diff options
| -rw-r--r-- | include/linux/bpf.h | 9 | ||||
| -rw-r--r-- | include/linux/bpf_verifier.h | 1 | ||||
| -rw-r--r-- | kernel/bpf/arraymap.c | 3 | ||||
| -rw-r--r-- | kernel/bpf/btf.c | 40 | ||||
| -rw-r--r-- | kernel/bpf/hashtab.c | 3 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 82 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/map_ptr_mixing.c | 2 |
7 files changed, 131 insertions, 9 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 07052d44bca1..1e1501ee53ce 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -92,6 +92,10 @@ struct bpf_map_ops { int (*map_mmap)(struct bpf_map *map, struct vm_area_struct *vma); __poll_t (*map_poll)(struct bpf_map *map, struct file *filp, struct poll_table_struct *pts); + + /* BTF name and id of struct allocated by map_alloc */ + const char * const map_btf_name; + int *map_btf_id; }; struct bpf_map_memory { @@ -1109,6 +1113,11 @@ static inline bool bpf_allow_ptr_leaks(void) return perfmon_capable(); } +static inline bool bpf_allow_ptr_to_map_access(void) +{ + return perfmon_capable(); +} + static inline bool bpf_bypass_spec_v1(void) { return perfmon_capable(); diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index ca08db4ffb5f..53c7bd568c5d 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -379,6 +379,7 @@ struct bpf_verifier_env { u32 used_map_cnt; /* number of used maps */ u32 id_gen; /* used to generate unique reg IDs */ bool allow_ptr_leaks; + bool allow_ptr_to_map_access; bool bpf_capable; bool bypass_spec_v1; bool bypass_spec_v4; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 11584618e861..e7caa48812fb 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -494,6 +494,7 @@ static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma) vma->vm_pgoff + pgoff); } +static int array_map_btf_id; const struct bpf_map_ops array_map_ops = { .map_alloc_check = array_map_alloc_check, .map_alloc = array_map_alloc, @@ -510,6 +511,8 @@ const struct bpf_map_ops array_map_ops = { .map_check_btf = array_map_check_btf, .map_lookup_batch = generic_map_lookup_batch, .map_update_batch = generic_map_update_batch, + .map_btf_name = "bpf_array", + .map_btf_id = &array_map_btf_id, }; const struct bpf_map_ops percpu_array_map_ops = { diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 3eb804618a53..e377d1981730 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3571,6 +3571,41 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf, return ctx_type; } +static const struct bpf_map_ops * const btf_vmlinux_map_ops[] = { +#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) +#define BPF_LINK_TYPE(_id, _name) +#define BPF_MAP_TYPE(_id, _ops) \ + [_id] = &_ops, +#include <linux/bpf_types.h> +#undef BPF_PROG_TYPE +#undef BPF_LINK_TYPE +#undef BPF_MAP_TYPE +}; + +static int btf_vmlinux_map_ids_init(const struct btf *btf, + struct bpf_verifier_log *log) +{ + const struct bpf_map_ops *ops; + int i, btf_id; + + for (i = 0; i < ARRAY_SIZE(btf_vmlinux_map_ops); ++i) { + ops = btf_vmlinux_map_ops[i]; + if (!ops || (!ops->map_btf_name && !ops->map_btf_id)) + continue; + if (!ops->map_btf_name || !ops->map_btf_id) { + bpf_log(log, "map type %d is misconfigured\n", i); + return -EINVAL; + } + btf_id = btf_find_by_name_kind(btf, ops->map_btf_name, + BTF_KIND_STRUCT); + if (btf_id < 0) + return btf_id; + *ops->map_btf_id = btf_id; + } + + return 0; +} + static int btf_translate_to_vmlinux(struct bpf_verifier_log *log, struct btf *btf, const struct btf_type *t, @@ -3633,6 +3668,11 @@ struct btf *btf_parse_vmlinux(void) /* btf_parse_vmlinux() runs under bpf_verifier_lock */ bpf_ctx_convert.t = btf_type_by_id(btf, btf_id); + /* find bpf map structs for map_ptr access checking */ + err = btf_vmlinux_map_ids_init(btf, log); + if (err < 0) + goto errout; + bpf_struct_ops_init(btf, log); btf_verifier_env_free(env); diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index b4b288a3c3c9..2c5999e02060 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1614,6 +1614,7 @@ htab_lru_map_lookup_and_delete_batch(struct bpf_map *map, true, false); } +static int htab_map_btf_id; const struct bpf_map_ops htab_map_ops = { .map_alloc_check = htab_map_alloc_check, .map_alloc = htab_map_alloc, @@ -1625,6 +1626,8 @@ const struct bpf_map_ops