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bpf: Add struct for bin_args arg in bpf_bprintf_prepare 

Adding struct bpf_bprintf_data to hold bin_args argument for
bpf_bprintf_prepare function.

We will add another return argument to bpf_bprintf_prepare and
pass the struct to bpf_bprintf_cleanup for proper cleanup in
following changes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221215214430.1336195-2-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2022-12-15 22:44:28 +01:00 committed by Daniel Borkmann
parent 0e43662e61
commit 78aa1cc940
4 changed files with 41 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
include/linux/bpf.h
View File

@ -2796,8 +2796,13 @@ bool btf_id_set_contains(const struct btf_id_set *set, u32 id);
#define MAX_BPRINTF_VARARGS 12
struct bpf_bprintf_data {
u32 *bin_args;
bool get_bin_args;
};
int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
u32 **bin_buf, u32 num_args);
u32 num_args, struct bpf_bprintf_data *data);
void bpf_bprintf_cleanup(void);
/* the implementation of the opaque uapi struct bpf_dynptr */

24
kernel/bpf/helpers.c
View File

@ -798,16 +798,16 @@ void bpf_bprintf_cleanup(void)
* Returns a negative value if fmt is an invalid format string or 0 otherwise.
*
* This can be used in two ways:
* - Format string verification only: when bin_args is NULL
* - Format string verification only: when data->get_bin_args is false
* - Arguments preparation: in addition to the above verification, it writes in
* bin_args a binary representation of arguments usable by bstr_printf where
* pointers from BPF have been sanitized.
* data->bin_args a binary representation of arguments usable by bstr_printf
* where pointers from BPF have been sanitized.
*
* In argument preparation mode, if 0 is returned, safe temporary buffers are
* allocated and bpf_bprintf_cleanup should be called to free them after use.
*/
int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
u32 **bin_args, u32 num_args)
u32 num_args, struct bpf_bprintf_data *data)
{
char *unsafe_ptr = NULL, *tmp_buf = NULL, *tmp_buf_end, *fmt_end;
size_t sizeof_cur_arg, sizeof_cur_ip;
@ -820,12 +820,12 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
return -EINVAL;
fmt_size = fmt_end - fmt;
if (bin_args) {
if (data->get_bin_args) {
if (num_args && try_get_fmt_tmp_buf(&tmp_buf))
return -EBUSY;
tmp_buf_end = tmp_buf + MAX_BPRINTF_BUF_LEN;
*bin_args = (u32 *)tmp_buf;
data->bin_args = (u32 *)tmp_buf;
}
for (i = 0; i < fmt_size; i++) {
@ -1026,24 +1026,26 @@ out:
}
BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt,
const void *, data, u32, data_len)
const void *, args, u32, data_len)
{
struct bpf_bprintf_data data = {
.get_bin_args = true,
};
int err, num_args;
u32 *bin_args;
if (data_len % 8 || data_len > MAX_BPRINTF_VARARGS * 8 ||
(data_len && !data))
(data_len && !args))
return -EINVAL;
num_args = data_len / 8;
/* ARG_PTR_TO_CONST_STR guarantees that fmt is zero-terminated so we
* can safely give an unbounded size.
*/
err = bpf_bprintf_prepare(fmt, UINT_MAX, data, &bin_args, num_args);
err = bpf_bprintf_prepare(fmt, UINT_MAX, args, num_args, &data);
if (err < 0)
return err;
err = bstr_printf(str, str_size, fmt, bin_args);
err = bstr_printf(str, str_size, fmt, data.bin_args);
bpf_bprintf_cleanup();

3
kernel/bpf/verifier.c
View File

@ -7612,6 +7612,7 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
struct bpf_reg_state *fmt_reg = &regs[BPF_REG_3];
struct bpf_reg_state *data_len_reg = &regs[BPF_REG_5];
struct bpf_map *fmt_map = fmt_reg->map_ptr;
struct bpf_bprintf_data data = {};
int err, fmt_map_off, num_args;
u64 fmt_addr;
char *fmt;
@ -7636,7 +7637,7 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
/* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
* can focus on validating the format specifiers.
*/
err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, NULL, num_args);
err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data);
if (err < 0)
verbose(env, "Invalid format string\n");

34
kernel/trace/bpf_trace.c
View File

@ -378,18 +378,20 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
u64, arg2, u64, arg3)
{
u64 args[MAX_TRACE_PRINTK_VARARGS] = { arg1, arg2, arg3 };
u32 *bin_args;
struct bpf_bprintf_data data = {
.get_bin_args = true,
};
static char buf[BPF_TRACE_PRINTK_SIZE];
unsigned long flags;
int ret;
ret = bpf_bprintf_prepare(fmt, fmt_size, args, &bin_args,
MAX_TRACE_PRINTK_VARARGS);
ret = bpf_bprintf_prepare(fmt, fmt_size, args,
MAX_TRACE_PRINTK_VARARGS, &data);
if (ret < 0)
return ret;
raw_spin_lock_irqsave(&trace_printk_lock, flags);
ret = bstr_printf(buf, sizeof(buf), fmt, bin_args);
ret = bstr_printf(buf, sizeof(buf), fmt, data.bin_args);
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
@ -427,25 +429,27 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
return &bpf_trace_printk_proto;
}
BPF_CALL_4(bpf_trace_vprintk, char *, fmt, u32, fmt_size, const void *, data,
BPF_CALL_4(bpf_trace_vprintk, char *, fmt, u32, fmt_size, const void *, args,
u32, data_len)
{
struct bpf_bprintf_data data = {
.get_bin_args = true,
};
static char buf[BPF_TRACE_PRINTK_SIZE];
unsigned long flags;
int ret, num_args;
u32 *bin_args;
if (data_len & 7 || data_len > MAX_BPRINTF_VARARGS * 8 ||
(data_len && !data))
(data_len && !args))
return -EINVAL;
num_args = data_len / 8;
ret = bpf_bprintf_prepare(fmt, fmt_size, data, &bin_args, num_args);
ret = bpf_bprintf_prepare(fmt, fmt_size, args, num_args, &data);
if (ret < 0)
return ret;
raw_spin_lock_irqsave(&trace_printk_lock, flags);
ret = bstr_printf(buf, sizeof(buf), fmt, bin_args);
ret = bstr_printf(buf, sizeof(buf), fmt, data.bin_args);
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
@ -472,21 +476,23 @@ const struct bpf_func_proto *bpf_get_trace_vprintk_proto(void)
}
BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
const void *, data, u32, data_len)
const void *, args, u32, data_len)
{
struct bpf_bprintf_data data = {
.get_bin_args = true,
};
int err, num_args;
u32 *bin_args;
if (data_len & 7 || data_len > MAX_BPRINTF_VARARGS * 8 ||
(data_len && !data))
(data_len && !args))
return -EINVAL;
num_args = data_len / 8;
err = bpf_bprintf_prepare(fmt, fmt_size, data, &bin_args, num_args);
err = bpf_bprintf_prepare(fmt, fmt_size, args, num_args, &data);
if (err < 0)
return err;
seq_bprintf(m, fmt, bin_args);
seq_bprintf(m, fmt, data.bin_args);
bpf_bprintf_cleanup();