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SubjectRe: [PATCH v3 04/12] ima: integrity appraisal extension
From
On Wed, Mar 21, 2012 at 8:54 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> IMA currently maintains an integrity measurement list used to assert the
> integrity of the running system to a third party.  The IMA-appraisal
> extension adds local integrity validation and enforcement of the
> measurement against a "good" value stored as an extended attribute
> 'security.ima'.  The initial methods for validating 'security.ima' are
> hashed based, which provides file data integrity, and digital signature
> based, which in addition to providing file data integrity, provides
> authenticity.
>
> This patch creates and maintains the 'security.ima' xattr, containing
> the file data hash measurement.  Protection of the xattr is provided by
> EVM, if enabled and configured.
>
> Based on policy, IMA calls evm_verifyxattr() to verify a file's metadata
> integrity and, assuming success, compares the file's current hash value
> with the one stored as an extended attribute in 'security.ima'.
>
> Changelog v3:
> - change appraisal default for filesystems without xattr support to fail
>
> Changelog v2:
> - fix audit msg 'res' value
> - removed unused 'ima_appraise=' values
>
> Changelog v1:
> - removed unused iint mutex (Dmitry Kasatkin)
> - setattr hook must not reset appraised (Dmitry Kasatkin)
> - evm_verifyxattr() now differentiates between no 'security.evm' xattr
>  (INTEGRITY_NOLABEL) and no EVM 'protected' xattrs included in the
>  'security.evm' (INTEGRITY_NOXATTRS).
> - replace hash_status with ima_status (Dmitry Kasatkin)
> - re-initialize slab element ima_status on free (Dmitry Kasatkin)
> - include 'security.ima' in EVM if CONFIG_IMA_APPRAISE, not CONFIG_IMA
> - merged half "ima: ima_must_appraise_or_measure API change" (Dmitry Kasatkin)
> - removed unnecessary error variable in process_measurement() (Dmitry Kasatkin)
> - use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured
>  (moved ima_inode_post_setattr() to ima_appraise.c)
> - make sure ima_collect_measurement() can read file
>
> Changelog:
> - add 'iint' to evm_verifyxattr() call (Dimitry Kasatkin)
> - fix the race condition between chmod, which takes the i_mutex and then
>  iint->mutex, and ima_file_free() and process_measurement(), which take
>  the locks in the reverse order, by eliminating iint->mutex. (Dmitry Kasatkin)
> - cleanup of ima_appraise_measurement() (Dmitry Kasatkin)
> - changes as a result of the iint not allocated for all regular files, but
>  only for those measured/appraised.
> - don't try to appraise new/empty files
> - expanded ima_appraisal description in ima/Kconfig
> - IMA appraise definitions required even if IMA_APPRAISE not enabled
> - add return value to ima_must_appraise() stub
> - unconditionally set status = INTEGRITY_PASS *after* testing status,
>  not before.  (Found by Joe Perches)
>
> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>

> ---
>  Documentation/kernel-parameters.txt   |    4 +
>  include/linux/xattr.h                 |    3 +
>  security/integrity/evm/evm_main.c     |    3 +
>  security/integrity/iint.c             |    3 +-
>  security/integrity/ima/Kconfig        |   15 +++
>  security/integrity/ima/Makefile       |    2 +
>  security/integrity/ima/ima.h          |   37 +++++++-
>  security/integrity/ima/ima_api.c      |   50 +++++++---
>  security/integrity/ima/ima_appraise.c |  168 +++++++++++++++++++++++++++++++++
>  security/integrity/ima/ima_crypto.c   |    8 ++-
>  security/integrity/ima/ima_main.c     |   78 ++++++++++-----
>  security/integrity/ima/ima_policy.c   |   32 +++++--
>  security/integrity/integrity.h        |    8 +-
>  13 files changed, 358 insertions(+), 53 deletions(-)
>  create mode 100644 security/integrity/ima/ima_appraise.c
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 033d4e6..a86765d 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1004,6 +1004,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>        ihash_entries=  [KNL]
>                        Set number of hash buckets for inode cache.
