diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ff8cd68c01b3..f8a45f109e96 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -309,6 +309,7 @@ enum bpf_arg_type { ARG_PTR_TO_PERCPU_BTF_ID, /* pointer to in-kernel percpu type */ ARG_PTR_TO_FUNC, /* pointer to a bpf program function */ ARG_PTR_TO_STACK_OR_NULL, /* pointer to stack or NULL */ + ARG_PTR_TO_CONST_STR, /* pointer to a null terminated read-only string */ __BPF_ARG_TYPE_MAX, }; @@ -1952,6 +1953,7 @@ extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto; extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto; extern const struct bpf_func_proto bpf_copy_from_user_proto; extern const struct bpf_func_proto bpf_snprintf_btf_proto; +extern const struct bpf_func_proto bpf_snprintf_proto; extern const struct bpf_func_proto bpf_per_cpu_ptr_proto; extern const struct bpf_func_proto bpf_this_cpu_ptr_proto; extern const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto; @@ -2077,4 +2079,24 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, struct btf_id_set; bool btf_id_set_contains(const struct btf_id_set *set, u32 id); +enum bpf_printf_mod_type { + BPF_PRINTF_INT, + BPF_PRINTF_LONG, + BPF_PRINTF_LONG_LONG, +}; + +/* Workaround for getting va_list handling working with different argument type + * combinations generically for 32 and 64 bit archs. + */ +#define BPF_CAST_FMT_ARG(arg_nb, args, mod) \ + (mod[arg_nb] == BPF_PRINTF_LONG_LONG || \ + (mod[arg_nb] == BPF_PRINTF_LONG && __BITS_PER_LONG == 64) \ + ? (u64)args[arg_nb] \ + : (u32)args[arg_nb]) + +int bpf_printf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, + u64 *final_args, enum bpf_printf_mod_type *mod, + u32 num_args); +void bpf_printf_cleanup(void); + #endif /* _LINUX_BPF_H */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index df164a44bb41..ec6d85a81744 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4708,6 +4708,33 @@ union bpf_attr { * Return * The number of traversed map elements for success, **-EINVAL** for * invalid **flags**. + * + * long bpf_snprintf(char *str, u32 str_size, const char *fmt, u64 *data, u32 data_len) + * Description + * Outputs a string into the **str** buffer of size **str_size** + * based on a format string stored in a read-only map pointed by + * **fmt**. + * + * Each format specifier in **fmt** corresponds to one u64 element + * in the **data** array. For strings and pointers where pointees + * are accessed, only the pointer values are stored in the *data* + * array. The *data_len* is the size of *data* in bytes. + * + * Formats **%s** and **%p{i,I}{4,6}** require to read kernel + * memory. Reading kernel memory may fail due to either invalid + * address or valid address but requiring a major memory fault. If + * reading kernel memory fails, the string for **%s** will be an + * empty string, and the ip address for **%p{i,I}{4,6}** will be 0. + * Not returning error to bpf program is consistent with what + * **bpf_trace_printk**\ () does for now. + * + * Return + * The strictly positive length of the formatted string, including + * the trailing zero character. If the return value is greater than + * **str_size**, **str** contains a truncated string, guaranteed to + * be zero-terminated except when **str_size** is 0. + * + * Or **-EBUSY** if the per-CPU memory copy buffer is busy. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -4875,6 +4902,7 @@ union bpf_attr { FN(sock_from_file), \ FN(check_mtu), \ FN(for_each_map_elem), \ + FN(snprintf), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index f306611c4ddf..85b26ca5aacd 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -669,6 +669,310 @@ const struct bpf_func_proto bpf_this_cpu_ptr_proto = { .arg1_type = ARG_PTR_TO_PERCPU_BTF_ID, }; +static int bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, + size_t bufsz) +{ + void __user *user_ptr = (__force void __user *)unsafe_ptr; + + buf[0] = 0; + + switch (fmt_ptype) { + case 's': +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if ((unsigned long)unsafe_ptr < TASK_SIZE) + return strncpy_from_user_nofault(buf, user_ptr, bufsz); + fallthrough; +#endif + case 'k': + return strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz); + case 'u': + return strncpy_from_user_nofault(buf, user_ptr, bufsz); + } + + return -EINVAL; +} + +/* Per-cpu temp buffers which can be used by printf-like helpers for %s or %p + */ +#define MAX_PRINTF_BUF_LEN 512 + +struct bpf_printf_buf { + char tmp_buf[MAX_PRINTF_BUF_LEN]; +}; +static DEFINE_PER_CPU(struct bpf_printf_buf, bpf_printf_buf); +static