From 1df9f0a73178718969ae47d813b8e7aab2cf073c Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Wed, 4 Feb 2009 09:07:02 -0500 Subject: Integrity: IMA file free imbalance The number of calls to ima_path_check()/ima_file_free() should be balanced. An extra call to fput(), indicates the file could have been accessed without first being measured. Although f_count is incremented/decremented in places other than fget/fput, like fget_light/fput_light and get_file, the current task must already hold a file refcnt. The call to __fput() is delayed until the refcnt becomes 0, resulting in ima_file_free() flagging any changes. - add hook to increment opencount for IPC shared memory(SYSV), shmat files, and /dev/zero - moved NULL iint test in opencount_get() Signed-off-by: Mimi Zohar Acked-by: Serge Hallyn Signed-off-by: James Morris --- security/integrity/ima/ima.h | 2 ++ security/integrity/ima/ima_iint.c | 17 ++++++++++++++++ security/integrity/ima/ima_main.c | 42 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 61 insertions(+) (limited to 'security') diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 42706b55492..e3c16a21a38 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -97,6 +97,7 @@ static inline unsigned long ima_hash_key(u8 *digest) /* iint cache flags */ #define IMA_MEASURED 1 +#define IMA_IINT_DUMP_STACK 512 /* integrity data associated with an inode */ struct ima_iint_cache { @@ -106,6 +107,7 @@ struct ima_iint_cache { struct mutex mutex; /* protects: version, flags, digest */ long readcount; /* measured files readcount */ long writecount; /* measured files writecount */ + long opencount; /* opens reference count */ struct kref refcount; /* ima_iint_cache reference count */ struct rcu_head rcu; }; diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c index 750db3c993a..1f035e8d29c 100644 --- a/security/integrity/ima/ima_iint.c +++ b/security/integrity/ima/ima_iint.c @@ -126,6 +126,7 @@ struct ima_iint_cache *ima_iint_find_insert_get(struct inode *inode) return iint; } +EXPORT_SYMBOL_GPL(ima_iint_find_insert_get); /* iint_free - called when the iint refcount goes to zero */ void iint_free(struct kref *kref) @@ -134,6 +135,21 @@ void iint_free(struct kref *kref) refcount); iint->version = 0; iint->flags = 0UL; + if (iint->readcount != 0) { + printk(KERN_INFO "%s: readcount: %ld\n", __FUNCTION__, + iint->readcount); + iint->readcount = 0; + } + if (iint->writecount != 0) { + printk(KERN_INFO "%s: writecount: %ld\n", __FUNCTION__, + iint->writecount); + iint->writecount = 0; + } + if (iint->opencount != 0) { + printk(KERN_INFO "%s: opencount: %ld\n", __FUNCTION__, + iint->opencount); + iint->opencount = 0; + } kref_set(&iint->refcount, 1); kmem_cache_free(iint_cache, iint); } @@ -174,6 +190,7 @@ static void init_once(void *foo) mutex_init(&iint->mutex); iint->readcount = 0; iint->writecount = 0; + iint->opencount = 0; kref_set(&iint->refcount, 1); } diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 871e356e8d6..f4e7266f5ae 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -66,6 +66,19 @@ void ima_file_free(struct file *file) return; mutex_lock(&iint->mutex); + if (iint->opencount <= 0) { + printk(KERN_INFO + "%s: %s open/free imbalance (r:%ld w:%ld o:%ld f:%ld)\n", + __FUNCTION__, file->f_dentry->d_name.name, + iint->readcount, iint->writecount, + iint->opencount, atomic_long_read(&file->f_count)); + if (!(iint->flags & IMA_IINT_DUMP_STACK)) { + dump_stack(); + iint->flags |= IMA_IINT_DUMP_STACK; + } + } + iint->opencount--; + if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) iint->readcount--; @@ -119,6 +132,7 @@ static int get_path_measurement(struct ima_iint_cache *iint, struct file *file, pr_info("%s dentry_open failed\n", filename); return rc; } + iint->opencount++; iint->readcount++; rc = ima_collect_measurement(iint, file); @@ -159,6 +173,7 @@ int ima_path_check(struct path *path, int mask) return 0; mutex_lock(&iint->mutex); + iint->opencount++; if ((mask & MAY_WRITE) || (mask == 0)) iint->writecount++; else if (mask & (MAY_READ | MAY_EXEC)) @@ -219,6 +234,21 @@ out: return rc; } +static void opencount_get(struct file *file) +{ + struct inode *inode = file->f_dentry->d_inode; + struct ima_iint_cache *iint; + + if (!ima_initialized || !S_ISREG(inode->i_mode)) + return; + iint = ima_iint_find_insert_get(inode); + if (!iint) + return; + mutex_lock(&iint->mutex); + iint->opencount++; + mutex_unlock(&iint->mutex); +} + /** * ima_file_mmap - based on policy, collect/store measurement. * @file: pointer to the file to be measured (May be NULL) @@ -242,6 +272,18 @@ int ima_file_mmap(struct file *file, unsigned long prot) return 0; } +/* + * ima_shm_check - IPC shm and shmat create/fput a file + * + * Maintain the opencount for these files to prevent unnecessary + * imbalance messages. + */ +void ima_shm_check(struct file *file) +{ + opencount_get(file); + return; +} + /** * ima_bprm_check - based on policy, collect/store measurement. * @bprm: contains the linux_binprm structure -- cgit v1.2.3