After the backport of the changes to fix CVE 2019-7308, the selftests also need to be fixed up, as was done originally in mainline 80c9b2fae87b ("bpf: add various test cases to selftests").

This is a backport of upstream commit 80c9b2fae87b ("bpf: add various test cases to selftests") adapted to 4.19 in order to fix the selftests that began to fail after CVE-2019-7308 fixes.

Suggested-by: Frank van der Linden fllinden@amazon.com Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- tools/testing/selftests/bpf/test_verifier.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 9db5a7378f40..fef1c9e3c4b8 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -2448,6 +2448,7 @@ static struct bpf_test tests[] = { }, .result = REJECT, .errstr = "invalid stack off=-79992 size=8", + .errstr_unpriv = "R1 stack pointer arithmetic goes out of range", }, { "PTR_TO_STACK store/load - out of bounds high", @@ -2844,6 +2845,8 @@ static struct bpf_test tests[] = { BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, -8), BPF_EXIT_INSN(), }, + .errstr_unpriv = "R1 stack pointer arithmetic goes out of range", + .result_unpriv = REJECT, .result = ACCEPT, }, { @@ -7457,6 +7460,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7481,6 +7485,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7507,6 +7512,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R8 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7532,6 +7538,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R8 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7580,6 +7587,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7651,6 +7659,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7702,6 +7711,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7729,6 +7739,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7755,6 +7766,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7784,6 +7796,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R7 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7814,6 +7827,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 4 }, .errstr = "R0 invalid mem access 'inv'", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7842,6 +7856,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, .result_unpriv = REJECT, }, @@ -7894,6 +7909,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.", + .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -8266,6 +8282,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "pointer offset 1073741822", + .errstr_unpriv = "R0 pointer arithmetic of map value goes out of range", .result = REJECT }, { @@ -8287,6 +8304,7 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "pointer offset -1073741822", + .errstr_unpriv = "R0 pointer arithmetic of map value goes out of range", .result = REJECT }, { @@ -8458,6 +8476,7 @@ static struct bpf_test tests[] = { BPF_EXIT_INSN() }, .errstr = "fp pointer offset 1073741822", + .errstr_unpriv = "R1 stack pointer arithmetic goes out of range", .result = REJECT }, {

From: Andrey Ignatov rdna@fb.com

commit 6c2afb674dbda9b736b8f09c976516e1e788860a upstream

Test the following narrow loads in test_verifier for context __sk_buff: * off=1, size=1 - ok; * off=2, size=1 - ok; * off=3, size=1 - ok; * off=0, size=2 - ok; * off=1, size=2 - fail; * off=0, size=2 - ok; * off=3, size=2 - fail.

Signed-off-by: Andrey Ignatov rdna@fb.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- tools/testing/selftests/bpf/test_verifier.c | 48 ++++++++++++++++----- 1 file changed, 38 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 29d42f7796d9..fdc093f29818 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -2002,29 +2002,27 @@ static struct bpf_test tests[] = { .result = ACCEPT, }, { - "check skb->hash byte load not permitted 1", + "check skb->hash byte load permitted 1", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1, offsetof(struct __sk_buff, hash) + 1), BPF_EXIT_INSN(), }, - .errstr = "invalid bpf_context access", - .result = REJECT, + .result = ACCEPT, }, { - "check skb->hash byte load not permitted 2", + "check skb->hash byte load permitted 2", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1, offsetof(struct __sk_buff, hash) + 2), BPF_EXIT_INSN(), }, - .errstr = "invalid bpf_context access", - .result = REJECT, + .result = ACCEPT, }, { - "check skb->hash byte load not permitted 3", + "check skb->hash byte load permitted 3", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), #if __BYTE_ORDER == __LITTLE_ENDIAN @@ -2036,8 +2034,7 @@ static struct bpf_test tests[] = { #endif BPF_EXIT_INSN(), }, - .errstr = "invalid bpf_context access", - .result = REJECT, + .result = ACCEPT, }, { "check cb access: byte, wrong type", @@ -2149,7 +2146,7 @@ static struct bpf_test tests[] = { .result = ACCEPT, }, { - "check skb->hash half load not permitted", + "check skb->hash half load permitted 2", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), #if __BYTE_ORDER == __LITTLE_ENDIAN @@ -2158,6 +2155,37 @@ static struct bpf_test tests[] = { #else BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1, offsetof(struct __sk_buff, hash)), +#endif + BPF_EXIT_INSN(), + }, + .result = ACCEPT, + }, + { + "check skb->hash half load not permitted, unaligned 1", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), +#if __BYTE_ORDER == __LITTLE_ENDIAN + BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, hash) + 1), +#else + BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, hash) + 3), +#endif + BPF_EXIT_INSN(), + }, + .errstr = "invalid bpf_context access", + .result = REJECT, + }, + { + "check skb->hash half load not permitted, unaligned 3", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), +#if __BYTE_ORDER == __LITTLE_ENDIAN + BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, hash) + 3), +#else + BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, hash) + 1), #endif BPF_EXIT_INSN(), },