>
> +       ima_appraise=   [IMA] appraise integrity measurements
> +                       Format: { "off" | "enforce" | "fix" }
> +                       default: "enforce"
> +
>        ima_audit=      [IMA]
>                        Format: { "0" | "1" }
>                        0 -- integrity auditing messages. (Default)
> diff --git a/include/linux/xattr.h b/include/linux/xattr.h
> index e5d1220..77a3e68 100644
> --- a/include/linux/xattr.h
> +++ b/include/linux/xattr.h
> @@ -33,6 +33,9 @@
>  #define XATTR_EVM_SUFFIX "evm"
>  #define XATTR_NAME_EVM XATTR_SECURITY_PREFIX XATTR_EVM_SUFFIX
>
> +#define XATTR_IMA_SUFFIX "ima"
> +#define XATTR_NAME_IMA XATTR_SECURITY_PREFIX XATTR_IMA_SUFFIX
> +
>  #define XATTR_SELINUX_SUFFIX "selinux"
>  #define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX
>
> diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
> index 8901501..eb54845 100644
> --- a/security/integrity/evm/evm_main.c
> +++ b/security/integrity/evm/evm_main.c
> @@ -34,6 +34,9 @@ char *evm_config_xattrnames[] = {
>  #ifdef CONFIG_SECURITY_SMACK
>        XATTR_NAME_SMACK,
>  #endif
> +#ifdef CONFIG_IMA_APPRAISE
> +       XATTR_NAME_IMA,
> +#endif
>        XATTR_NAME_CAPS,
>        NULL
>  };
> diff --git a/security/integrity/iint.c b/security/integrity/iint.c
> index 399641c..e600986 100644
> --- a/security/integrity/iint.c
> +++ b/security/integrity/iint.c
> @@ -74,6 +74,7 @@ static void iint_free(struct integrity_iint_cache *iint)
>  {
>        iint->version = 0;
>        iint->flags = 0UL;
> +       iint->ima_status = INTEGRITY_UNKNOWN;
>        iint->evm_status = INTEGRITY_UNKNOWN;
>        kmem_cache_free(iint_cache, iint);
>  }
> @@ -157,7 +158,7 @@ static void init_once(void *foo)
>        memset(iint, 0, sizeof *iint);
>        iint->version = 0;
>        iint->flags = 0UL;
> -       mutex_init(&iint->mutex);
> +       iint->ima_status = INTEGRITY_UNKNOWN;
>        iint->evm_status = INTEGRITY_UNKNOWN;
>  }
>
> diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
> index 35664fe..b7465a1 100644
> --- a/security/integrity/ima/Kconfig
> +++ b/security/integrity/ima/Kconfig
> @@ -54,3 +54,18 @@ config IMA_LSM_RULES
>        default y
>        help
>          Disabling this option will disregard LSM based policy rules.
> +
> +config IMA_APPRAISE
> +       bool "Appraise integrity measurements"
> +       depends on IMA
> +       default n
> +       help
> +         This option enables local measurement integrity appraisal.
> +         It requires the system to be labeled with a security extended
> +         attribute containing the file hash measurement.  To protect
> +         the security extended attributes from offline attack, enable
> +         and configure EVM.
> +
> +         For more information on integrity appraisal refer to:
> +         <http://linux-ima.sourceforge.net>
> +         If unsure, say N.
> diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
> index 5690c02..bd31516 100644
> --- a/security/integrity/ima/Makefile
> +++ b/security/integrity/ima/Makefile
> @@ -7,3 +7,5 @@ obj-$(CONFIG_IMA) += ima.o
>
>  ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
>         ima_policy.o ima_audit.o
> +
> +ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index 3ccf7ac..d5bf463 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -40,6 +40,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
>  extern int ima_initialized;
>  extern int ima_used_chip;
>  extern char *ima_hash;
> +extern int ima_appraise;
>
>  /* IMA inode template definition */
>  struct ima_template_data {
> @@ -98,6 +99,7 @@ static inline unsigned long ima_hash_key(u8 *digest)
>  }
>
>  /* LIM API function definitions */
> +int ima_must_appraise_or_measure(struct inode *inode, int mask, int function);
>  int ima_must_measure(struct inode *inode, int mask, int function);
>  int ima_collect_measurement(struct integrity_iint_cache *iint,
>                            struct file *file);
> @@ -114,14 +116,45 @@ struct integrity_iint_cache *integrity_iint_insert(struct inode *inode);
>  struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
>
>  /* IMA policy related functions */
> -enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK };
> +enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK, POST_SETATTR };
>
> -int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask);
> +int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
> +                    int flags);
>  void ima_init_policy(void);
>  void ima_update_policy(void);
>  ssize_t ima_parse_add_rule(char *);
>  void ima_delete_rules(void);
>
> +/* Appraise integrity measurements */
> +#define IMA_APPRAISE_ENFORCE   0x01
> +#define IMA_APPRAISE_FIX       0x02
> +
> +#ifdef CONFIG_IMA_APPRAISE
> +int ima_appraise_measurement(struct integrity_iint_cache *iint,
> +                            struct file *file, const unsigned char *filename);
> +int ima_must_appraise(struct inode *inode, enum ima_hooks func, int mask);
> +void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);
> +
> +#else
> +static inline int ima_appraise_measurement(struct integrity_iint_cache *iint,
> +                                          struct file *file,
> +                                          const unsigned char *filename)
> +{
> +       return INTEGRITY_UNKNOWN;
> +}
> +
> +static inline int ima_must_appraise(struct inode *inode,
> +                                   enum ima_hooks func, int mask)
> +{
> +       return 0;
> +}
> +
> +static inline void ima_update_xattr(struct integrity_iint_cache *iint,
> +                                   struct file *file)
> +{
> +}
> +#endif
> +
>  /* LSM based policy rules require audit */
>  #ifdef CONFIG_IMA_LSM_RULES
>
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> index 88a2788..55deeb1 100644
> --- a/security/integrity/ima/ima_api.c
> +++ b/security/integrity/ima/ima_api.c
> @@ -9,13 +9,17 @@
>  * License.
>  *
>  * File: ima_api.c
> - *     Implements must_measure, collect_measurement, store_measurement,
> - *     and store_template.
> + *     Implements must_appraise_or_measure, collect_measurement,
> + *     appraise_measurement, store_measurement and store_template.
>  */
>  #include <linux/module.h>
>  #include <linux/slab.h>
> -
> +#include <linux/file.h>
> +#include <linux/fs.h>
> +#include <linux/xattr.h>
> +#include <linux/evm.h>
>  #include "ima.h"
> +
>  static const char *IMA_TEMPLATE_NAME = "ima";
>
>  /*
> @@ -93,7 +97,7 @@ err_out:
>  }
>
>  /**
> - * ima_must_measure - measure decision based on policy.
> + * ima_must_appraise_or_measure - appraise & measure decision based on policy.
>  * @inode: pointer to inode to measure
>  * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
>  * @function: calling function (FILE_CHECK, BPRM_CHECK, FILE_MMAP)
> @@ -105,15 +109,22 @@ err_out:
>  *     mask: contains the permission mask
>  *     fsmagic: hex value
>  *
> - * Return 0 to measure. For matching a DONT_MEASURE policy, no policy,
> - * or other error, return an error code.
> -*/
> -int ima_must_measure(struct inode *inode, int mask, int function)
> + * Returns IMA_MEASURE, IMA_APPRAISE mask.
