ * register is rejected because the previous variable offset stack
+ * write might have overwritten the spilled pointer (i.e. we lose track
+ * of the spilled register when we analyze the write).
+ */
+ .errstr = "R2 invalid mem access 'scalar'",
+ .result = REJECT,
+},
+{
+ "indirect variable-offset stack access, unbounded",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_2, 6),
+ BPF_MOV64_IMM(BPF_REG_3, 28),
+ /* Fill the top 16 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ /* Get an unknown value. */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_1, offsetof(struct bpf_sock_ops,
+ bytes_received)),
+ /* Check the lower bound but don't check the upper one. */
+ BPF_JMP_IMM(BPF_JSLT, BPF_REG_4, 0, 4),
+ /* Point the lower bound to initialized stack. Offset is now in range
+ * from fp-16 to fp+0x7fffffffffffffef, i.e. max value is unbounded.
+ */
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_4, 16),
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_10),
+ BPF_MOV64_IMM(BPF_REG_5, 8),
+ /* Dereference it indirectly. */
+ BPF_EMIT_CALL(BPF_FUNC_getsockopt),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "invalid unbounded variable-offset indirect access to stack R4",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_SOCK_OPS,
+},
+{
+ "indirect variable-offset stack access, max out of bound",
+ .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 indirectly */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 5 },
+ .errstr = "invalid variable-offset indirect access to stack R2",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+ "indirect variable-offset stack access, min out of bound",
+ .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, 516),
+ /* add it to fp. We now have either fp-516 or fp-512, but
+ * we don't know which
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* dereference it indirectly */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 5 },
+ .errstr = "invalid variable-offset indirect access to stack R2",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+ "indirect variable-offset stack access, max_off+size > max_initialized",
+ .insns = {
+ /* Fill only the second from top 8 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 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, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, but we don't know
+ * which. fp-12 size 8 is partially uninitialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 5 },
+ .errstr = "invalid indirect read from stack R2 var_off",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+ "indirect variable-offset stack access, min_off < min_initialized",
+ .insns = {
+ /* Fill only 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, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, but we don't know
+ * which. fp-16 size 8 is partially uninitialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 5 },
+ .errstr = "invalid indirect read from stack R2 var_off",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+ "indirect variable-offset stack access, priv vs unpriv",
+ .insns = {
+ /* Fill the top 16 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+ 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, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, we don't know
+ * which, but either way it points to initialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 6 },
+ .errstr_unpriv = "R2 variable stack access prohibited for !root",
+ .result_unpriv = REJECT,
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+},
+{
+ "indirect variable-offset stack access, uninitialized",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_2, 6),
+ BPF_MOV64_IMM(BPF_REG_3, 28),
+ /* Fill the top 16 bytes of the stack. */
+ BPF_ST_MEM(BPF_W, BPF_REG_10, -16, 0),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ /* Get an unknown value. */
+ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1, 0),
+ /* Make it small and 4-byte aligned. */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_4, 4),
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_4, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, we don't know
+ * which, but either way it points to initialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_10),
+ BPF_MOV64_IMM(BPF_REG_5, 8),
+ /* Dereference it indirectly. */
+ BPF_EMIT_CALL(BPF_FUNC_getsockopt),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "invalid indirect read from stack R4 var_off",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_SOCK_OPS,
+},
+{
+ "indirect variable-offset stack access, ok",
+ .insns = {
+ /* Fill the top 16 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+ 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, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, we don't know
+ * which, but either way it points to initialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 6 },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+},