htab_map_ops = { .map_gen_lookup = htab_map_gen_lookup, .map_seq_show_elem = htab_map_seq_show_elem, BATCH_OPS(htab), + .map_btf_name = "bpf_htab", + .map_btf_id = &htab_map_btf_id, }; const struct bpf_map_ops htab_lru_map_ops = { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a1857c4ffaaf..7460f967cb75 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1351,6 +1351,19 @@ static void mark_reg_not_init(struct bpf_verifier_env *env, __mark_reg_not_init(env, regs + regno); } +static void mark_btf_ld_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, u32 regno, + enum bpf_reg_type reg_type, u32 btf_id) +{ + if (reg_type == SCALAR_VALUE) { + mark_reg_unknown(env, regs, regno); + return; + } + mark_reg_known_zero(env, regs, regno); + regs[regno].type = PTR_TO_BTF_ID; + regs[regno].btf_id = btf_id; +} + #define DEF_NOT_SUBREG (0) static void init_reg_state(struct bpf_verifier_env *env, struct bpf_func_state *state) @@ -3182,19 +3195,68 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, if (ret < 0) return ret; - if (atype == BPF_READ && value_regno >= 0) { - if (ret == SCALAR_VALUE) { - mark_reg_unknown(env, regs, value_regno); - return 0; - } - mark_reg_known_zero(env, regs, value_regno); - regs[value_regno].type = PTR_TO_BTF_ID; - regs[value_regno].btf_id = btf_id; + if (atype == BPF_READ && value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, btf_id); + + return 0; +} + +static int check_ptr_to_map_access(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, + int regno, int off, int size, + enum bpf_access_type atype, + int value_regno) +{ + struct bpf_reg_state *reg = regs + regno; + struct bpf_map *map = reg->map_ptr; + const struct btf_type *t; + const char *tname; + u32 btf_id; + int ret; + + if (!btf_vmlinux) { + verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n"); + return -ENOTSUPP; + } + + if (!map->ops->map_btf_id || !*map->ops->map_btf_id) { + verbose(env, "map_ptr access not supported for map type %d\n", + map->map_type); + return -ENOTSUPP; + } + + t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id); + tname = btf_name_by_offset(btf_vmlinux, t->name_off); + + if (!env->allow_ptr_to_map_access) { + verbose(env, + "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + tname); + return -EPERM; } + if (off < 0) { + verbose(env, "R%d is %s invalid negative access: off=%d\n", + regno, tname, off); + return -EACCES; + } + + if (atype != BPF_READ) { + verbose(env, "only read from %s is supported\n", tname); + return -EACCES; + } + + ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id); + if (ret < 0) + return ret; + + if (value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, btf_id); + return 0; } + /* check whether memory at (regno + off) is accessible for t = (read | write) * if t==write, value_regno is a register which value is stored into memory * if t==read, value_regno is a register which will receive the value from memory @@ -3363,6 +3425,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn } else if (reg->type == PTR_TO_BTF_ID) { err = check_ptr_to_btf_access(env, regs, regno, off, size, t, value_regno); + } else if (reg->type == CONST_PTR_TO_MAP) { + err = check_ptr_to_map_access(env, regs, regno, off, size, t, + value_regno); } else { verbose(env, "R%d invalid mem access '%s'\n", regno, reg_type_str[reg->type]); @@ -10951,6 +11016,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, env->strict_alignment = false; env->allow_ptr_leaks = bpf_allow_ptr_leaks(); + env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access(); env->bypass_spec_v1 = bpf_bypass_spec_v1(); env->bypass_spec_v4 = bpf_bypass_spec_v4(); env->bpf_capable = bpf_capable(); diff --git a/tools/testing/selftests/bpf/verifier/map_ptr_mixing.c b/tools/testing/selftests/bpf/verifier/map_ptr_mixing.c index cd26ee6b7b1d..1f2b8c4cb26d 100644 --- a/tools/testing/selftests/bpf/verifier/map_ptr_mixing.c +++ b/tools/testing/selftests/bpf/verifier/map_ptr_mixing.c @@ -56,7 +56,7 @@ .fixup_map_in_map = { 16 }, .fixup_map_array_48b = { 13 }, .result = REJECT, - .errstr = "R0 invalid mem access 'map_ptr'", + .errstr = "only read from bpf_array is supported", }, { "cond: two branches returning different map pointers for lookup (tail, tail)", |