From: Alexei Starovoitov ast@kernel.org

commit fb8d251ee2a6bf4d7f4af5548e9c8f4fb5f90402 upstream

This patch extends is_branch_taken() logic from JMP+K instructions to JMP+X instructions. Conditional branches are often done when src and dst registers contain known scalars. In such case the verifier can follow the branch that is going to be taken when program executes. That speeds up the verification and is essential feature to support bounded loops.

Signed-off-by: Alexei Starovoitov ast@kernel.org Acked-by: Andrii Nakryiko andriin@fb.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net [OP: drop is_jmp32 parameter from is_branch_taken() calls and adjust context] Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- kernel/bpf/verifier.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f49f84b71a6b..275c1078d80b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4127,8 +4127,9 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, struct bpf_verifier_state *this_branch = env->cur_state; struct bpf_verifier_state *other_branch; struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs; - struct bpf_reg_state *dst_reg, *other_branch_regs; + struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL; u8 opcode = BPF_OP(insn->code); + int pred = -1; int err;

if (opcode > BPF_JSLE) { @@ -4152,6 +4153,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, insn->src_reg); return -EACCES; } + src_reg = &regs[insn->src_reg]; } else { if (insn->src_reg != BPF_REG_0) { verbose(env, "BPF_JMP uses reserved fields\n"); @@ -4166,19 +4168,21 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,

dst_reg = &regs[insn->dst_reg];

- if (BPF_SRC(insn->code) == BPF_K) { - int pred = is_branch_taken(dst_reg, insn->imm, opcode); - - if (pred == 1) { - /* only follow the goto, ignore fall-through */ - *insn_idx += insn->off; - return 0; - } else if (pred == 0) { - /* only follow fall-through branch, since - * that's where the program will go - */ - return 0; - } + if (BPF_SRC(insn->code) == BPF_K) + pred = is_branch_taken(dst_reg, insn->imm, opcode); + else if (src_reg->type == SCALAR_VALUE && + tnum_is_const(src_reg->var_off)) + pred = is_branch_taken(dst_reg, src_reg->var_off.value, + opcode); + if (pred == 1) { + /* only follow the goto, ignore fall-through */ + *insn_idx += insn->off; + return 0; + } else if (pred == 0) { + /* only follow fall-through branch, since + * that's where the program will go + */ + return 0; }

other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,

From: Daniel Borkmann daniel@iogearbox.net

[ no upstream commit ]

Switch the comparison, so that is_branch_taken() will recognize that below branch is never taken:

[...] 17: [...] R1_w=inv0 [...] R8_w=inv(id=0,smin_value=-2147483648,smax_value=-1,umin_value=18446744071562067968,var_off=(0xffffffff80000000; 0x7fffffff)) [...] 17: (67) r8 <<= 32 18: [...] R8_w=inv(id=0,smax_value=-4294967296,umin_value=9223372036854775808,umax_value=18446744069414584320,var_off=(0x8000000000000000; 0x7fffffff00000000)) [...] 18: (c7) r8 s>>= 32 19: [...] R8_w=inv(id=0,smin_value=-2147483648,smax_value=-1,umin_value=18446744071562067968,var_off=(0xffffffff80000000; 0x7fffffff)) [...] 19: (6d) if r1 s> r8 goto pc+16 [...] R1_w=inv0 [...] R8_w=inv(id=0,smin_value=-2147483648,smax_value=-1,umin_value=18446744071562067968,var_off=(0xffffffff80000000; 0x7fffffff)) [...] [...]

Currently we check for is_branch_taken() only if either K is source, or source is a scalar value that is const. For upstream it would be good to extend this properly to check whether dst is const and src not.

For the sake of the test_verifier, it is probably not needed here:

# ./test_verifier 101 #101/p bpf_get_stack return R0 within range OK Summary: 1 PASSED, 0 SKIPPED, 0 FAILED

I haven't seen this issue in test_progs* though, they are passing fine:

# ./test_progs-no_alu32 -t get_stack Switching to flavor 'no_alu32' subdirectory... #20 get_stack_raw_tp:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

# ./test_progs -t get_stack #20 get_stack_raw_tp:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Alexei Starovoitov ast@kernel.org Acked-by: John Fastabend john.fastabend@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [OP: backport to 4.19] Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- tools/testing/selftests/bpf/test_verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index da985a5e7cc5..662d6acaaab0 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -12263,7 +12263,7 @@ static struct bpf_test tests[] = { BPF_MOV64_REG(BPF_REG_8, BPF_REG_0), BPF_ALU64_IMM(BPF_LSH, BPF_REG_8, 32), BPF_ALU64_IMM(BPF_ARSH, BPF_REG_8, 32), - BPF_JMP_REG(BPF_JSGT, BPF_REG_1, BPF_REG_8, 16), + BPF_JMP_REG(BPF_JSLT, BPF_REG_8, BPF_REG_1, 16), BPF_ALU64_REG(BPF_SUB, BPF_REG_9, BPF_REG_8), BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_8),

From: Daniel Borkmann daniel@iogearbox.net

commit 24c109bb1537c12c02aeed2d51a347b4d6a9b76e upstream.

The mixed signed bounds check really belongs into retrieve_ptr_limit() instead of outside of it in adjust_ptr_min_max_vals(). The reason is that this check is not tied to PTR_TO_MAP_VALUE only, but to all pointer types that we handle in retrieve_ptr_limit() and given errors from the latter propagate back to adjust_ptr_min_max_vals() and lead to rejection of the program, it's a better place to reside to avoid anything slipping through for future types. The reason why we must reject such off_reg is that we otherwise would not be able to derive a mask, see details in 9d7eceede769 ("bpf: restrict unknown scalars of mixed signed bounds for unprivileged").

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: John Fastabend john.fastabend@gmail.com Acked-by: Alexei Starovoitov ast@kernel.org [fllinden@amazon.com: backport to 5.4] Signed-off-by: Frank van der Linden fllinden@amazon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [OP: backport to 4.19] Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- kernel/bpf/verifier.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4edae9b29cd1..cdef8c7769ef 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2730,12 +2730,18 @@ static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) }

static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, - u32 *ptr_limit, u8 opcode, bool off_is_neg) + const struct bpf_reg_state *off_reg, + u32 *ptr_limit, u8 opcode) { + bool off_is_neg = off_reg->smin_value < 0; bool mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg); u32 off, max;

+ if (!tnum_is_const(off_reg->var_off) && + (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) + return -EACCES; + switch (ptr_reg->type) { case PTR_TO_STACK: /* Offset 0 is out-of-bounds, but acceptable start for the @@ -2826,7 +2832,7 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, alu_state |= ptr_is_dst_reg ? BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;

- err = retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg); + err = retrieve_ptr_limit(ptr_reg, off_reg, &alu_limit, opcode); if (err < 0) return err;

@@ -2871,8 +2877,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; - u32 dst = insn->dst_reg, src = insn->src_reg; u8 opcode = BPF_OP(insn->code); + u32 dst = insn->dst_reg; int ret;

dst_reg = &regs[dst]; @@ -2909,12 +2915,6 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, dst); return -EACCES; } - if (ptr_reg->type == PTR_TO_MAP_VALUE && - !env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { - verbose(env, "R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n", - off_reg == dst_reg ? dst : src); - return -EACCES; - }

/* In case of 'scalar += pointer', dst_reg inherits pointer type and id. * The id may be overwritten later if we create a new variable offset.

From: Daniel Borkmann daniel@iogearbox.net

commit a6aaece00a57fa6f22575364b3903dfbccf5345d upstream

Consolidate all error handling and provide more user-friendly error messages from sanitize_ptr_alu() and sanitize_val_alu().

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: John Fastabend john.fastabend@gmail.com Acked-by: Alexei Starovoitov ast@kernel.org [fllinden@amazon.com: backport to 5.4] Signed-off-by: Frank van der Linden fllinden@amazon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- kernel/bpf/verifier.c | 84 +++++++++++++++++++++++++++++++------------ 1 file changed, 62 insertions(+), 22 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index adc833c6088f..473b59126f61 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2729,6 +2729,14 @@ static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) return &env->insn_aux_data[env->insn_idx]; }

+enum { + REASON_BOUNDS = -1, + REASON_TYPE = -2, + REASON_PATHS = -3, + REASON_LIMIT = -4, + REASON_STACK = -5, +}; + static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, const struct bpf_reg_state *off_reg, u32 *alu_limit, u8 opcode) @@ -2740,7 +2748,7 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,

if (!tnum_is_const(off_reg->var_off) && (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) - return -EACCES; + return REASON_BOUNDS;

switch (ptr_reg->type) { case PTR_TO_STACK: @@ -2764,11 +2772,11 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, } break; default: - return -EINVAL; + return REASON_TYPE; }

if (ptr_limit >= max) - return -ERANGE; + return REASON_LIMIT; *alu_limit = ptr_limit; return 0; } @@ -2788,7 +2796,7 @@ static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, if (aux->alu_state && (aux->alu_state != alu_state || aux->alu_limit != alu_limit)) - return -EACCES; + return REASON_PATHS;

/* Corresponding fixup done in fixup_bpf_calls(). */ aux->alu_state = alu_state; @@ -2861,7 +2869,46 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, ret = push_stack(env, env->insn_idx + 1, env->insn_idx, true); if (!ptr_is_dst_reg && ret) *dst_reg = tmp; - return !ret ? -EFAULT : 0; + return !ret ? REASON_STACK : 0; +} + +static int sanitize_err(struct bpf_verifier_env *env, + const struct bpf_insn *insn, int reason, + const struct bpf_reg_state *off_reg, + const struct bpf_reg_state *dst_reg) +{ + static const char *err = "pointer arithmetic with it prohibited for !root"; + const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub"; + u32 dst = insn->dst_reg, src = insn->src_reg; + + switch (reason) { + case REASON_BOUNDS: + verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n", + off_reg == dst_reg ? dst : src, err); + break; + case REASON_TYPE: + verbose(env, "R%d has pointer with unsupported alu operation, %s\n", + off_reg == dst_reg ? src : dst, err); + break; + case REASON_PATHS: + verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n", + dst, op, err); + break; + case REASON_LIMIT: + verbose(env, "R%d tried to %s beyond pointer bounds, %s\n", + dst, op, err); + break; + case REASON_STACK: + verbose(env, "R%d could not be pushed for speculative verification, %s\n", + dst, err); + break; + default: + verbose(env, "verifier internal error: unknown reason (%d)\n", + reason); + break; + } + + return -EACCES; }

