diff options
Diffstat (limited to 'security/integrity/evm')
| -rw-r--r-- | security/integrity/evm/Makefile | 1 | ||||
| -rw-r--r-- | security/integrity/evm/evm_main.c | 24 | ||||
| -rw-r--r-- | security/integrity/evm/evm_posix_acl.c | 26 |
3 files changed, 46 insertions, 5 deletions
diff --git a/security/integrity/evm/Makefile b/security/integrity/evm/Makefile index 0787d262b9e..7393c415a06 100644 --- a/security/integrity/evm/Makefile +++ b/security/integrity/evm/Makefile @@ -4,3 +4,4 @@ obj-$(CONFIG_EVM) += evm.o evm-y := evm_main.o evm_crypto.o evm_secfs.o +evm-$(CONFIG_FS_POSIX_ACL) += evm_posix_acl.o diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 7d4247535f9..73c008d047c 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -177,7 +177,14 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry) /* * evm_protect_xattr - protect the EVM extended attribute * - * Prevent security.evm from being modified or removed. + * Prevent security.evm from being modified or removed without the + * necessary permissions or when the existing value is invalid. + * + * The posix xattr acls are 'system' prefixed, which normally would not + * affect security.evm. An interesting side affect of writing posix xattr + * acls is their modifying of the i_mode, which is included in security.evm. + * For posix xattr acls only, permit security.evm, even if it currently + * doesn't exist, to be updated. */ static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name, const void *xattr_value, size_t xattr_value_len) @@ -187,9 +194,15 @@ static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name, if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) { if (!capable(CAP_SYS_ADMIN)) return -EPERM; - } else if (!evm_protected_xattr(xattr_name)) - return 0; - + } else if (!evm_protected_xattr(xattr_name)) { + if (!posix_xattr_acl(xattr_name)) + return 0; + evm_status = evm_verify_current_integrity(dentry); + if ((evm_status == INTEGRITY_PASS) || + (evm_status == INTEGRITY_NOLABEL)) + return 0; + return -EPERM; + } evm_status = evm_verify_current_integrity(dentry); return evm_status == INTEGRITY_PASS ? 0 : -EPERM; } @@ -240,7 +253,8 @@ int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name) void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, const void *xattr_value, size_t xattr_value_len) { - if (!evm_initialized || !evm_protected_xattr(xattr_name)) + if (!evm_initialized || (!evm_protected_xattr(xattr_name) + && !posix_xattr_acl(xattr_name))) return; evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len); diff --git a/security/integrity/evm/evm_posix_acl.c b/security/integrity/evm/evm_posix_acl.c new file mode 100644 index 00000000000..b1753e98bf9 --- /dev/null +++ b/security/integrity/evm/evm_posix_acl.c @@ -0,0 +1,26 @@ +/* + * Copyright (C) 2011 IBM Corporation + * + * Author: + * Mimi Zohar <zohar@us.ibm.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, version 2 of the License. + */ + +#include <linux/module.h> +#include <linux/xattr.h> + +int posix_xattr_acl(char *xattr) +{ + int xattr_len = strlen(xattr); + + if ((strlen(XATTR_NAME_POSIX_ACL_ACCESS) == xattr_len) + && (strncmp(XATTR_NAME_POSIX_ACL_ACCESS, xattr, xattr_len) == 0)) + return 1; + if ((strlen(XATTR_NAME_POSIX_ACL_DEFAULT) == xattr_len) + && (strncmp(XATTR_NAME_POSIX_ACL_DEFAULT, xattr, xattr_len) == 0)) + return 1; + return 0; +} |