DEFINE_PER_CPU(int, bpf_printf_buf_used); + +static int try_get_fmt_tmp_buf(char **tmp_buf) +{ + struct bpf_printf_buf *bufs; + int used; + + if (*tmp_buf) + return 0; + + preempt_disable(); + used = this_cpu_inc_return(bpf_printf_buf_used); + if (WARN_ON_ONCE(used > 1)) { + this_cpu_dec(bpf_printf_buf_used); + preempt_enable(); + return -EBUSY; + } + bufs = this_cpu_ptr(&bpf_printf_buf); + *tmp_buf = bufs->tmp_buf; + + return 0; +} + +void bpf_printf_cleanup(void) +{ + if (this_cpu_read(bpf_printf_buf_used)) { + this_cpu_dec(bpf_printf_buf_used); + preempt_enable(); + } +} + +/* + * bpf_parse_fmt_str - Generic pass on format strings for printf-like helpers + * + * 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 final_args and mod are NULL + * - Arguments preparation: in addition to the above verification, it writes in + * final_args a copy of raw_args where pointers from BPF have been sanitized + * into pointers safe to use by snprintf. This also writes in the mod array + * the size requirement of each argument, usable by BPF_CAST_FMT_ARG for ex. + * + * In argument preparation mode, if 0 is returned, safe temporary buffers are + * allocated and bpf_printf_cleanup should be called to free them after use. + */ +int bpf_printf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, + u64 *final_args, enum bpf_printf_mod_type *mod, + u32 num_args) +{ + char *unsafe_ptr = NULL, *tmp_buf = NULL, *fmt_end; + size_t tmp_buf_len = MAX_PRINTF_BUF_LEN; + int err, i, num_spec = 0, copy_size; + enum bpf_printf_mod_type cur_mod; + u64 cur_arg; + char fmt_ptype; + + if (!!final_args != !!mod) + return -EINVAL; + + fmt_end = strnchr(fmt, fmt_size, 0); + if (!fmt_end) + return -EINVAL; + fmt_size = fmt_end - fmt; + + for (i = 0; i < fmt_size; i++) { + if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) { + err = -EINVAL; + goto cleanup; + } + + if (fmt[i] != '%') + continue; + + if (fmt[i + 1] == '%') { + i++; + continue; + } + + if (num_spec >= num_args) { + err = -EINVAL; + goto cleanup; + } + + /* The string is zero-terminated so if fmt[i] != 0, we can + * always access fmt[i + 1], in the worst case it will be a 0 + */ + i++; + + /* skip optional "[0 +-][num]" width formatting field */ + while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' || + fmt[i] == ' ') + i++; + if (fmt[i] >= '1' && fmt[i] <= '9') { + i++; + while (fmt[i] >= '0' && fmt[i] <= '9') + i++; + } + + if (fmt[i] == 'p') { + cur_mod = BPF_PRINTF_LONG; + + if ((fmt[i + 1] == 'k' || fmt[i + 1] == 'u') && + fmt[i + 2] == 's') { + fmt_ptype = fmt[i + 1]; + i += 2; + goto fmt_str; + } + + if (fmt[i + 1] == 0 || isspace(fmt[i + 1]) || + ispunct(fmt[i + 1]) || fmt[i + 1] == 'K' || + fmt[i + 1] == 'x' || fmt[i + 1] == 'B' || + fmt[i + 1] == 's' || fmt[i + 1] == 'S') { + /* just kernel pointers */ + if (final_args) + cur_arg = raw_args[num_spec]; + goto fmt_next; + } + + /* only support "%pI4", "%pi4", "%pI6" and "%pi6". */ + if ((fmt[i + 1] != 'i' && fmt[i + 1] != 'I') || + (fmt[i + 2] != '4' && fmt[i + 2] != '6')) { + err = -EINVAL; + goto cleanup; + } + + i += 2; + if (!final_args) + goto fmt_next; + + if (try_get_fmt_tmp_buf(&tmp_buf)) { + err = -EBUSY; + goto out; + } + + copy_size = (fmt[i + 2] == '4') ? 4 : 16; + if (tmp_buf_len < copy_size) { + err = -ENOSPC; + goto cleanup; + } + + unsafe_ptr = (char *)(long)raw_args[num_spec]; + err = copy_from_kernel_nofault(tmp_buf, unsafe_ptr, + copy_size); + if (err < 0) + memset(tmp_buf, 0, copy_size); + cur_arg = (u64)(long)tmp_buf; + tmp_buf += copy_size; + tmp_buf_len -= copy_size; + + goto fmt_next; + } else if (fmt[i] == 's') { + cur_mod = BPF_PRINTF_LONG; + fmt_ptype = fmt[i]; +fmt_str: + if (fmt[i + 1] != 0 && + !isspace(fmt[i + 1]) && + !ispunct(fmt[i + 1])) { + err = -EINVAL; + goto cleanup; + } + + if (!final_args) + goto fmt_next; + + if (try_get_fmt_tmp_buf(&tmp_buf)) { + err = -EBUSY; + goto out; + } + + if (!tmp_buf_len) { + err = -ENOSPC; + goto cleanup; + } + + unsafe_ptr = (char *)(long)raw_args[num_spec]; + err = bpf_trace_copy_string(tmp_buf, unsafe_ptr, + fmt_ptype, tmp_buf_len); + if (err < 0) { + tmp_buf[0] = '\0'; + err = 1; + } + + cur_arg = (u64)(long)tmp_buf; + tmp_buf += err; + tmp_buf_len -= err; + + goto fmt_next; + } + + cur_mod = BPF_PRINTF_INT; + + if (fmt[i] == 'l') { + cur_mod = BPF_PRINTF_LONG; + i++; + } + if (fmt[i] == 'l') { + cur_mod = BPF_PRINTF_LONG_LONG; + i++; + } + + if (fmt[i] != 'i' && fmt[i] != 'd' && fmt[i] != 'u' && + fmt[i] != 'x' && fmt[i] != 'X') { + err = -EINVAL; + goto cleanup; + } + + if (final_args) + cur_arg = raw_args[num_spec]; +fmt_next: + if (final_args) { + mod[num_spec] = cur_mod; + final_args[num_spec] = cur_arg; + } + num_spec++; + } + + err = 0; +cleanup: + if (err) + bpf_printf_cleanup(); +out: + return err; +} + +#define MAX_SNPRINTF_VARARGS 12 + +BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt, + const void *, data, u32, data_len) +{ + enum bpf_printf_mod_type mod[MAX_SNPRINTF_VARARGS]; + u64 args[MAX_SNPRINTF_VARARGS]; + int err, num_args; + + if (data_len % 8 || data_len > MAX_SNPRINTF_VARARGS * 8 || + (data_len && !data)) + 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_printf_prepare(fmt, UINT_MAX, data, args, mod, num_args); + if (err < 0) + return err; + + /* Maximumly we can have MAX_SNPRINTF_VARARGS parameters, just give + * all of them to snprintf(). + */ + err = snprintf(str, str_size, fmt, BPF_CAST_FMT_ARG(0, args, mod), + BPF_CAST_FMT_ARG(1, args, mod), BPF_CAST_FMT_ARG(2, args, mod), + BPF_CAST_FMT_ARG(3, args, mod), BPF_CAST_FMT_ARG(4, args, mod), + BPF_CAST_FMT_ARG(5, args, mod), BPF_CAST_FMT_ARG(6, args, mod), + BPF_CAST_FMT_ARG(7, args, mod), BPF_CAST_FMT_ARG(8, args, mod), + BPF_CAST_FMT_ARG(9, args, mod), BPF_CAST_FMT_ARG(10, args, mod), + BPF_CAST_FMT_ARG(11, args, mod)); + + bpf_printf_cleanup(); + + return err + 1; +} + +const struct bpf_func_proto bpf_snprintf_proto = { + .func = bpf_snprintf, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM_OR_NULL, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_PTR_TO_CONST_STR, + .arg4_type = ARG_PTR_TO_MEM_OR_NULL, + .arg5_type = ARG_CONST_SIZE_OR_ZERO, +}; + const struct bpf_func_proto bpf_get_current_task_proto __weak; const struct bpf_func_proto bpf_probe_read_user_proto __weak; const struct bpf_func_proto bpf_probe_read_user_str_proto __weak; @@ -757,6 +1061,8 @@ bpf_base_func_proto(enum bpf_func_id func_id) return &bpf_probe_read_kernel_str_proto; case BPF_FUNC_snprintf_btf: return &bpf_snprintf_btf_proto; + case BPF_FUNC_snprintf: + return &bpf_snprintf_proto; default: return NULL; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 852541a435ef..994ef36c5f60 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4787,6 +4787,7 @@ static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALU static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_PERCPU_BTF_ID } }; static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; +static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } }; static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_MAP_KEY] = &map_key_value_types, @@ -4817,6 +4818,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, [ARG_PTR_TO_FUNC] = &func_ptr_types, [ARG_PTR_TO_STACK_OR_NULL] = &stack_ptr_types, + [ARG_PTR_TO_CONST_STR] = &const_str_ptr_types, }; static int check_reg_type(struct bpf_verifier_env *env, u32 regno, @@ -5067,6 +5069,45 @@ skip_type_check: if (err) return err; err = check_ptr_alignment(env, reg, 0, size, true); + } else if (arg_type == ARG_PTR_TO_CONST_STR) { + struct bpf_map *map = reg->map_ptr; + int map_off; + u64 map_addr; + char *str_ptr; + + if (reg->type != PTR_TO_MAP_VALUE || !map || + !bpf_map_is_rdonly(map)) { + verbose(env, "R%d does not point to a readonly map'\n", regno); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a constant address'\n", regno); + return -EACCES; + } + + if (!map->ops->map_direct_value_addr) { + verbose(env, "no direct value access support for this map type\n"); + return -EACCES; + } + + err = check_map_access(env, regno, reg->off, + map->value_size - reg->off, false); + if (err) + return err; + + map_off = reg->off + reg->var_off.value; + err = map->ops->map_direct_value_addr(map, &map_addr, map_off); + if (err) { + verbose(env, "direct value access on string failed\n"); + return err; + } + + str_ptr = (char *)(long)(map_addr); + if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) { + verbose(env, "string is not zero-terminated\n"); + return -EINVAL; + } } return err; @@ -5877,6 +5918,41 @@ static int check_reference_leak(struct bpf_verifier_env *env) return state->acquired_refs ? -EINVAL : 0; } +static int check_bpf_snprintf_call(struct bpf_verifier_env *env, + struct bpf_reg_state *regs) +{ + struct bpf_reg_state *fmt_reg = ®s[BPF_REG_3]; + struct bpf_reg_state *data_len_reg = ®s[BPF_REG_5]; + struct bpf_map *fmt_map = fmt_reg->map_ptr; + int err, fmt_map_off, num_args; + u64 fmt_addr; + char *fmt; + + /* data must be an array of u64 */ + if (data_len_reg->var_off.value % 8) + return -EINVAL; + num_args = data_len_reg->var_off.value / 