diff options
| author | Andrii Nakryiko <andrii@kernel.org> | 2024-02-12 15:32:20 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-02-13 18:46:47 -0800 |
| commit | 879bbe7aa4afa80acf72a1cad7f52416ea78c52d (patch) | |
| tree | 7167d3b75c871d1ba5001c27c13a751e2f0b77a8 /kernel/bpf | |
| parent | 824c58fb1090ae5e502284400682e30841280a87 (diff) | |
bpf: don't infer PTR_TO_CTX for programs with unnamed context type
For program types that don't have named context type name (e.g., BPF
iterator programs or tracepoint programs), ctx_tname will be a non-NULL
empty string. For such programs it shouldn't be possible to have
PTR_TO_CTX argument for global subprogs based on type name alone.
arg:ctx tag is the only way to have PTR_TO_CTX passed into global
subprog for such program types.
Fix this loophole, which currently would assume PTR_TO_CTX whenever
user uses a pointer to anonymous struct as an argument to their global
subprogs. This happens in practice with the following (quite common, in
practice) approach:
typedef struct { /* anonymous */
int x;
} my_type_t;
int my_subprog(my_type_t *arg) { ... }
User's intent is to have PTR_TO_MEM argument for `arg`, but verifier
will complain about expecting PTR_TO_CTX.
This fix also closes unintended s390x-specific KPROBE handling of
PTR_TO_CTX case. Selftest change is necessary to accommodate this.
Fixes: 91cc1a99740e ("bpf: Annotate context types")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240212233221.2575350-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/btf.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 26dc0876e426..6ff0bd1a91d5 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5746,6 +5746,9 @@ again: bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n"); return false; } + /* program types without named context types work only with arg:ctx tag */ + if (ctx_tname[0] == '\0') + return false; /* only compare that prog's ctx type name is the same as * kernel expects. No need to compare field by field. * It's ok for bpf prog to do: |