diff options
| -rw-r--r-- | src/commonlib/bsd/cbfs_private.c | 23 | ||||
| -rw-r--r-- | src/commonlib/bsd/include/commonlib/bsd/cbfs_mdata.h | 3 | ||||
| -rw-r--r-- | src/lib/cbfs.c | 61 |
3 files changed, 74 insertions, 13 deletions
diff --git a/src/commonlib/bsd/cbfs_private.c b/src/commonlib/bsd/cbfs_private.c index 91f81e0db4..16bab7cbb8 100644 --- a/src/commonlib/bsd/cbfs_private.c +++ b/src/commonlib/bsd/cbfs_private.c @@ -190,3 +190,26 @@ const void *cbfs_find_attr(const union cbfs_mdata *mdata, uint32_t attr_tag, siz return NULL; } + +const struct vb2_hash *cbfs_file_hash(const union cbfs_mdata *mdata) +{ + /* Hashes are variable-length attributes, so need to manually check the length. */ + const struct cbfs_file_attr_hash *attr = + cbfs_find_attr(mdata, CBFS_FILE_ATTR_TAG_HASH, 0); + if (!attr) + return NULL; /* no hash */ + const size_t asize = be32toh(attr->len); + + const struct vb2_hash *hash = &attr->hash; + const size_t hsize = vb2_digest_size(hash->algo); + if (!hsize) { + ERROR("Hash algo %u for '%s' unsupported.\n", hash->algo, mdata->h.filename); + return NULL; + } + if (hsize != asize - offsetof(struct cbfs_file_attr_hash, hash.raw)) { + ERROR("Hash attribute size for '%s' (%zu) incorrect for algo %u.\n", + mdata->h.filename, asize, hash->algo); + return NULL; + } + return hash; +} diff --git a/src/commonlib/bsd/include/commonlib/bsd/cbfs_mdata.h b/src/commonlib/bsd/include/commonlib/bsd/cbfs_mdata.h index df13427c5f..ed5c378973 100644 --- a/src/commonlib/bsd/include/commonlib/bsd/cbfs_mdata.h +++ b/src/commonlib/bsd/include/commonlib/bsd/cbfs_mdata.h @@ -24,4 +24,7 @@ union cbfs_mdata { else caller is responsible for checking the |len| field to avoid reading out-of-bounds. */ const void *cbfs_find_attr(const union cbfs_mdata *mdata, uint32_t attr_tag, size_t size_check); +/* Returns pointer to CBFS file hash structure in metadata attributes, or NULL if invalid. */ +const struct vb2_hash *cbfs_file_hash(const union cbfs_mdata *mdata); + #endif /* _COMMONLIB_BSD_CBFS_MDATA_H_ */ diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c index 9135b2f83f..23e8f41db1 100644 --- a/src/lib/cbfs.c +++ b/src/lib/cbfs.c @@ -186,11 +186,27 @@ static inline bool cbfs_lzma_enabled(void) return true; } -static size_t cbfs_load_and_decompress(const struct region_device *rdev, - void *buffer, size_t buffer_size, uint32_t compression) +static inline bool cbfs_file_hash_mismatch(const void *buffer, size_t size, + const struct vb2_hash *file_hash) +{ + /* Avoid linking hash functions when verification is disabled. */ + if (!CONFIG(CBFS_VERIFICATION)) + return false; + + /* If there is no file hash, always count that as a mismatch. */ + if (file_hash && vb2_hash_verify(buffer, size, file_hash) == VB2_SUCCESS) + return false; + + printk(BIOS_CRIT, "CBFS file hash mismatch!