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| author | Hao Luo <haoluo@google.com> | 2022-04-29 02:57:49 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-01 18:22:26 +0300 |
| commit | 2a77c58726aba893129a369ed3d2be004dda41cd (patch) | |
| tree | ba67c8a18a0e49b9e274345f1d0cf254d300b349 /include/linux/bpf.h | |
| parent | 15166bb3000fc8b5faa8fa606eb25d300e6892ef (diff) | |
| download | linux-2a77c58726aba893129a369ed3d2be004dda41cd.tar.xz | |
bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.
commit 216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20 upstream.
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
Cc: stable@vger.kernel.org # 5.15.x
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/bpf.h')
| -rw-r--r-- | include/linux/bpf.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1cb5aae0fcb6..c5c4b6f09e23 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -307,7 +307,9 @@ enum bpf_type_flag { /* PTR may be NULL. */ PTR_MAYBE_NULL = BIT(0 + BPF_BASE_TYPE_BITS), - /* MEM is read-only. */ + /* MEM is read-only. When applied on bpf_arg, it indicates the arg is + * compatible with both mutable and immutable memory. + */ MEM_RDONLY = BIT(1 + BPF_BASE_TYPE_BITS), __BPF_TYPE_LAST_FLAG = MEM_RDONLY, |