From: Roberto Sassu <roberto.sassu@huawei.com>
Invoking digest_cache_get() inside the iint->mutex critical region can
cause deadlocks due to the fact that IMA can be recursively invoked for
reading the digest list. The deadlock would occur if the digest_cache LSM
attempts to read the same inode that is already locked by IMA.
However, since the digest_cache LSM makes sure that the above situation
never happens, as it checks the inodes, it is safe to call
digest_cache_get() inside the critical region and nest the iint->mutex
when the DIGEST_LIST_CHECK hook is executed.
Add a lockdep subclass to the iint->mutex, that is 0 if the IMA hook
executed is not DIGEST_LIST_CHECK, and 1 when it is. Since lockdep allows
nesting with higher classes and subclasses, that effectively eliminates the
warning about the unsafe lock.
Pass the new lockdep subclass (nested variable) from ima_inode_get() to
ima_iint_init_always() and ima_iint_lockdep_annotate().
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima.h | 2 +-
security/integrity/ima/ima_iint.c | 11 ++++++-----
security/integrity/ima/ima_main.c | 6 +++---
3 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index cea4517e73ab..c9140a57b591 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -216,7 +216,7 @@ static inline void ima_inode_set_iint(const struct inode *inode,
}
struct ima_iint_cache *ima_iint_find(struct inode *inode);
-struct ima_iint_cache *ima_inode_get(struct inode *inode);
+struct ima_iint_cache *ima_inode_get(struct inode *inode, bool nested);
void ima_inode_free(struct inode *inode);
void __init ima_iintcache_init(void);
diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
index e7c9c216c1c6..b4f476fae437 100644
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -41,7 +41,7 @@ struct ima_iint_cache *ima_iint_find(struct inode *inode)
* See ovl_lockdep_annotate_inode_mutex_key() for more details.
*/
static inline void ima_iint_lockdep_annotate(struct ima_iint_cache *iint,
- struct inode *inode)
+ struct inode *inode, bool nested)
{
#ifdef CONFIG_LOCKDEP
static struct lock_class_key ima_iint_mutex_key[IMA_MAX_NESTING];
@@ -56,7 +56,7 @@ static inline void ima_iint_lockdep_annotate(struct ima_iint_cache *iint,
}
static void ima_iint_init_always(struct ima_iint_cache *iint,
- struct inode *inode)
+ struct inode *inode, bool nested)
{
iint->ima_hash = NULL;
iint->version = 0;
@@ -69,7 +69,7 @@ static void ima_iint_init_always(struct ima_iint_cache *iint,
iint->ima_creds_status = INTEGRITY_UNKNOWN;
iint->measured_pcrs = 0;
mutex_init(&iint->mutex);
- ima_iint_lockdep_annotate(iint, inode);
+ ima_iint_lockdep_annotate(iint, inode, nested);
}
static void ima_iint_free(struct ima_iint_cache *iint)
@@ -82,13 +82,14 @@ static void ima_iint_free(struct ima_iint_cache *iint)
/**
* ima_inode_get - Find or allocate an iint associated with an inode
* @inode: Pointer to the inode
+ * @nested: Whether or not the iint->mutex lock can be nested
*
* Find an iint associated with an inode, and allocate a new one if not found.
* Caller must lock i_mutex.
*
* Return: An iint on success, NULL on error.
*/
-struct ima_iint_cache *ima_inode_get(struct inode *inode)
+struct ima_iint_cache *ima_inode_get(struct inode *inode, bool nested)
{
struct ima_iint_cache *iint;
@@ -100,7 +101,7 @@ struct ima_iint_cache *ima_inode_get(struct inode *inode)
if (!iint)
return NULL;
- ima_iint_init_always(iint, inode);
+ ima_iint_init_always(iint, inode, nested);
inode->i_flags |= S_IMA;
ima_inode_set_iint(inode, iint);
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 780627b0cde7..18285fc8ac07 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -248,7 +248,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
inode_lock(inode);
if (action) {
- iint = ima_inode_get(inode);
+ iint = ima_inode_get(inode, func == DIGEST_LIST_CHECK);
if (!iint)
rc = -ENOMEM;
}
@@ -699,7 +699,7 @@ static void ima_post_create_tmpfile(struct mnt_idmap *idmap,
return;
/* Nothing to do if we can't allocate memory */
- iint = ima_inode_get(inode);
+ iint = ima_inode_get(inode, false);
if (!iint)
return;
@@ -731,7 +731,7 @@ static void ima_post_path_mknod(struct mnt_idmap *idmap, struct dentry *dentry)
return;
/* Nothing to do if we can't allocate memory */
- iint = ima_inode_get(inode);
+ iint = ima_inode_get(inode, false);
if (!iint)
return;
--
2.34.1On Wed, 2024-02-14 at 15:35 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Invoking digest_cache_get() inside the iint->mutex critical region can
> cause deadlocks due to the fact that IMA can be recursively invoked for
> reading the digest list. The deadlock would occur if the digest_cache LSM
> attempts to read the same inode that is already locked by IMA.
