Commit 57d46577 authored by Richard Guy Briggs's avatar Richard Guy Briggs Committed by Paul Moore
Browse files

audit: ignore fcaps on umount 

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: default avatarRichard Guy Briggs <rgb@redhat.com>
[PM: merge fuzz in audit_log_fcaps()]
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 05c7a9cb

fs/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -2720,7 +2720,7 @@ filename_mountpoint(int dfd, struct filename *name, struct path *path, 
	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;

fs/namespace.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/audit.h

+10 −5
Original line number Diff line number Diff line
@@ -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)
@@ -248,6 +249,7 @@ extern void __audit_getname(struct filename *name); 


#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 *);
@@ -308,12 +310,15 @@ 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)

include/linux/namei.h

+3 −0
Original line number Diff line number Diff line
@@ -24,6 +24,8 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; 
 *  - 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 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; 
#define LOOKUP_REVAL		0x0020

#define LOOKUP_RCU		0x0040

#define LOOKUP_NO_REVAL		0x0080

#define LOOKUP_NO_EVAL		0x0100



/*

 * Intent data

kernel/audit.c

+9 −1
Original line number Diff line number Diff line
@@ -2082,6 +2082,10 @@ 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 cap_frootid=%d",
@@ -2114,7 +2118,7 @@ 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;
@@ -2123,6 +2127,10 @@ 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);

}

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