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| author | Hao Luo <haoluo@google.com> | 2021-12-17 03:31:51 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-12-19 00:27:41 +0300 |
| commit | 216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20 (patch) | |
| tree | 2f384f14c9f5cc1441c17ce395cefa9577b872ee /kernel/bpf/syscall.c | |
| parent | 34d3a78c681e8e7844b43d1a2f4671a04249c821 (diff) | |
| download | linux-216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20.tar.xz | |
bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.
Some helper functions may modify its arguments, for example,
bpf_d_path, bpf_get_stack etc. Previously, their argument types
were marked as ARG_PTR_TO_MEM, which is compatible with read-only
mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate,
but technically incorrect, to modify a read-only memory by passing
it into one of such helper functions.
This patch tags the bpf_args compatible with immutable memory with
MEM_RDONLY flag. The arguments that don't have this flag will be
only compatible with mutable memory types, preventing the helper
from modifying a read-only memory. The bpf_args that have
MEM_RDONLY are compatible with both mutable memory and immutable
memory.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211217003152.48334-9-haoluo@google.com
Diffstat (limited to 'kernel/bpf/syscall.c')
| -rw-r--r-- | kernel/bpf/syscall.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index da07bdf71697..fa4505f9b611 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4773,7 +4773,7 @@ static const struct bpf_func_proto bpf_sys_bpf_proto = { .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_ANYTHING, - .arg2_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_PTR_TO_MEM | MEM_RDONLY, .arg3_type = ARG_CONST_SIZE, }; |