On Thu, 2011-05-19 at 01:05 -0500, Serge E. Hallyn wrote: > Quoting Mimi Zohar (zohar@xxxxxxxxxxxxxxxxxx): > > EVM protects a file's security extended attributes(xattrs) against integrity > > attacks. This patchset provides the framework and an initial method. The > > initial method maintains an HMAC-sha1 value across the security extended > > attributes, storing the HMAC value as the extended attribute 'security.evm'. > > Other methods of validating the integrity of a file's metadata will be posted > > separately (eg. EVM-digital-signatures). > > > > While this patchset does authenticate the security xattrs, and > > cryptographically binds them to the inode, coming extensions will bind other > > directory and inode metadata for more complete protection. To help simplify > > the review and upstreaming process, each extension will be posted separately > > (eg. IMA-appraisal, IMA-appraisal-directory). For a general overview of the > > proposed Linux integrity subsystem, refer to Dave Safford's whitepaper: > > http://downloads.sf.net/project/linux-ima/linux-ima/Integrity_overview.pdf. > > > > EVM depends on the Kernel Key Retention System to provide it with a > > trusted/encrypted key for the HMAC-sha1 operation. The key is loaded onto the > > root's keyring using keyctl. Until EVM receives notification that the key has > > been successfully loaded onto the keyring (echo 1 > <securityfs>/evm), EVM can > > not create or validate the 'security.evm' xattr, but returns INTEGRITY_UNKNOWN. > > Loading the key and signaling EVM should be done as early as possible. Normally > > this is done in the initramfs, which has already been measured as part of the > > trusted boot. For more information on creating and loading existing > > trusted/encrypted keys, refer to Documentation/keys-trusted-encrypted.txt. A > > sample dracut patch, which loads the trusted/encrypted key and enables EVM, is > > available from http://linu-ima.sourceforge.net/#EVM. > > That should read http://linux-ima.sourceforge.net/#EVM. Thanks for catching that. > > Based on the LSMs enabled, the set of EVM protected security xattrs is defined > > at compile. EVM adds the following three calls to the existing security hooks: > > evm_inode_setxattr(), evm_inode_post_setxattr(), and evm_inode_removexattr. To > > initialize and update the 'security.evm' extended attribute, EVM defines three > > calls: evm_inode_post_init(), evm_inode_post_setattr() and > > evm_inode_post_removexattr() hooks. To verify the integrity of a security > > xattr, EVM exports evm_verifyxattr(). > > > > Changelog: > > - locking based on i_mutex, remove evm_mutex > > - using trusted/encrypted keys for storing the EVM key used in the HMAC-sha1 > > operation. > > - replaced crypto hash with shash (Dmitry Kasatkin) > > - support for additional methods of verifying the security xattrs > > (Dmitry Kasatkin) > > - iint not allocated for all regular files, but only for those appraised > > - Use cap_sys_admin in lieu of cap_mac_admin > > - Use __vfs_setxattr_noperm(), without permission checks, from EVM > > > > Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxx> > > --- > > Documentation/ABI/testing/evm | 23 +++ > > include/linux/integrity.h | 7 + > > include/linux/xattr.h | 3 + > > security/integrity/Kconfig | 3 +- > > security/integrity/Makefile | 2 + > > security/integrity/evm/Kconfig | 12 ++ > > security/integrity/evm/Makefile | 6 + > > security/integrity/evm/evm.h | 34 ++++ > > security/integrity/evm/evm_crypto.c | 177 ++++++++++++++++++++++ > > security/integrity/evm/evm_main.c | 283 +++++++++++++++++++++++++++++++++++ > > security/integrity/evm/evm_secfs.c | 108 +++++++++++++ > > security/integrity/iint.c | 1 + > > security/integrity/integrity.h | 1 + > > 13 files changed, 659 insertions(+), 1 deletions(-) > > create mode 100644 Documentation/ABI/testing/evm > > create mode 100644 security/integrity/evm/Kconfig > > create mode 100644 security/integrity/evm/Makefile > > create mode 100644 security/integrity/evm/evm.h > > create mode 