From: Al Viro <viro@xxxxxxxxxxxxxxxxxx> 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. Suggested-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/linux-fsdevel/20241113043003.GH3387508@ZenIV/ Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> Signed-off-by: Jan Kara <jack@xxxxxxx> Link: https://patch.msgid.link/d1231137e7b661a382459e79a764259509a4115d.1731684329.git.josef@xxxxxxxxxxxxxx --- fs/fcntl.c | 4 ++-- fs/notify/fanotify/fanotify_user.c | 25 ++++++++++++++++--------- fs/open.c | 23 +++++++++++++++++++---- include/linux/fs.h | 6 +++--- include/uapi/asm-generic/fcntl.h | 1 - 5 files changed, 40 insertions(+), 19 deletions(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index 22dd9dcce7ec..ebd1c82bfb6b 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -1161,10 +1161,10 @@ 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, diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 8e2d43fc6f7c..83ee591744e9 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -101,8 +101,7 @@ 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 | \ @@ -259,12 +258,11 @@ 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, - current_cred()); + new_file = dentry_open_nonotify(path, group->fanotify_data.f_flags, + current_cred()); if (IS_ERR(new_file)) { put_unused_fd(client_fd); client_fd = PTR_ERR(new_file); @@ -1415,6 +1413,7 @@ 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); @@ -1483,7 +1482,7 @@ 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) @@ -1561,10 +1560,18 @@ 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: diff --git a/fs/open.c b/fs/open.c index 6c4950f19cfb..480c3798da2a 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1122,6 +1122,23 @@ 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 @@ -1219,7 +1236,7 @@ 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); @@ -1227,9 +1244,7 @@ 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; diff --git a/include/linux/fs.h b/include/linux/fs.h index 3559446279c1..24598d707578 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2728,6 +2728,8 @@ 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); @@ -3625,11 +3627,9 @@ 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) { diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h index 80f37a0d40d7..613475285643 100644 --- a/include/uapi/asm-generic/fcntl.h +++ b/include/uapi/asm-generic/fcntl.h @@ -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 -- 2.35.3
