Commit 430e68d1 authored by Quentin Monnet's avatar Quentin Monnet Committed by Daniel Borkmann
Browse files

bpf: export function to write into verifier log buffer 



Rename the BPF verifier `verbose()` to `bpf_verifier_log_write()` and
export it, so that other components (in particular, drivers for BPF
offload) can reuse the user buffer log to dump error messages at
verification time.

Renaming `verbose()` was necessary in order to avoid a name so generic
to be exported to the global namespace. However to prevent too much pain
for backports, the calls to `verbose()` in the kernel BPF verifier were
not changed. Instead, use function aliasing to make `verbose` point to
`bpf_verifier_log_write`. Another solution could consist in making a
wrapper around `verbose()`, but since it is a variadic function, I don't
see a clean way without creating two identical wrappers, one for the
verifier and one to export.

Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent c087aa8b

include/linux/bpf_verifier.h

+3 −0
Original line number Diff line number Diff line
@@ -192,6 +192,9 @@ struct bpf_verifier_env { 
	u32 subprog_cnt;

};



__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,

					   const char *fmt, ...);



static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)

{

	struct bpf_verifier_state *cur = env->cur_state;

kernel/bpf/verifier.c

+12 −4
Original line number Diff line number Diff line
@@ -169,10 +169,10 @@ struct bpf_call_arg_meta { 
static DEFINE_MUTEX(bpf_verifier_lock);



/* log_level controls verbosity level of eBPF verifier.

 * verbose() is used to dump the verification trace to the log, so the user

 * can figure out what's wrong with the program

 * bpf_verifier_log_write() is used to dump the verification trace to the log,

 * so the user can figure out what's wrong with the program

 */

static __printf(2, 3) void verbose(struct bpf_verifier_env *env,

__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,

					   const char *fmt, ...)

{

	struct bpf_verifer_log *log = &env->log;
@@ -197,6 +197,14 @@ static __printf(2, 3) void verbose(struct bpf_verifier_env *env, 
	else

		log->ubuf = NULL;

}

EXPORT_SYMBOL_GPL(bpf_verifier_log_write);

/* Historically bpf_verifier_log_write was called verbose, but the name was too

 * generic for symbol export. The function was renamed, but not the calls in

 * the verifier to avoid complicating backports. Hence the alias below.

 */

static __printf(2, 3) void verbose(struct bpf_verifier_env *env,

				   const char *fmt, ...)

	__attribute__((alias("bpf_verifier_log_write")));



static bool type_is_pkt_pointer(enum bpf_reg_type type)

{

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