100644 security/integrity/evm/evm_crypto.c > > create mode 100644 security/integrity/evm/evm_main.c > > create mode 100644 security/integrity/evm/evm_secfs.c > > > > diff --git a/Documentation/ABI/testing/evm b/Documentation/ABI/testing/evm > > new file mode 100644 > > index 0000000..37c4e02 > > --- /dev/null > > +++ b/Documentation/ABI/testing/evm > > @@ -0,0 +1,23 @@ > > +What: security/evm > > +Date: March 2011 > > +Contact: Mimi Zohar <zohar@xxxxxxxxxx> > > +Description: > > + EVM protects a file's security extended attributes(xattrs) > > + against integrity attacks. The initial method maintains an > > + HMAC-sha1 value across the extended attributes, storing the > > + value as the extended attribute 'security.evm'. > > + > > + EVM depends on the Kernel Key Retention System to provide it > > + with a trusted/encrypted key for the HMAC-sha1 operation. > > + The key is loaded onto the root's keyring using keyctl. Until > > + EVM receives notification that the key has been successfully > > + loaded onto the keyring (echo 1 > <securityfs>/evm), EVM > > + can not create or validate the 'security.evm' xattr, but > > + returns INTEGRITY_UNKNOWN. Loading the key and signaling EVM > > + should be done as early as possible. Normally this is done > > + in the initramfs, which has already been measured as part > > + of the trusted boot. For more information on creating and > > + loading existing trusted/encrypted keys, refer to: > > + Documentation/keys-trusted-encrypted.txt. (A sample dracut > > + patch, which loads the trusted/encrypted key and enables > > + EVM, is available from http://linu-ima.sourceforge.net/#EVM.) > > diff --git a/include/linux/integrity.h b/include/linux/integrity.h > > index 9059812..e715a2a 100644 > > --- a/include/linux/integrity.h > > +++ b/include/linux/integrity.h > > @@ -12,6 +12,13 @@ > > > > #include <linux/fs.h> > > > > +enum integrity_status { > > + INTEGRITY_PASS = 0, > > + INTEGRITY_FAIL, > > + INTEGRITY_NOLABEL, > > + INTEGRITY_UNKNOWN, > > +}; > > + > > #ifdef CONFIG_INTEGRITY > > extern int integrity_inode_alloc(struct inode *inode); > > extern void integrity_inode_free(struct inode *inode); > > diff --git a/include/linux/xattr.h b/include/linux/xattr.h > > index 953a0d5..61a9a349 100644 > > --- a/include/linux/xattr.h > > +++ b/include/linux/xattr.h > > @@ -34,6 +34,9 @@ > > #define XATTR_USER_PREFIX_LEN (sizeof (XATTR_USER_PREFIX) - 1) > > > > /* Security namespace */ > > +#define XATTR_EVM_SUFFIX "evm" > > +#define XATTR_NAME_EVM XATTR_SECURITY_PREFIX XATTR_EVM_SUFFIX > > + > > #define XATTR_SELINUX_SUFFIX "selinux" > > #define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX > > > > diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig > > index 2704691..4bf00ac 100644 > > --- a/security/integrity/Kconfig > > +++ b/security/integrity/Kconfig > > @@ -1,6 +1,7 @@ > > # > > config INTEGRITY > > def_bool y > > - depends on IMA > > + depends on IMA || EVM > > > > source security/integrity/ima/Kconfig > > +source security/integrity/evm/Kconfig > > diff --git a/security/integrity/Makefile b/security/integrity/Makefile > > index 6eddd61..0ae44ae 100644 > > --- a/security/integrity/Makefile > > +++ b/security/integrity/Makefile > > @@ -8,3 +8,5 @@ integrity-y := iint.o > > > > subdir-$(CONFIG_IMA) += ima > > obj-$(CONFIG_IMA) += ima/built-in.o > > +subdir-$(CONFIG_EVM) += evm > > +obj-$(CONFIG_EVM) += evm/built-in.o > > diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig > > new file mode 100644 > > index 0000000..73f6540 > > --- /dev/null > > +++ b/security/integrity/evm/Kconfig > > @@ -0,0 +1,12 @@ > > +config EVM > > + boolean "EVM support" > > + depends on SECURITY && KEYS && ENCRYPTED_KEYS > > + select CRYPTO_HMAC > > + select CRYPTO_MD5 > > + select CRYPTO_SHA1 > > + default n > > + help > > + EVM protects a file's security extended attributes against > > + integrity attacks. > > + > > + If you are unsure how to answer this question, answer N. > > diff --git a/security/integrity/evm/Makefile b/security/integrity/evm/Makefile > > new file mode 100644 > > index 0000000..0787d26 > > --- /dev/null > > +++ b/security/integrity/evm/Makefile > > @@ -0,0 +1,6 @@ > > +# > > +# Makefile for building the Extended Verification Module(EVM) > > +# > > +obj-$(CONFIG_EVM) += evm.o > > + > > +evm-y := evm_main.o evm_crypto.o evm_secfs.o > > diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h > > new file mode 100644 > > index 0000000..f2bbe43 > > --- /dev/null > > +++ b/security/integrity/evm/evm.h > > @@ -0,0 +1,34 @@ > > +/* > > + * Copyright (C) 2005-2010 IBM Corporation > > + * > > + * Authors: > > + * Mimi Zohar <zohar@xxxxxxxxxx> > > + * Kylene Hall <kjhall@xxxxxxxxxx> > > + * > > + * 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. > > + * > > + * File: evm.h > > + * > > + */ > > +#include <linux/security.h> > > +#include "../integrity.h" > > + > > +extern int evm_initialized; > > +extern char *evm_hmac; > > +extern int evm_hmac_size; > > + > > +/* List of EVM protected security xattrs */ > > +extern char *evm_config_xattrnames[]; > > + > > +extern int evm_init_key(void); > > +extern int evm_update_evmxattr(struct dentry *dentry, > > + const char *req_xattr_name, > > + const char *req_xattr_value, > > + size_t req_xattr_value_len); > > +extern int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name, > > + const char *req_xattr_value, > > + size_t req_xattr_value_len, char *digest); > > +extern int evm_init_secfs(void); > > +extern void evm_cleanup_secfs(void); > > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c > > new file mode 100644 > > index 0000000..c43be5a > > --- /dev/null > > +++ b/security/integrity/evm/evm_crypto.c > > @@ -0,0 +1,177 @@ > > +/* > > + * Copyright (C) 2005-2010 IBM Corporation > > + * > > + * Authors: > > + * Mimi Zohar <zohar@xxxxxxxxxx> > > + * Kylene Hall <kjhall@xxxxxxxxxx> > > + * > > + * 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. > > + * > > + * File: evm_crypto.c > > + * Using root's kernel master key (kmk), calculate the HMAC > > + */ > > + > > +#include <linux/module.h> > > +#include <linux/crypto.h> > > +#include <linux/xattr.h> > > +#include <keys/encrypted-type.h> > > The rule historically has been linux/ includes come first. I could > be wrong but suspect that's still the case here. No, you're correct. > > +#include <linux/scatterlist.h> > > +#include "evm.h" > > + > > +#define EVMKEY "evm-key" > > +#define MAX_KEY_SIZE 128 > > +static unsigned char evmkey[MAX_KEY_SIZE]; > > +static int evmkey_len = MAX_KEY_SIZE; > > + > > +static int init_desc(struct hash_desc *desc) > > +{ > > + int rc; > > + > > + desc->tfm = crypto_alloc_hash(evm_hmac, 0, CRYPTO_ALG_ASYNC); > > + if (IS_ERR(desc->tfm)) { > > + pr_info("Can not allocate %s (reason: %ld)\n", > > + evm_hmac, PTR_ERR(desc->tfm)); > > + rc = PTR_ERR(desc->tfm); > > + return rc; > > + } > > + desc->flags = 0; > > + crypto_hash_setkey(desc->tfm, evmkey, evmkey_len); > > crypto_hash_setkey() can fail, right? Yes, will add the check. > > + rc = crypto_hash_init(desc); > > + if (rc) > > + crypto_free_hash(desc->tfm); > > + return rc; > > +} > > + > > +/* Protect against 'cutting & pasting' security.evm xattr, include inode > > + * specific info. > > + * > > + * (Additional directory/file metadata needs to be added for more complete > > + * protection.) > > + */ > > +static void hmac_add_misc(struct hash_desc *desc, struct inode *inode, > > + char *digest) > > +{ > > + struct h_misc { > > + unsigned long ino; > > + __u32 generation; > > + uid_t uid; > > + gid_t gid; > > + umode_t mode; > > + } hmac_misc; > > + struct scatterlist sg[1]; > > + > > + memset(&hmac_misc, 0, sizeof hmac_misc); > > + hmac_misc.ino = inode->i_ino; > > + hmac_misc.generation = inode->i_generation; > > + hmac_misc.uid = inode->i_uid; > > + hmac_misc.gid = inode->i_gid; > > + hmac_misc.mode = inode->i_mode; > > + sg_init_one(sg, &hmac_misc, sizeof hmac_misc); > > + crypto_hash_update(desc, sg, sizeof hmac_misc); > > + crypto_hash_final(desc, digest); > > +} > > + > > +/* > > + * Calculate