diff options
author | David S. Miller <davem@davemloft.net> | 2020-02-29 15:53:35 -0800 |
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committer | David S. Miller <davem@davemloft.net> | 2020-02-29 15:53:35 -0800 |
commit | 9f0ca0c1a50a7de5c71970aa452941199ed210d9 (patch) | |
tree | b7e19ab2e5bbc951141fb90489923b50b8f263f3 /kernel/bpf/verifier.c | |
parent | 9a834f9b04bc5ed2db27eb45b0cc6415ce7c314c (diff) | |
parent | 812285fa5ab129e3a55682314bf235f701564310 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says:
====================
pull-request: bpf-next 2020-02-28
The following pull-request contains BPF updates for your *net-next* tree.
We've added 41 non-merge commits during the last 7 day(s) which contain
a total of 49 files changed, 1383 insertions(+), 499 deletions(-).
The main changes are:
1) BPF and Real-Time nicely co-exist.
2) bpftool feature improvements.
3) retrieve bpf_sk_storage via INET_DIAG.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r-- | kernel/bpf/verifier.c | 40 |
1 files changed, 31 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6d15dfbd4b88..289383edfc8c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8143,26 +8143,48 @@ static bool is_tracing_prog_type(enum bpf_prog_type type) } } +static bool is_preallocated_map(struct bpf_map *map) +{ + if (!check_map_prealloc(map)) + return false; + if (map->inner_map_meta && !check_map_prealloc(map->inner_map_meta)) + return false; + return true; +} + static int check_map_prog_compatibility(struct bpf_verifier_env *env, struct bpf_map *map, struct bpf_prog *prog) { - /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use - * preallocated hash maps, since doing memory allocation - * in overflow_handler can crash depending on where nmi got - * triggered. + /* + * Validate that trace type programs use preallocated hash maps. + * + * For programs attached to PERF events this is mandatory as the + * perf NMI can hit any arbitrary code sequence. + * + * All other trace types using preallocated hash maps are unsafe as + * well because tracepoint or kprobes can be inside locked regions + * of the memory allocator or at a place where a recursion into the + * memory allocator would see inconsistent state. + * + * On RT enabled kernels run-time allocation of all trace type + * programs is strictly prohibited due to lock type constraints. On + * !RT kernels it is allowed for backwards compatibility reasons for + * now, but warnings are emitted so developers are made aware of + * the unsafety and can fix their programs before this is enforced. */ - if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { - if (!check_map_prealloc(map)) { + if (is_tracing_prog_type(prog->type) && !is_preallocated_map(map)) { + if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { verbose(env, "perf_event programs can only use preallocated hash map\n"); return -EINVAL; } - if (map->inner_map_meta && - !check_map_prealloc(map->inner_map_meta)) { - verbose(env, "perf_event programs can only use preallocated inner hash map\n"); + if (IS_ENABLED(CONFIG_PREEMPT_RT)) { + verbose(env, "trace type programs can only use preallocated hash map\n"); return -EINVAL; } + WARN_ONCE(1, "trace type BPF program uses run-time allocation\n"); + verbose(env, "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n"); } if ((is_tracing_prog_type(prog->type) || |