diff options
Diffstat (limited to 'fs/inode.c')
| -rw-r--r-- | fs/inode.c | 168 |
1 files changed, 124 insertions, 44 deletions
diff --git a/fs/inode.c b/fs/inode.c index d2bdc407c94b..524ee91f74a6 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2010,67 +2010,57 @@ static int __remove_privs(struct user_namespace *mnt_userns, return notify_change(mnt_userns, dentry, &newattrs, NULL); } -/* - * Remove special file priviledges (suid, capabilities) when file is written - * to or truncated. - */ -int file_remove_privs(struct file *file) +static int __file_remove_privs(struct file *file, unsigned int flags) { struct dentry *dentry = file_dentry(file); struct inode *inode = file_inode(file); + int error; int kill; - int error = 0; - /* - * Fast path for nothing security related. - * As well for non-regular files, e.g. blkdev inodes. - * For example, blkdev_write_iter() might get here - * trying to remove privs which it is not allowed to. - */ if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) return 0; kill = dentry_needs_remove_privs(dentry); - if (kill < 0) + if (kill <= 0) return kill; - if (kill) - error = __remove_privs(file_mnt_user_ns(file), dentry, kill); + + if (flags & IOCB_NOWAIT) + return -EAGAIN; + + error = __remove_privs(file_mnt_user_ns(file), dentry, kill); if (!error) inode_has_no_xattr(inode); return error; } -EXPORT_SYMBOL(file_remove_privs); /** - * file_update_time - update mtime and ctime time - * @file: file accessed + * file_remove_privs - remove special file privileges (suid, capabilities) + * @file: file to remove privileges from + * + * When file is modified by a write or truncation ensure that special + * file privileges are removed. * - * Update the mtime and ctime members of an inode and mark the inode - * for writeback. Note that this function is meant exclusively for - * usage in the file write path of filesystems, and filesystems may - * choose to explicitly ignore update via this function with the - * S_NOCMTIME inode flag, e.g. for network filesystem where these - * timestamps are handled by the server. This can return an error for - * file systems who need to allocate space in order to update an inode. + * Return: 0 on success, negative errno on failure. */ +int file_remove_privs(struct file *file) +{ + return __file_remove_privs(file, 0); +} +EXPORT_SYMBOL(file_remove_privs); -int file_update_time(struct file *file) +static int inode_needs_update_time(struct inode *inode, struct timespec64 *now) { - struct inode *inode = file_inode(file); - struct timespec64 now; int sync_it = 0; - int ret; /* First try to exhaust all avenues to not sync */ if (IS_NOCMTIME(inode)) return 0; - now = current_time(inode); - if (!timespec64_equal(&inode->i_mtime, &now)) + if (!timespec64_equal(&inode->i_mtime, now)) sync_it = S_MTIME; - if (!timespec64_equal(&inode->i_ctime, &now)) + if (!timespec64_equal(&inode->i_ctime, now)) sync_it |= S_CTIME; if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode)) @@ -2079,37 +2069,127 @@ int file_update_time(struct file *file) if (!sync_it) return 0; - /* Finally allowed to write? Takes lock. */ - if (__mnt_want_write_file(file)) - return 0; + return sync_it; +} + +static int __file_update_time(struct file *file, struct timespec64 *now, + int sync_mode) +{ + int ret = 0; + struct inode *inode = file_inode(file); - ret = inode_update_time(inode, &now, sync_it); - __mnt_drop_write_file(file); + /* try to update time settings */ + if (!__mnt_want_write_file(file)) { + ret = inode_update_time(inode, now, sync_mode); + __mnt_drop_write_file(file); + } return ret; } + +/** + * file_update_time - update mtime and ctime time + * @file: file accessed + * + * Update the mtime and ctime members of an inode and mark the inode for + * writeback. Note that this function is meant exclusively for usage in + * the file write path of filesystems, and filesystems may choose to + * explicitly ignore updates via this function with the _NOCMTIME inode + * flag, e.g. for network filesystem where these imestamps are handled + * by the server. This can return an error for file systems who need to + * allocate space in order to update an inode. + * + * Return: 0 on success, negative errno on failure. + */ +int file_update_time(struct file *file) +{ + int ret; + struct inode *inode = file_inode(file); + struct timespec64 now = current_time(inode); + + ret = inode_needs_update_time(inode, &now); + if (ret <= 0) + return ret; + + return __file_update_time(file, &now, ret); +} EXPORT_SYMBOL(file_update_time); -/* Caller must hold the file's inode lock */ -int file_modified(struct file *file) +/** + * file_modified_flags - handle mandated vfs changes when modifying a file + * @file: file that was modified + * @flags: kiocb flags + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * If IOCB_NOWAIT is set, special file privileges will not be removed and + * time settings will not be updated. It will return -EAGAIN. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ +static int file_modified_flags(struct file *file, int flags) { - int err; + int ret; + struct inode *inode = file_inode(file); + struct timespec64 now = current_time(inode); /* * Clear the security bits if the process is not being run by root. * This keeps people from modifying setuid and setgid binaries. */ - err = file_remove_privs(file); - if (err) - return err; + ret = __file_remove_privs(file, flags); + if (ret) + return ret; if (unlikely(file->f_mode & FMODE_NOCMTIME)) return 0; - return file_update_time(file); + ret = inode_needs_update_time(inode, &now); + if (ret <= 0) + return ret; + if (flags & IOCB_NOWAIT) + return -EAGAIN; + + return __file_update_time(file, &now, ret); +} + +/** + * file_modified - handle mandated vfs changes when modifying a file + * @file: file that was modified + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ +int file_modified(struct file *file) +{ + return file_modified_flags(file, 0); } EXPORT_SYMBOL(file_modified); +/** + * kiocb_modified - handle mandated vfs changes when modifying a file + * @iocb: iocb that was modified + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ +int kiocb_modified(struct kiocb *iocb) +{ + return file_modified_flags(iocb->ki_filp, iocb->ki_flags); +} +EXPORT_SYMBOL_GPL(kiocb_modified); + int inode_needs_sync(struct inode *inode) { if (IS_SYNC(inode)) |