the HMAC value across the set of protected security xattrs. > > + * > > + * Instead of retrieving the requested xattr, for performance, calculate > > + * the hmac using the requested xattr value. Don't alloc/free memory for > > + * each xattr, but attempt to re-use the previously allocated memory. > > + */ > > +int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name, > > + const char *req_xattr_value, size_t req_xattr_value_len, > > + char *digest) > > +{ > > + struct inode *inode = dentry->d_inode; > > + struct hash_desc desc; > > + struct scatterlist sg[1]; > > + char **xattrname; > > + size_t xattr_size = 0; > > + char *xattr_value = NULL; > > + int error; > > + int size; > > + > > + if (!inode->i_op || !inode->i_op->getxattr) > > + return -EOPNOTSUPP; > > + error = init_desc(&desc); > > + if (error) > > + return error; > > + > > + error = -ENODATA; > > + for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) { > > + if ((req_xattr_name && req_xattr_value) > > + && !strcmp(*xattrname, req_xattr_name)) { > > Is this special case only here to avoid one vfs_getxattr_alloc(), > or is there another reason for it? Right, it's to avoid making an unecessary vfs_getxattr_alloc() call. > > + error = 0; > > + sg_init_one(sg, req_xattr_value, req_xattr_value_len); > > + crypto_hash_update(&desc, sg, req_xattr_value_len); > > + continue; > > + } > > + size = vfs_getxattr_alloc(dentry, *xattrname, > > + &xattr_value, xattr_size, GFP_NOFS); > > + if (size == -ENOMEM) { > > + error = -ENOMEM; > > + goto out; > > + } > > + if (size < 0) > > + continue; > > + > > + error = 0; > > + xattr_size = size; > > + sg_init_one(sg, xattr_value, xattr_size); > > + crypto_hash_update(&desc, sg, xattr_size); > > + } > > + hmac_add_misc(&desc, inode, digest); > > + kfree(xattr_value); > > +out: > > + crypto_free_hash(desc.tfm); > > + return error; > > +} > > + > > +/* > > + * Calculate the hmac and update security.evm xattr > > + * > > + * Expects to be called with i_mutex locked. > > + */ > > +int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, > > + const char *xattr_value, size_t xattr_value_len) > > +{ > > + struct inode *inode = dentry->d_inode; > > + u8 hmac[MAX_DIGEST_SIZE]; > > + int rc = 0; > > + > > + rc = evm_calc_hmac(dentry, xattr_name, xattr_value, > > + xattr_value_len, hmac); > > + if (rc == 0) > > + rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM, > > + hmac, evm_hmac_size, 0); > > + else if (rc == -ENODATA) > > + rc = inode->i_op->removexattr(dentry, XATTR_NAME_EVM); > > + return rc; > > +} > > + > > +/* > > + * Get the key from the TPM for the SHA1-HMAC > > + */ > > +int evm_init_key(void) > > +{ > > + struct key *evm_key; > > + struct encrypted_key_payload *ekp; > > + > > + evm_key = request_key(&key_type_encrypted, EVMKEY, NULL); > > + if (IS_ERR(evm_key)) > > + return -ENOENT; > > + > > + down_read(&evm_key->sem); > > + ekp = evm_key->payload.data; > > + evmkey_len = ekp->decrypted_datalen > MAX_KEY_SIZE ? MAX_KEY_SIZE : > > If decrypted_datalen > MAX_KEY_SIZE, shouldn't you assume something went > wrong and return an error? Yes, it's probably a good idea to return something meaningful, rather than letting it fail latter on use. :-) > > + ekp->decrypted_datalen; > > + memcpy(evmkey, ekp->decrypted_data, evmkey_len); > > + > > + /* burn the original key contents */ > > + memset(ekp->decrypted_data, 0, evmkey_len); > > You're potentially leaving akp->decrypted_datalen - evmkey_len bits > unburned. Right, it should be: memset(ekp->decrypted_data, 0, ekp->decrypted_datalen); > > + up_read(&evm_key->sem); > > + key_put(evm_key); > > + return 0; > > +} > > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > > new file mode 100644 > > index 0000000..66d7544 > > --- /dev/null > > +++ b/security/integrity/evm/evm_main.c > > @@ -0,0 +1,283 @@ > > +/* > > + * Copyright (C) 2005-2010 IBM Corporation > > + * > > + * Author: > > + * Mimi Zohar <zohar@xxxxxxxxxx> > > + * Kylene Hall <kjhall@xxxxxxxxxx> > > + * > > + * 