\n"); + return true; +} + +static size_t cbfs_load_and_decompress(const struct region_device *rdev, void *buffer, + size_t buffer_size, uint32_t compression, + const struct vb2_hash *file_hash) { size_t in_size = region_device_sz(rdev); - size_t out_size; + size_t out_size = 0; void *map; DEBUG("Decompressing %zu bytes to %p with algo %d\n", in_size, buffer, compression); @@ -201,6 +217,8 @@ static size_t cbfs_load_and_decompress(const struct region_device *rdev, return 0; if (rdev_readat(rdev, buffer, 0, in_size) != in_size) return 0; + if (cbfs_file_hash_mismatch(buffer, in_size, file_hash)) + return 0; return in_size; case CBFS_COMPRESS_LZ4: @@ -213,9 +231,11 @@ static size_t cbfs_load_and_decompress(const struct region_device *rdev, if (map == NULL) return 0; - timestamp_add_now(TS_START_ULZ4F); - out_size = ulz4fn(map, in_size, buffer, buffer_size); - timestamp_add_now(TS_END_ULZ4F); + if (!cbfs_file_hash_mismatch(map, in_size, file_hash)) { + timestamp_add_now(TS_START_ULZ4F); + out_size = ulz4fn(map, in_size, buffer, buffer_size); + timestamp_add_now(TS_END_ULZ4F); + } rdev_munmap(rdev, map); @@ -228,10 +248,12 @@ static size_t cbfs_load_and_decompress(const struct region_device *rdev, if (map == NULL) return 0; - /* Note: timestamp not useful for memory-mapped media (x86) */ - timestamp_add_now(TS_START_ULZMA); - out_size = ulzman(map, in_size, buffer, buffer_size); - timestamp_add_now(TS_END_ULZMA); + if (!cbfs_file_hash_mismatch(map, in_size, file_hash)) { + /* Note: timestamp not useful for memory-mapped media (x86) */ + timestamp_add_now(TS_START_ULZMA); + out_size = ulzman(map, in_size, buffer, buffer_size); + timestamp_add_now(TS_END_ULZMA); + } rdev_munmap(rdev, map); @@ -318,11 +340,18 @@ void *_cbfs_alloc(const char *name, cbfs_allocator_t allocator, void *arg, if (size_out) *size_out = size; + const struct vb2_hash *file_hash = NULL; + if (CONFIG(CBFS_VERIFICATION)) + file_hash = cbfs_file_hash(&mdata); + /* allocator == NULL means do a cbfs_map() */ if (allocator) { loc = allocator(arg, size, &mdata); } else if (compression == CBFS_COMPRESS_NONE) { - return rdev_mmap_full(&rdev); + void *mapping = rdev_mmap_full(&rdev); + if (!mapping || cbfs_file_hash_mismatch(mapping, size, file_hash)) + return NULL; + return mapping; } else if (!CBFS_CACHE_AVAILABLE) { ERROR("Cannot map compressed file %s on x86\n", mdata.h.filename); return NULL; @@ -335,7 +364,7 @@ void *_cbfs_alloc(const char *name, cbfs_allocator_t allocator, void *arg, return NULL; } - size = cbfs_load_and_decompress(&rdev, loc, size, compression); + size = cbfs_load_and_decompress(&rdev, loc, size, compression, file_hash); if (!size) return NULL; @@ -384,12 +413,18 @@ cb_err_t cbfs_prog_stage_load(struct prog *pstage) prog_set_entry(pstage, prog_start(pstage) + be32toh(sattr->entry_offset), NULL); + const struct vb2_hash *file_hash = NULL; + if (CONFIG(CBFS_VERIFICATION)) + file_hash = cbfs_file_hash(&mdata); + /* Hacky way to not load programs over read only media. The stages * that would hit this path initialize themselves. */ if ((ENV_BOOTBLOCK || ENV_SEPARATE_VERSTAGE) && !CONFIG(NO_XIP_EARLY_STAGES) && CONFIG(BOOT_DEVICE_MEMORY_MAPPED)) { void *mapping = rdev_mmap_full(&rdev); rdev_munmap(&rdev, mapping); + if (cbfs_file_hash_mismatch(mapping, region_device_sz(&rdev), file_hash)) + return CB_CBFS_HASH_MISMATCH; if (mapping == prog_start(pstage)) return CB_SUCCESS; } @@ -405,7 +440,7 @@ cb_err_t cbfs_prog_stage_load(struct prog *pstage) } size_t fsize = cbfs_load_and_decompress(&rdev, prog_start(pstage), prog_size(pstage), - compression); + compression, file_hash); if (!fsize) return CB_ERR; |