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author | Daniel Borkmann <daniel@iogearbox.net> | 2019-04-09 23:20:05 +0200 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2019-04-10 02:05:46 +0200 |
commit | 591fe9888d7809d9ee5c828020b6c6ae27c37229 (patch) | |
tree | 7032fc4e23d63b9cd0b301338e1bc49965eb175b /kernel/bpf/arraymap.c | |
parent | bpf: do not retain flags that are not tied to map lifetime (diff) | |
download | linux-591fe9888d7809d9ee5c828020b6c6ae27c37229.tar.xz linux-591fe9888d7809d9ee5c828020b6c6ae27c37229.zip |
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/arraymap.c')
-rw-r--r-- | kernel/bpf/arraymap.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 1a6e9861d554..217b10bd9f48 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -22,7 +22,7 @@ #include "map_in_map.h" #define ARRAY_CREATE_FLAG_MASK \ - (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY) + (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK) static void bpf_array_free_percpu(struct bpf_array *array) { @@ -63,6 +63,7 @@ int array_map_alloc_check(union bpf_attr *attr) if (attr->max_entries == 0 || attr->key_size != 4 || attr->value_size == 0 || attr->map_flags & ~ARRAY_CREATE_FLAG_MASK || + !bpf_map_flags_access_ok(attr->map_flags) || (percpu && numa_node != NUMA_NO_NODE)) return -EINVAL; @@ -472,6 +473,9 @@ static int fd_array_map_alloc_check(union bpf_attr *attr) /* only file descriptors can be stored in this type of map */ if (attr->value_size != sizeof(u32)) return -EINVAL; + /* Program read-only/write-only not supported for special maps yet. */ + if (attr->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG)) + return -EINVAL; return array_map_alloc_check(attr); } |