/linux/src/fs/namei.c
C | 1433 lines | 952 code | 177 blank | 304 comment | 247 complexity | 2d3e11e8be013de68c690a999f574d0e MD5 | raw file
Possible License(s): GPL-2.0
- /*
- * linux/fs/namei.c
- *
- * Copyright (C) 1991, 1992 Linus Torvalds
- *
- * OSKit support added by the University of Utah, 1997
- */
- /*
- * Some corrections by tytso.
- */
- /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
- * lookup logic.
- */
- #include <linux/mm.h>
- #include <linux/proc_fs.h>
- #include <linux/smp_lock.h>
- #include <linux/quotaops.h>
- #include <asm/uaccess.h>
- #include <asm/unaligned.h>
- #include <asm/semaphore.h>
- #include <asm/page.h>
- #include <asm/pgtable.h>
- #include <asm/namei.h>
- /* This can be removed after the beta phase. */
- #define CACHE_SUPERVISE /* debug the correctness of dcache entries */
- #undef DEBUG /* some other debugging */
- #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
- #ifndef OSKIT
- /* [Feb-1997 T. Schoebel-Theuer]
- * Fundamental changes in the pathname lookup mechanisms (namei)
- * were necessary because of omirr. The reason is that omirr needs
- * to know the _real_ pathname, not the user-supplied one, in case
- * of symlinks (and also when transname replacements occur).
- *
- * The new code replaces the old recursive symlink resolution with
- * an iterative one (in case of non-nested symlink chains). It does
- * this with calls to <fs>_follow_link().
- * As a side effect, dir_namei(), _namei() and follow_link() are now
- * replaced with a single function lookup_dentry() that can handle all
- * the special cases of the former code.
- *
- * With the new dcache, the pathname is stored at each inode, at least as
- * long as the refcount of the inode is positive. As a side effect, the
- * size of the dcache depends on the inode cache and thus is dynamic.
- *
- * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
- * resolution to correspond with current state of the code.
- *
- * Note that the symlink resolution is not *completely* iterative.
- * There is still a significant amount of tail- and mid- recursion in
- * the algorithm. Also, note that <fs>_readlink() is not used in
- * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
- * may return different results than <fs>_follow_link(). Many virtual
- * filesystems (including /proc) exhibit this behavior.
- */
- /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
- * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
- * and the name already exists in form of a symlink, try to create the new
- * name indicated by the symlink. The old code always complained that the
- * name already exists, due to not following the symlink even if its target
- * is nonexistent. The new semantics affects also mknod() and link() when
- * the name is a symlink pointing to a non-existant name.
- *
- * I don't know which semantics is the right one, since I have no access
- * to standards. But I found by trial that HP-UX 9.0 has the full "new"
- * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
- * "old" one. Personally, I think the new semantics is much more logical.
- * Note that "ln old new" where "new" is a symlink pointing to a non-existing
- * file does succeed in both HP-UX and SunOs, but not in Solaris
- * and in the old Linux semantics.
- */
- /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
- * semantics. See the comments in "open_namei" and "do_link" below.
- *
- * [10-Sep-98 Alan Modra] Another symlink change.
- */
- /* In order to reduce some races, while at the same time doing additional
- * checking and hopefully speeding things up, we copy filenames to the
- * kernel data space before using them..
- *
- * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
- */
- static inline int do_getname(const char *filename, char *page)
- {
- int retval;
- unsigned long len = PAGE_SIZE;
- if ((unsigned long) filename >= TASK_SIZE) {
- if (!segment_eq(get_fs(), KERNEL_DS))
- return -EFAULT;
- } else if (TASK_SIZE - (unsigned long) filename < PAGE_SIZE)
- len = TASK_SIZE - (unsigned long) filename;
- retval = strncpy_from_user((char *)page, filename, len);
- if (retval > 0) {
- if (retval < len)
- return 0;
- return -ENAMETOOLONG;
- } else if (!retval)
- retval = -ENOENT;
- return retval;
- }
- #endif /* OSKIT */
- char * getname(const char * filename)
- {
- #ifdef OSKIT
- return (char *)filename;
- #else
- char *tmp, *result;
- result = ERR_PTR(-ENOMEM);
- tmp = __getname();
- if (tmp) {
- int retval = do_getname(filename, tmp);
- result = tmp;
- if (retval < 0) {
- putname(tmp);
- result = ERR_PTR(retval);
- }
- }
- return result;
- #endif /* OSKIT */
- }
- /*
- * permission()
- *
- * is used to check for read/write/execute permissions on a file.
