From 8e7ae2518f5265f0ef09d561748098fde5a87ccd Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 13 Mar 2020 18:02:09 -0700 Subject: bpf: Sanitize the bpf_struct_ops tcp-cc name The bpf_struct_ops tcp-cc name should be sanitized in order to avoid problematic chars (e.g. whitespaces). This patch reuses the bpf_obj_name_cpy() for accepting the same set of characters in order to keep a consistent bpf programming experience. A "size" param is added. Also, the strlen is returned on success so that the caller (like the bpf_tcp_ca here) can error out on empty name. The existing callers of the bpf_obj_name_cpy() only need to change the testing statement to "if (err < 0)". For all these existing callers, the err will be overwritten later, so no extra change is needed for the new strlen return value. v3: - reverse xmas tree style v2: - Save the orig_src to avoid "end - size" (Andrii) Fixes: 0baf26b0fcd7 ("bpf: tcp: Support tcp_congestion_ops in bpf") Signed-off-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200314010209.1131542-1-kafai@fb.com --- include/linux/bpf.h | 1 + kernel/bpf/syscall.c | 25 ++++++++++++++----------- net/ipv4/bpf_tcp_ca.c | 7 ++----- 3 files changed, 17 insertions(+), 16 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 49b1a70e12c8..212991f6f2a5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -160,6 +160,7 @@ static inline void copy_map_value(struct bpf_map *map, void *dst, void *src) } void copy_map_value_locked(struct bpf_map *map, void *dst, void *src, bool lock_src); +int bpf_obj_name_cpy(char *dst, const char *src, unsigned int size); struct bpf_offload_dev; struct bpf_offloaded_map; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0c7fb0d4836d..2857b7dda382 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -696,14 +696,15 @@ int bpf_get_file_flag(int flags) offsetof(union bpf_attr, CMD##_LAST_FIELD) - \ sizeof(attr->CMD##_LAST_FIELD)) != NULL -/* dst and src must have at least BPF_OBJ_NAME_LEN number of bytes. - * Return 0 on success and < 0 on error. +/* dst and src must have at least "size" number of bytes. + * Return strlen on success and < 0 on error. */ -static int bpf_obj_name_cpy(char *dst, const char *src) +int bpf_obj_name_cpy(char *dst, const char *src, unsigned int size) { - const char *end = src + BPF_OBJ_NAME_LEN; + const char *end = src + size; + const char *orig_src = src; - memset(dst, 0, BPF_OBJ_NAME_LEN); + memset(dst, 0, size); /* Copy all isalnum(), '_' and '.' chars. */ while (src < end && *src) { if (!isalnum(*src) && @@ -712,11 +713,11 @@ static int bpf_obj_name_cpy(char *dst, const char *src) *dst++ = *src++; } - /* No '\0' found in BPF_OBJ_NAME_LEN number of bytes */ + /* No '\0' found in "size" number of bytes */ if (src == end) return -EINVAL; - return 0; + return src - orig_src; } int map_check_no_btf(const struct bpf_map *map, @@ -810,8 +811,9 @@ static int map_create(union bpf_attr *attr) if (IS_ERR(map)) return PTR_ERR(map); - err = bpf_obj_name_cpy(map->name, attr->map_name); - if (err) + err = bpf_obj_name_cpy(map->name, attr->map_name, + sizeof(attr->map_name)); + if (err < 0) goto free_map; atomic64_set(&map->refcnt, 1); @@ -2098,8 +2100,9 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) goto free_prog; prog->aux->load_time = ktime_get_boottime_ns(); - err = bpf_obj_name_cpy(prog->aux->name, attr->prog_name); - if (err) + err = bpf_obj_name_cpy(prog->aux->name, attr->prog_name, + sizeof(attr->prog_name)); + if (err < 0) goto free_prog; /* run eBPF verifier */ diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 574972bc7299..2bf3abeb1456 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -184,7 +184,6 @@ static int bpf_tcp_ca_init_member(const struct btf_type *t, { const struct tcp_congestion_ops *utcp_ca; struct tcp_congestion_ops *tcp_ca; - size_t tcp_ca_name_len; int prog_fd; u32 moff; @@ -199,13 +198,11 @@ static int bpf_tcp_ca_init_member(const struct btf_type *t, tcp_ca->flags = utcp_ca->flags; return 1; case offsetof(struct tcp_congestion_ops, name): - tcp_ca_name_len = strnlen(utcp_ca->name, sizeof(utcp_ca->name)); - if (!tcp_ca_name_len || - tcp_ca_name_len == sizeof(utcp_ca->name)) + if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, + sizeof(tcp_ca->name)) <= 0) return -EINVAL; if (tcp_ca_find(utcp_ca->name)) return -EEXIST; - memcpy(tcp_ca->name, utcp_ca->name, sizeof(tcp_ca->name)); return 1; } -- cgit