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. > > + * > > + * File: evm_main.c > > + * implements evm_inode_setxattr, evm_inode_post_setxattr, > > + * evm_inode_removexattr, and evm_verifyxattr > > + */ > > + > > +#include <linux/module.h> > > +#include <linux/crypto.h> > > +#include <linux/xattr.h> > > +#include <linux/integrity.h> > > +#include "evm.h" > > + > > +int evm_initialized; > > + > > +char *evm_hmac = "hmac(sha1)"; > > +int evm_hmac_size = SHA1_DIGEST_SIZE; > > + > > +char *evm_config_xattrnames[] = { > > +#ifdef CONFIG_SECURITY_SELINUX > > + XATTR_NAME_SELINUX, > > +#endif > > +#ifdef CONFIG_SECURITY_SMACK > > + XATTR_NAME_SMACK, > > +#endif > > + XATTR_NAME_CAPS, > > + NULL > > +}; > > + > > +/* > > + * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr > > + * > > + * Compute the HMAC on the dentry's protected set of extended attributes > > + * and compare it against the stored security.evm xattr. (For performance, > > + * use the previoulsy retrieved xattr value and length to calculate the > > + * HMAC.) > > + * > > + * Returns integrity status > > + */ > > +static enum integrity_status evm_verify_hmac(struct dentry *dentry, > > + const char *xattr_name, > > + char *xattr_value, > > + size_t xattr_value_len, > > + struct integrity_iint_cache *iint) > > +{ > > + char hmac_val[MAX_DIGEST_SIZE]; > > + int rc; > > + > > + if (iint->hmac_status != INTEGRITY_UNKNOWN) > > + return iint->hmac_status; > > + > > + memset(hmac_val, 0, sizeof hmac_val); > > + rc = evm_calc_hmac(dentry, xattr_name, xattr_value, > > + xattr_value_len, hmac_val); > > + if (rc < 0) > > + return INTEGRITY_UNKNOWN; > > + > > + rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, hmac_val, sizeof hmac_val, > > + GFP_NOFS); > > + if (rc < 0) > > + goto err_out; > > + iint->hmac_status = INTEGRITY_PASS; > > + return iint->hmac_status; > > + > > +err_out: > > + switch (rc) { > > + case -ENODATA: /* file not labelled */ > > + iint->hmac_status = INTEGRITY_NOLABEL; > > + break; > > + case -EINVAL: > > + iint->hmac_status = INTEGRITY_FAIL; > > + break; > > + default: > > + iint->hmac_status = INTEGRITY_UNKNOWN; > > + } > > + return iint->hmac_status; > > +} > > + > > +static int evm_protected_xattr(const char *req_xattr_name) > > +{ > > + char **xattrname; > > + int found = 0; > > + > > + for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) { > > + if (strncmp(req_xattr_name, *xattrname, > > + strlen(req_xattr_name)) == 0) { > > Can you put a comment here as to why currently checking the lengths is > unnecessary due to the xattrs which exist? (Or add a length comparison) yes, length checking is necessary. > > + found = 1; > > + break; > > + } > > + } > > + return found; > > +} > > + > > +/** > > + * evm_verifyxattr - verify the integrity of the requested xattr > > + * @dentry: object of the verify xattr > > + * @xattr_name: requested xattr > > + * @xattr_value: requested xattr value > > + * @xattr_value_len: requested xattr value length > > + * > > + * Calculate the HMAC for the given dentry and verify it against the stored > > + * security.evm xattr. For performance, use the xattr value and length > > + * previously retrieved to calculate the HMAC. > > + * > > + * Returns the xattr integrity status. > > + * > > + * This function requires the caller to lock the inode's i_mutex before it > > + * is executed. > > + */ > > +enum integrity_status evm_verifyxattr(struct dentry *dentry, > > + const char *xattr_name, > > + void *xattr_value, size_t xattr_value_len) > > +{ > > + struct inode *inode = dentry->d_inode; > > + struct integrity_iint_cache *iint; > > + enum integrity_status status; > > + > > + if (!evm_initialized || !evm_protected_xattr(xattr_name)) > > + return INTEGRITY_UNKNOWN; > > + > > + iint = integrity_iint_find(inode); > > + if (!iint) > > + return INTEGRITY_UNKNOWN; > > + status = evm_verify_hmac(dentry, xattr_name, xattr_value, > > + xattr_value_len, iint); > > + return status; > > +} > > +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_inode_setxattr - protect the EVM extended