> + *
> + */
> +int ima_must_appraise_or_measure(struct inode *inode, int mask, int function)
>  {
> -       int must_measure;
> +       int flags = IMA_MEASURE | IMA_APPRAISE;
> +
> +       if (!ima_appraise)
> +               flags &= ~IMA_APPRAISE;
> +
> +       return ima_match_policy(inode, function, mask, flags);
> +}
>
> -       must_measure = ima_match_policy(inode, function, mask);
> -       return must_measure ? 0 : -EACCES;
> +int ima_must_measure(struct inode *inode, int mask, int function)
> +{
> +       return ima_match_policy(inode, function, mask, IMA_MEASURE);
>  }
>
>  /*
> @@ -129,16 +140,24 @@ int ima_must_measure(struct inode *inode, int mask, int function)
>  int ima_collect_measurement(struct integrity_iint_cache *iint,
>                            struct file *file)
>  {
> -       int result = -EEXIST;
> +       struct inode *inode = file->f_dentry->d_inode;
> +       const char *filename = file->f_dentry->d_name.name;
> +       int result = 0;
>
> -       if (!(iint->flags & IMA_MEASURED)) {
> +       if (!(iint->flags & IMA_COLLECTED)) {
>                u64 i_version = file->f_dentry->d_inode->i_version;
>
>                memset(iint->digest, 0, IMA_DIGEST_SIZE);
>                result = ima_calc_hash(file, iint->digest);
> -               if (!result)
> +               if (!result) {
>                        iint->version = i_version;
> +                       iint->flags |= IMA_COLLECTED;
> +               }
>        }
> +       if (result)
> +               integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
> +                                   filename, "collect_data", "failed",
> +                                   result, 0);
>        return result;
>  }
>
> @@ -167,6 +186,9 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
>        struct ima_template_entry *entry;
>        int violation = 0;
>
> +       if (iint->flags & IMA_MEASURED)
> +               return;
> +
>        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
>        if (!entry) {
>                integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
> new file mode 100644
> index 0000000..4865f61
> --- /dev/null
> +++ b/security/integrity/ima/ima_appraise.c
> @@ -0,0 +1,168 @@
> +/*
> + * 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/file.h>
> +#include <linux/fs.h>
> +#include <linux/xattr.h>
> +#include <linux/magic.h>
> +#include <linux/ima.h>
> +#include <linux/evm.h>
> +
> +#include "ima.h"
> +
> +static int __init default_appraise_setup(char *str)
> +{
> +       if (strncmp(str, "off", 3) == 0)
> +               ima_appraise = 0;
> +       else if (strncmp(str, "fix", 3) == 0)
> +               ima_appraise = IMA_APPRAISE_FIX;
> +       return 1;
> +}
> +
> +__setup("ima_appraise=", default_appraise_setup);
> +
> +/*
> + * ima_must_appraise - set appraise flag
> + *
> + * Return 1 to appraise
> + */
> +int ima_must_appraise(struct inode *inode, enum ima_hooks func, int mask)
> +{
> +       return 0;
> +}
> +
> +static void ima_fix_xattr(struct dentry *dentry,
> +                         struct integrity_iint_cache *iint)
> +{
> +       iint->digest[0] = IMA_XATTR_DIGEST;
> +       __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
> +                             iint->digest, IMA_DIGEST_SIZE + 1, 0);
> +}
> +
> +/*
> + * ima_appraise_measurement - appraise file measurement
> + *
> + * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
> + * Assuming success, compare the xattr hash with the collected measurement.
> + *
> + * Return 0 on success, error code otherwise
> + */
> +int ima_appraise_measurement(struct integrity_iint_cache *iint,
> +                            struct file *file, const unsigned char *filename)
> +{
> +       struct dentry *dentry = file->f_dentry;
> +       struct inode *inode = dentry->d_inode;
> +       u8 xattr_value[IMA_DIGEST_SIZE];
> +       enum integrity_status status = INTEGRITY_UNKNOWN;
> +       const char *op = "appraise_data";
> +       char *cause = "unknown";
> +       int rc;
> +
> +       if (!ima_appraise)
> +               return 0;
> +       if (!inode->i_op->getxattr)
> +               return INTEGRITY_UNKNOWN;
> +
> +       if (iint->flags & IMA_APPRAISED)
> +               return iint->ima_status;
> +
> +       rc = inode->i_op->getxattr(dentry, XATTR_NAME_IMA, xattr_value,
> +                                  IMA_DIGEST_SIZE);
> +       if (rc <= 0) {
> +               if (rc && rc != -ENODATA)
> +                       goto out;
> +
> +               cause = "missing-hash";
> +               status =
> +                   (inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL;
> +               goto out;
> +       }
> +
> +       status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
> +       if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
> +               if ((status == INTEGRITY_NOLABEL)
> +                   || (status == INTEGRITY_NOXATTRS))
> +                       cause = "missing-HMAC";
> +               else if (status == INTEGRITY_FAIL)
> +                       cause = "invalid-HMAC";
> +               goto out;
> +       }
> +
> +       rc = memcmp(xattr_value, iint->digest, IMA_DIGEST_SIZE);
> +       if (rc) {
> +               status = INTEGRITY_FAIL;
> +               cause = "invalid-hash";
> +               print_hex_dump_bytes("security.ima: ", DUMP_PREFIX_NONE,
> +                                    xattr_value, IMA_DIGEST_SIZE);
> +               print_hex_dump_bytes("collected: ", DUMP_PREFIX_NONE,
> +                                    iint->digest, IMA_DIGEST_SIZE);
> +               goto out;
> +       }
> +       status = INTEGRITY_PASS;
> +       iint->flags |= IMA_APPRAISED;
> +out:
> +       if (status != INTEGRITY_PASS) {
> +               if (ima_appraise & IMA_APPRAISE_FIX) {
> +                       ima_fix_xattr(dentry, iint);
> +                       status = INTEGRITY_PASS;
> +               }
> +               integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
> +                                   op, cause, rc, 0);
> +       }
> +       iint->ima_status = status;
> +       return status;
> +}
> +
> +/*
> + * ima_update_xattr - update 'security.ima' hash value
> + */
> +void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
> +{
> +       struct dentry *dentry = file->f_dentry;
> +       int rc = 0;
> +
> +       rc = ima_collect_measurement(iint, file);
> +       if (rc < 0)
> +               return;
> +       ima_fix_xattr(dentry, iint);
> +}
> +
> +/**
> + * ima_inode_post_setattr - reflect file metadata changes
> + * @dentry: pointer to the affected dentry
> + *
> + * Changes to a dentry's metadata might result in needing to appraise.
> + *
> + * This function is called from notify_change(), which expects the caller
> + * to lock the inode's i_mutex.
> + */
> +void ima_inode_post_setattr(struct dentry *dentry)
> +{
> +       struct inode *inode = dentry->d_inode;
> +       struct integrity_iint_cache *iint;
> +       int must_appraise, rc;
> +
> +       if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode)
> +           || !inode->i_op->removexattr)
> +               return;
> +
> +       must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
> +       iint = integrity_iint_find(inode);
> +       if (iint) {
> +               if (must_appraise)
> +                       iint->flags |= IMA_APPRAISE;
> +               else
> +                       iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED);
> +       }
> +       if (!must_appraise)
> +               rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
> +       return;
> +}
> diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
> index 9b3ade7..b21ee5b 100644
> --- a/security/integrity/ima/ima_crypto.c
> +++ b/security/integrity/ima/ima_crypto.c
> @@ -48,7 +48,7 @@ int ima_calc_hash(struct file *file, char *digest)
>        struct scatterlist sg[1];
>        loff_t i_size, offset = 0;
>        char *rbuf;
> -       int rc;
> +       int rc, read = 0;
>
>        rc = init_desc(&desc);
>        if (rc != 0)
> @@ -59,6 +59,10 @@ int ima_calc_hash(struct file *file, char *digest)
>                rc = -ENOMEM;
>                goto out;
>        }
> +       if (!(file->f_mode & FMODE_READ)) {
> +               file->f_mode |= FMODE_READ;
> +               read = 1;
> +       }
>        i_size = i_size_read(file->f_dentry->d_inode);
>        while (offset < i_size) {
>                int rbuf_len;
> @@ -80,6 +84,8 @@ int ima_calc_hash(struct file *file, char *digest)
>        kfree(rbuf);
>        if (!rc)
>                rc = crypto_hash_final(&desc, digest);
> +       if (read)
> +               file->f_mode &= ~FMODE_READ;
>  out:
