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

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3de24cf..cc390ba 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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 */

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index af30c6c..7dbf6bb 100644 (file)
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -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();
 

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a5255a0..faa358b 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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");
 

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3bbd3f0..3e849c3 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -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();