attribute > > + * @dentry: pointer to the affected dentry > > + * @xattr_name: pointer to the affected extended attribute name > > + * @xattr_value: pointer to the new extended attribute value > > + * @xattr_value_len: pointer to the new extended attribute value length > > + * > > + * Prevent 'security.evm' from being modified > > + */ > > +int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name, > > + const void *xattr_value, size_t xattr_value_len) > > +{ > > + return evm_protect_xattr(dentry, xattr_name, xattr_value, > > + xattr_value_len); > > +} > > + > > +/** > > + * evm_inode_removexattr - protect the EVM extended attribute > > + * @dentry: pointer to the affected dentry > > + * @xattr_name: pointer to the affected extended attribute name > > + * > > + * Prevent 'security.evm' from being removed. > > + */ > > +int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name) > > +{ > > + return evm_protect_xattr(dentry, xattr_name, NULL, 0); > > +} > > + > > +/** > > + * evm_inode_post_setxattr - update 'security.evm' to reflect the changes > > + * @dentry: pointer to the affected dentry > > + * @xattr_name: pointer to the affected extended attribute name > > + * @xattr_value: pointer to the new extended attribute value > > + * @xattr_value_len: pointer to the new extended attribute value length > > + * > > + * Update the HMAC stored in 'security.evm' to reflect the change. > > + * > > + * No need to take the i_mutex lock here, as this function is called from > > + * __vfs_setxattr_noperm(). The caller of which has taken the inode's > > + * i_mutex lock. > > + */ > > +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)) > > + return; > > + > > + evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len); > > + return; > > +} > > + > > +/** > > + * evm_inode_post_removexattr - update 'security.evm' after removing the xattr > > + * @dentry: pointer to the affected dentry > > + * @xattr_name: pointer to the affected extended attribute name > > + * > > + * Update the HMAC stored in 'security.evm' to reflect removal of the xattr. > > + */ > > +void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) > > +{ > > + struct inode *inode = dentry->d_inode; > > + > > + if (!evm_initialized || !evm_protected_xattr(xattr_name)) > > + return; > > + > > + mutex_lock(&inode->i_mutex); > > + evm_update_evmxattr(dentry, xattr_name, NULL, 0); > > + mutex_unlock(&inode->i_mutex); > > + return; > > +} > > + > > +/** > > + * evm_inode_post_setattr - update 'security.evm' after modifying metadata > > + * @dentry: pointer to the affected dentry > > + * @ia_valid: for the UID and GID status > > + * > > + * For now, update the HMAC stored in 'security.evm' to reflect UID/GID > > + * changes. > > + * > > + * This function is called from notify_change(), which expects the caller > > + * to lock the inode's i_mutex. > > + */ > > +void evm_inode_post_setattr(struct dentry *dentry, int ia_valid) > > +{ > > + if (!evm_initialized) > > + return; > > + > > + if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) > > + evm_update_evmxattr(dentry, NULL, NULL, 0); > > + return; > > +} > > + > > +static struct crypto_hash *tfm_hmac; /* preload crypto alg */ > > +static int __init init_evm(void) > > +{ > > + int error; > > + > > + tfm_hmac = crypto_alloc_hash(evm_hmac, 0, CRYPTO_ALG_ASYNC); > > + error = evm_init_secfs(); > > + if (error < 0) { > > + printk(KERN_INFO "EVM: Error registering secfs\n"); > > + goto err; > > + } > > +err: > > + return error; > > +} > > + > > +static void __exit cleanup_evm(void) > > +{ > > + evm_cleanup_secfs(); > > + crypto_free_hash(tfm_hmac); > > +} > > + > > +/* > > + * evm_display_config - list the EVM protected security extended attributes > > + */ > > +static int __init evm_display_config(void) > > +{ > > + char **xattrname; > > + > > + for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) > > + printk(KERN_INFO "EVM: %s\n", *xattrname); > > + return 0; > > +} > > + > > +pure_initcall(evm_display_config); > > +late_initcall(init_evm); > > + > > +MODULE_DESCRIPTION("Extended