* [PATCH AUTOSEL 4.19 080/252] selinux: fall back to ref-walk if audit is required
[not found] <20200214161147.15842-1-sashal@kernel.org>
@ 2020-02-14 16:08 ` Sasha Levin
2020-02-14 16:09 ` [PATCH AUTOSEL 4.19 085/252] selinux: ensure we cleanup the internal AVC counters on error in avc_insert() Sasha Levin
2020-02-14 16:09 ` [PATCH AUTOSEL 4.19 115/252] selinux: ensure we cleanup the internal AVC counters on error in avc_update() Sasha Levin
2 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2020-02-14 16:08 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Stephen Smalley, Will Deacon, Al Viro, Paul Moore, Sasha Levin, selinux
From: Stephen Smalley <sds@tycho.nsa.gov>
[ Upstream commit 0188d5c025ca8fe756ba3193bd7d150139af5a88 ]
commit bda0be7ad994 ("security: make inode_follow_link RCU-walk aware")
passed down the rcu flag to the SELinux AVC, but failed to adjust the
test in slow_avc_audit() to also return -ECHILD on LSM_AUDIT_DATA_DENTRY.
Previously, we only returned -ECHILD if generating an audit record with
LSM_AUDIT_DATA_INODE since this was only relevant from inode_permission.
Move the handling of MAY_NOT_BLOCK to avc_audit() and its inlined
equivalent in selinux_inode_permission() immediately after we determine
that audit is required, and always fall back to ref-walk in this case.
Fixes: bda0be7ad994 ("security: make inode_follow_link RCU-walk aware")
Reported-by: Will Deacon <will@kernel.org>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/selinux/avc.c | 24 +++++-------------------
security/selinux/hooks.c | 11 +++++++----
security/selinux/include/avc.h | 8 +++++---
3 files changed, 17 insertions(+), 26 deletions(-)
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 5de18a6d5c3f0..0622cae510461 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -496,7 +496,7 @@ static inline int avc_xperms_audit(struct selinux_state *state,
if (likely(!audited))
return 0;
return slow_avc_audit(state, ssid, tsid, tclass, requested,
- audited, denied, result, ad, 0);
+ audited, denied, result, ad);
}
static void avc_node_free(struct rcu_head *rhead)
@@ -766,8 +766,7 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
noinline int slow_avc_audit(struct selinux_state *state,
u32 ssid, u32 tsid, u16 tclass,
u32 requested, u32 audited, u32 denied, int result,
- struct common_audit_data *a,
- unsigned int flags)
+ struct common_audit_data *a)
{
struct common_audit_data stack_data;
struct selinux_audit_data sad;
@@ -777,17 +776,6 @@ noinline int slow_avc_audit(struct selinux_state *state,
a->type = LSM_AUDIT_DATA_NONE;
}
- /*
- * When in a RCU walk do the audit on the RCU retry. This is because
- * the collection of the dname in an inode audit message is not RCU
- * safe. Note this may drop some audits when the situation changes
- * during retry. However this is logically just as if the operation
- * happened a little later.
- */
- if ((a->type == LSM_AUDIT_DATA_INODE) &&
- (flags & MAY_NOT_BLOCK))
- return -ECHILD;
-
sad.tclass = tclass;
sad.requested = requested;
sad.ssid = ssid;
@@ -860,16 +848,14 @@ static int avc_update_node(struct selinux_avc *avc,
/*
* If we are in a non-blocking code path, e.g. VFS RCU walk,
* then we must not add permissions to a cache entry
- * because we cannot safely audit the denial. Otherwise,
+ * because we will not audit the denial. Otherwise,
* during the subsequent blocking retry (e.g. VFS ref walk), we
* will find the permissions already granted in the cache entry
* and won't audit anything at all, leading to silent denials in
* permissive mode that only appear when in enforcing mode.
*
- * See the corresponding handling in slow_avc_audit(), and the
- * logic in selinux_inode_follow_link and selinux_inode_permission
- * for the VFS MAY_NOT_BLOCK flag, which is transliterated into
- * AVC_NONBLOCKING for avc_has_perm_noaudit().
+ * See the corresponding handling of MAY_NOT_BLOCK in avc_audit()
+ * and selinux_inode_permission().
