Commit ebe55960 authored by Al Viro's avatar Al Viro Committed by Jan Kara
Browse files

fs: get rid of __FMODE_NONOTIFY kludge 



All it takes to get rid of the __FMODE_NONOTIFY kludge is switching
fanotify from anon_inode_getfd() to anon_inode_getfile_fmode() and adding
a dentry_open_nonotify() helper to be used by fanotify on the other path.
That's it - no more weird shit in OPEN_FMODE(), etc.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/linux-fsdevel/20241113043003.GH3387508@ZenIV/


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Link: https://patch.msgid.link/d1231137e7b661a382459e79a764259509a4115d.1731684329.git.josef@toxicpanda.com
parent b86545e0

fs/fcntl.c

+2 −2
Original line number Diff line number Diff line
@@ -1158,10 +1158,10 @@ static int __init fcntl_init(void) 
	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY

	 * is defined as O_NONBLOCK on some platforms and not on others.

	 */

	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=

	BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ !=

		HWEIGHT32(

			(VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |

			__FMODE_EXEC | __FMODE_NONOTIFY));

			__FMODE_EXEC));



	fasync_cache = kmem_cache_create("fasync_cache",

					 sizeof(struct fasync_struct), 0,

fs/notify/fanotify/fanotify_user.c

+16 −9
Original line number Diff line number Diff line
@@ -100,8 +100,7 @@ static void __init fanotify_sysctls_init(void) 
 *

 * Internal and external open flags are stored together in field f_flags of

 * struct file. Only external open flags shall be allowed in event_f_flags.

 * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be

 * excluded.

 * Internal flags like FMODE_EXEC shall be excluded.

 */

#define	FANOTIFY_INIT_ALL_EVENT_F_BITS				( \

		O_ACCMODE	| O_APPEND	| O_NONBLOCK	| \
@@ -258,11 +257,10 @@ static int create_fd(struct fsnotify_group *group, const struct path *path, 
		return client_fd;



	/*

	 * we need a new file handle for the userspace program so it can read even if it was

	 * originally opened O_WRONLY.

	 * We provide an fd for the userspace program, so it could access the

	 * file without generating fanotify events itself.

	 */

	new_file = dentry_open(path,

			       group->fanotify_data.f_flags | __FMODE_NONOTIFY,

	new_file = dentry_open_nonotify(path, group->fanotify_data.f_flags,

					current_cred());

	if (IS_ERR(new_file)) {

		put_unused_fd(client_fd);
@@ -1409,6 +1407,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	unsigned int fid_mode = flags & FANOTIFY_FID_BITS;

	unsigned int class = flags & FANOTIFY_CLASS_BITS;

	unsigned int internal_flags = 0;

	struct file *file;



	pr_debug("%s: flags=%x event_f_flags=%x\n",

		 __func__, flags, event_f_flags);
@@ -1477,7 +1476,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	    (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))

		return -EINVAL;



	f_flags = O_RDWR | __FMODE_NONOTIFY;

	f_flags = O_RDWR;

	if (flags & FAN_CLOEXEC)

		f_flags |= O_CLOEXEC;

	if (flags & FAN_NONBLOCK)
@@ -1555,10 +1554,18 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
			goto out_destroy_group;

	}



	fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);

	fd = get_unused_fd_flags(f_flags);

	if (fd < 0)

		goto out_destroy_group;



	file = anon_inode_getfile_fmode("[fanotify]", &fanotify_fops, group,

					f_flags, FMODE_NONOTIFY);

	if (IS_ERR(file)) {

		fd = PTR_ERR(file);

		put_unused_fd(fd);

		goto out_destroy_group;

	}

	fd_install(fd, file);

	return fd;



out_destroy_group:

fs/open.c

+19 −4
Original line number Diff line number Diff line
@@ -1105,6 +1105,23 @@ struct file *dentry_open(const struct path *path, int flags, 
}

EXPORT_SYMBOL(dentry_open);



struct file *dentry_open_nonotify(const struct path *path, int flags,

				  const struct cred *cred)

{

	struct file *f = alloc_empty_file(flags, cred);

	if (!IS_ERR(f)) {

		int error;



		f->f_mode |= FMODE_NONOTIFY;

		error = vfs_open(path, f);

		if (error) {

			fput(f);

			f = ERR_PTR(error);

		}

	}

	return f;

}



/**

 * dentry_create - Create and open a file

 * @path: path to create
@@ -1202,7 +1219,7 @@ inline struct open_how build_open_how(int flags, umode_t mode) 
inline int build_open_flags(const struct open_how *how, struct open_flags *op)

{

	u64 flags = how->flags;

	u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;

	u64 strip = O_CLOEXEC;

	int lookup_flags = 0;

	int acc_mode = ACC_MODE(flags);
@@ -1210,9 +1227,7 @@ inline int build_open_flags(const struct open_how *how, struct open_flags *op) 
			 "struct open_flags doesn't yet handle flags > 32 bits");



	/*

	 * Strip flags that either shouldn't be set by userspace like

	 * FMODE_NONOTIFY or that aren't relevant in determining struct

	 * open_flags like O_CLOEXEC.

	 * Strip flags that aren't relevant in determining struct open_flags.

	 */

	flags &= ~strip;

include/linux/fs.h

+3 −3
Original line number Diff line number Diff line
@@ -2751,6 +2751,8 @@ static inline struct file *file_open_root_mnt(struct vfsmount *mnt, 
}

struct file *dentry_open(const struct path *path, int flags,

			 const struct cred *creds);

struct file *dentry_open_nonotify(const struct path *path, int flags,

				  const struct cred *cred);

struct file *dentry_create(const struct path *path, int flags, umode_t mode,

			   const struct cred *cred);

struct path *backing_file_user_path(struct file *f);
@@ -3707,11 +3709,9 @@ struct ctl_table; 
int __init list_bdev_fs_names(char *buf, size_t size);



#define __FMODE_EXEC		((__force int) FMODE_EXEC)

#define __FMODE_NONOTIFY	((__force int) FMODE_NONOTIFY)



#define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])

#define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \

					    (flag & __FMODE_NONOTIFY)))

#define OPEN_FMODE(flag) ((__force fmode_t)((flag + 1) & O_ACCMODE))



static inline bool is_sxid(umode_t mode)

{

include/uapi/asm-generic/fcntl.h

+0 −1
Original line number Diff line number Diff line
@@ -6,7 +6,6 @@ 


/*

 * FMODE_EXEC is 0x20

 * FMODE_NONOTIFY is 0x4000000

 * These cannot be used by userspace O_* until internal and external open

 * flags are split.

 * -Eric Paris