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(a)redhat.com&gt; --- 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

Like 42d5e37654e4 ("audit: filter PATH records keyed on filesystem magic") Any user or remote filesystem could become unavailable and effectively block on a forced unmount. -a always,exit -S umount2 -F key=umount2 Provide a method to ignore these user and remote filesystems to prevent them from being impossible to unmount. Extend the "AUDIT_FILTER_FS" filter that uses the field type AUDIT_FSTYPE keying off the filesystem 4-octet hexadecimal magic identifier to filter specific filesystems to cover audit_inode() to address this blockage. An example rule would look like: -a never,filesystem -F fstype=0x517B -F key=ignore_smb -a never,filesystem -F fstype=0x6969 -F key=ignore_nfs Arguably the better way to address this issue is to disable auditing processes that touch removable filesystems. Please see the github issue tracker https://github.com/linux-audit/audit-kernel/issues/100 Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; --- kernel/auditsc.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/kernel/auditsc.c b/kernel/auditsc.c index d39a7fbaf944..59d6d3fbc00e 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1777,10 +1777,33 @@ void __audit_inode(struct filename *name, const struct dentry *dentry, struct inode *inode = d_backing_inode(dentry); struct audit_names *n; bool parent = flags & AUDIT_INODE_PARENT; + struct audit_entry *e; + struct list_head *list = &audit_filter_list[AUDIT_FILTER_FS]; + int i; if (!context->in_syscall) return; + rcu_read_lock(); + if (!list_empty(list)) { + list_for_each_entry_rcu(e, list, list) { + for (i = 0; i < e->rule.field_count; i++) { + struct audit_field *f = &e->rule.fields[i]; + + if (f->type == AUDIT_FSTYPE) { + if (audit_comparator(inode->i_sb->s_magic, + f->op, f->val)) { + if (e->rule.action == AUDIT_NEVER) { + rcu_read_unlock(); + return; + } + } + } + } + } + } + rcu_read_unlock(); + if (!name) goto out_alloc; -- 1.8.3.1