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Message-Id: <218e806e61cd5ae2fd38f9d546f953f86c763b58.1542149969.git.rgb@redhat.com>
Date: Fri, 16 Nov 2018 12:33:13 -0500
From: Richard Guy Briggs <rgb@...hat.com>
To: linux-fsdevel@...r.kernel.org, viro@...IV.linux.org.uk,
LKML <linux-kernel@...r.kernel.org>,
Linux-Audit Mailing List <linux-audit@...hat.com>
Cc: Paul Moore <paul@...l-moore.com>, Eric Paris <eparis@...hat.com>,
Steve Grubb <sgrubb@...hat.com>,
Richard Guy Briggs <rgb@...hat.com>
Subject: [RFC PATCH ghak100 V1 1/2] audit: avoid fcaps on MNT_FORCE
Don't fetch fcaps when umount2 is called with MNT_FORCE to avoid a
process hang while it waits for the missing resource to (possibly never)
re-appear.
Note the comment above user_path_mountpoint_at():
* A umount is a special case for path walking. We're not actually interested
* in the inode in this situation, and ESTALE errors can be a problem. We
* simply want track down the dentry and vfsmount attached at the mountpoint
* and avoid revalidating the last component.
This can happen on ceph, cifs, 9p, lustre, fuse (gluster) or NFS.
Please see the github issue tracker
https://github.com/linux-audit/audit-kernel/issues/100
Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
---
fs/namei.c | 2 +-
fs/namespace.c | 3 +++
include/linux/audit.h | 8 ++++++--
kernel/audit.c | 5 +++--
kernel/audit.h | 2 +-
kernel/auditsc.c | 6 +++---
6 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 0cab6494978c..5ac8410b704c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2720,7 +2720,7 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
if (unlikely(error == -ESTALE))
error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
if (likely(!error))
- audit_inode(name, path->dentry, 0);
+ audit_inode(name, path->dentry, flags & LOOKUP_NO_REVAL);
restore_nameidata();
putname(name);
return error;
diff --git a/fs/namespace.c b/fs/namespace.c
index 99186556f8d3..5bae5bbd4e1f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1636,6 +1636,9 @@ int ksys_umount(char __user *name, int flags)
if (!(flags & UMOUNT_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
+ if (!(flags & MNT_FORCE))
+ lookup_flags |= LOOKUP_NO_REVAL;
+
retval = user_path_mountpoint_at(AT_FDCWD, name, lookup_flags, &path);
if (retval)
goto out;
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 9334fbef7bae..503f1710c9d0 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -25,6 +25,7 @@
#include <linux/sched.h>
#include <linux/ptrace.h>
+#include <linux/namei.h> /* LOOKUP_* */
#include <uapi/linux/audit.h>
#define AUDIT_INO_UNSET ((unsigned long)-1)
@@ -229,6 +230,7 @@ extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
#define AUDIT_INODE_PARENT 1 /* dentry represents the parent */
#define AUDIT_INODE_HIDDEN 2 /* audit record should be hidden */
+#define AUDIT_INODE_NOREVAL 4 /* audit record incomplete */
extern void __audit_inode(struct filename *name, const struct dentry *dentry,
unsigned int flags);
extern void __audit_file(const struct file *);
@@ -289,11 +291,13 @@ static inline void audit_getname(struct filename *name)
}
static inline void audit_inode(struct filename *name,
const struct dentry *dentry,
- unsigned int parent) {
+ unsigned int lflags) {
if (unlikely(!audit_dummy_context())) {
unsigned int flags = 0;
- if (parent)
+ if (lflags & LOOKUP_PARENT)
flags |= AUDIT_INODE_PARENT;
+ if (lflags & LOOKUP_NO_REVAL)
+ flags |= AUDIT_INODE_NOREVAL;
__audit_inode(name, dentry, flags);
}
}
diff --git a/kernel/audit.c b/kernel/audit.c
index 2a8058764aa6..45ca6d15ce89 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2097,7 +2097,7 @@ static inline int audit_copy_fcaps(struct audit_names *name,
/* Copy inode data into an audit_names. */
void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
- struct inode *inode)
+ struct inode *inode, unsigned int flags)
{
name->ino = inode->i_ino;
name->dev = inode->i_sb->s_dev;
@@ -2106,7 +2106,8 @@ void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
name->gid = inode->i_gid;
name->rdev = inode->i_rdev;
security_inode_getsecid(inode, &name->osid);
- audit_copy_fcaps(name, dentry);
+ if (!(flags & AUDIT_INODE_NOREVAL))
+ audit_copy_fcaps(name, dentry);
}
/**
diff --git a/kernel/audit.h b/kernel/audit.h
index 214e14948370..7db09151c2d0 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -212,7 +212,7 @@ struct audit_context {
extern void audit_copy_inode(struct audit_names *name,
const struct dentry *dentry,
- struct inode *inode);
+ struct inode *inode, unsigned int flags);
extern void audit_log_cap(struct audit_buffer *ab, char *prefix,
kernel_cap_t *cap);
extern void audit_log_name(struct audit_context *context,
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b2d1f043f17f..d39a7fbaf944 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1846,7 +1846,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
n->type = AUDIT_TYPE_NORMAL;
}
handle_path(dentry);
- audit_copy_inode(n, dentry, inode);
+ audit_copy_inode(n, dentry, inode, flags & AUDIT_INODE_NOREVAL);
}
void __audit_file(const struct file *file)
@@ -1947,7 +1947,7 @@ void __audit_inode_child(struct inode *parent,
n = audit_alloc_name(context, AUDIT_TYPE_PARENT);
if (!n)
return;
- audit_copy_inode(n, NULL, parent);
+ audit_copy_inode(n, NULL, parent, 0);
}
if (!found_child) {
@@ -1966,7 +1966,7 @@ void __audit_inode_child(struct inode *parent,
}
if (inode)
- audit_copy_inode(found_child, dentry, inode);
+ audit_copy_inode(found_child, dentry, inode, 0);
else
found_child->ino = AUDIT_INO_UNSET;
}
--
1.8.3.1
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