Add bpf_strtol and bpf_strtoul to convert a string to long and unsigned long correspondingly. It's similar to user space strtol(3) and strtoul(3) with a few changes to the API: * instead of NUL-terminated C string the helpers expect buffer and buffer length; * resulting long or unsigned long is returned in a separate result-argument; * return value is used to indicate success or failure, on success number of consumed bytes is returned that can be used to identify position to read next if the buffer is expected to contain multiple integers; * instead of *base* argument, *flags* is used that provides base in 5 LSB, other bits are reserved for future use; * number of supported bases is limited. Documentation for the new helpers is provided in bpf.h UAPI. The helpers are made available to BPF_PROG_TYPE_CGROUP_SYSCTL programs to be able to convert string input to e.g. "ulongvec" output. E.g. "net/ipv4/tcp_mem" consists of three ulong integers. They can be parsed by calling to bpf_strtoul three times. Implementation notes: Implementation includes "../../lib/kstrtox.h" to reuse integer parsing functions. It's done exactly same way as fs/proc/base.c already does. Unfortunately existing kstrtoX function can't be used directly since they fail if any invalid character is present right after integer in the string. Existing simple_strtoX functions can't be used either since they're obsolete and don't handle overflow properly.
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| @@ -2575,6 +2575,53 @@ union bpf_attr { · 2574 unmodified lines | ||
| 2575 | 2575 | * **-E2BIG** if the *buf_len* is too big. |
| 2576 | 2576 | * |
| 2577 | 2577 | * **-EINVAL** if sysctl is being read. |
| 2578 | + * | |
| 2579 | + * int bpf_strtol(const char *buf, size_t buf_len, u64 flags, long *res) | |
| 2580 | + * Description | |
| 2581 | + * Convert the initial part of the string from buffer *buf* of | |
| 2582 | + * size *buf_len* to a long integer according to the given base | |
| 2583 | + * and save the result in *res*. | |
| 2584 | + * | |
| 2585 | + * The string may begin with an arbitrary amount of white space | |
| 2586 | + * (as determined by isspace(3)) followed by a single optional '-' | |
| 2587 | + * sign. | |
| 2588 | + * | |
| 2589 | + * Five least significant bits of *flags* encode base, other bits | |
| 2590 | + * are currently unused. | |
| 2591 | + * | |
| 2592 | + * Base must be either 8, 10, 16 or 0 to detect it automatically | |
| 2593 | + * similar to user space strtol(3). | |
| 2594 | + * Return | |
| 2595 | + * Number of characters consumed on success. Must be positive but | |
| 2596 | + * no more than buf_len. | |
| 2597 | + * | |
| 2598 | + * **-EINVAL** if no valid digits were found or unsupported base | |
| 2599 | + * was provided. | |
| 2600 | + * | |
| 2601 | + * **-ERANGE** if resulting value was out of range. | |
| 2602 | + * | |
| 2603 | + * int bpf_strtoul(const char *buf, size_t buf_len, u64 flags, unsigned long *res) | |
| 2604 | + * Description | |
| 2605 | + * Convert the initial part of the string from buffer *buf* of | |
| 2606 | + * size *buf_len* to an unsigned long integer according to the | |
| 2607 | + * given base and save the result in *res*. | |
| 2608 | + * | |
| 2609 | + * The string may begin with an arbitrary amount of white space | |
| 2610 | + * (as determined by isspace(3)). | |
| 2611 | + * | |
| 2612 | + * Five least significant bits of *flags* encode base, other bits | |
| 2613 | + * are currently unused. | |
| 2614 | + * | |
| 2615 | + * Base must be either 8, 10, 16 or 0 to detect it automatically | |
| 2616 | + * similar to user space strtoul(3). | |
| 2617 | + * Return | |
| 2618 | + * Number of characters consumed on success. Must be positive but | |
| 2619 | + * no more than buf_len. | |
| 2620 | + * | |
| 2621 | + * **-EINVAL** if no valid digits were found or unsupported base | |
| 2622 | + * was provided. | |
| 2623 | + * | |
| 2624 | + * **-ERANGE** if resulting value was out of range. | |
| 2578 | 2625 | */ |
| 2579 | 2626 | #define __BPF_FUNC_MAPPER(FN) \ |
| 2580 | 2627 | FN(unspec), \ |
| @@ -2681,7 +2728,9 @@ union bpf_attr { · 100 unmodified lines | ||
| 2681 | 2728 | FN(sysctl_get_name), \ |
| 2682 | 2729 | FN(sysctl_get_current_value), \ |
| 2683 | 2730 | FN(sysctl_get_new_value), \ |
| 2684 | − FN(sysctl_set_new_value), | |
| 2731 | + FN(sysctl_set_new_value), \ | |
| 2732 | + FN(strtol), \ | |
| 2733 | + FN(strtoul), | |
| 2685 | 2734 | |
| 2686 | 2735 | /* integer value in 'imm' field of BPF_CALL instruction selects which helper |
| 2687 | 2736 | * function eBPF program intends to call |