>
> However, since the digest_cache LSM makes sure that the above situation
> never happens, as it checks the inodes, it is safe to call
> digest_cache_get() inside the critical region and nest the iint->mutex
> when the DIGEST_LIST_CHECK hook is executed.
>
> Add a lockdep subclass to the iint->mutex, that is 0 if the IMA hook
> executed is not DIGEST_LIST_CHECK, and 1 when it is. Since lockdep allows
> nesting with higher classes and subclasses, that effectively eliminates the
> warning about the unsafe lock.
>
> Pass the new lockdep subclass (nested variable) from ima_inode_get() to
> ima_iint_init_always() and ima_iint_lockdep_annotate().
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
> security/integrity/ima/ima.h | 2 +-
> security/integrity/ima/ima_iint.c | 11 ++++++-----
> security/integrity/ima/ima_main.c | 6 +++---
> 3 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index cea4517e73ab..c9140a57b591 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -216,7 +216,7 @@ static inline void ima_inode_set_iint(const struct inode
> *inode,
> }
>
> struct ima_iint_cache *ima_iint_find(struct inode *inode);
> -struct ima_iint_cache *ima_inode_get(struct inode *inode);
> +struct ima_iint_cache *ima_inode_get(struct inode *inode, bool nested);
> void ima_inode_free(struct inode *inode);
> void __init ima_iintcache_init(void);
>
> diff --git a/security/integrity/ima/ima_iint.c
> b/security/integrity/ima/ima_iint.c
> index e7c9c216c1c6..b4f476fae437 100644
> --- a/security/integrity/ima/ima_iint.c
> +++ b/security/integrity/ima/ima_iint.c
> @@ -41,7 +41,7 @@ struct ima_iint_cache *ima_iint_find(struct inode *inode)
> * See ovl_lockdep_annotate_inode_mutex_key() for more details.
> */
> static inline void ima_iint_lockdep_annotate(struct ima_iint_cache *iint,
> - struct inode *inode)
> + struct inode *inode, bool nested)
> {
> #ifdef CONFIG_LOCKDEP
> static struct lock_class_key ima_iint_mutex_key[IMA_MAX_NESTING];
"nested" is being pushed all the way down to here, perhaps I'm missing
something, but I don't see it being used in any of the patches.
Mimi
> @@ -56,7 +56,7 @@ static inline void ima_iint_lockdep_annotate(struct
> ima_iint_cache *iint,
> }
>
> static void ima_iint_init_always(struct ima_iint_cache *iint,
> - struct inode *inode)
> + struct inode *inode, bool nested)
> {
> iint->ima_hash = NULL;
> iint->version = 0;
> @@ -69,7 +69,7 @@ static void ima_iint_init_always(struct ima_iint_cache
> *iint,
> iint->ima_creds_status = INTEGRITY_UNKNOWN;
> iint->measured_pcrs = 0;
> mutex_init(&iint->mutex);
> - ima_iint_lockdep_annotate(iint, inode);
> + ima_iint_lockdep_annotate(iint, inode, nested);
> }
>
> static void ima_iint_free(struct ima_iint_cache *iint)
> @@ -82,13 +82,14 @@ static void ima_iint_free(struct ima_iint_cache *iint)
> /**
> * ima_inode_get - Find or allocate an iint associated with an inode
> * @inode: Pointer to the inode
> + * @nested: Whether or not the iint->mutex lock can be nested
> *
> * Find an iint associated with an inode, and allocate a new one if not
> found.
> * Caller must lock i_mutex.
> *
> * Return: An iint on success, NULL on error.
