3bd858ab1c
Introduce is_owner_or_cap() macro in fs.h, and convert over relevant users to it. This is done because we want to avoid bugs in the future where we check for only effective fsuid of the current task against a file's owning uid, without simultaneously checking for CAP_FOWNER as well, thus violating its semantics. [ XFS uses special macros and structures, and in general looked ... untouchable, so we leave it alone -- but it has been looked over. ] The (current->fsuid != inode->i_uid) check in generic_permission() and exec_permission_lite() is left alone, because those operations are covered by CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH. Similarly operations falling under the purview of CAP_CHOWN and CAP_LEASE are also left alone. Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in> Cc: Al Viro <viro@ftp.linux.org.uk> Acked-by: Serge E. Hallyn <serge@hallyn.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
171 lines
4.1 KiB
C
171 lines
4.1 KiB
C
/*
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* linux/fs/attr.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* changes by Thomas Schoebel-Theuer
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*/
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#include <linux/module.h>
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#include <linux/time.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/capability.h>
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#include <linux/fsnotify.h>
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#include <linux/fcntl.h>
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#include <linux/quotaops.h>
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#include <linux/security.h>
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/* Taken over from the old code... */
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/* POSIX UID/GID verification for setting inode attributes. */
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int inode_change_ok(struct inode *inode, struct iattr *attr)
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{
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int retval = -EPERM;
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unsigned int ia_valid = attr->ia_valid;
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/* If force is set do it anyway. */
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if (ia_valid & ATTR_FORCE)
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goto fine;
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/* Make sure a caller can chown. */
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if ((ia_valid & ATTR_UID) &&
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(current->fsuid != inode->i_uid ||
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attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
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goto error;
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/* Make sure caller can chgrp. */
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if ((ia_valid & ATTR_GID) &&
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(current->fsuid != inode->i_uid ||
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(!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
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!capable(CAP_CHOWN))
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goto error;
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/* Make sure a caller can chmod. */
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if (ia_valid & ATTR_MODE) {
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if (!is_owner_or_cap(inode))
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goto error;
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/* Also check the setgid bit! */
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if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
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inode->i_gid) && !capable(CAP_FSETID))
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attr->ia_mode &= ~S_ISGID;
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}
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/* Check for setting the inode time. */
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if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
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if (!is_owner_or_cap(inode))
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goto error;
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}
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fine:
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retval = 0;
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error:
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return retval;
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}
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EXPORT_SYMBOL(inode_change_ok);
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int inode_setattr(struct inode * inode, struct iattr * attr)
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{
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unsigned int ia_valid = attr->ia_valid;
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if (ia_valid & ATTR_SIZE &&
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attr->ia_size != i_size_read(inode)) {
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int error = vmtruncate(inode, attr->ia_size);
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if (error)
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return error;
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}
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if (ia_valid & ATTR_UID)
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inode->i_uid = attr->ia_uid;
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if (ia_valid & ATTR_GID)
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inode->i_gid = attr->ia_gid;
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if (ia_valid & ATTR_ATIME)
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inode->i_atime = timespec_trunc(attr->ia_atime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_MTIME)
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inode->i_mtime = timespec_trunc(attr->ia_mtime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_CTIME)
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inode->i_ctime = timespec_trunc(attr->ia_ctime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_MODE) {
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umode_t mode = attr->ia_mode;
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if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
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mode &= ~S_ISGID;
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inode->i_mode = mode;
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}
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mark_inode_dirty(inode);
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return 0;
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}
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EXPORT_SYMBOL(inode_setattr);
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int notify_change(struct dentry * dentry, struct iattr * attr)
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{
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struct inode *inode = dentry->d_inode;
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mode_t mode;
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int error;
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struct timespec now;
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unsigned int ia_valid = attr->ia_valid;
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mode = inode->i_mode;
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now = current_fs_time(inode->i_sb);
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attr->ia_ctime = now;
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if (!(ia_valid & ATTR_ATIME_SET))
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attr->ia_atime = now;
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if (!(ia_valid & ATTR_MTIME_SET))
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attr->ia_mtime = now;
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if (ia_valid & ATTR_KILL_SUID) {
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attr->ia_valid &= ~ATTR_KILL_SUID;
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if (mode & S_ISUID) {
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if (!(ia_valid & ATTR_MODE)) {
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ia_valid = attr->ia_valid |= ATTR_MODE;
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attr->ia_mode = inode->i_mode;
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}
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attr->ia_mode &= ~S_ISUID;
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}
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}
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if (ia_valid & ATTR_KILL_SGID) {
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attr->ia_valid &= ~ ATTR_KILL_SGID;
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if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
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if (!(ia_valid & ATTR_MODE)) {
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ia_valid = attr->ia_valid |= ATTR_MODE;
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attr->ia_mode = inode->i_mode;
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}
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attr->ia_mode &= ~S_ISGID;
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}
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}
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if (!attr->ia_valid)
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return 0;
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if (ia_valid & ATTR_SIZE)
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down_write(&dentry->d_inode->i_alloc_sem);
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if (inode->i_op && inode->i_op->setattr) {
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error = security_inode_setattr(dentry, attr);
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if (!error)
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error = inode->i_op->setattr(dentry, attr);
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} else {
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error = inode_change_ok(inode, attr);
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if (!error)
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error = security_inode_setattr(dentry, attr);
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if (!error) {
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if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
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(ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
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error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
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if (!error)
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error = inode_setattr(inode, attr);
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}
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}
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if (ia_valid & ATTR_SIZE)
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up_write(&dentry->d_inode->i_alloc_sem);
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if (!error)
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fsnotify_change(dentry, ia_valid);
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return error;
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}
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EXPORT_SYMBOL(notify_change);
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