- * We use "fsuid" for this, letting us set arbitrary permissions
- * for filesystem access without changing the "normal" uids which
- * are used for other things..
- */
- int permission(struct inode * inode,int mask)
- {
- int mode = inode->i_mode;
- if (inode->i_op && inode->i_op->permission)
- return inode->i_op->permission(inode, mask);
- else if ((mask & S_IWOTH) && IS_RDONLY(inode) &&
- (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
- return -EROFS; /* Nobody gets write access to a read-only fs */
- else if ((mask & S_IWOTH) && IS_IMMUTABLE(inode))
- return -EACCES; /* Nobody gets write access to an immutable file */
- else if (current->fsuid == inode->i_uid)
- mode >>= 6;
- else if (in_group_p(inode->i_gid))
- mode >>= 3;
- if (((mode & mask & S_IRWXO) == mask) || capable(CAP_DAC_OVERRIDE))
- return 0;
- /* read and search access */
- if ((mask == S_IROTH) ||
- (S_ISDIR(mode) && !(mask & ~(S_IROTH | S_IXOTH))))
- if (capable(CAP_DAC_READ_SEARCH))
- return 0;
- return -EACCES;
- }
- /*
- * get_write_access() gets write permission for a file.
- * put_write_access() releases this write permission.
- * This is used for regular files.
- * We cannot support write (and maybe mmap read-write shared) accesses and
- * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
- * can have the following values:
- * 0: no writers, no VM_DENYWRITE mappings
- * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
- * > 0: (i_writecount) users are writing to the file.
- */
- int get_write_access(struct inode * inode)
- {
- #ifdef OSKIT
- /* This doesn't need to do anything since i_writecount is only
- so exec can do ETXTBSY. */
- #else
- if (inode->i_writecount < 0)
- return -ETXTBSY;
- inode->i_writecount++;
- #endif /* OSKIT */
- return 0;
- }
- void put_write_access(struct inode * inode)
- {
- #ifdef OSKIT
- /* This doesn't need to do anything since i_writecount is only
- so exec can do ETXTBSY. */
- #else
- inode->i_writecount--;
- #endif
- }
- /*
- * "." and ".." are special - ".." especially so because it has to be able
- * to know about the current root directory and parent relationships
- */
- static struct dentry * reserved_lookup(struct dentry * parent, struct qstr * name)
- {
- struct dentry *result = NULL;
- if (name->name[0] == '.') {
- switch (name->len) {
- default:
- break;
- case 2:
- if (name->name[1] != '.')
- break;
- if (parent != current->fs->root)
- parent = parent->d_covers->d_parent;
- /* fallthrough */
- case 1:
- result = parent;
- }
- }
- return dget(result);
- }
- /*
- * Internal lookup() using the new generic dcache.
- */
- static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, int flags)
- {
- struct dentry * dentry = d_lookup(parent, name);
- if (dentry && dentry->d_op && dentry->d_op->d_revalidate) {
- if (!dentry->d_op->d_revalidate(dentry, flags) && !d_invalidate(dentry)) {
- dput(dentry);
- dentry = NULL;
- }
- }
- return dentry;
- }
- /*
- * This is called when everything else fails, and we actually have
- * to go to the low-level filesystem to find out what we should do..
- *
- * We get the directory semaphore, and after getting that we also
- * make sure that nobody added the entry to the dcache in the meantime..
- */
- static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, int flags)
- {
- struct dentry * result;
- struct inode *dir = parent->d_inode;
- down(&dir->i_sem);
- /*
- * First re-do the cached lookup just in case it was created
- * while we waited for the directory semaphore..