>        crypto_free_hash(desc.tfm);
>        return rc;
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 5b222eb..fba2f7b 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -22,12 +22,19 @@
>  #include <linux/mount.h>
>  #include <linux/mman.h>
>  #include <linux/slab.h>
> +#include <linux/xattr.h>
>  #include <linux/ima.h>
>
>  #include "ima.h"
>
>  int ima_initialized;
>
> +#ifdef CONFIG_IMA_APPRAISE
> +int ima_appraise = IMA_APPRAISE_ENFORCE;
> +#else
> +int ima_appraise;
> +#endif
> +
>  char *ima_hash = "sha1";
>  static int __init hash_setup(char *str)
>  {
> @@ -52,7 +59,7 @@ static void ima_rdwr_violation_check(struct file *file)
>        struct dentry *dentry = file->f_path.dentry;
>        struct inode *inode = dentry->d_inode;
>        fmode_t mode = file->f_mode;
> -       int rc;
> +       int must_measure;
>        bool send_tomtou = false, send_writers = false;
>
>        if (!S_ISREG(inode->i_mode) || !ima_initialized)
> @@ -66,8 +73,8 @@ static void ima_rdwr_violation_check(struct file *file)
>                goto out;
>        }
>
> -       rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
> -       if (rc < 0)
> +       must_measure = ima_must_measure(inode, MAY_READ, FILE_CHECK);
> +       if (!must_measure)
>                goto out;
>
>        if (atomic_read(&inode->i_writecount) > 0)
> @@ -84,17 +91,21 @@ out:
>  }
>
>  static void ima_check_last_writer(struct integrity_iint_cache *iint,
> -                                 struct inode *inode,
> -                                 struct file *file)
> +                                 struct inode *inode, struct file *file)
>  {
>        fmode_t mode = file->f_mode;
>
> -       mutex_lock(&iint->mutex);
> -       if (mode & FMODE_WRITE &&
> -           atomic_read(&inode->i_writecount) == 1 &&
> -           iint->version != inode->i_version)
> -               iint->flags &= ~IMA_MEASURED;
> -       mutex_unlock(&iint->mutex);
> +       if (!(mode & FMODE_WRITE))
> +               return;
> +
> +       mutex_lock(&inode->i_mutex);
> +       if (atomic_read(&inode->i_writecount) == 1 &&
> +           iint->version != inode->i_version) {
> +               iint->flags &= ~(IMA_COLLECTED | IMA_APPRAISED | IMA_MEASURED);
> +               if (iint->flags & IMA_APPRAISE)
> +                       ima_update_xattr(iint, file);
> +       }
> +       mutex_unlock(&inode->i_mutex);
>  }
>
>  /**
> @@ -123,14 +134,17 @@ static int process_measurement(struct file *file, const unsigned char *filename,
>  {
>        struct inode *inode = file->f_dentry->d_inode;
>        struct integrity_iint_cache *iint;
> -       int rc = 0;
> +       int rc = -ENOMEM, action, must_appraise;
>
>        if (!ima_initialized || !S_ISREG(inode->i_mode))
>                return 0;
>
> -       rc = ima_must_measure(inode, mask, function);
> -       if (rc != 0)
> -               return rc;
> +       /* Determine if in appraise/measurement policy,
> +        * returns IMA_MEASURE, IMA_APPRAISE bitmask.  */
> +       action = ima_must_appraise_or_measure(inode, mask, function);
> +       if (!action)
> +               return 0;
> +
>  retry:
>        iint = integrity_iint_find(inode);
>        if (!iint) {
> @@ -140,18 +154,32 @@ retry:
>                return rc;
>        }
>
> -       mutex_lock(&iint->mutex);
> +       must_appraise = action & IMA_APPRAISE;
>
> -       rc = iint->flags & IMA_MEASURED ? 1 : 0;
> -       if (rc != 0)
> +       mutex_lock(&inode->i_mutex);
> +
> +       /* Determine if already appraised/measured based on bitmask
> +        * (IMA_MEASURE, IMA_MEASURED, IMA_APPRAISE, IMA_APPRAISED) */
> +       iint->flags |= action;
> +       action &= ~((iint->flags & (IMA_MEASURED | IMA_APPRAISED)) >> 1);
> +
> +       /* Nothing to do, just return existing appraised status */
> +       if (!action) {
> +               if (iint->flags & IMA_APPRAISED)
> +                       rc = iint->ima_status;
>                goto out;
> +       }
>
>        rc = ima_collect_measurement(iint, file);
> -       if (!rc)
> +       if (rc != 0)
> +               goto out;
> +       if (action & IMA_MEASURE)
>                ima_store_measurement(iint, file, filename);
> +       if (action & IMA_APPRAISE)
> +               rc = ima_appraise_measurement(iint, file, filename);
>  out:
> -       mutex_unlock(&iint->mutex);
> -       return rc;
