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authorSascha Hauer <s.hauer@pengutronix.de>2018-03-01 13:38:45 +0100
committerMimi Zohar <zohar@linux.vnet.ibm.com>2018-03-25 07:26:31 -0400
commit70946c4ac2a9e036e3cf7048cd670507f5074b04 (patch)
tree4aa0507018b17e9f20acea856124e95967f98d19 /security
parentf5e51fa368fd6612608bc36f39e55cde08ce0039 (diff)
downloadlinux-stericsson-70946c4ac2a9e036e3cf7048cd670507f5074b04.tar.gz
evm: check for remount ro in progress before writing
EVM might update the evm xattr while the VFS performs a remount to readonly mode. This is not properly checked for, additionally check the s_readonly_remount superblock flag before writing. The bug can for example be observed with UBIFS. UBIFS checks the free space on the device before and after a remount. With EVM enabled the free space sometimes differs between both checks. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/evm/evm_main.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 7a968faca739..9ea9c19a545c 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -124,6 +124,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
struct evm_ima_xattr_data *xattr_data = NULL;
struct evm_ima_xattr_data calc;
enum integrity_status evm_status = INTEGRITY_PASS;
+ struct inode *inode;
int rc, xattr_len;
if (iint && (iint->evm_status == INTEGRITY_PASS ||
@@ -178,12 +179,15 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
(const char *)xattr_data, xattr_len,
calc.digest, sizeof(calc.digest));
if (!rc) {
+ inode = d_backing_inode(dentry);
+
if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
if (iint)
iint->flags |= EVM_IMMUTABLE_DIGSIG;
evm_status = INTEGRITY_PASS_IMMUTABLE;
- } else if (!IS_RDONLY(d_backing_inode(dentry)) &&
- !IS_IMMUTABLE(d_backing_inode(dentry))) {
+ } else if (!IS_RDONLY(inode) &&
+ !(inode->i_sb->s_readonly_remount) &&
+ !IS_IMMUTABLE(inode)) {
evm_update_evmxattr(dentry, xattr_name,
xattr_value,
xattr_value_len);