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evm: limit verifying current security.evm integrity

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evm_protect_xattr unnecessarily validates the current security.evm
integrity, before updating non-evm protected extended attributes
and other file metadata. This patch limits validating the current
security.evm integrity to evm protected metadata.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
This commit is contained in:
Mimi Zohar 2011-08-11 01:22:30 -04:00
parent fb88c2b6cb
commit a924ce0b35
1 changed files with 24 additions and 34 deletions
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58
security/integrity/evm/evm_main.c
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@ -158,21 +158,6 @@ enum integrity_status evm_verifyxattr(struct dentry *dentry,
}
EXPORT_SYMBOL_GPL(evm_verifyxattr);
/*
* evm_protect_xattr - protect the EVM extended attribute
*
* Prevent security.evm from being modified or removed.
*/
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
}
return 0;
}
/*
* evm_verify_current_integrity - verify the dentry's metadata integrity
* @dentry: pointer to the affected dentry
@ -189,6 +174,26 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
}
/*
* evm_protect_xattr - protect the EVM extended attribute
*
* Prevent security.evm from being modified or removed.
*/
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
enum integrity_status evm_status;
if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
} else if (!evm_protected_xattr(xattr_name))
return 0;
evm_status = evm_verify_current_integrity(dentry);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
}
/**
* evm_inode_setxattr - protect the EVM extended attribute
* @dentry: pointer to the affected dentry
@ -202,16 +207,8 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
const void *xattr_value, size_t xattr_value_len)
{
enum integrity_status evm_status;
int ret;
ret = evm_protect_xattr(dentry, xattr_name, xattr_value,
xattr_value_len);
if (ret)
return ret;
evm_status = evm_verify_current_integrity(dentry);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
return evm_protect_xattr(dentry, xattr_name, xattr_value,
xattr_value_len);
}
/**
@ -224,14 +221,7 @@ int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
*/
int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
{
enum integrity_status evm_status;
int ret;
ret = evm_protect_xattr(dentry, xattr_name, NULL, 0);
if (ret)
return ret;
evm_status = evm_verify_current_integrity(dentry);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
return evm_protect_xattr(dentry, xattr_name, NULL, 0);
}
/**
@ -286,7 +276,7 @@ int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
unsigned int ia_valid = attr->ia_valid;
enum integrity_status evm_status;
if (ia_valid & ~(ATTR_MODE | ATTR_UID | ATTR_GID))
if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
return 0;
evm_status = evm_verify_current_integrity(dentry);
return evm_status == INTEGRITY_PASS ? 0 : -EPERM;