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[46.132.186.175]) by smtp.gmail.com with ESMTPSA id h1sm771635lja.18.2019.09.02.02.49.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2019 02:49:27 -0700 (PDT) From: Janne Karhunen To: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, zohar@linux.ibm.com, linux-mm@kvack.org, viro@zeniv.linux.org.uk Cc: Konsta Karsisto , Janne Karhunen Subject: [PATCH 3/3] ima: update the file measurement on writes Date: Mon, 2 Sep 2019 12:45:40 +0300 Message-Id: <20190902094540.12786-3-janne.karhunen@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190902094540.12786-1-janne.karhunen@gmail.com> References: <20190902094540.12786-1-janne.karhunen@gmail.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: From: Konsta Karsisto Hook do_writepages() in order to do IMA measurement of an inode that is written out. Depends on commit 72649b7862a7 ("ima: keep the integrity state of open files up to date")' Signed-off-by: Konsta Karsisto Signed-off-by: Janne Karhunen --- include/linux/ima.h | 10 +++ mm/page-writeback.c | 7 ++ security/integrity/iint.c | 3 + security/integrity/ima/ima.h | 14 ++++ security/integrity/ima/ima_main.c | 115 ++++++++++++++++++++++++++++-- security/integrity/integrity.h | 6 ++ 6 files changed, 150 insertions(+), 5 deletions(-) diff --git a/include/linux/ima.h b/include/linux/ima.h index 6736844e90d3..9d83f4beac7f 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -96,6 +96,8 @@ static inline void ima_kexec_cmdline(const void *buf, int size) {} #if ((defined CONFIG_IMA) && defined(CONFIG_IMA_MEASURE_WRITES)) void ima_file_update(struct file *file); void ima_file_delayed_update(struct file *file); +void ima_inode_update(struct inode *inode); +void ima_inode_delayed_update(struct inode *inode); #else static inline void ima_file_update(struct file *file) { @@ -105,6 +107,14 @@ static inline void ima_file_delayed_update(struct file *file) { return; } +static inline void ima_inode_update(struct inode *inode) +{ + return; +} +static inline void ima_inode_delayed_update(struct inode *inode) +{ + return; +} #endif #ifndef CONFIG_IMA_KEXEC diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 1804f64ff43c..d5041c625529 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include "internal.h" @@ -2347,6 +2348,12 @@ int do_writepages(struct address_space *mapping, struct writeback_control *wbc) cond_resched(); congestion_wait(BLK_RW_ASYNC, HZ/50); } + if (ret == 0) { + if (wbc->sync_mode == WB_SYNC_ALL) + ima_inode_update(mapping->host); + else + ima_inode_delayed_update(mapping->host); + } return ret; } diff --git a/security/integrity/iint.c b/security/integrity/iint.c index e12c4900510f..bac15a2b8bee 100644 --- a/security/integrity/iint.c +++ b/security/integrity/iint.c @@ -82,6 +82,8 @@ static void iint_free(struct integrity_iint_cache *iint) iint->ima_creds_status = INTEGRITY_UNKNOWN; iint->evm_status = INTEGRITY_UNKNOWN; iint->measured_pcrs = 0; + WARN_ON(iint->ima_work.file); + WARN_ON(!list_empty(&iint->file_list)); kmem_cache_free(iint_cache, iint); } @@ -161,6 +163,7 @@ static void init_once(void *foo) iint->ima_read_status = INTEGRITY_UNKNOWN; iint->ima_creds_status = INTEGRITY_UNKNOWN; iint->evm_status = INTEGRITY_UNKNOWN; + INIT_LIST_HEAD(&iint->file_list); mutex_init(&iint->mutex); } diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 195e67631f70..04ba4888b764 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -162,6 +162,10 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event, void *lsm_data); #if ((defined CONFIG_IMA) && defined(CONFIG_IMA_MEASURE_WRITES)) void ima_cancel_measurement(struct integrity_iint_cache *iint); +void ima_get_file(struct integrity_iint_cache *iint, + struct file *file); +void ima_put_file(struct integrity_iint_cache *iint, + struct file *file); #else static inline void ima_cancel_measurement(struct integrity_iint_cache *iint) { @@ -172,6 +176,16 @@ static inline void ima_init_measurement(struct integrity_iint_cache *iint, { return; } +static inline void ima_get_file(struct integrity_iint_cache *iint, + struct file *file) +{ + return; +} +static inline void ima_put_file(struct integrity_iint_cache *iint, + struct file *file) +{ + return; +} #endif /* diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 46d28cdb6466..affc74a07125 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -12,7 +12,8 @@ * * File: ima_main.c * implements the IMA hooks: ima_bprm_check, ima_file_mmap, - * ima_file_delayed_update, ima_file_update and ima_file_check. + * ima_file_update, ima_file_delayed_update, ima_inode_update, + * ima_inode_delayed_update and ima_file_check. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt @@ -157,6 +158,7 @@ static void ima_check_last_writer(struct integrity_iint_cache *iint, ima_cancel_measurement(iint); mutex_lock(&iint->mutex); + ima_put_file(iint, file); if (atomic_read(&inode->i_writecount) == 1) { update = test_and_clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); @@ -295,6 +297,12 @@ static int process_measurement(struct file *file, const struct cred *cred, set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); } + if (must_appraise && (file->f_mode & FMODE_WRITE)) + set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); + + /* Cache file for measurements triggered from inode writeback */ + ima_get_file(iint, file); + /* Nothing to do, just return existing appraised status */ if (!action) { if (must_appraise) { @@ -362,12 +370,9 @@ static int process_measurement(struct file *file, const struct cred *cred, out: if (pathbuf) __putname(pathbuf); - if (must_appraise) { + if (must_appraise) if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE)) return -EACCES; - if (file->f_mode & FMODE_WRITE) - set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); - } return 0; } @@ -425,6 +430,42 @@ int ima_bprm_check(struct linux_binprm *bprm) } #ifdef CONFIG_IMA_MEASURE_WRITES +void ima_get_file(struct integrity_iint_cache *iint, + struct file *file) +{ + struct ima_fl_entry *e; + + if (!iint || !file) + return; + if (!(file->f_mode & FMODE_WRITE) || + !test_bit(IMA_UPDATE_XATTR, &iint->atomic_flags)) + return; + + list_for_each_entry(e, &iint->file_list, list) { + if (e->file == file) + return; + } + e = kmalloc(sizeof(*e), GFP_KERNEL); + if (!e) + return; + e->file = file; + list_add(&e->list, &iint->file_list); +} + +void ima_put_file(struct integrity_iint_cache *iint, + struct file *file) +{ + struct ima_fl_entry *e; + + list_for_each_entry(e, &iint->file_list, list) { + if (e->file == file) { + list_del(&e->list); + kfree(e); + break; + } + } +} + static unsigned long ima_inode_update_delay(struct inode *inode) { unsigned long blocks, msecs; @@ -454,6 +495,7 @@ void ima_cancel_measurement(struct integrity_iint_cache *iint) return; cancel_delayed_work_sync(&iint->ima_work.work); + iint->ima_work.file = NULL; iint->ima_work.state = IMA_WORK_CANCELLED; } @@ -499,6 +541,69 @@ void ima_file_delayed_update(struct file *file) } EXPORT_SYMBOL_GPL(ima_file_delayed_update); +/** + * ima_inode_delayed_update - delayed measurement update of an inode + * @inode: dirty inode chosen for writeback + * + * Schedule work to measure the first available 'struct file' cached + * in the iint entry that references this inode. This allows IMA to + * track inode writebacks. + * + * Note that we haven't incremented the refcount for the files we keep + * track of in order to not mess up the normal file refcounting. If we + * see a file whose f_count is already zero, we simply skip it. If we + * fail to find any available file reference, the measurement will be + * handled by the ima_check_last_writer(). + */ +void ima_inode_delayed_update(struct inode *inode) +{ + struct integrity_iint_cache *iint; + struct ima_fl_entry *e; + bool found = false; + + iint = integrity_iint_find(inode); + if (!iint) + return; + + if (iint->ima_work.state == IMA_WORK_ACTIVE) + return; + + mutex_lock(&iint->mutex); + list_for_each_entry(e, &iint->file_list, list) { + if (file_count(e->file) == 0) + continue; + found = true; + break; + } + mutex_unlock(&iint->mutex); + if (found && e->file) + ima_file_delayed_update(e->file); +} +EXPORT_SYMBOL_GPL(ima_inode_delayed_update); + +void ima_inode_update(struct inode *inode) +{ + struct integrity_iint_cache *iint; + struct ima_fl_entry *e; + bool found = false; + + iint = integrity_iint_find(inode); + if (!iint) + return; + + mutex_lock(&iint->mutex); + list_for_each_entry(e, &iint->file_list, list) { + if (file_count(e->file) == 0) + continue; + found = true; + break; + } + mutex_unlock(&iint->mutex); + if (found && e->file) + ima_file_update(e->file); +} +EXPORT_SYMBOL_GPL(ima_inode_update); + /** * ima_file_update - update the file measurement * @file: pointer to file structure being updated diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 0f80c3d2e079..17af72683b87 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -132,6 +132,11 @@ struct ima_work_entry { uint8_t state; }; +struct ima_fl_entry { + struct list_head list; + struct file *file; +}; + /* integrity data associated with an inode */ struct integrity_iint_cache { struct rb_node rb_node; /* rooted in integrity_iint_tree */ @@ -149,6 +154,7 @@ struct integrity_iint_cache { enum integrity_status evm_status:4; struct ima_digest_data *ima_hash; struct ima_work_entry ima_work; + struct list_head file_list; }; /* rbtree tree calls to lookup, insert, delete -- 2.17.1