- *
- * FIXME! This could use version numbering or similar to
- * avoid unnecessary cache lookups.
- */
- result = cached_lookup(parent, name, flags);
- if (!result) {
- struct dentry * dentry = d_alloc(parent, name);
- result = ERR_PTR(-ENOMEM);
- if (dentry) {
- result = dir->i_op->lookup(dir, dentry);
- if (result)
- dput(dentry);
- else
- result = dentry;
- }
- }
- up(&dir->i_sem);
- return result;
- }
- static struct dentry * do_follow_link(struct dentry *base, struct dentry *dentry, unsigned int follow)
- {
- struct inode * inode = dentry->d_inode;
- if ((follow & LOOKUP_FOLLOW)
- && inode && inode->i_op && inode->i_op->follow_link) {
- if (current->link_count < 5) {
- struct dentry * result;
- current->link_count++;
- /* This eats the base */
- result = inode->i_op->follow_link(dentry, base, follow);
- current->link_count--;
- dput(dentry);
- return result;
- }
- dput(dentry);
- dentry = ERR_PTR(-ELOOP);
- }
- dput(base);
- return dentry;
- }
- static inline struct dentry * follow_mount(struct dentry * dentry)
- {
- struct dentry * mnt = dentry->d_mounts;
- if (mnt != dentry) {
- dget(mnt);
- dput(dentry);
- dentry = mnt;
- }
- return dentry;
- }
- /*
- * Name resolution.
- *
- * This is the basic name resolution function, turning a pathname
- * into the final dentry.
- */
- struct dentry * lookup_dentry(const char * name, struct dentry * base, unsigned int lookup_flags)
- {
- struct dentry * dentry;
- struct inode *inode;
- if (*name == '/') {
- if (base)
- dput(base);
- do {
- name++;
- } while (*name == '/');
- __prefix_lookup_dentry(name, lookup_flags);
- base = dget(current->fs->root);
- } else if (!base) {
- base = dget(current->fs->pwd);
- }
- if (!*name)
- goto return_base;
- inode = base->d_inode;
- lookup_flags &= LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_SLASHOK;
- /* At this point we know we have a real path component. */
- for(;;) {
- int err;
- unsigned long hash;
- struct qstr this;
- unsigned int flags;
- unsigned int c;
- err = permission(inode, MAY_EXEC);
- dentry = ERR_PTR(err);
- if (err)
- break;
- this.name = name;
- c = *(const unsigned char *)name;
- hash = init_name_hash();
- do {
- name++;
- hash = partial_name_hash(c, hash);
- c = *(const unsigned char *)name;
- } while (c && (c != '/'));
- this.len = name - (const char *) this.name;
- this.hash = end_name_hash(hash);
- /* remove trailing slashes? */
- flags = lookup_flags;
- if (c) {
- char tmp;
- flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
- do {
- tmp = *++name;
- } while (tmp == '/');
- if (tmp)
- flags |= LOOKUP_CONTINUE;
- }
- /*
- * See if the low-level filesystem might want
- * to use its own hash..
- */
- if (base->d_op && base->d_op->d_hash) {
- int error;
- error = base->d_op->d_hash(base, &this);
- if (error < 0) {
- dentry = ERR_PTR(error);
- break;
- }
- }
- /* This does the actual lookups.. */
- dentry = reserved_lookup(base, &this);
- if (!dentry) {
- dentry = cached_lookup(base, &this, flags);
- if (!dentry) {
- dentry = real_lookup(base, &this, flags);
- if (IS_ERR(dentry))
- break;
- }
- }
- /* Check mountpoints.. */
- dentry = follow_mount(dentry);
- base = do_follow_link(base, dentry, flags);
- if (IS_ERR(base))
- goto return_base;
- inode = base->d_inode;
- if (flags & LOOKUP_DIRECTORY) {
- if (!inode)
- goto no_inode;
- dentry = ERR_PTR(-ENOTDIR);
- if (!inode->i_op || !inode->i_op->lookup)
- break;
- if (flags & LOOKUP_CONTINUE)
- continue;
- }
- return_base:
- return base;
- /*
- * The case of a nonexisting file is special.