/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. @@ -2934,10 +2981,9 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, switch (opcode) { case BPF_ADD: ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg); - if (ret < 0) { - verbose(env, "R%d tried to add from different maps, paths, or prohibited types\n", dst); - return ret; - } + if (ret < 0) + return sanitize_err(env, insn, ret, off_reg, dst_reg); + /* We can take a fixed offset as long as it doesn't overflow * the s32 'off' field */ @@ -2989,10 +3035,9 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, break; case BPF_SUB: ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg); - if (ret < 0) { - verbose(env, "R%d tried to sub from different maps, paths, or prohibited types\n", dst); - return ret; - } + if (ret < 0) + return sanitize_err(env, insn, ret, off_reg, dst_reg); + if (dst_reg == off_reg) { /* scalar -= pointer. Creates an unknown scalar */ verbose(env, "R%d tried to subtract pointer from scalar\n", @@ -3109,7 +3154,6 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, s64 smin_val, smax_val; u64 umin_val, umax_val; u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; - u32 dst = insn->dst_reg; int ret;

if (insn_bitness == 32) { @@ -3146,10 +3190,8 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, switch (opcode) { case BPF_ADD: ret = sanitize_val_alu(env, insn); - if (ret < 0) { - verbose(env, "R%d tried to add from different pointers or scalars\n", dst); - return ret; - } + if (ret < 0) + return sanitize_err(env, insn, ret, NULL, NULL); if (signed_add_overflows(dst_reg->smin_value, smin_val) || signed_add_overflows(dst_reg->smax_value, smax_val)) { dst_reg->smin_value = S64_MIN; @@ -3170,10 +3212,8 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, break; case BPF_SUB: ret = sanitize_val_alu(env, insn); - if (ret < 0) { - verbose(env, "R%d tried to sub from different pointers or scalars\n", dst); - return ret; - } + if (ret < 0) + return sanitize_err(env, insn, ret, NULL, NULL); if (signed_sub_overflows(dst_reg->smin_value, smax_val) || signed_sub_overflows(dst_reg->smax_value, smin_val)) { /* Overflow possible, we know nothing */

From: Daniel Borkmann daniel@iogearbox.net

commit f528819334881fd622fdadeddb3f7edaed8b7c9b upstream.

Add a small sanitize_needed() helper function and move sanitize_val_alu() out of the main opcode switch. In upcoming work, we'll move sanitize_ptr_alu() as well out of its opcode switch so this helps to streamline both.

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: John Fastabend john.fastabend@gmail.com Acked-by: Alexei Starovoitov ast@kernel.org [fllinden@amazon.com: backported to 5.4] Signed-off-by: Frank van der Linden fllinden@amazon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- kernel/bpf/verifier.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index faa2a4c3467d..094f70876923 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2815,6 +2815,11 @@ static int sanitize_val_alu(struct bpf_verifier_env *env, return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0); }

+static bool sanitize_needed(u8 opcode) +{ + return opcode == BPF_ADD || opcode == BPF_SUB; +} + static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg, @@ -3207,11 +3212,14 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, return 0; }

- switch (opcode) { - case BPF_ADD: + if (sanitize_needed(opcode)) { ret = sanitize_val_alu(env, insn); if (ret < 0) return sanitize_err(env, insn, ret, NULL, NULL); + } + + switch (opcode) { + case BPF_ADD: if (signed_add_overflows(dst_reg->smin_value, smin_val) || signed_add_overflows(dst_reg->smax_value, smax_val)) { dst_reg->smin_value = S64_MIN; @@ -3231,9 +3239,6 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); break; case BPF_SUB: - ret = sanitize_val_alu(env, insn); - if (ret < 0) - return sanitize_err(env, insn, ret, NULL, NULL); if (signed_sub_overflows(dst_reg->smin_value, smax_val) || signed_sub_overflows(dst_reg->smax_value, smin_val)) { /* Overflow possible, we know nothing */

From: Daniel Borkmann daniel@iogearbox.net

commit d7a5091351756d0ae8e63134313c455624e36a13 upstream

Update various selftest error messages:

* The 'Rx tried to sub from different maps, paths, or prohibited types' is reworked into more specific/differentiated error messages for better guidance.

