diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2019-04-09 23:20:05 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2019-04-09 17:05:46 -0700 |
| commit | 591fe9888d7809d9ee5c828020b6c6ae27c37229 (patch) | |
| tree | 7032fc4e23d63b9cd0b301338e1bc49965eb175b /kernel/bpf/hashtab.c | |
| parent | be70bcd53de66e86f2726e576307cbdaebd3b1a5 (diff) | |
bpf: add program side {rd, wr}only support for maps
This work adds two new map creation flags BPF_F_RDONLY_PROG
and BPF_F_WRONLY_PROG in order to allow for read-only or
write-only BPF maps from a BPF program side.
Today we have BPF_F_RDONLY and BPF_F_WRONLY, but this only
applies to system call side, meaning the BPF program has full
read/write access to the map as usual while bpf(2) calls with
map fd can either only read or write into the map depending
on the flags. BPF_F_RDONLY_PROG and BPF_F_WRONLY_PROG allows
for the exact opposite such that verifier is going to reject
program loads if write into a read-only map or a read into a
write-only map is detected. For read-only map case also some
helpers are forbidden for programs that would alter the map
state such as map deletion, update, etc. As opposed to the two
BPF_F_RDONLY / BPF_F_WRONLY flags, BPF_F_RDONLY_PROG as well
as BPF_F_WRONLY_PROG really do correspond to the map lifetime.
We've enabled this generic map extension to various non-special
maps holding normal user data: array, hash, lru, lpm, local
storage, queue and stack. Further generic map types could be
followed up in future depending on use-case. Main use case
here is to forbid writes into .rodata map values from verifier
side.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/hashtab.c')
| -rw-r--r-- | kernel/bpf/hashtab.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index fed15cf94dca..192d32e77db3 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -23,7 +23,7 @@ #define HTAB_CREATE_FLAG_MASK \ (BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE | \ - BPF_F_RDONLY | BPF_F_WRONLY | BPF_F_ZERO_SEED) + BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED) struct bucket { struct hlist_nulls_head head; @@ -262,8 +262,8 @@ static int htab_map_alloc_check(union bpf_attr *attr) /* Guard against local DoS, and discourage production use. */ return -EPERM; - if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK) - /* reserved bits should not be used */ + if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK || + !bpf_map_flags_access_ok(attr->map_flags)) return -EINVAL; if (!lru && percpu_lru) |