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flashrom: Check for flash access restricitons in read_flash()

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Skip read-protected regions if FLASHROM_FLAG_SKIP_UNREADABLE_REGIONS is
true. If the flag is false, read operations that include an
read-protected region will return an error.

BUG=b:260440773
BRANCH=none
TEST=flashrom -r on dedede (JSL)

Change-Id: I22c795d7d08ef8bf773733d9952967b2fa2ef299
CoAuthored-by: Edward O'Callaghan <quasisec@google.com>
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/70514
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
This commit is contained in:
Nikolai Artemiev 2022-12-09 15:17:05 +11:00 committed by Edward O'Callaghan
parent a018234400
commit 23018faa98
1 changed files with 67 additions and 2 deletions
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69
flashrom.c
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@ -359,6 +359,21 @@ char *extract_programmer_param_str(const struct programmer_cfg *cfg, const char
return extract_param(&cfg->params, param_name, ",");
}
static void get_flash_region(const struct flashctx *flash, int addr, struct flash_region *region)
{
if ((flash->mst->buses_supported & BUS_PROG) && flash->mst->opaque.get_region) {
flash->mst->opaque.get_region(flash, addr, region);
} else if (flash->mst->buses_supported & BUS_SPI && flash->mst->spi.get_region) {
flash->mst->spi.get_region(flash, addr, region);
} else {
region->name = strdup("");
region->start = 0;
region->end = flashrom_flash_getsize(flash);
region->read_prot = false;
region->write_prot = false;
}
}
/* special unit-test hook */
erasefunc_t *g_test_erase_injector;
@ -508,10 +523,60 @@ static read_func_t *lookup_read_func_ptr(const struct flashchip *chip)
return NULL;
}
/*
* @brief Wrapper for flash->read() with additional high-level policy.
*
* @param flash flash chip
* @param buf buffer to store data in
* @param start start address
* @param len number of bytes to read
* @return 0 on success,
* -1 if any read fails.
*
* This wrapper simplifies most cases when the flash chip needs to be read
* since policy decisions such as non-fatal error handling is centralized.
*/
int read_flash(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
{
read_func_t *read_func = lookup_read_func_ptr(flash->chip);
return read_func(flash, buf, start, len);
unsigned int read_len;
for (unsigned int addr = start; addr < start + len; addr += read_len) {
struct flash_region region;
get_flash_region(flash, addr, &region);
read_len = min(start + len, region.end) - addr;
uint8_t *rbuf = buf + addr - start;
if (region.read_prot) {
if (flash->flags.skip_unwritable_regions) {
msg_gdbg("%s: cannot read inside %s region (%#08x..%#08x), "
"filling (%#08x..%#08x) with erased value instead.\n",
__func__, region.name, region.start, region.end - 1,
addr, addr + read_len - 1);
free(region.name);
memset(rbuf, ERASED_VALUE(flash), read_len);
continue;
}
msg_gerr("%s: cannot read inside %s region (%#08x..%#08x).\n",
__func__, region.name, region.start, region.end - 1);
free(region.name);
return -1;
}
msg_gdbg("%s: %s region (%#08x..%#08x) is readable, reading range (%#08x..%#08x).\n",
__func__, region.name, region.start, region.end - 1, addr, addr + read_len - 1);
free(region.name);
read_func_t *read_func = lookup_read_func_ptr(flash->chip);
int ret = read_func(flash, rbuf, addr, read_len);
if (ret) {
msg_gerr("%s: failed to read (%#08x..%#08x).\n", __func__, addr, addr + read_len - 1);
return -1;
}
}
return 0;
}
/*