diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 743fc2f3c24b..f8e6b40c2121 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -31,6 +31,7 @@ #include <linux/module.h> #include <linux/cpumask.h> #include <linux/cnum.h> +#include <linux/gcd.h> #include <linux/bpf_mem_alloc.h> #include <net/xdp.h> #include <linux/trace_events.h> @@ -17291,6 +17292,51 @@ int bpf_set_reg_range(struct bpf_verifier_env *env, struct bpf_reg_state *reg, return reg_bounds_sanity_check(env, reg, "bpf_set_reg_range"); } +/* + * Checks if pointer and packet metadata matches between two registers. + * For use with bpf_reg_union(). + */ +bool bpf_reg_union_compatible(const struct bpf_reg_state *a, const struct bpf_reg_state *b) +{ + if (a->type != b->type) + return false; + if (a->type == SCALAR_VALUE) + return true; + return !memcmp(a, b, offsetof(struct bpf_reg_state, var_off)) && + a->id == b->id && a->parent_id == b->parent_id && a->map_uid == b->map_uid; +} + +/* + * Extends acc's scalar range to include src's scalar range. + * Caller must ensure that other kinds of metadata is compatible. + * Caller must clear acc's scalar ID. + */ +int bpf_reg_union(struct bpf_verifier_env *env, struct bpf_reg_state *acc, + const struct bpf_reg_state *src) +{ + u16 base, step; + + if (!bpf_reg_union_compatible(acc, src)) { + verifier_bug(env, "union of incompatible registers"); + return -EFAULT; + } + acc->r64 = cnum64_union(acc->r64, src->r64); + acc->r32 = cnum32_union(acc->r32, src->r32); + acc->var_off = tnum_union(acc->var_off, src->var_off); + + /* Retain a common congruence if the bases agree modulo the gcd. */ + step = gcd(acc->step, src->step); + base = acc->base % step; + if (base != src->base % step) { + reg_step_reset(acc); + } else { + acc->base = base; + acc->step = step; + } + reg_bounds_sync(acc); + return reg_bounds_sanity_check(env, acc, "bpf_reg_union"); +} + /* check validity of 32-bit and 64-bit arithmetic operations */ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) { |