> +       mutex_unlock(&inode->i_mutex);
> +       return (rc && must_appraise) ? -EACCES : 0;
>  }
>
>  /**
> @@ -167,14 +195,14 @@ out:
>  */
>  int ima_file_mmap(struct file *file, unsigned long prot)
>  {
> -       int rc;
> +       int rc = 0;
>
>        if (!file)
>                return 0;
>        if (prot & PROT_EXEC)
>                rc = process_measurement(file, file->f_dentry->d_name.name,
>                                         MAY_EXEC, FILE_MMAP);
> -       return 0;
> +       return (ima_appraise & IMA_APPRAISE_ENFORCE) ? rc : 0;
>  }
>  EXPORT_SYMBOL_GPL(ima_file_mmap);
>
> @@ -197,7 +225,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
>
>        rc = process_measurement(bprm->file, bprm->filename,
>                                 MAY_EXEC, BPRM_CHECK);
> -       return 0;
> +       return (ima_appraise & IMA_APPRAISE_ENFORCE) ? rc : 0;
>  }
>
>  /**
> @@ -218,7 +246,7 @@ int ima_file_check(struct file *file, int mask)
>        rc = process_measurement(file, file->f_dentry->d_name.name,
>                                 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
>                                 FILE_CHECK);
> -       return 0;
> +       return (ima_appraise & IMA_APPRAISE_ENFORCE) ? rc : 0;
>  }
>  EXPORT_SYMBOL_GPL(ima_file_check);
>
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index d8edff2..8ee301c 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -25,7 +25,13 @@
>  #define IMA_FSMAGIC    0x0004
>  #define IMA_UID                0x0008
>
> -enum ima_action { UNKNOWN = -1, DONT_MEASURE = 0, MEASURE };
> +#define UNKNOWN                        0
> +#define MEASURE                        1       /* same as IMA_MEASURE */
> +#define DONT_MEASURE           2
> +#define MEASURE_MASK           3
> +#define APPRAISE               4       /* same as IMA_APPRAISE */
> +#define DONT_APPRAISE          8
> +#define APPRAISE_MASK          12
>
>  #define MAX_LSM_RULES 6
>  enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
> @@ -34,7 +40,7 @@ enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
>
>  struct ima_measure_rule_entry {
>        struct list_head list;
> -       enum ima_action action;
> +       int action;
>        unsigned int flags;
>        enum ima_hooks func;
>        int mask;
> @@ -161,18 +167,28 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
>  * as elements in the list are never deleted, nor does the list
>  * change.)
>  */
> -int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
> +int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
> +                    int flags)
>  {
>        struct ima_measure_rule_entry *entry;
> +       int action = 0, actmask = flags | (flags << 1);
>
>        list_for_each_entry(entry, ima_measure, list) {
> -               bool rc;
>
> -               rc = ima_match_rules(entry, inode, func, mask);
> -               if (rc)
> -                       return entry->action;
> +               if (!(entry->action & actmask))
> +                       continue;
> +
> +               if (!ima_match_rules(entry, inode, func, mask))
> +                       continue;
> +
> +               action |= (entry->action & (IMA_APPRAISE | IMA_MEASURE));
> +               actmask &= (entry->action & APPRAISE_MASK) ?
> +                   ~APPRAISE_MASK : ~MEASURE_MASK;
> +               if (!actmask)
> +                       break;
>        }
> -       return 0;
> +
> +       return action;
>  }
>
>  /**
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index 7a25ece..295702d 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -16,7 +16,11 @@
>  #include <crypto/sha.h>
>
>  /* iint cache flags */
> -#define IMA_MEASURED           0x01
> +#define IMA_MEASURE            1
> +#define IMA_MEASURED           2
> +#define IMA_APPRAISE           4
> +#define IMA_APPRAISED          8
> +#define IMA_COLLECTED          16
>
>  enum evm_ima_xattr_type {
>        IMA_XATTR_DIGEST = 0x01,
> @@ -36,7 +40,7 @@ struct integrity_iint_cache {
>        u64 version;            /* track inode changes */
>        unsigned char flags;
>        u8 digest[SHA1_DIGEST_SIZE];
> -       struct mutex mutex;     /* protects: version, flags, digest */
> +       enum integrity_status ima_status;
>        enum integrity_status evm_status;
>  };
>
> --
> 1.7.6.5
>
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