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| author |  Hao Luo <haoluo@google.com>
| 2021-12-16 16:31:51 -0800 |
|---|---|---|
| committer |  Alexei Starovoitov <ast@kernel.org>
| 2021-12-18 13:27:41 -0800 |
| commit | 216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20 (patch) | |
| tree | 2f384f14c9f5cc1441c17ce395cefa9577b872ee /include/linux/bpf.h | |
| parent | bpf: Make per_cpu_ptr return rdonly PTR_TO_MEM. (diff) | |
| download | linux-216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20.tar.gz linux-216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20.tar.bz2 linux-216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20.zip | |
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 '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 567d83bf28f9..26753139d5b4 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -311,7 +311,9 @@ 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, |