*/
if (flags & AVC_NONBLOCKING)
return 0;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 040c843968dc6..c574285966f9d 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3171,8 +3171,7 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode,
static noinline int audit_inode_permission(struct inode *inode,
u32 perms, u32 audited, u32 denied,
- int result,
- unsigned flags)
+ int result)
{
struct common_audit_data ad;
struct inode_security_struct *isec = inode->i_security;
@@ -3183,7 +3182,7 @@ static noinline int audit_inode_permission(struct inode *inode,
rc = slow_avc_audit(&selinux_state,
current_sid(), isec->sid, isec->sclass, perms,
- audited, denied, result, &ad, flags);
+ audited, denied, result, &ad);
if (rc)
return rc;
return 0;
@@ -3230,7 +3229,11 @@ static int selinux_inode_permission(struct inode *inode, int mask)
if (likely(!audited))
return rc;
- rc2 = audit_inode_permission(inode, perms, audited, denied, rc, flags);
+ /* fall back to ref-walk if we have to generate audit */
+ if (flags & MAY_NOT_BLOCK)
+ return -ECHILD;
+
+ rc2 = audit_inode_permission(inode, perms, audited, denied, rc);
if (rc2)
return rc2;
return rc;
diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h
index 74ea50977c201..cf4cc3ef959b5 100644
--- a/security/selinux/include/avc.h
+++ b/security/selinux/include/avc.h
@@ -100,8 +100,7 @@ static inline u32 avc_audit_required(u32 requested,
int slow_avc_audit(struct selinux_state *state,
u32 ssid, u32 tsid, u16 tclass,
u32 requested, u32 audited, u32 denied, int result,
- struct common_audit_data *a,
- unsigned flags);
+ struct common_audit_data *a);
/**
* avc_audit - Audit the granting or denial of permissions.
@@ -135,9 +134,12 @@ static inline int avc_audit(struct selinux_state *state,
audited = avc_audit_required(requested, avd, result, 0, &denied);
if (likely(!audited))
return 0;
+ /* fall back to ref-walk if we have to generate audit */
+ if (flags & MAY_NOT_BLOCK)
+ return -ECHILD;
return slow_avc_audit(state, ssid, tsid, tclass,
requested, audited, denied, result,
- a, flags);
+ a);
}
#define AVC_STRICT 1 /* Ignore permissive mode. */
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH AUTOSEL 4.19 085/252] selinux: ensure we cleanup the internal AVC counters on error in avc_insert()
[not found] <20200214161147.15842-1-sashal@kernel.org>
2020-02-14 16:08 ` [PATCH AUTOSEL 4.19 080/252] selinux: fall back to ref-walk if audit is required Sasha Levin
@ 2020-02-14 16:09 ` Sasha Levin
2020-02-14 16:09 ` [PATCH AUTOSEL 4.19 115/252] selinux: ensure we cleanup the internal AVC counters on error in avc_update() Sasha Levin
2 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2020-02-14 16:09 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Paul Moore, rsiddoji, Stephen Smalley, Sasha Levin, selinux
From: Paul Moore <paul@paul-moore.com>
[ Upstream commit d8db60cb23e49a92cf8cada3297395c7fa50fdf8 ]
Fix avc_insert() to call avc_node_kill() if we've already allocated
an AVC node and the code fails to insert the node in the cache.
Fixes: fa1aa143ac4a ("selinux: extended permissions for ioctls")
Reported-by: rsiddoji@codeaurora.org
Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/selinux/avc.c | 51 ++++++++++++++++++++----------------------
1 file changed, 24 insertions(+), 27 deletions(-)
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 0622cae510461..83eef39c8a799 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -689,40 +689,37 @@ static struct avc_node *avc_insert(struct selinux_avc *avc,
struct avc_node *pos, *node = NULL;
int hvalue;
unsigned long flag;
+ spinlock_t *lock;
+ struct hlist_head *head;
if (avc_latest_notif_update(avc, avd->seqno, 1))
- goto out;
+ return NULL;
node = avc_alloc_node(avc);
- if (node) {
- struct hlist_head *head;
- spinlock_t *lock;
- int rc = 0;
-
- hvalue = avc_hash(ssid, tsid, tclass);
- avc_node_populate(node, ssid, tsid, tclass, avd);
- rc = avc_xperms_populate(node, xp_node);
- if (rc) {
- kmem_cache_free(avc_node_cachep, node);
- return NULL;
- }
- head = &avc->avc_cache.slots[hvalue];
- lock = &avc->avc_cache.slots_lock[hvalue];
+ if (!node)
+ return NULL;
- spin_lock_irqsave(lock, flag);
- hlist_for_each_entry(pos, head, list) {
- if (pos->ae.ssid == ssid &&
- pos->ae.tsid == tsid &&
- pos->ae.tclass == tclass) {
- avc_node_replace(avc, node, pos);
- goto found;
- }
+ avc_node_populate(node, ssid, tsid, tclass, avd);
+ if (avc_xperms_populate(node, xp_node)) {
+ avc_node_kill(avc, node);
+ return NULL;
+ }
+
+ hvalue = avc_hash(ssid, tsid, tclass);
+ head = &avc->avc_cache.slots[hvalue];
+ lock = &avc->avc_cache.slots_lock[hvalue];
+ spin_lock_irqsave(lock, flag);
+ hlist_for_each_entry(pos, head, list) {
+ if (pos->ae.ssid == ssid &&
+ pos->ae.tsid == tsid &&
+ pos->ae.tclass == tclass) {
+ avc_node_replace(avc, node, pos);
+ goto found;
}
- hlist_add_head_rcu(&node->list, head);
-found:
- spin_unlock_irqrestore(lock, flag);
}
-out:
+ hlist_add_head_rcu(&node->list, head);
+found:
+ spin_unlock_irqrestore(lock, flag);
return node;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread