From f5e51fa368fd6612608bc36f39e55cde08ce0039 Mon Sep 17 00:00:00 2001 From: Thiago Jung Bauermann Date: Thu, 15 Mar 2018 17:33:42 -0300 Subject: ima: Improvements in ima_appraise_measurement() Replace nested ifs in the EVM xattr verification logic with a switch statement, making the code easier to understand. Also, add comments to the if statements in the out section and constify the cause variable. Signed-off-by: Mimi Zohar Signed-off-by: Thiago Jung Bauermann Acked-by: Serge Hallyn --- security/integrity/ima/ima_appraise.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) (limited to 'security') diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 0c5f94b7b9c3..8bd7a0733e51 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -215,7 +215,7 @@ int ima_appraise_measurement(enum ima_hooks func, int xattr_len, int opened) { static const char op[] = "appraise_data"; - char *cause = "unknown"; + const char *cause = "unknown"; struct dentry *dentry = file_dentry(file); struct inode *inode = d_backing_inode(dentry); enum integrity_status status = INTEGRITY_UNKNOWN; @@ -241,16 +241,22 @@ int ima_appraise_measurement(enum ima_hooks func, } status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint); - if ((status != INTEGRITY_PASS) && - (status != INTEGRITY_PASS_IMMUTABLE) && - (status != INTEGRITY_UNKNOWN)) { - if ((status == INTEGRITY_NOLABEL) - || (status == INTEGRITY_NOXATTRS)) - cause = "missing-HMAC"; - else if (status == INTEGRITY_FAIL) - cause = "invalid-HMAC"; + switch (status) { + case INTEGRITY_PASS: + case INTEGRITY_PASS_IMMUTABLE: + case INTEGRITY_UNKNOWN: + break; + case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ + case INTEGRITY_NOLABEL: /* No security.evm xattr. */ + cause = "missing-HMAC"; + goto out; + case INTEGRITY_FAIL: /* Invalid HMAC/signature. */ + cause = "invalid-HMAC"; goto out; + default: + WARN_ONCE(true, "Unexpected integrity status %d\n", status); } + switch (xattr_value->type) { case IMA_XATTR_DIGEST_NG: /* first byte contains algorithm id */ @@ -316,17 +322,20 @@ out: integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, op, cause, rc, 0); } else if (status != INTEGRITY_PASS) { + /* Fix mode, but don't replace file signatures. */ if ((ima_appraise & IMA_APPRAISE_FIX) && (!xattr_value || xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { if (!ima_fix_xattr(dentry, iint)) status = INTEGRITY_PASS; - } else if ((inode->i_size == 0) && - (iint->flags & IMA_NEW_FILE) && - (xattr_value && - xattr_value->type == EVM_IMA_XATTR_DIGSIG)) { + } + + /* Permit new files with file signatures, but without data. */ + if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE && + xattr_value && xattr_value->type == EVM_IMA_XATTR_DIGSIG) { status = INTEGRITY_PASS; } + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, op, cause, rc, 0); } else { -- cgit v1.2.3-59-g8ed1b