* The change into 'value -4294967168 makes map_value pointer be out of bounds' is due to moving the mixed bounds check into the speculation handling and thus occuring slightly later than above mentioned sanity check.

* The change into 'math between map_value pointer and register with unbounded min value' is similarly due to register sanity check coming before the mixed bounds check.

* The case of 'map access: known scalar += value_ptr from different maps' now loads fine given masks are the same from the different paths (despite max map value size being different).

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: John Fastabend john.fastabend@gmail.com Acked-by: Alexei Starovoitov ast@kernel.org [OP: 4.19 backport, account for split test_verifier and different / missing tests] Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- tools/testing/selftests/bpf/test_verifier.c | 35 +++++++-------------- 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 662d6acaaab0..e1e4b6ab83f7 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -2873,7 +2873,7 @@ static struct bpf_test tests[] = { BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, -8), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R1 tried to add from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 stack pointer arithmetic goes out of range", .result_unpriv = REJECT, .result = ACCEPT, }, @@ -7501,7 +7501,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7526,7 +7525,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7553,7 +7551,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R8 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7579,7 +7576,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R8 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7628,7 +7624,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7700,7 +7695,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7752,7 +7746,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7780,7 +7773,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7807,7 +7799,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7837,7 +7828,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R7 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7868,7 +7858,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 4 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, }, { @@ -7897,7 +7886,6 @@ static struct bpf_test tests[] = { }, .fixup_map1 = { 3 }, .errstr = "unbounded min value", - .errstr_unpriv = "R1 has unknown scalar with mixed signed bounds", .result = REJECT, .result_unpriv = REJECT, }, @@ -9799,7 +9787,7 @@ static struct bpf_test tests[] = { BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "R0 tried to subtract pointer from scalar", .result = REJECT, }, @@ -9814,7 +9802,7 @@ static struct bpf_test tests[] = { BPF_ALU64_REG(BPF_SUB, BPF_REG_1, BPF_REG_0), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R1 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .result_unpriv = REJECT, .result = ACCEPT, .retval = 1, @@ -9827,22 +9815,23 @@ static struct bpf_test tests[] = { BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "R0 tried to subtract pointer from scalar", .result = REJECT, }, { "check deducing bounds from const, 4", .insns = { + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_JMP_IMM(BPF_JSLE, BPF_REG_0, 0, 1), BPF_EXIT_INSN(), BPF_JMP_IMM(BPF_JSGE, BPF_REG_0, 0, 1), BPF_EXIT_INSN(), - BPF_ALU64_REG(BPF_SUB, BPF_REG_1, BPF_REG_0), + BPF_ALU64_REG(BPF_SUB, BPF_REG_6, BPF_REG_0), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R1 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R6 has pointer with unsupported alu operation", .result_unpriv = REJECT, .result = ACCEPT, }, @@ -9854,7 +9843,7 @@ static struct bpf_test tests[] = { BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "R0 tried to subtract pointer from scalar", .result = REJECT, }, @@ -9867,7 +9856,7 @@ static struct bpf_test tests[] = { BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "R0 tried to subtract pointer from scalar", .result = REJECT, }, @@ -9881,7 +9870,7 @@ static struct bpf_test tests[] = { offsetof(struct __sk_buff, mark)), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R1 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "dereference of modified ctx ptr", .result = REJECT, }, @@ -9895,7 +9884,7 @@ static struct bpf_test tests[] = { offsetof(struct __sk_buff, mark)), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R1 tried to add from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "dereference of modified ctx ptr", .result = REJECT, }, @@ -9907,7 +9896,7 @@ static struct bpf_test tests[] = { BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", + .errstr_unpriv = "R1 has pointer with unsupported alu operation", .errstr = "R0 tried to subtract pointer from scalar", .result = REJECT, },

