/* * linux/fs/attr.c * * Copyright (C) 1991, 1992 Linus Torvalds * changes by Thomas Schoebel-Theuer */ #include <linux/module.h> #include <linux/time.h> #include <linux/mm.h> #include <linux/string.h> #include <linux/capability.h> #include <linux/fsnotify.h> #include <linux/fcntl.h> #include <linux/security.h> /* Taken over from the old code... */ /* POSIX UID/GID verification for setting inode attributes. */ int inode_change_ok(const struct inode *inode, struct iattr *attr) { int retval = -EPERM; unsigned int ia_valid = attr->ia_valid; /* If force is set do it anyway. */ if (ia_valid & ATTR_FORCE) goto fine; /* Make sure a caller can chown. */ if ((ia_valid & ATTR_UID) && (current_fsuid() != inode->i_uid || attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN)) goto error; /* Make sure caller can chgrp. */ if ((ia_valid & ATTR_GID) && (current_fsuid() != inode->i_uid || (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) && !capable(CAP_CHOWN)) goto error; /* Make sure a caller can chmod. */ if (ia_valid & ATTR_MODE) { if (!is_owner_or_cap(inode)) goto error; /* Also check the setgid bit! */ if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : inode->i_gid) && !capable(CAP_FSETID)) attr->ia_mode &= ~S_ISGID; } /* Check for setting the inode time. */ if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) { if (!is_owner_or_cap(inode)) goto error; } fine: retval = 0; error: return retval; } EXPORT_SYMBOL(inode_change_ok); /** * inode_newsize_ok - may this inode be truncated to a given size * @inode: the inode to be truncated * @offset: the new size to assign to the inode * @Returns: 0 on success, -ve errno on failure * * inode_newsize_ok will check filesystem limits and ulimits to check that the * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ * when necessary. Caller must not proceed with inode size change if failure is * returned. @inode must be a file (not directory), with appropriate * permissions to allow truncate (inode_newsize_ok does NOT check these * conditions). * * inode_newsize_ok must be called with i_mutex held. */ int inode_newsize_ok(const struct inode *inode, loff_t offset) { if (inode->i_size < offset) { unsigned long limit; limit = rlimit(RLIMIT_FSIZE); if (limit != RLIM_INFINITY && offset > limit) goto out_sig; if (offset > inode->i_sb->s_maxbytes) goto out_big; } else { /* * truncation of in-use swapfiles is disallowed - it would * cause subsequent swapout to scribble on the now-freed * blocks. */ if (IS_SWAPFILE(inode)) return -ETXTBSY; } return 0; out_sig: send_sig(SIGXFSZ, current, 0); out_big: return -EFBIG; } EXPORT_SYMBOL(inode_newsize_ok); int inode_setattr(struct inode * inode, struct iattr * attr) { unsigned int ia_valid = attr->ia_valid; if (ia_valid & ATTR_SIZE && attr->ia_size != i_size_read(inode)) { int error = vmtruncate(inode, attr->ia_size); if (error) return error; } if (ia_valid & ATTR_UID) inode->i_uid = attr->ia_uid; if (ia_valid & ATTR_GID) inode->i_gid = attr->ia_gid; if (ia_valid & ATTR_ATIME) inode->i_atime = timespec_trunc(attr->ia_atime, inode->i_sb->s_time_gran); if (ia_valid & ATTR_MTIME) inode->i_mtime = timespec_trunc(attr->ia_mtime, inode->i_sb->s_time_gran); if (ia_valid & ATTR_CTIME) inode->i_ctime = timespec_trunc(attr->ia_ctime, inode->i_sb->s_time_gran); if (ia_valid & ATTR_MODE) { umode_t mode = attr->ia_mode; if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) mode &= ~S_ISGID; inode->i_mode = mode; } mark_inode_dirty(inode); return 0; } EXPORT_SYMBOL(inode_setattr); int notify_change(struct dentry * dentry, struct iattr * attr) { struct inode *inode = dentry->d_inode; mode_t mode = inode->i_mode; int error; struct timespec now; unsigned int ia_valid = attr->ia_valid; if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) return -EPERM; } now = current_fs_time(inode->i_sb); attr->ia_ctime = now; if (!(ia_valid & ATTR_ATIME_SET)) attr->ia_atime = now; if (!(ia_valid & ATTR_MTIME_SET)) attr->ia_mtime = now; if (ia_valid & ATTR_KILL_PRIV) { attr->ia_valid &= ~ATTR_KILL_PRIV; ia_valid &= ~ATTR_KILL_PRIV; error = security_inode_need_killpriv(dentry); if (error > 0) error = security_inode_killpriv(dentry); if (error) return error; } /* * We now pass ATTR_KILL_S*ID to the lower level setattr function so * that the function has the ability to reinterpret a mode change * that's due to these bits. This adds an implicit restriction that * no function will ever call notify_change with both ATTR_MODE and * ATTR_KILL_S*ID set. */ if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && (ia_valid & ATTR_MODE)) BUG(); if (ia_valid & ATTR_KILL_SUID) { if (mode & S_ISUID) { ia_valid = attr->ia_valid |= ATTR_MODE; attr->ia_mode = (inode->i_mode & ~S_ISUID); } } if (ia_valid & ATTR_KILL_SGID) { if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { if (!(ia_valid & ATTR_MODE)) { ia_valid = attr->ia_valid |= ATTR_MODE; attr->ia_mode = inode->i_mode; } attr->ia_mode &= ~S_ISGID; } } if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) return 0; error = security_inode_setattr(dentry, attr); if (error) return error; if (ia_valid & ATTR_SIZE) down_write(&dentry->d_inode->i_alloc_sem); if (inode->i_op && inode->i_op->setattr) { error = inode->i_op->setattr(dentry, attr); } else { error = inode_change_ok(inode, attr); if (!error) error = inode_setattr(inode, attr); } if (ia_valid & ATTR_SIZE) up_write(&dentry->d_inode->i_alloc_sem); if (!error) fsnotify_change(dentry, ia_valid); return error; } EXPORT_SYMBOL(notify_change);