8; + + /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const + * and map_direct_value_addr is set. + */ + fmt_map_off = fmt_reg->off + fmt_reg->var_off.value; + err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr, + fmt_map_off); + if (err) + return err; + fmt = (char *)(long)fmt_addr + fmt_map_off; + + /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we + * can focus on validating the format specifiers. + */ + err = bpf_printf_prepare(fmt, UINT_MAX, NULL, NULL, NULL, num_args); + if (err < 0) + verbose(env, "Invalid format string\n"); + + return err; +} + static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx_p) { @@ -5991,6 +6067,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn return -EINVAL; } + if (func_id == BPF_FUNC_snprintf) { + err = check_bpf_snprintf_call(env, regs); + if (err < 0) + return err; + } + /* reset caller saved regs */ for (i = 0; i < CALLER_SAVED_REGS; i++) { mark_reg_not_init(env, regs, caller_saved[i]); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 0d23755c2747..2a8bcdc927c7 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -372,188 +372,38 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void) return &bpf_probe_write_user_proto; } -static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, - size_t bufsz) -{ - void __user *user_ptr = (__force void __user *)unsafe_ptr; - - buf[0] = 0; - - switch (fmt_ptype) { - case 's': -#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE - if ((unsigned long)unsafe_ptr < TASK_SIZE) { - strncpy_from_user_nofault(buf, user_ptr, bufsz); - break; - } - fallthrough; -#endif - case 'k': - strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz); - break; - case 'u': - strncpy_from_user_nofault(buf, user_ptr, bufsz); - break; - } -} - static DEFINE_RAW_SPINLOCK(trace_printk_lock); -#define BPF_TRACE_PRINTK_SIZE 1024 +#define MAX_TRACE_PRINTK_VARARGS 3 +#define BPF_TRACE_PRINTK_SIZE 1024 -static __printf(1, 0) int bpf_do_trace_printk(const char *fmt, ...) -{ - static char buf[BPF_TRACE_PRINTK_SIZE]; - unsigned long flags; - va_list ap; - int ret; - - raw_spin_lock_irqsave(&trace_printk_lock, flags); - va_start(ap, fmt); - ret = vsnprintf(buf, sizeof(buf), fmt, ap); - va_end(ap); - /* vsnprintf() will not append null for zero-length strings */ - if (ret == 0) - buf[0] = '\0'; - trace_bpf_trace_printk(buf); - raw_spin_unlock_irqrestore(&trace_printk_lock, flags); - - return ret; -} - -/* - * Only limited trace_printk() conversion specifiers allowed: - * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s - */ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, u64, arg2, u64, arg3) { - int i, mod[3] = {}, fmt_cnt = 0; - char buf[64], fmt_ptype; - void *unsafe_ptr = NULL; - bool str_seen = false; + u64 args[MAX_TRACE_PRINTK_VARARGS] = { arg1, arg2, arg3 }; + enum bpf_printf_mod_type mod[MAX_TRACE_PRINTK_VARARGS]; + static char buf[BPF_TRACE_PRINTK_SIZE]; + unsigned long flags; + int ret; - /* - * bpf_check()->check_func_arg()->check_stack_boundary() - * guarantees that fmt points to bpf program stack, - * fmt_size bytes of it were initialized and fmt_size > 0 - */ - if (fmt[--fmt_size] != 0) - return -EINVAL; + ret = bpf_printf_prepare(fmt, fmt_size, args, args, mod, + MAX_TRACE_PRINTK_VARARGS); + if (ret < 0) + return ret; - /* check format string for allowed specifiers */ - for (i = 0; i < fmt_size; i++) { - if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) - return -EINVAL; + ret = snprintf(buf, sizeof(buf), fmt, BPF_CAST_FMT_ARG(0, args, mod), + BPF_CAST_FMT_ARG(1, args, mod), BPF_CAST_FMT_ARG(2, args, mod)); + /* snprintf() will not append null for zero-length strings */ + if (ret == 0) + buf[0] = '\0'; - if (fmt[i] != '%') - continue; + raw_spin_lock_irqsave(&trace_printk_lock, flags); + trace_bpf_trace_printk(buf); + raw_spin_unlock_irqrestore(&trace_printk_lock, flags); - if (fmt_cnt >= 3) - return -EINVAL; + bpf_printf_cleanup(); - /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ - i++; - if (fmt[i] == 'l') { - mod[fmt_cnt]++; - i++; - } else if (fmt[i] == 'p') { - mod[fmt_cnt]++; - if ((fmt[i + 1] == 'k' || - fmt[i + 1] == 'u') && - fmt[i + 2] == 's') { - fmt_ptype = fmt[i + 1]; - i += 2; - goto fmt_str; - } - - if (fmt[i + 1] == 'B') { - i++; - goto fmt_next; - } - - /* disallow any further format extensions */ - if (fmt[i + 1] != 0 && - !isspace(fmt[i + 1]) && - !ispunct(fmt[i + 1])) - return -EINVAL; - - goto fmt_next; - } else if (fmt[i] == 's') { - mod[fmt_cnt]++; - fmt_ptype = fmt[i]; -fmt_str: - if (str_seen) - /* allow only one '%s' per fmt string */ - return -EINVAL; - str_seen = true; - - if (fmt[i + 1] != 0 && - !isspace(fmt[i + 1]) && - !ispunct(fmt[i + 1])) - return -EINVAL; - - switch (fmt_cnt) { - case 0: - unsafe_ptr = (void *)(long)arg1; - arg1 = (long)buf; - break; - case 1: - unsafe_ptr = (void *)(long)arg2; - arg2 = (long)buf; - break; - case 2: - unsafe_ptr = (void *)(long)arg3; - arg3 = (long)buf; - break; - } - - bpf_trace_copy_string(buf, unsafe_ptr, fmt_ptype, - sizeof(buf)); - goto fmt_next; - } - - if (fmt[i] == 'l') { - mod[fmt_cnt]++; - i++; - } - - if (fmt[i] != 'i' && fmt[i] != 'd' && - fmt[i] != 'u' && fmt[i] != 'x') - return -EINVAL; -fmt_next: - fmt_cnt++; - } - -/* Horrid workaround for getting va_list handling working with different - * argument type combinations generically for 32 and 64 bit archs. - */ -#define __BPF_TP_EMIT() __BPF_ARG3_TP() -#define __BPF_TP(...) \ - bpf_do_trace_printk(fmt, ##__VA_ARGS__) - -#define __BPF_ARG1_TP(...) \ - ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ - ? __BPF_TP(arg1, ##__VA_ARGS__) \ - : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \ - ? __BPF_TP((long)arg1, ##__VA_ARGS__) \ - : __BPF_TP((u32)arg1, ##__VA_ARGS__))) - -#define __BPF_ARG2_TP(...) \ - ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \ - ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \ - : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \ - ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \ - : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__))) - -#define __BPF_ARG3_TP(...) \ - ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \ - ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \ - : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \ - ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \ - : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__))) - - return __BPF_TP_EMIT(); + return ret; } static const struct bpf_func_proto bpf_trace_printk_proto = { @@ -581,184 +431,37 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void) } #define MAX_SEQ_PRINTF_VARARGS 12 -#define MAX_SEQ_PRINTF_MAX_MEMCPY 6 -#define MAX_SEQ_PRINTF_STR_LEN 128 - -struct bpf_seq_printf_buf { - char buf[MAX_SEQ_PRINTF_MAX_MEMCPY][MAX_SEQ_PRINTF_STR_LEN]; -}; -static DEFINE_PER_CPU(struct bpf_seq_printf_buf, bpf_seq_printf_buf); -static DEFINE_PER_CPU(int, bpf_seq_printf_buf_used); BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, const void *, data, u32, data_len) { - int err = -EINVAL, fmt_cnt = 0, memcpy_cnt = 0; - int i, buf_used, copy_size, num_args; - u64 params[MAX_SEQ_PRINTF_VARARGS]; - struct bpf_seq_printf_buf *bufs; - const u64 *args = data; - - buf_used = this_cpu_inc_return(bpf_seq_printf_buf_used); - if (WARN_ON_ONCE(buf_used > 1)) { - err = -EBUSY; - goto out; - } - - bufs = this_cpu_ptr(&bpf_seq_printf_buf); - - /* - * bpf_check()->check_func_arg()->check_stack_boundary() - * guarantees that fmt points to bpf program stack, - * fmt_size bytes of it were initialized and fmt_size > 0 - */ - if (fmt[--fmt_size] != 0) - goto out; - - if (data_len & 7) - goto out; - - for (i = 0; i < fmt_size; i++) { - if (fmt[i] == '%') { - if (fmt[i + 1] == '%') - i++; - else if (!data || !data_len) - goto out; - } - } + enum bpf_printf_mod_type mod[MAX_SEQ_PRINTF_VARARGS]; + u64 args[MAX_SEQ_PRINTF_VARARGS]; + int err, num_args; + if (data_len & 7 || data_len > MAX_SEQ_PRINTF_VARARGS * 8 || + (data_len && !data)) + return -EINVAL; num_args = data_len / 8; - /* check format string for allowed specifiers */ - for (i = 0; i < fmt_size; i++) { - /* only printable ascii for now. */ - if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) { - err = -EINVAL; - goto out; - } - - if (fmt[i] != '%') - continue; - - if (fmt[i + 1] == '%') { - i++; - continue; - } - - if (fmt_cnt >= MAX_SEQ_PRINTF_VARARGS) { - err = -E2BIG; - goto out; - } - - if (fmt_cnt >= num_args) { - err = -EINVAL; - goto out; - } - - /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ - i++; - - /* skip optional "[0 +-][num]" width formating field */ - while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' || - fmt[i] == ' ') - i++; - if (fmt[i] >= '1' && fmt[i] <= '9') { - i++; - while (fmt[i] >= '0' && fmt[i] <= '9') - i++; - } - - if (fmt[i] == 's') { - void *unsafe_ptr; - - /* try our best to copy */ - if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) { - err = -E2BIG; - goto out; - } - - unsafe_ptr = (void *)(long)args[fmt_cnt]; - err = strncpy_from_kernel_nofault(bufs->buf[memcpy_cnt], - unsafe_ptr, MAX_SEQ_PRINTF_STR_LEN); - if (err < 