From d623876646be119439999a229a2c3ce30fd197fb Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 8 Feb 2019 22:25:54 -0800 Subject: bpf: Fix narrow load on a bpf_sock returned from sk_lookup() By adding this test to test_verifier: { "reference tracking: access sk->src_ip4 (narrow load)", .insns = { BPF_SK_LOOKUP, BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), BPF_LDX_MEM(BPF_H, BPF_REG_2, BPF_REG_0, offsetof(struct bpf_sock, src_ip4) + 2), BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), BPF_EMIT_CALL(BPF_FUNC_sk_release), BPF_EXIT_INSN(), }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = ACCEPT, }, The above test loads 2 bytes from sk->src_ip4 where sk is obtained by bpf_sk_lookup_tcp(). It hits an internal verifier error from convert_ctx_accesses(): [root@arch-fb-vm1 bpf]# ./test_verifier 665 665 Failed to load prog 'Invalid argument'! 0: (b7) r2 = 0 1: (63) *(u32 *)(r10 -8) = r2 2: (7b) *(u64 *)(r10 -16) = r2 3: (7b) *(u64 *)(r10 -24) = r2 4: (7b) *(u64 *)(r10 -32) = r2 5: (7b) *(u64 *)(r10 -40) = r2 6: (7b) *(u64 *)(r10 -48) = r2 7: (bf) r2 = r10 8: (07) r2 += -48 9: (b7) r3 = 36 10: (b7) r4 = 0 11: (b7) r5 = 0 12: (85) call bpf_sk_lookup_tcp#84 13: (bf) r6 = r0 14: (15) if r0 == 0x0 goto pc+3 R0=sock(id=1,off=0,imm=0) R6=sock(id=1,off=0,imm=0) R10=fp0,call_-1 fp-8=????0000 fp-16=0000mmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm refs=1 15: (69) r2 = *(u16 *)(r0 +26) 16: (bf) r1 = r6 17: (85) call bpf_sk_release#86 18: (95) exit from 14 to 18: safe processed 20 insns (limit 131072), stack depth 48 bpf verifier is misconfigured Summary: 0 PASSED, 0 SKIPPED, 1 FAILED The bpf_sock_is_valid_access() is expecting src_ip4 can be narrowly loaded (meaning load any 1 or 2 bytes of the src_ip4) by marking info->ctx_field_size. However, this marked ctx_field_size is not used. This patch fixes it. Due to the recent refactoring in test_verifier, this new test will be added to the bpf-next branch (together with the bpf_tcp_sock patchset) to avoid merge conflict. Fixes: c64b7983288e ("bpf: Add PTR_TO_SOCKET verifier type") Cc: Joe Stringer Signed-off-by: Martin KaFai Lau Acked-by: Joe Stringer Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 56674a7c3778..8f295b790297 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1617,12 +1617,13 @@ static int check_flow_keys_access(struct bpf_verifier_env *env, int off, return 0; } -static int check_sock_access(struct bpf_verifier_env *env, u32 regno, int off, - int size, enum bpf_access_type t) +static int check_sock_access(struct bpf_verifier_env *env, int insn_idx, + u32 regno, int off, int size, + enum bpf_access_type t) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = ®s[regno]; - struct bpf_insn_access_aux info; + struct bpf_insn_access_aux info = {}; if (reg->smin_value < 0) { verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", @@ -1636,6 +1637,8 @@ static int check_sock_access(struct bpf_verifier_env *env, u32 regno, int off, return -EACCES; } + env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; + return 0; } @@ -2032,7 +2035,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn verbose(env, "cannot write into socket\n"); return -EACCES; } - err = check_sock_access(env, regno, off, size, t); + err = check_sock_access(env, insn_idx, regno, off, size, t); if (!err && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else { -- cgit v1.2.3 From 3defaf2f15b2bfd86c6664181ac009e91985f8ac Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Sun, 10 Feb 2019 12:52:35 -0800 Subject: bpf: fix lockdep false positive in stackmap Lockdep warns about false positive: [ 11.211460] ------------[ cut here ]------------ [ 11.211936] DEBUG_LOCKS_WARN_ON(depth <= 0) [ 11.211985] WARNING: CPU: 0 PID: 141 at ../kernel/locking/lockdep.c:3592 lock_release+0x1ad/0x280 [ 11.213134] Modules linked in: [ 11.214954] RIP: 0010:lock_release+0x1ad/0x280 [ 11.223508] Call Trace: [ 11.223705] [ 11.223874] ? __local_bh_enable+0x7a/0x80 [ 11.224199] up_read+0x1c/0xa0 [ 11.224446] do_up_read+0x12/0x20 [ 11.224713] irq_work_run_list+0x43/0x70 [ 11.225030] irq_work_run+0x26/0x50 [ 11.225310] smp_irq_work_interrupt+0x57/0x1f0 [ 11.225662] irq_work_interrupt+0xf/0x20 since rw_semaphore is released in a different task vs task that locked the sema. It is expected behavior. Fix the warning with up_read_non_owner() and rwsem_release() annotation. Fixes: bae77c5eb5b2 ("bpf: enable stackmap with build_id in nmi context") Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- kernel/bpf/stackmap.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index d43b14535827..950ab2f28922 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -44,7 +44,7 @@ static void do_up_read(struct irq_work *entry) struct stack_map_irq_work *work; work = container_of(entry, struct stack_map_irq_work, irq_work); - up_read(work->sem); + up_read_non_owner(work->sem); work->sem = NULL; } @@ -338,6 +338,12 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, } else { work->sem = ¤t->mm->mmap_sem; irq_work_queue(&work->irq_work); + /* + * The irq_work will release the mmap_sem with + * up_read_non_owner(). The rwsem_release() is called + * here to release the lock from lockdep's perspective. + */ + rwsem_release(¤t->mm->mmap_sem.dep_map, 1, _RET_IP_); } } -- cgit v1.2.3