[PATCH ghak100 V2 2/2] audit: ignore fcaps on umount
Richard Guy Briggs
rgb at redhat.com
Wed Jan 23 18:35:00 UTC 2019
Don't fetch fcaps when umount2 is called 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 at redhat.com>
---
fs/namei.c | 2 +-
fs/namespace.c | 2 ++
include/linux/audit.h | 15 ++++++++++-----
include/linux/namei.h | 3 +++
kernel/audit.c | 10 +++++++++-
kernel/audit.h | 2 +-
kernel/auditsc.c | 6 +++---
7 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 914178cdbe94..87d7710a2e1d 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_EVAL);
restore_nameidata();
putname(name);
return error;
diff --git a/fs/namespace.c b/fs/namespace.c
index a677b59efd74..e5de0e372df2 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1640,6 +1640,8 @@ int ksys_umount(char __user *name, int flags)
if (!(flags & UMOUNT_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
+ lookup_flags |= LOOKUP_NO_EVAL;
+
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 a625c29a2ea2..5d914b534536 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)
@@ -225,6 +226,7 @@ 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_NOEVAL 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 *);
@@ -285,12 +287,15 @@ 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 flags) {
if (unlikely(!audit_dummy_context())) {
- unsigned int flags = 0;
- if (parent)
- flags |= AUDIT_INODE_PARENT;
- __audit_inode(name, dentry, flags);
+ unsigned int aflags = 0;
+
+ if (flags & LOOKUP_PARENT)
+ aflags |= AUDIT_INODE_PARENT;
+ if (flags & LOOKUP_NO_EVAL)
+ aflags |= AUDIT_INODE_NOEVAL;
+ __audit_inode(name, dentry, aflags);
}
}
static inline void audit_file(struct file *file)
diff --git a/include/linux/namei.h b/include/linux/namei.h
index a78606e8e3df..9138b4471dbf 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -24,6 +24,8 @@
* - internal "there are more path components" flag
* - dentry cache is untrusted; force a real lookup
* - suppress terminal automount
+ * - skip revalidation
+ * - don't fetch xattrs on audit_inode
*/
#define LOOKUP_FOLLOW 0x0001
#define LOOKUP_DIRECTORY 0x0002
@@ -33,6 +35,7 @@
#define LOOKUP_REVAL 0x0020
#define LOOKUP_RCU 0x0040
#define LOOKUP_NO_REVAL 0x0080
+#define LOOKUP_NO_EVAL 0x0100
/*
* Intent data
diff --git a/kernel/audit.c b/kernel/audit.c
index ca55ccb46b76..45d5131943eb 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2081,6 +2081,10 @@ void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
{
+ if (name->fcap_ver == -1) {
+ audit_log_format(ab, " cap_fe=? cap_fver=? cap_fp=? cap_fi=?");
+ return;
+ }
audit_log_cap(ab, "cap_fp", &name->fcap.permitted);
audit_log_cap(ab, "cap_fi", &name->fcap.inheritable);
audit_log_format(ab, " cap_fe=%d cap_fver=%x",
@@ -2111,7 +2115,7 @@ 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;
@@ -2120,6 +2124,10 @@ 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);
+ if (flags & AUDIT_INODE_NOEVAL) {
+ name->fcap_ver = -1;
+ return;
+ }
audit_copy_fcaps(name, dentry);
}
diff --git a/kernel/audit.h b/kernel/audit.h
index 6ffb70575082..25ab276be8e5 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -214,7 +214,7 @@ 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 3d05d5fc6240..9a1257afc4d4 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1853,7 +1853,7 @@ 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_NOEVAL);
}
void __audit_file(const struct file *file)
@@ -1952,7 +1952,7 @@ 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) {
@@ -1971,7 +1971,7 @@ 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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