^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) #include <linux/cache.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) #include <linux/crc32.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) #include <linux/init.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include <linux/libfdt.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/mm_types.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/types.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/pgtable.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <linux/random.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <asm/cacheflush.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <asm/fixmap.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) #include <asm/kernel-pgtable.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #include <asm/memory.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) #include <asm/mmu.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) #include <asm/sections.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) #include <asm/setup.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) enum kaslr_status {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) KASLR_ENABLED,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) KASLR_DISABLED_CMDLINE,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) KASLR_DISABLED_NO_SEED,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) KASLR_DISABLED_FDT_REMAP,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) static enum kaslr_status __initdata kaslr_status;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) u64 __ro_after_init module_alloc_base;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) u16 __initdata memstart_offset_seed;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) static __init u64 get_kaslr_seed(void *fdt)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) int node, len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) fdt64_t *prop;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) u64 ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) node = fdt_path_offset(fdt, "/chosen");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) if (node < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) prop = fdt_getprop_w(fdt, node, "kaslr-seed", &len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) if (!prop || len != sizeof(u64))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) ret = fdt64_to_cpu(*prop);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) *prop = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) struct arm64_ftr_override kaslr_feature_override __initdata;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) * This routine will be executed with the kernel mapped at its default virtual
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) * address, and if it returns successfully, the kernel will be remapped, and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * start_kernel() will be executed from a randomized virtual offset. The
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) * relocation will result in all absolute references (e.g., static variables
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) * containing function pointers) to be reinitialized, and zero-initialized
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) * .bss variables will be reset to 0.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) u64 __init kaslr_early_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) void *fdt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) u64 seed, offset, mask, module_range;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) unsigned long raw;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) * Set a reasonable default for module_alloc_base in case
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) * we end up running with module randomization disabled.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) module_alloc_base = (u64)_etext - MODULES_VSIZE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) __flush_dcache_area(&module_alloc_base, sizeof(module_alloc_base));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) * Try to map the FDT early. If this fails, we simply bail,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) * and proceed with KASLR disabled. We will make another
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) * attempt at mapping the FDT in setup_machine()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) fdt = get_early_fdt_ptr();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) if (!fdt) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) kaslr_status = KASLR_DISABLED_FDT_REMAP;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) * Retrieve (and wipe) the seed from the FDT
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) seed = get_kaslr_seed(fdt);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) * Check if 'nokaslr' appears on the command line, and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) * return 0 if that is the case.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) if (kaslr_feature_override.val & kaslr_feature_override.mask & 0xf) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) kaslr_status = KASLR_DISABLED_CMDLINE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) * Mix in any entropy obtainable architecturally if enabled
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) * and supported.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) if (arch_get_random_seed_long_early(&raw))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) seed ^= raw;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) if (!seed) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) kaslr_status = KASLR_DISABLED_NO_SEED;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) * OK, so we are proceeding with KASLR enabled. Calculate a suitable
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) * kernel image offset from the seed. Let's place the kernel in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) * middle half of the VMALLOC area (VA_BITS_MIN - 2), and stay clear of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) * the lower and upper quarters to avoid colliding with other
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) * allocations.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) * Even if we could randomize at page granularity for 16k and 64k pages,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) * let's always round to 2 MB so we don't interfere with the ability to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) * map using contiguous PTEs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) mask = ((1UL << (VA_BITS_MIN - 2)) - 1) & ~(SZ_2M - 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) offset = BIT(VA_BITS_MIN - 3) + (seed & mask);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) /* use the top 16 bits to randomize the linear region */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) memstart_offset_seed = seed >> 48;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) if (!IS_ENABLED(CONFIG_KASAN_VMALLOC) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) IS_ENABLED(CONFIG_KASAN_SW_TAGS)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) * KASAN without KASAN_VMALLOC does not expect the module region
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) * to intersect the vmalloc region, since shadow memory is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) * allocated for each module at load time, whereas the vmalloc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) * region is shadowed by KASAN zero pages. So keep modules
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) * out of the vmalloc region if KASAN is enabled without
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) * KASAN_VMALLOC, and put the kernel well within 4 GB of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) * module region.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) return offset % SZ_2G;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) * Randomize the module region over a 2 GB window covering the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * kernel. This reduces the risk of modules leaking information
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) * about the address of the kernel itself, but results in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) * branches between modules and the core kernel that are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) * resolved via PLTs. (Branches between modules will be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) * resolved normally.)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) module_range = SZ_2G - (u64)(_end - _stext);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) module_alloc_base = max((u64)_end + offset - SZ_2G,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) (u64)MODULES_VADDR);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) * Randomize the module region by setting module_alloc_base to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) * a PAGE_SIZE multiple in the range [_etext - MODULES_VSIZE,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) * _stext) . This guarantees that the resulting region still
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) * covers [_stext, _etext], and that all relative branches can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) * be resolved without veneers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) module_range = MODULES_VSIZE - (u64)(_etext - _stext);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) module_alloc_base = (u64)_etext + offset - MODULES_VSIZE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) /* use the lower 21 bits to randomize the base of the module region */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) module_alloc_base &= PAGE_MASK;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) __flush_dcache_area(&module_alloc_base, sizeof(module_alloc_base));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) __flush_dcache_area(&memstart_offset_seed, sizeof(memstart_offset_seed));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) return offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) static int __init kaslr_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) switch (kaslr_status) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) case KASLR_ENABLED:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) pr_info("KASLR enabled\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) case KASLR_DISABLED_CMDLINE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) pr_info("KASLR disabled on command line\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) case KASLR_DISABLED_NO_SEED:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) pr_warn("KASLR disabled due to lack of seed\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) case KASLR_DISABLED_FDT_REMAP:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) pr_warn("KASLR disabled due to FDT remapping failure\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) core_initcall(kaslr_init)
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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