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author | Daniel Borkmann <daniel@iogearbox.net> | 2019-04-09 23:20:05 +0200 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2019-04-09 17:05:46 -0700 |
commit | 591fe9888d7809d9ee5c828020b6c6ae27c37229 (patch) | |
tree | 7032fc4e23d63b9cd0b301338e1bc49965eb175b /include/linux/bpf.h | |
parent | be70bcd53de66e86f2726e576307cbdaebd3b1a5 (diff) | |
download | linux-591fe9888d7809d9ee5c828020b6c6ae27c37229.tar.gz linux-591fe9888d7809d9ee5c828020b6c6ae27c37229.tar.bz2 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 'include/linux/bpf.h')
-rw-r--r-- | include/linux/bpf.h | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index bd93a592dd29..be20804631b5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -430,6 +430,35 @@ struct bpf_array { #define BPF_COMPLEXITY_LIMIT_INSNS 1000000 /* yes. 1M insns */ #define MAX_TAIL_CALL_CNT 32 +#define BPF_F_ACCESS_MASK (BPF_F_RDONLY | \ + BPF_F_RDONLY_PROG | \ + BPF_F_WRONLY | \ + BPF_F_WRONLY_PROG) + +#define BPF_MAP_CAN_READ BIT(0) +#define BPF_MAP_CAN_WRITE BIT(1) + +static inline u32 bpf_map_flags_to_cap(struct bpf_map *map) +{ + u32 access_flags = map->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG); + + /* Combination of BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG is + * not possible. + */ + if (access_flags & BPF_F_RDONLY_PROG) + return BPF_MAP_CAN_READ; + else if (access_flags & BPF_F_WRONLY_PROG) + return BPF_MAP_CAN_WRITE; + else + return BPF_MAP_CAN_READ | BPF_MAP_CAN_WRITE; +} + +static inline bool bpf_map_flags_access_ok(u32 access_flags) +{ + return (access_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG)) != + (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG); +} + struct bpf_event_entry { struct perf_event *event; struct file *perf_file; |