Verification Module"); > > +MODULE_LICENSE("GPL"); > > diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c > > new file mode 100644 > > index 0000000..ac76299 > > --- /dev/null > > +++ b/security/integrity/evm/evm_secfs.c > > @@ -0,0 +1,108 @@ > > +/* > > + * Copyright (C) 2010 IBM Corporation > > + * > > + * Authors: > > + * Mimi Zohar <zohar@xxxxxxxxxx> > > + * > > + * 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. > > + * > > + * File: evm_secfs.c > > + * - Used to signal when key is on keyring > > + * - Get the key and enable EVM > > + */ > > + > > +#include <linux/uaccess.h> > > +#include <linux/module.h> > > +#include "evm.h" > > + > > +static struct dentry *evm_init_tpm; > > + > > +/** > > + * evm_read_key - read() for <securityfs>/evm > > + * > > + * @filp: file pointer, not actually used > > + * @buf: where to put the result > > + * @count: maximum to send along > > + * @ppos: where to start > > + * > > + * Returns number of bytes read or error code, as appropriate > > + */ > > +static ssize_t evm_read_key(struct file *filp, char __user *buf, > > + size_t count, loff_t *ppos) > > +{ > > + char temp[80]; > > + ssize_t rc; > > + > > + if (*ppos != 0) > > + return 0; > > + > > + sprintf(temp, "%d", evm_initialized); > > + rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp)); > > + > > + return rc; > > +} > > + > > +/** > > + * evm_write_key - write() for <securityfs>/evm > > + * @file: file pointer, not actually used > > + * @buf: where to get the data from > > + * @count: bytes sent > > + * @ppos: where to start > > + * > > + * Used to signal that key is on the kernel key ring. > > + * - get the integrity hmac key from the kernel key ring > > + * - create list of hmac protected extended attributes > > + * Returns number of bytes written or error code, as appropriate > > + */ > > +static ssize_t evm_write_key(struct file *file, const char __user *buf, > > + size_t count, loff_t *ppos) > > +{ > > + char temp[80]; > > + int i, error; > > + > > + if (!capable(CAP_SYS_ADMIN) || evm_initialized) > > + return -EPERM; > > + > > + if (count >= sizeof(temp) || count == 0) > > + return -EINVAL; > > + > > + if (copy_from_user(temp, buf, count) != 0) > > + return -EFAULT; > > + > > + temp[count] = '\0'; > > + > > + if ((sscanf(temp, "%d", &i) != 1) || (i != 1)) > > + return -EINVAL; > > + > > + error = evm_init_key(); > > + if (!error) { > > + evm_initialized = 1; > > + pr_info("EVM: initialized\n"); > > + } else > > + pr_err("EVM: initialization failed\n"); > > + return count; > > +} > > + > > +static const struct file_operations evm_key_ops = { > > + .read = evm_read_key, > > + .write = evm_write_key, > > +}; > > + > > +int __init evm_init_secfs(void) > > +{ > > + int error = 0; > > + > > + evm_init_tpm = securityfs_create_file("evm", S_IRUSR | S_IRGRP, > > + NULL, NULL, &evm_key_ops); > > + if (!evm_init_tpm || IS_ERR(evm_init_tpm)) > > + error = -EFAULT; > > + return error; > > +} > > + > > +void __exit evm_cleanup_secfs(void) > > +{ > > + if (evm_init_tpm) > > + securityfs_remove(evm_init_tpm); > > +} > > diff --git a/security/integrity/iint.c b/security/integrity/iint.c > > index d17de48..991df20 100644 > > --- a/security/integrity/iint.c > > +++ b/security/integrity/iint.c > > @@ -157,6 +157,7 @@ static void init_once(void *foo) > > iint->version = 0; > > iint->flags = 0UL; > > mutex_init(&iint->mutex); > > + iint->hmac_status = INTEGRITY_UNKNOWN; > > } > > > > static int __init integrity_iintcache_init(void) > > diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h > > index 2217a28..2232cd1 100644 > > --- a/security/integrity/integrity.h > > +++ b/security/integrity/integrity.h > > @@ -28,6 +28,7 @@ struct integrity_iint_cache { > > unsigned char flags; > > u8 digest[MAX_DIGEST_SIZE]; > > struct mutex mutex; /* protects: version, flags, digest */ > > + enum integrity_status hmac_status; > > }; > > > > /* rbtree tree calls to lookup, insert, delete -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
