From: Roberto Sassu <roberto.sassu@huawei.com> hulk inclusion category: feature feature: IMA Digest Lists extension bugzilla: 46797 ------------------------------------------------- This patch adds support in EVM to verify file metadata digest with digest lists. Metadata digest, calculated in the same way as for portable signatures, is searched in the digest lists only if the file has the security.evm xattr with type EVM_IMA_XATTR_DIGEST_LIST. If the found digest is marked as immutable, content and xattr/attr updates are not allowed. Otherwise, after verification, the existing security.evm with the new type will be replaced with an HMAC, similarly to non-portable signatures. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Signed-off-by: Tianxing Zhang <zhangtianxing3@huawei.com> Reviewed-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Signed-off-by: zhoushuiqing <zhoushuiqing2@huawei.com> --- security/integrity/evm/evm_crypto.c | 9 ++-- security/integrity/evm/evm_main.c | 78 ++++++++++++++++++++++++++--- 2 files changed, 77 insertions(+), 10 deletions(-) diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 033804f5a5f2..259c7c98bb35 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -154,7 +154,8 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode, /* Don't include the inode or generation number in portable * signatures */ - if (type != EVM_XATTR_PORTABLE_DIGSIG) { + if (type != EVM_XATTR_PORTABLE_DIGSIG && + type != EVM_IMA_XATTR_DIGEST_LIST) { hmac_misc.ino = inode->i_ino; hmac_misc.generation = inode->i_generation; } @@ -171,7 +172,8 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode, hmac_misc.mode = inode->i_mode; crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc)); if ((evm_hmac_attrs & EVM_ATTR_FSUUID) && - type != EVM_XATTR_PORTABLE_DIGSIG) + type != EVM_XATTR_PORTABLE_DIGSIG && + type != EVM_IMA_XATTR_DIGEST_LIST) crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE); crypto_shash_final(desc, digest); @@ -337,7 +339,8 @@ static int evm_is_immutable(struct dentry *dentry, struct inode *inode) rc = 0; goto out; } - if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) + if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG || + xattr_data->type == EVM_IMA_XATTR_DIGEST_LIST) rc = 1; else rc = 0; diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index cf24c5255583..c681838a0b66 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -128,7 +128,7 @@ static bool evm_hmac_disabled(void) return true; } -static int evm_find_protected_xattrs(struct dentry *dentry) +static int evm_find_protected_xattrs(struct dentry *dentry, int *ima_present) { struct inode *inode = d_backing_inode(dentry); struct xattr_list *xattr; @@ -145,6 +145,8 @@ static int evm_find_protected_xattrs(struct dentry *dentry) continue; return error; } + if (!strcmp(xattr->name, XATTR_NAME_IMA)) + *ima_present = 1; count++; } @@ -173,9 +175,14 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, struct evm_ima_xattr_data *xattr_data = NULL; struct signature_v2_hdr *hdr; enum integrity_status evm_status = INTEGRITY_PASS; + enum integrity_status saved_evm_status = INTEGRITY_UNKNOWN; struct evm_digest digest; + struct ima_digest *found_digest; struct inode *inode; - int rc, xattr_len, evm_immutable = 0; + struct signature_v2_hdr evm_fake_xattr = { + .type = EVM_IMA_XATTR_DIGEST_LIST, + .version = 2, .hash_algo = HASH_ALGO_SHA256 }; + int rc, xattr_len, evm_immutable = 0, ima_present = 0; if (iint && (iint->evm_status == INTEGRITY_PASS || iint->evm_status == INTEGRITY_PASS_IMMUTABLE)) @@ -189,7 +196,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, if (rc <= 0) { evm_status = INTEGRITY_FAIL; if (rc == -ENODATA) { - rc = evm_find_protected_xattrs(dentry); + rc = evm_find_protected_xattrs(dentry, &ima_present); if (rc > 0) evm_status = INTEGRITY_NOLABEL; else if (rc == 0) @@ -197,7 +204,20 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, } else if (rc == -EOPNOTSUPP) { evm_status = INTEGRITY_UNKNOWN; } - goto out; + /* IMA added a fake xattr, set also EVM fake xattr */ + if (!ima_present && xattr_name && + !strcmp(xattr_name, XATTR_NAME_IMA) && + xattr_value_len > 2) { + evm_fake_xattr.hash_algo = + ((struct evm_ima_xattr_data *)xattr_value)->data[0]; + xattr_data = + (struct evm_ima_xattr_data *)&evm_fake_xattr; + rc = sizeof(evm_fake_xattr); + } + if (xattr_data != (struct evm_ima_xattr_data *)&evm_fake_xattr) + goto out; + + saved_evm_status = evm_status; } xattr_len = rc; @@ -255,12 +275,54 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, } } break; + case EVM_IMA_XATTR_DIGEST_LIST: + /* At this point, we cannot determine whether metadata are + * immutable or not. However, it is safe to return the + * fail_immutable error, as HMAC will not be created for this + * security.evm type. + */ + evm_immutable = 1; + + if (xattr_len < offsetof(struct signature_v2_hdr, keyid)) { + evm_status = INTEGRITY_FAIL; + goto out; + } + + hdr = (struct signature_v2_hdr *)xattr_data; + digest.hdr.algo = hdr->hash_algo; + rc = evm_calc_hash(dentry, xattr_name, xattr_value, + xattr_value_len, xattr_data->type, &digest); + if (rc) + break; + + found_digest = ima_lookup_digest(digest.digest, hdr->hash_algo, + COMPACT_METADATA); + if (!found_digest) { + rc = -ENOENT; + break; + } + + if (!ima_digest_allow(found_digest, IMA_APPRAISE)) { + rc = -EACCES; + break; + } + + if (ima_digest_is_immutable(found_digest)) { + if (iint) + iint->flags |= EVM_IMMUTABLE_DIGSIG; + evm_status = INTEGRITY_PASS_IMMUTABLE; + } else { + evm_status = INTEGRITY_PASS; + } + break; default: rc = -EINVAL; break; } - if (rc) { + if (rc && xattr_data == (struct evm_ima_xattr_data *)&evm_fake_xattr) { + evm_status = saved_evm_status; + } else if (rc) { if (rc == -ENODATA) evm_status = INTEGRITY_NOXATTRS; else if (evm_immutable) @@ -273,7 +335,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, out: if (iint) iint->evm_status = evm_status; - kfree(xattr_data); + if (xattr_data != (struct evm_ima_xattr_data *)&evm_fake_xattr) + kfree(xattr_data); return evm_status; } @@ -581,7 +644,8 @@ int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, if (!xattr_value_len) return -EINVAL; if (xattr_data->type != EVM_IMA_XATTR_DIGSIG && - xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG) + xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG && + xattr_data->type != EVM_IMA_XATTR_DIGEST_LIST) return -EPERM; } return evm_protect_xattr(idmap, dentry, xattr_name, xattr_value, -- 2.33.0