From: Daniel Borkmann daniel@iogearbox.net

commit 3d0220f6861d713213b015b582e9f21e5b28d2e0 upstream

Add a container structure struct bpf_sanitize_info which holds the current aux info, and update call-sites to sanitize_ptr_alu() to pass it in. This is needed for passing in additional state later on.

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Piotr Krysiuk piotras@gmail.com Acked-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- kernel/bpf/verifier.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index faae834aac49..0066ea8ecdaa 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2815,15 +2815,19 @@ static bool sanitize_needed(u8 opcode) return opcode == BPF_ADD || opcode == BPF_SUB; }

+struct bpf_sanitize_info { + struct bpf_insn_aux_data aux; +}; + static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg, const struct bpf_reg_state *off_reg, struct bpf_reg_state *dst_reg, - struct bpf_insn_aux_data *tmp_aux, + struct bpf_sanitize_info *info, const bool commit_window) { - struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : tmp_aux; + struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux; struct bpf_verifier_state *vstate = env->cur_state; bool off_is_imm = tnum_is_const(off_reg->var_off); bool off_is_neg = off_reg->smin_value < 0; @@ -2852,8 +2856,8 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, /* In commit phase we narrow the masking window based on * the observed pointer move after the simulated operation. */ - alu_state = tmp_aux->alu_state; - alu_limit = abs(tmp_aux->alu_limit - alu_limit); + alu_state = info->aux.alu_state; + alu_limit = abs(info->aux.alu_limit - alu_limit); } else { alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0; alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0; @@ -2983,7 +2987,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; - struct bpf_insn_aux_data tmp_aux = {}; + struct bpf_sanitize_info info = {}; u8 opcode = BPF_OP(insn->code); u32 dst = insn->dst_reg; int ret; @@ -3035,7 +3039,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,

if (sanitize_needed(opcode)) { ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg, - &tmp_aux, false); + &info, false); if (ret < 0) return sanitize_err(env, insn, ret, off_reg, dst_reg); } @@ -3176,7 +3180,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, return -EACCES; if (sanitize_needed(opcode)) { ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg, - &tmp_aux, true); + &info, true); if (ret < 0) return sanitize_err(env, insn, ret, off_reg, dst_reg); }

From: Daniel Borkmann daniel@iogearbox.net

commit a7036191277f9fa68d92f2071ddc38c09b1e5ee5 upstream

In 801c6058d14a ("bpf: Fix leakage of uninitialized bpf stack under speculation") we replaced masking logic with direct loads of immediates if the register is a known constant. Given in this case we do not apply any masking, there is also no reason for the operation to be truncated under the speculative domain.

Therefore, there is also zero reason for the verifier to branch-off and simulate this case, it only needs to do it for unknown but bounded scalars. As a side-effect, this also enables few test cases that were previously rejected due to simulation under zero truncation.

Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Piotr Krysiuk piotras@gmail.com Acked-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- kernel/bpf/verifier.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a235342507a8..1f4c88ce58de 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2874,8 +2874,12 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, /* If we're in commit phase, we're done here given we already * pushed the truncated dst_reg into the speculative verification * stack. + * + * Also, when register is a known constant, we rewrite register-based + * operation to immediate-based, and thus do not need masking (and as + * a consequence, do not need to simulate the zero-truncation either). */ - if (commit_window) + if (commit_window || off_is_imm) return 0;

/* Simulate and find potential out-of-bounds access under