diff options
Diffstat (limited to 'target/linux/generic/files/drivers/platform/mikrotik/routerboot.c')
| -rw-r--r-- | target/linux/generic/files/drivers/platform/mikrotik/routerboot.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c b/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c new file mode 100644 index 0000000000..172db02533 --- /dev/null +++ b/target/linux/generic/files/drivers/platform/mikrotik/routerboot.c @@ -0,0 +1,183 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Driver for MikroTik RouterBoot flash data. Common routines. + * + * Copyright (C) 2020 Thibaut VARÈNE <hacks+kernel@slashdirt.org> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/types.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/sysfs.h> + +#include "routerboot.h" + +static struct kobject *rb_kobj; + +/** + * routerboot_tag_find() - Locate a given tag in routerboot config data. + * @bufhead: the buffer to look into. Must start with a tag node. + * @buflen: size of bufhead + * @tag_id: the tag identifier to look for + * @pld_ofs: will be updated with tag payload offset in bufhead, if tag found + * @pld_len: will be updated with tag payload size, if tag found + * + * This incarnation of tag_find() does only that: it finds a specific routerboot + * tag node in the input buffer. Routerboot tag nodes are u32 values: + * - The low nibble is the tag identification number, + * - The high nibble is the tag payload length (node excluded) in bytes. + * The payload immediately follows the tag node. Tag nodes are 32bit-aligned. + * The returned pld_ofs will always be aligned. pld_len may not end on 32bit + * boundary (the only known case is when parsing ERD data). + * The nodes are cpu-endian on the flash media. The payload is cpu-endian when + * applicable. Tag nodes are not ordered (by ID) on flash. + * + * Return: 0 on success (tag found) or errno + */ +int routerboot_tag_find(const u8 *bufhead, const size_t buflen, const u16 tag_id, + u16 *pld_ofs, u16 *pld_len) +{ + const u32 *datum, *bufend; + u32 node; + u16 id, len; + int ret; + + if (!bufhead || !tag_id) + return -EINVAL; + + ret = -ENOENT; + datum = (const u32 *)bufhead; + bufend = (const u32 *)(bufhead + buflen); + + while (datum < bufend) { + node = *datum++; + + /* Tag list ends with null node */ + if (!node) + break; + + id = node & 0xFFFF; + len = node >> 16; + + if (tag_id == id) { + if (datum >= bufend) + break; + + if (pld_ofs) + *pld_ofs = (u16)((u8 *)datum - bufhead); + if (pld_len) + *pld_len = len; + + ret = 0; + break; + } + + /* + * The only known situation where len may not end on 32bit + * boundary is within ERD data. Since we're only extracting + * one tag (the first and only one) from that data, we should + * never need to forcefully ALIGN(). Do it anyway, this is not a + * performance path. + */ + len = ALIGN(len, sizeof(*datum)); + datum += len / sizeof(*datum); + } + + return ret; +} + +/** + * routerboot_rle_decode() - Simple RLE (MikroTik variant) decoding routine. + * @in: input buffer to decode + * @inlen: size of in + * @out: output buffer to write decoded data to + * @outlen: pointer to out size when function is called, will be updated with + * size of decoded output on return + * + * MikroTik's variant of RLE operates as follows, considering a signed run byte: + * - positive run => classic RLE + * - negative run => the next -<run> bytes must be copied verbatim + * The API is matched to the lzo1x routines for convenience. + * + * NB: The output buffer cannot overlap with the input buffer. + * + * Return: 0 on success or errno + */ +int routerboot_rle_decode(const u8 *in, size_t inlen, u8 *out, size_t *outlen) +{ + int ret, run, nbytes; // use native types for speed + u8 byte; + + if (!in || (inlen < 2) || !out) + return -EINVAL; + + ret = -ENOSPC; + nbytes = 0; + while (inlen >= 2) { + run = *in++; + inlen--; + + /* Verbatim copies */ + if (run & 0x80) { + /* Invert run byte sign */ + run = ~run & 0xFF; + run++; + + if (run > inlen) + goto fail; + + inlen -= run; + + nbytes += run; + if (nbytes > *outlen) + goto fail; + + /* Basic memcpy */ + while (run-- > 0) + *out++ = *in++; + } + /* Stream of half-words RLE: <run><byte>. run == 0 is ignored */ + else { + byte = *in++; + inlen--; + + nbytes += run; + if (nbytes > *outlen) + goto fail; + + while (run-- > 0) + *out++ = byte; + } + } + + ret = 0; +fail: + *outlen = nbytes; + return ret; +} + +static int __init routerboot_init(void) +{ + rb_kobj = kobject_create_and_add("mikrotik", firmware_kobj); + if (!rb_kobj) + return -ENOMEM; + + return rb_hardconfig_init(rb_kobj); +} + +static void __exit routerboot_exit(void) +{ + rb_hardconfig_exit(); + kobject_put(rb_kobj); // recursive afaict +} + +module_init(routerboot_init); +module_exit(routerboot_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("MikroTik RouterBoot sysfs support"); +MODULE_AUTHOR("Thibaut VARENE"); |