From 5e7b30205cef80f6bb922e61834437ca7bff5837 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 4 Aug 2020 22:50:56 -0700 Subject: bpf: Change uapi for bpf iterator map elements Commit a5cbe05a6673 ("bpf: Implement bpf iterator for map elements") added bpf iterator support for map elements. The map element bpf iterator requires info to identify a particular map. In the above commit, the attr->link_create.target_fd is used to carry map_fd and an enum bpf_iter_link_info is added to uapi to specify the target_fd actually representing a map_fd: enum bpf_iter_link_info { BPF_ITER_LINK_UNSPEC = 0, BPF_ITER_LINK_MAP_FD = 1, MAX_BPF_ITER_LINK_INFO, }; This is an extensible approach as we can grow enumerator for pid, cgroup_id, etc. and we can unionize target_fd for pid, cgroup_id, etc. But in the future, there are chances that more complex customization may happen, e.g., for tasks, it could be filtered based on both cgroup_id and user_id. This patch changed the uapi to have fields __aligned_u64 iter_info; __u32 iter_info_len; for additional iter_info for link_create. The iter_info is defined as union bpf_iter_link_info { struct { __u32 map_fd; } map; }; So future extension for additional customization will be easier. The bpf_iter_link_info will be passed to target callback to validate and generic bpf_iter framework does not need to deal it any more. Note that map_fd = 0 will be considered invalid and -EBADF will be returned to user space. Fixes: a5cbe05a6673 ("bpf: Implement bpf iterator for map elements") Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200805055056.1457463-1-yhs@fb.com --- include/linux/bpf.h | 10 ++++---- include/uapi/linux/bpf.h | 15 ++++++------ kernel/bpf/bpf_iter.c | 58 +++++++++++++++++++++++------------------------ kernel/bpf/map_iter.c | 37 +++++++++++++++++++++++------- kernel/bpf/syscall.c | 2 +- net/core/bpf_sk_storage.c | 37 +++++++++++++++++++++++------- 6 files changed, 102 insertions(+), 57 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cef4ef0d2b4e..55f694b63164 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1214,15 +1214,17 @@ struct bpf_iter_aux_info { struct bpf_map *map; }; -typedef int (*bpf_iter_check_target_t)(struct bpf_prog *prog, - struct bpf_iter_aux_info *aux); +typedef int (*bpf_iter_attach_target_t)(struct bpf_prog *prog, + union bpf_iter_link_info *linfo, + struct bpf_iter_aux_info *aux); +typedef void (*bpf_iter_detach_target_t)(struct bpf_iter_aux_info *aux); #define BPF_ITER_CTX_ARG_MAX 2 struct bpf_iter_reg { const char *target; - bpf_iter_check_target_t check_target; + bpf_iter_attach_target_t attach_target; + bpf_iter_detach_target_t detach_target; u32 ctx_arg_info_size; - enum bpf_iter_link_info req_linfo; struct bpf_ctx_arg_aux ctx_arg_info[BPF_ITER_CTX_ARG_MAX]; const struct bpf_iter_seq_info *seq_info; }; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b134e679e9db..0480f893facd 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -81,6 +81,12 @@ struct bpf_cgroup_storage_key { __u32 attach_type; /* program attach type */ }; +union bpf_iter_link_info { + struct { + __u32 map_fd; + } map; +}; + /* BPF syscall commands, see bpf(2) man-page for details. */ enum bpf_cmd { BPF_MAP_CREATE, @@ -249,13 +255,6 @@ enum bpf_link_type { MAX_BPF_LINK_TYPE, }; -enum bpf_iter_link_info { - BPF_ITER_LINK_UNSPEC = 0, - BPF_ITER_LINK_MAP_FD = 1, - - MAX_BPF_ITER_LINK_INFO, -}; - /* cgroup-bpf attach flags used in BPF_PROG_ATTACH command * * NONE(default): No further bpf programs allowed in the subtree. @@ -623,6 +622,8 @@ union bpf_attr { }; __u32 attach_type; /* attach type */ __u32 flags; /* extra