From 92117d8443bc5afacc8d5ba82e541946310f106e Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 27 Apr 2016 18:56:20 -0700 Subject: bpf: fix refcnt overflow On a system with >32Gbyte of phyiscal memory and infinite RLIMIT_MEMLOCK, the malicious application may overflow 32-bit bpf program refcnt. It's also possible to overflow map refcnt on 1Tb system. Impose 32k hard limit which means that the same bpf program or map cannot be shared by more than 32k processes. Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs") Reported-by: Jann Horn Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/bpf/verifier.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'kernel/bpf/verifier.c') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index db2574e7b8b0..89bcaa0966da 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2049,15 +2049,18 @@ static int replace_map_fd_with_map_ptr(struct verifier_env *env) return -E2BIG; } - /* remember this map */ - env->used_maps[env->used_map_cnt++] = map; - /* hold the map. If the program is rejected by verifier, * the map will be released by release_maps() or it * will be used by the valid program until it's unloaded * and all maps are released in free_bpf_prog_info() */ - bpf_map_inc(map, false); + map = bpf_map_inc(map, false); + if (IS_ERR(map)) { + fdput(f); + return PTR_ERR(map); + } + env->used_maps[env->used_map_cnt++] = map; + fdput(f); next_insn: insn++; -- cgit v1.2.3 From 6aff67c85c9e5a4bc99e5211c1bac547936626ca Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 27 Apr 2016 18:56:21 -0700 Subject: bpf: fix check_map_func_compatibility logic The commit 35578d798400 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter") introduced clever way to check bpf_helper<->map_type compatibility. Later on commit a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") adjusted the logic and inadvertently broke it. Get rid of the clever bool compare and go back to two-way check from map and from helper perspective. Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") Reported-by: Jann Horn Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/bpf/verifier.c | 65 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 40 insertions(+), 25 deletions(-) (limited to 'kernel/bpf/verifier.c') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 89bcaa0966da..c5c17a62f509 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -239,16 +239,6 @@ static const char * const reg_type_str[] = { [CONST_IMM] = "imm", }; -static const struct { - int map_type; - int func_id; -} func_limit[] = { - {BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call}, - {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read}, - {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_output}, - {BPF_MAP_TYPE_STACK_TRACE, BPF_FUNC_get_stackid}, -}; - static void print_verifier_state(struct verifier_env *env) { enum bpf_reg_type t; @@ -921,27 +911,52 @@ static int check_func_arg(struct verifier_env *env, u32 regno, static int check_map_func_compatibility(struct bpf_map *map, int func_id) { - bool bool_map, bool_func; - int i; - if (!map) return 0; - for (i = 0; i < ARRAY_SIZE(func_limit); i++) { - bool_map = (map->map_type == func_limit[i].map_type); - bool_func = (func_id == func_limit[i].func_id); - /* only when map & func pair match it can continue. - * don't allow any other map type to be passed into - * the special func; - */ - if (bool_func && bool_map != bool_func) { - verbose("cannot pass map_type %d into func %d\n", - map->map_type, func_id); - return -EINVAL; - } + /* We need a two way check, first is from map perspective ... */ + switch (map->map_type) { + case BPF_MAP_TYPE_PROG_ARRAY: + if (func_id != BPF_FUNC_tail_call) + goto error; + break; + case BPF_MAP_TYPE_PERF_EVENT_ARRAY: + if (func_id != BPF_FUNC_perf_event_read && + func_id != BPF_FUNC_perf_event_output) + goto error; + break; + case BPF_MAP_TYPE_STACK_TRACE: + if (func_id != BPF_FUNC_get_stackid) + goto error; + break; + default: + break; + } + + /* ... and second from the function itself. */ + switch (func_id) { + case BPF_FUNC_tail_call: + if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) + goto error; + break; + case BPF_FUNC_perf_event_read: + case BPF_FUNC_perf_event_output: + if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) + goto error; + break; + case BPF_FUNC_get_stackid: + if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) + goto error; + break; + default: + break; } return 0; +error: + verbose("cannot pass map_type %d into func %d\n", + map->map_type, func_id); + return -EINVAL; } static int check_call(struct verifier_env *env, int func_id) -- cgit v1.2.3