> */
> -struct ima_iint_cache *ima_inode_get(struct inode *inode)
> +struct ima_iint_cache *ima_inode_get(struct inode *inode, bool nested)
> {
> struct ima_iint_cache *iint;
>
> @@ -100,7 +101,7 @@ struct ima_iint_cache *ima_inode_get(struct inode *inode)
> if (!iint)
> return NULL;
>
> - ima_iint_init_always(iint, inode);
> + ima_iint_init_always(iint, inode, nested);
>
> inode->i_flags |= S_IMA;
> ima_inode_set_iint(inode, iint);
> diff --git a/security/integrity/ima/ima_main.c
> b/security/integrity/ima/ima_main.c
> index 780627b0cde7..18285fc8ac07 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -248,7 +248,7 @@ static int process_measurement(struct file *file, const
> struct cred *cred,
> inode_lock(inode);
>
> if (action) {
> - iint = ima_inode_get(inode);
> + iint = ima_inode_get(inode, func == DIGEST_LIST_CHECK);
> if (!iint)
> rc = -ENOMEM;
> }
> @@ -699,7 +699,7 @@ static void ima_post_create_tmpfile(struct mnt_idmap
> *idmap,
> return;
>
> /* Nothing to do if we can't allocate memory */
> - iint = ima_inode_get(inode);
> + iint = ima_inode_get(inode, false);
> if (!iint)
> return;
>
> @@ -731,7 +731,7 @@ static void ima_post_path_mknod(struct mnt_idmap *idmap,
> struct dentry *dentry)
> return;
>
> /* Nothing to do if we can't allocate memory */
> - iint = ima_inode_get(inode);
> + iint = ima_inode_get(inode, false);
> if (!iint)
> return;
>
On Thu, 2024-03-07 at 14:42 -0500, Mimi Zohar wrote:
> On Wed, 2024-02-14 at 15:35 +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> >
> > Invoking digest_cache_get() inside the iint->mutex critical region can
> > cause deadlocks due to the fact that IMA can be recursively invoked for
> > reading the digest list. The deadlock would occur if the digest_cache LSM
> > attempts to read the same inode that is already locked by IMA.
> >
> > However, since the digest_cache LSM makes sure that the above situation
> > never happens, as it checks the inodes, it is safe to call
> > digest_cache_get() inside the critical region and nest the iint->mutex
> > when the DIGEST_LIST_CHECK hook is executed.
> >
> > Add a lockdep subclass to the iint->mutex, that is 0 if the IMA hook
> > executed is not DIGEST_LIST_CHECK, and 1 when it is. Since lockdep allows
> > nesting with higher classes and subclasses, that effectively eliminates the
> > warning about the unsafe lock.
> >
> > Pass the new lockdep subclass (nested variable) from ima_inode_get() to
> > ima_iint_init_always() and ima_iint_lockdep_annotate().
> >
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > ---
> > security/integrity/ima/ima.h | 2 +-
> > security/integrity/ima/ima_iint.c | 11 ++++++-----
> > security/integrity/ima/ima_main.c | 6 +++---
> > 3 files changed, 10 insertions(+), 9 deletions(-)
> >
> > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> > index cea4517e73ab..c9140a57b591 100644
> > --- a/security/integrity/ima/ima.h
> > +++ b/security/integrity/ima/ima.h
> > @@ -216,7 +216,7 @@ static inline void ima_inode_set_iint(const struct inode
> > *inode,
> > }
> >
> > struct ima_iint_cache *ima_iint_find(struct inode *inode);
> > -struct ima_iint_cache *ima_inode_get(struct inode *inode);
> > +struct ima_iint_cache *ima_inode_get(struct inode *inode, bool nested);
> > void ima_inode_free(struct inode *inode);
> > void __init ima_iintcache_init(void);
> >
> > diff --git a/security/integrity/ima/ima_iint.c
> > b/security/integrity/ima/ima_iint.c
> > index e7c9c216c1c6..b4f476fae437 100644
> > --- a/security/integrity/ima/ima_iint.c
> > +++ b/security/integrity/ima/ima_iint.c
> > @@ -41,7 +41,7 @@ struct ima_iint_cache *ima_iint_find(struct inode *inode)
> > * See ovl_lockdep_annotate_inode_mutex_key() for more details.