0) - bufs->buf[memcpy_cnt][0] = '\0'; - params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt]; - - fmt_cnt++; - memcpy_cnt++; - continue; - } - - if (fmt[i] == 'p') { - if (fmt[i + 1] == 0 || - fmt[i + 1] == 'K' || - fmt[i + 1] == 'x' || - fmt[i + 1] == 'B') { - /* just kernel pointers */ - params[fmt_cnt] = args[fmt_cnt]; - fmt_cnt++; - continue; - } - - /* only support "%pI4", "%pi4", "%pI6" and "%pi6". */ - if (fmt[i + 1] != 'i' && fmt[i + 1] != 'I') { - err = -EINVAL; - goto out; - } - if (fmt[i + 2] != '4' && fmt[i + 2] != '6') { - err = -EINVAL; - goto out; - } - - if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) { - err = -E2BIG; - goto out; - } - - - copy_size = (fmt[i + 2] == '4') ? 4 : 16; - - err = copy_from_kernel_nofault(bufs->buf[memcpy_cnt], - (void *) (long) args[fmt_cnt], - copy_size); - if (err < 0) - memset(bufs->buf[memcpy_cnt], 0, copy_size); - params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt]; - - i += 2; - fmt_cnt++; - memcpy_cnt++; - continue; - } - - if (fmt[i] == 'l') { - i++; - if (fmt[i] == 'l') - i++; - } - - if (fmt[i] != 'i' && fmt[i] != 'd' && - fmt[i] != 'u' && fmt[i] != 'x' && - fmt[i] != 'X') { - err = -EINVAL; - goto out; - } - - params[fmt_cnt] = args[fmt_cnt]; - fmt_cnt++; - } + err = bpf_printf_prepare(fmt, fmt_size, data, args, mod, num_args); + if (err < 0) + return err; /* Maximumly we can have MAX_SEQ_PRINTF_VARARGS parameter, just give * all of them to seq_printf(). */ - seq_printf(m, fmt, params[0], params[1], params[2], params[3], - params[4], params[5], params[6], params[7], params[8], - params[9], params[10], params[11]); + seq_printf(m, fmt, BPF_CAST_FMT_ARG(0, args, mod), + BPF_CAST_FMT_ARG(1, args, mod), BPF_CAST_FMT_ARG(2, args, mod), + BPF_CAST_FMT_ARG(3, args, mod), BPF_CAST_FMT_ARG(4, args, mod), + BPF_CAST_FMT_ARG(5, args, mod), BPF_CAST_FMT_ARG(6, args, mod), + BPF_CAST_FMT_ARG(7, args, mod), BPF_CAST_FMT_ARG(8, args, mod), + BPF_CAST_FMT_ARG(9, args, mod), BPF_CAST_FMT_ARG(10, args, mod), + BPF_CAST_FMT_ARG(11, args, mod)); - err = seq_has_overflowed(m) ? -EOVERFLOW : 0; -out: - this_cpu_dec(bpf_seq_printf_buf_used); - return err; + bpf_printf_cleanup(); + + return seq_has_overflowed(m) ? -EOVERFLOW : 0; } BTF_ID_LIST_SINGLE(btf_seq_file_ids, struct, seq_file) @@ -1373,6 +1076,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_task_storage_delete_proto; case BPF_FUNC_for_each_map_elem: return &bpf_for_each_map_elem_proto; + case BPF_FUNC_snprintf: + return &bpf_snprintf_proto; default: return NULL; } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index df164a44bb41..ec6d85a81744 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4708,6 +4708,33 @@ union bpf_attr { * Return * The number of traversed map elements for success, **-EINVAL** for * invalid **flags**. + * + * long bpf_snprintf(char *str, u32 str_size, const char *fmt, u64 *data, u32 data_len) + * Description + * Outputs a string into the **str** buffer of size **str_size** + * based on a format string stored in a read-only map pointed by + * **fmt**. + * + * Each format specifier in **fmt** corresponds to one u64 element + * in the **data** array. For strings and pointers where pointees + * are accessed, only the pointer values are stored in the *data* + * array. The *data_len* is the size of *data* in bytes. + * + * Formats **%s** and **%p{i,I}{4,6}** require to read kernel + * memory. Reading kernel memory may fail due to either invalid + * address or valid address but requiring a major memory fault. If + * reading kernel memory fails, the string for **%s** will be an + * empty string, and the ip address for **%p{i,I}{4,6}** will be 0. + * Not returning error to bpf program is consistent with what + * **bpf_trace_printk**\ () does for now. + * + * Return + * The strictly positive length of the formatted string, including + * the trailing zero character. If the return value is greater than + * **str_size**, **str** contains a truncated string, guaranteed to + * be zero-terminated except when **str_size** is 0. + * + * Or **-EBUSY** if the per-CPU memory copy buffer is busy. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -4875,6 +4902,7 @@ union bpf_attr { FN(sock_from_file), \ FN(check_mtu), \ FN(for_each_map_elem), \ + FN(snprintf), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h index f9ef37707888..8c954ebc0c7c 100644 --- a/tools/lib/bpf/bpf_tracing.h +++ b/tools/lib/bpf/bpf_tracing.h @@ -413,20 +413,56 @@ typeof(name(0)) name(struct pt_regs *ctx) \ } \ static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args) +#define ___bpf_fill0(arr, p, x) do {} while (0) +#define ___bpf_fill1(arr, p, x) arr[p] = x +#define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args) +#define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args) +#define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args) +#define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args) +#define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args) +#define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args) +#define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args) +#define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args) +#define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args) +#define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args) +#define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args) +#define ___bpf_fill(arr, args...) \ + ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args) + /* * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values * in a structure. */ -#define BPF_SEQ_PRINTF(seq, fmt, args...) \ - ({ \ - _Pragma("GCC diagnostic push") \ - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ - static const char ___fmt[] = fmt; \ - unsigned long long ___param[] = { args }; \ - _Pragma("GCC diagnostic pop") \ - int ___ret = bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ - ___param, sizeof(___param)); \ - ___ret; \ - }) +#define BPF_SEQ_PRINTF(seq, fmt, args...) \ +({ \ + static const char ___fmt[] = fmt; \ + unsigned long long ___param[___bpf_narg(args)]; \ + \ + _Pragma("GCC diagnostic push") \ + _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ + ___bpf_fill(___param, args); \ + _Pragma("GCC diagnostic pop") \ + \ + bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ + ___param, sizeof(___param)); \ +}) + +/* + * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of + * an array of u64. + */ +#define BPF_SNPRINTF(out, out_size, fmt, args...) \ +({ \ + static const char ___fmt[] = fmt; \ + unsigned long long ___param[___bpf_narg(args)]; \ + \ + _Pragma("GCC diagnostic push") \ + _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ + ___bpf_fill(___param, args); \ + _Pragma("GCC diagnostic pop") \ + \ + bpf_snprintf(out, out_size, ___fmt, \ + ___param, sizeof(___param)); \ +}) #endif diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c new file mode 100644 index 000000000000..a958c22aec75 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c @@ -0,0 +1,125 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Google LLC. */ + +#include +#include "test_snprintf.skel.h" +#include "test_snprintf_single.skel.h" + +#define EXP_NUM_OUT "-8 9 96 -424242 1337 DABBAD00" +#define EXP_NUM_RET sizeof(EXP_NUM_OUT) + +#define EXP_IP_OUT "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001" +#define EXP_IP_RET sizeof(EXP_IP_OUT) + +/* The third specifier, %pB, depends on compiler inlining so don't check it */ +#define EXP_SYM_OUT "schedule schedule+0x0/" +#define MIN_SYM_RET sizeof(EXP_SYM_OUT) + +/* The third specifier, %p, is a hashed pointer which changes on every reboot */ +#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 " +#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr") + +#define EXP_STR_OUT "str1 longstr" +#define EXP_STR_RET sizeof(EXP_STR_OUT) + +#define EXP_OVER_OUT "%over" +#define EXP_OVER_RET 10 + +#define EXP_PAD_OUT " 4 000" +#define EXP_PAD_RET 900007 + +#define EXP_NO_ARG_OUT "simple case" +#define EXP_NO_ARG_RET 12 + +#define EXP_NO_BUF_RET 29 + +void test_snprintf_positive(void) +{ + char exp_addr_out[] = EXP_ADDR_OUT; + char exp_sym_out[] = EXP_SYM_OUT; + struct test_snprintf *skel; + + skel = test_snprintf__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + if (!ASSERT_OK(test_snprintf__attach(skel), "skel_attach")) + goto cleanup; + + /* trigger tracepoint */ + usleep(1); + + ASSERT_STREQ(skel->bss->num_out, EXP_NUM_OUT, "num_out"); + ASSERT_EQ(skel->bss->num_ret, EXP_NUM_RET, "num_ret"); + + ASSERT_STREQ(skel->bss->ip_out, EXP_IP_OUT, "ip_out"); + ASSERT_EQ(skel->bss->ip_ret, EXP_IP_RET, "ip_ret"); + + ASSERT_OK(memcmp(skel->bss->sym_out, exp_sym_out, + sizeof(exp_sym_out) - 1), "sym_out"); + ASSERT_LT(MIN_SYM_RET, skel->bss->sym_ret, "sym_ret"); + + ASSERT_OK(memcmp(skel->bss->addr_out, exp_addr_out, + sizeof(exp_addr_out) - 