flags */ + __aligned_u64 iter_info; /* extra bpf_iter_link_info */ + __u32 iter_info_len; /* iter_info length */ } link_create; struct { /* struct used by BPF_LINK_UPDATE command */ diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index 363b9cafc2d8..b6715964b685 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -338,8 +338,8 @@ static void bpf_iter_link_release(struct bpf_link *link) struct bpf_iter_link *iter_link = container_of(link, struct bpf_iter_link, link); - if (iter_link->aux.map) - bpf_map_put_with_uref(iter_link->aux.map); + if (iter_link->tinfo->reg_info->detach_target) + iter_link->tinfo->reg_info->detach_target(&iter_link->aux); } static void bpf_iter_link_dealloc(struct bpf_link *link) @@ -390,15 +390,35 @@ bool bpf_link_is_iter(struct bpf_link *link) int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) { + union bpf_iter_link_info __user *ulinfo; struct bpf_link_primer link_primer; struct bpf_iter_target_info *tinfo; - struct bpf_iter_aux_info aux = {}; + union bpf_iter_link_info linfo; struct bpf_iter_link *link; - u32 prog_btf_id, target_fd; + u32 prog_btf_id, linfo_len; bool existed = false; - struct bpf_map *map; int err; + if (attr->link_create.target_fd || attr->link_create.flags) + return -EINVAL; + + memset(&linfo, 0, sizeof(union bpf_iter_link_info)); + + ulinfo = u64_to_user_ptr(attr->link_create.iter_info); + linfo_len = attr->link_create.iter_info_len; + if (!ulinfo ^ !linfo_len) + return -EINVAL; + + if (ulinfo) { + err = bpf_check_uarg_tail_zero(ulinfo, sizeof(linfo), + linfo_len); + if (err) + return err; + linfo_len = min_t(u32, linfo_len, sizeof(linfo)); + if (copy_from_user(&linfo, ulinfo, linfo_len)) + return -EFAULT; + } + prog_btf_id = prog->aux->attach_btf_id; mutex_lock(&targets_mutex); list_for_each_entry(tinfo, &targets, list) { @@ -411,13 +431,6 @@ int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) if (!existed) return -ENOENT; - /* Make sure user supplied flags are target expected. */ - target_fd = attr->link_create.target_fd; - if (attr->link_create.flags != tinfo->reg_info->req_linfo) - return -EINVAL; - if (!attr->link_create.flags && target_fd) - return -EINVAL; - link = kzalloc(sizeof(*link), GFP_USER | __GFP_NOWARN); if (!link) return -ENOMEM; @@ -431,28 +444,15 @@ int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) return err; } - if (tinfo->reg_info->req_linfo == BPF_ITER_LINK_MAP_FD) { - map = bpf_map_get_with_uref(target_fd); - if (IS_ERR(map)) { - err = PTR_ERR(map); - goto cleanup_link; - } - - aux.map = map; - err = tinfo->reg_info->check_target(prog, &aux); + if (tinfo->reg_info->attach_target) { + err = tinfo->reg_info->attach_target(prog, &linfo, &link->aux); if (err) { - bpf_map_put_with_uref(map); - goto cleanup_link; + bpf_link_cleanup(&link_primer); + return err; } - - link->aux.map = map; } return bpf_link_settle(&link_primer); - -cleanup_link: - bpf_link_cleanup(&link_primer); - return err; } static void init_seq_meta(struct bpf_iter_priv_data *priv_data, diff --git a/kernel/bpf/map_iter.c b/kernel/bpf/map_iter.c index fbe1f557cb88..af86048e5afd 100644 --- a/kernel/bpf/map_iter.c +++ b/kernel/bpf/map_iter.c @@ -98,12 +98,21 @@ static struct bpf_iter_reg bpf_map_reg_info = { .seq_info = &bpf_map_seq_info, }; -static int bpf_iter_check_map(struct bpf_prog *prog, - struct bpf_iter_aux_info *aux) +static int bpf_iter_attach_map(struct bpf_prog *prog, + union bpf_iter_link_info *linfo, + struct bpf_iter_aux_info *aux) { u32 key_acc_size, value_acc_size, key_size, value_size; - struct bpf_map *map = aux->map; + struct bpf_map *map; bool is_percpu = false; + int err = -EINVAL; + + if (!linfo->map.map_fd) + return -EBADF; + + map = bpf_map_get_with_uref(linfo->map.map_fd); + if (IS_ERR(map)) + return PTR_ERR(map); if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH || map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH || @@ -112,7 +121,7 @@ static int bpf_iter_check_map(struct bpf_prog *prog, else if (map->map_type != BPF_MAP_TYPE_HASH && map->map_type != BPF_MAP_TYPE_LRU_HASH && map->map_type != BPF_MAP_TYPE_ARRAY) - return -EINVAL; + goto put_map; key_acc_size = prog->aux->max_rdonly_access; value_acc_size = prog->aux->max_rdwr_access; @@ -122,10 +131,22 @@ static int bpf_iter_check_map(struct bpf_prog *prog, else value_size = round_up(map->value_size, 8) * num_possible_cpus(); - if (key_acc_size > key_size || value_acc_size > value_size) - return -EACCES; + if (key_acc_size > key_size || value_acc_size > value_size) { + err = -EACCES; + goto put_map; + } + aux->map = map; return 0; + +put_map: + bpf_map_put_with_uref(map); + return err; +} + +static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux) +{ + bpf_map_put_with_uref(aux->map); } DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta, @@ -133,8 +154,8 @@ DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta, static const struct bpf_iter_reg bpf_map_elem_reg_info = { .target = "bpf_map_elem", - .check_target = bpf_iter_check_map, - .req_linfo = BPF_ITER_LINK_MAP_FD, + .attach_target = bpf_iter_attach_map, + .detach_target = bpf_iter_detach_map, .ctx_arg_info_size = 2, .ctx_arg_info = { { offsetof(struct bpf_iter__bpf_map_elem, key), diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 2f343ce15747..86299a292214 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3883,7 +3883,7 @@ static int tracing_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog * return -EINVAL; } -#define BPF_LINK_CREATE_LAST_FIELD link_create.flags +#define BPF_LINK_CREATE_LAST_FIELD link_create.iter_info_len static int link_create(union bpf_attr *attr) { enum bpf_prog_type ptype; diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index d3377c90a291..b988f48153a4 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -1384,18 +1384,39 @@ static int bpf_iter_init_sk_storage_map(void *priv_data, return 0; } -static int bpf_iter_check_map(struct bpf_prog *prog, - struct bpf_iter_aux_info *aux) +static int bpf_iter_attach_map(struct bpf_prog *prog, + union bpf_iter_link_info *linfo, + struct bpf_iter_aux_info *aux) { - struct bpf_map *map = aux->map; + struct bpf_map *map; + int err = -EINVAL; + + if (!linfo->map.map_fd) + return -EBADF; + + map = bpf_map_get_with_uref(linfo->map.map_fd); + if (IS_ERR(map)) + return PTR_ERR(map); if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) - return -EINVAL; + goto put_map; - if (prog->aux->max_rdonly_access > map->value_size) - return -EACCES; + if (prog->aux->max_rdonly_access > map->value_size) { + err = -EACCES; + goto put_map; + } + aux->map = map; return 0; + +put_map: + bpf_map_put_with_uref(map); + return err; +} + +static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux) +{ + bpf_map_put_with_uref(aux->map); } static const struct seq_operations bpf_sk_storage_map_seq_ops = { @@ -1414,8 +1435,8 @@ static const struct bpf_iter_seq_info iter_seq_info = { static struct bpf_iter_reg bpf_sk_storage_map_reg_info = { .target = "bpf_sk_storage_map", - .check_target = bpf_iter_check_map, - .req_linfo = BPF_ITER_LINK_MAP_FD, + .attach_target = bpf_iter_attach_map, + .detach_target = bpf_iter_detach_map, .ctx_arg_info_size = 2, .ctx_arg_info = { { offsetof(struct bpf_iter__bpf_sk_storage_map, sk), -- cgit v1.2.3