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authorDavid S. Miller <davem@davemloft.net>2018-01-18 09:17:04 -0500
committerDavid S. Miller <davem@davemloft.net>2018-01-18 09:17:04 -0500
commit7155f8f391576f133ed26c8d6bb8c7f03ceb404a (patch)
treec1c219defbaaf8ac3569b4e2ebccd76bda627a31 /kernel
parentad9294dbc227cbc8e173b3b963e7dd9af5314f77 (diff)
parent6f16101e6a8b4324c36e58a29d9e0dbb287cdedb (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Daniel Borkmann says: ==================== pull-request: bpf 2018-01-18 The following pull-request contains BPF updates for your *net* tree. The main changes are: 1) Fix a divide by zero due to wrong if (src_reg == 0) check in 64-bit mode. Properly handle this in interpreter and mask it also generically in verifier to guard against similar checks in JITs, from Eric and Alexei. 2) Fix a bug in arm64 JIT when tail calls are involved and progs have different stack sizes, from Daniel. 3) Reject stores into BPF context that are not expected BPF_STX | BPF_MEM variant, from Daniel. 4) Mark dst reg as unknown on {s,u}bounds adjustments when the src reg has derived bounds from dead branches, from Daniel. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/core.c4
-rw-r--r--kernel/bpf/verifier.c64
2 files changed, 55 insertions, 13 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 51ec2dda7f08..7949e8b8f94e 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -956,7 +956,7 @@ select_insn:
DST = tmp;
CONT;
ALU_MOD_X:
- if (unlikely(SRC == 0))
+ if (unlikely((u32)SRC == 0))
return 0;
tmp = (u32) DST;
DST = do_div(tmp, (u32) SRC);
@@ -975,7 +975,7 @@ select_insn:
DST = div64_u64(DST, SRC);
CONT;
ALU_DIV_X:
- if (unlikely(SRC == 0))
+ if (unlikely((u32)SRC == 0))
return 0;
tmp = (u32) DST;
do_div(tmp, (u32) SRC);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 20eb04fd155e..13551e623501 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -978,6 +978,13 @@ static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
return __is_pointer_value(env->allow_ptr_leaks, cur_regs(env) + regno);
}
+static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
+{
+ const struct bpf_reg_state *reg = cur_regs(env) + regno;
+
+ return reg->type == PTR_TO_CTX;
+}
+
static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
int off, int size, bool strict)
@@ -1258,6 +1265,12 @@ static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_ins
return -EACCES;
}
+ if (is_ctx_reg(env, insn->dst_reg)) {
+ verbose(env, "BPF_XADD stores into R%d context is not allowed\n",
+ insn->dst_reg);
+ return -EACCES;
+ }
+
/* check whether atomic_add can read the memory */
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_READ, -1);
@@ -1882,17 +1895,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
dst_reg = &regs[dst];
- if (WARN_ON_ONCE(known && (smin_val != smax_val))) {
- print_verifier_state(env, env->cur_state);
- verbose(env,
- "verifier internal error: known but bad sbounds\n");
- return -EINVAL;
- }
- if (WARN_ON_ONCE(known && (umin_val != umax_val))) {
- print_verifier_state(env, env->cur_state);
- verbose(env,
- "verifier internal error: known but bad ubounds\n");
- return -EINVAL;
+ if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
+ smin_val > smax_val || umin_val > umax_val) {
+ /* Taint dst register if offset had invalid bounds derived from
+ * e.g. dead branches.
+ */
+ __mark_reg_unknown(dst_reg);
+ return 0;
}
if (BPF_CLASS(insn->code) != BPF_ALU64) {
@@ -2084,6 +2093,15 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
src_known = tnum_is_const(src_reg.var_off);
dst_known = tnum_is_const(dst_reg->var_off);
+ if ((src_known && (smin_val != smax_val || umin_val != umax_val)) ||
+ smin_val > smax_val || umin_val > umax_val) {
+ /* Taint dst register if offset had invalid bounds derived from
+ * e.g. dead branches.
+ */
+ __mark_reg_unknown(dst_reg);
+ return 0;
+ }
+
if (!src_known &&
opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) {
__mark_reg_unknown(dst_reg);
@@ -3993,6 +4011,12 @@ static int do_check(struct bpf_verifier_env *env)
if (err)
return err;
+ if (is_ctx_reg(env, insn->dst_reg)) {
+ verbose(env, "BPF_ST stores into R%d context is not allowed\n",
+ insn->dst_reg);
+ return -EACCES;
+ }
+
/* check that memory (dst_reg + off) is writeable */
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
BPF_SIZE(insn->code), BPF_WRITE,
@@ -4445,6 +4469,24 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
int i, cnt, delta = 0;
for (i = 0; i < insn_cnt; i++, insn++) {
+ if (insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
+ insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
+ /* due to JIT bugs clear upper 32-bits of src register
+ * before div/mod operation
+ */
+ insn_buf[0] = BPF_MOV32_REG(insn->src_reg, insn->src_reg);
+ insn_buf[1] = *insn;
+ cnt = 2;
+ new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
+ if (!new_prog)
+ return -ENOMEM;
+
+ delta += cnt - 1;
+ env->prog = prog = new_prog;
+ insn = new_prog->insnsi + i + delta;
+ continue;
+ }
+
if (insn->code != (BPF_JMP | BPF_CALL))
continue;