> > */
> > static inline void ima_iint_lockdep_annotate(struct ima_iint_cache *iint,
> > - struct inode *inode)
> > + struct inode *inode, bool nested)
> > {
> > #ifdef CONFIG_LOCKDEP
> > static struct lock_class_key ima_iint_mutex_key[IMA_MAX_NESTING];
>
>
> "nested" is being pushed all the way down to here, perhaps I'm missing
> something, but I don't see it being used in any of the patches.
Must have gone away during a conflict resolution...
That should have been:
@@ -85,12 +85,13 @@ static inline void iint_lockdep_annotate(struct integrity_iint_cache *iint,
if (WARN_ON_ONCE(depth < 0 || depth >= IMA_MAX_NESTING))
depth = 0;
- lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]);
+ lockdep_set_class_and_subclass(&iint->mutex, &iint_mutex_key[depth],
+ nested);
#endif
}
static void iint_init_always(struct integrity_iint_cache *iint,
- struct inode *inode)
+ struct inode *inode, bool nested)
{
iint->ima_hash = NULL;
iint->version = 0;
Thanks
Roberto
> Mimi
>
> > @@ -56,7 +56,7 @@ static inline void ima_iint_lockdep_annotate(struct
> > ima_iint_cache *iint,
> > }
> >
> > static void ima_iint_init_always(struct ima_iint_cache *iint,
> > - struct inode *inode)
> > + struct inode *inode, bool nested)
> > {
> > iint->ima_hash = NULL;
> > iint->version = 0;
> > @@ -69,7 +69,7 @@ static void ima_iint_init_always(struct ima_iint_cache
> > *iint,
> > iint->ima_creds_status = INTEGRITY_UNKNOWN;
> > iint->measured_pcrs = 0;
> > mutex_init(&iint->mutex);
> > - ima_iint_lockdep_annotate(iint, inode);
> > + ima_iint_lockdep_annotate(iint, inode, nested);
> > }
> >
> > static void ima_iint_free(struct ima_iint_cache *iint)
> > @@ -82,13 +82,14 @@ static void ima_iint_free(struct ima_iint_cache *iint)
> > /**
> > * ima_inode_get - Find or allocate an iint associated with an inode
> > * @inode: Pointer to the inode
> > + * @nested: Whether or not the iint->mutex lock can be nested
> > *
> > * Find an iint associated with an inode, and allocate a new one if not
> > found.
> > * Caller must lock i_mutex.
> > *
> > * Return: An iint on success, NULL on error.
> > */
> > -struct ima_iint_cache *ima_inode_get(struct inode *inode)
> > +struct ima_iint_cache *ima_inode_get(struct inode *inode, bool nested)
> > {
> > struct ima_iint_cache *iint;
> >
> > @@ -100,7 +101,7 @@ struct ima_iint_cache *ima_inode_get(struct inode *inode)
> > if (!iint)
> > return NULL;
> >
> > - ima_iint_init_always(iint, inode);
> > + ima_iint_init_always(iint, inode, nested);
> >
> > inode->i_flags |= S_IMA;
> > ima_inode_set_iint(inode, iint);
> > diff --git a/security/integrity/ima/ima_main.c
> > b/security/integrity/ima/ima_main.c
> > index 780627b0cde7..18285fc8ac07 100644
> > --- a/security/integrity/ima/ima_main.c
> > +++ b/security/integrity/ima/ima_main.c
> > @@ -248,7 +248,7 @@ static int process_measurement(struct file *file, const
> > struct cred *cred,
> > inode_lock(inode);
> >
> > if (action) {
> > - iint = ima_inode_get(inode);
> > + iint = ima_inode_get(inode, func == DIGEST_LIST_CHECK);
> > if (!iint)
> > rc = -ENOMEM;
> > }
> > @@ -699,7 +699,7 @@ static void ima_post_create_tmpfile(struct mnt_idmap
> > *idmap,
> > return;
> >
> > /* Nothing to do if we can't allocate memory */
> > - iint = ima_inode_get(inode);
> > + iint = ima_inode_get(inode, false);
> > if (!iint)
> > return;
> >
> > @@ -731,7 +731,7 @@ static void ima_post_path_mknod(struct mnt_idmap *idmap,
> > struct dentry *dentry)
> > return;
> >
> > /* Nothing to do if we can't allocate memory */
> > - iint = ima_inode_get(inode);
> > + iint = ima_inode_get(inode, false);
> > if (!iint)
> > return;
> >
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