1), "addr_out"); + ASSERT_EQ(skel->bss->addr_ret, EXP_ADDR_RET, "addr_ret"); + + ASSERT_STREQ(skel->bss->str_out, EXP_STR_OUT, "str_out"); + ASSERT_EQ(skel->bss->str_ret, EXP_STR_RET, "str_ret"); + + ASSERT_STREQ(skel->bss->over_out, EXP_OVER_OUT, "over_out"); + ASSERT_EQ(skel->bss->over_ret, EXP_OVER_RET, "over_ret"); + + ASSERT_STREQ(skel->bss->pad_out, EXP_PAD_OUT, "pad_out"); + ASSERT_EQ(skel->bss->pad_ret, EXP_PAD_RET, "pad_ret"); + + ASSERT_STREQ(skel->bss->noarg_out, EXP_NO_ARG_OUT, "no_arg_out"); + ASSERT_EQ(skel->bss->noarg_ret, EXP_NO_ARG_RET, "no_arg_ret"); + + ASSERT_EQ(skel->bss->nobuf_ret, EXP_NO_BUF_RET, "no_buf_ret"); + +cleanup: + test_snprintf__destroy(skel); +} + +#define min(a, b) ((a) < (b) ? (a) : (b)) + +/* Loads an eBPF object calling bpf_snprintf with up to 10 characters of fmt */ +static int load_single_snprintf(char *fmt) +{ + struct test_snprintf_single *skel; + int ret; + + skel = test_snprintf_single__open(); + if (!skel) + return -EINVAL; + + memcpy(skel->rodata->fmt, fmt, min(strlen(fmt) + 1, 10)); + + ret = test_snprintf_single__load(skel); + test_snprintf_single__destroy(skel); + + return ret; +} + +void test_snprintf_negative(void) +{ + ASSERT_OK(load_single_snprintf("valid %d"), "valid usage"); + + ASSERT_ERR(load_single_snprintf("0123456789"), "no terminating zero"); + ASSERT_ERR(load_single_snprintf("%d %d"), "too many specifiers"); + ASSERT_ERR(load_single_snprintf("%pi5"), "invalid specifier 1"); + ASSERT_ERR(load_single_snprintf("%a"), "invalid specifier 2"); + ASSERT_ERR(load_single_snprintf("%"), "invalid specifier 3"); + ASSERT_ERR(load_single_snprintf("%12345678"), "invalid specifier 4"); + ASSERT_ERR(load_single_snprintf("%--------"), "invalid specifier 5"); + ASSERT_ERR(load_single_snprintf("\x80"), "non ascii character"); + ASSERT_ERR(load_single_snprintf("\x1"), "non printable character"); +} + +void test_snprintf(void) +{ + if (test__start_subtest("snprintf_positive")) + test_snprintf_positive(); + if (test__start_subtest("snprintf_negative")) + test_snprintf_negative(); +} diff --git a/tools/testing/selftests/bpf/progs/test_snprintf.c b/tools/testing/selftests/bpf/progs/test_snprintf.c new file mode 100644 index 000000000000..951a0301c553 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_snprintf.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Google LLC. */ + +#include +#include +#include + +char num_out[64] = {}; +long num_ret = 0; + +char ip_out[64] = {}; +long ip_ret = 0; + +char sym_out[64] = {}; +long sym_ret = 0; + +char addr_out[64] = {}; +long addr_ret = 0; + +char str_out[64] = {}; +long str_ret = 0; + +char over_out[6] = {}; +long over_ret = 0; + +char pad_out[10] = {}; +long pad_ret = 0; + +char noarg_out[64] = {}; +long noarg_ret = 0; + +long nobuf_ret = 0; + +extern const void schedule __ksym; + +SEC("raw_tp/sys_enter") +int handler(const void *ctx) +{ + /* Convenient values to pretty-print */ + const __u8 ex_ipv4[] = {127, 0, 0, 1}; + const __u8 ex_ipv6[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}; + static const char str1[] = "str1"; + static const char longstr[] = "longstr"; + + /* Integer types */ + num_ret = BPF_SNPRINTF(num_out, sizeof(num_out), + "%d %u %x %li %llu %lX", + -8, 9, 150, -424242, 1337, 0xDABBAD00); + /* IP addresses */ + ip_ret = BPF_SNPRINTF(ip_out, sizeof(ip_out), "%pi4 %pI6", + &ex_ipv4, &ex_ipv6); + /* Symbol lookup formatting */ + sym_ret = BPF_SNPRINTF(sym_out, sizeof(sym_out), "%ps %pS %pB", + &schedule, &schedule, &schedule); + /* Kernel pointers */ + addr_ret = BPF_SNPRINTF(addr_out, sizeof(addr_out), "%pK %px %p", + 0, 0xFFFF00000ADD4E55, 0xFFFF00000ADD4E55); + /* Strings embedding */ + str_ret = BPF_SNPRINTF(str_out, sizeof(str_out), "%s %+05s", + str1, longstr); + /* Overflow */ + over_ret = BPF_SNPRINTF(over_out, sizeof(over_out), "%%overflow"); + /* Padding of fixed width numbers */ + pad_ret = BPF_SNPRINTF(pad_out, sizeof(pad_out), "%5d %0900000X", 4, 4); + /* No args */ + noarg_ret = BPF_SNPRINTF(noarg_out, sizeof(noarg_out), "simple case"); + /* No buffer */ + nobuf_ret = BPF_SNPRINTF(NULL, 0, "only interested in length %d", 60); + + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/test_snprintf_single.c b/tools/testing/selftests/bpf/progs/test_snprintf_single.c new file mode 100644 index 000000000000..402adaf344f9 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_snprintf_single.c @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Google LLC. */ + +#include +#include + +/* The format string is filled from the userspace such that loading fails */ +static const char fmt[10]; + +SEC("raw_tp/sys_enter") +int handler(const void *ctx) +{ + unsigned long long arg = 42; + + bpf_snprintf(NULL, 0, fmt, &arg, sizeof(arg)); + + return 0; +} + +char _license[] SEC("license") = "GPL";