- *
- * In the middle of a pathname lookup (ie when
- * LOOKUP_CONTINUE is set), it's an obvious
- * error and returns ENOENT.
- *
- * At the end of a pathname lookup it's legal,
- * and we return a negative dentry. However, we
- * get here only if there were trailing slashes,
- * which is legal only if we know it's supposed
- * to be a directory (ie "mkdir"). Thus the
- * LOOKUP_SLASHOK flag.
- */
- no_inode:
- dentry = ERR_PTR(-ENOENT);
- if (flags & LOOKUP_CONTINUE)
- break;
- if (flags & LOOKUP_SLASHOK)
- goto return_base;
- break;
- }
- dput(base);
- return dentry;
- }
- /*
- * namei()
- *
- * is used by most simple commands to get the inode of a specified name.
- * Open, link etc use their own routines, but this is enough for things
- * like 'chmod' etc.
- *
- * namei exists in two versions: namei/lnamei. The only difference is
- * that namei follows links, while lnamei does not.
- */
- struct dentry * __namei(const char *pathname, unsigned int lookup_flags)
- {
- char *name;
- struct dentry *dentry;
- name = getname(pathname);
- dentry = (struct dentry *) name;
- if (!IS_ERR(name)) {
- dentry = lookup_dentry(name, NULL, lookup_flags);
- putname(name);
- if (!IS_ERR(dentry)) {
- if (!dentry->d_inode) {
- dput(dentry);
- dentry = ERR_PTR(-ENOENT);
- }
- }
- }
- return dentry;
- }
- /*
- * It's inline, so penalty for filesystems that don't use sticky bit is
- * minimal.
- */
- static inline int check_sticky(struct inode *dir, struct inode *inode)
- {
- if (!(dir->i_mode & S_ISVTX))
- return 0;
- if (inode->i_uid == current->fsuid)
- return 0;
- if (dir->i_uid == current->fsuid)
- return 0;
- return !capable(CAP_FOWNER);
- }
- /*
- * Check whether we can remove a link victim from directory dir, check
- * whether the type of victim is right.
- * 1. We can't do it if dir is read-only (done in permission())
- * 2. We should have write and exec permissions on dir
- * 3. We can't remove anything from append-only dir
- * 4. We can't do anything with immutable dir (done in permission())
- * 5. If the sticky bit on dir is set we should either
- * a. be owner of dir, or
- * b. be owner of victim, or
- * c. have CAP_FOWNER capability
- * 6. If the victim is append-only or immutable we can't do antyhing with
- * links pointing to it.
- * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
- * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
- * 9. We can't remove a root or mountpoint.
- */
- static inline int may_delete(struct inode *dir,struct dentry *victim, int isdir)
- {
- int error;
- if (!victim->d_inode || victim->d_parent->d_inode != dir)
- return -ENOENT;
- error = permission(dir,MAY_WRITE | MAY_EXEC);
- if (error)
- return error;
- if (IS_APPEND(dir))
- return -EPERM;
- if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
- IS_IMMUTABLE(victim->d_inode))
- return -EPERM;
- if (isdir) {
- if (!S_ISDIR(victim->d_inode->i_mode))
- return -ENOTDIR;
- if (IS_ROOT(victim))
- return -EBUSY;
- if (victim->d_mounts != victim->d_covers)
- return -EBUSY;
- } else if (S_ISDIR(victim->d_inode->i_mode))
- return -EISDIR;
- return 0;
- }
- /* Check whether we can create an object with dentry child in directory
- * dir.
- * 1. We can't do it if child already exists (open has special treatment for
- * this case, but since we are inlined it's OK)
- * 2. We can't do it if dir is read-only (done in permission())
- * 3. We should have write and exec permissions on dir
- * 4. We can't do it if dir is immutable (done in permission())
- */
- static inline int may_create(struct inode *dir, struct dentry *child) {
- if (child->d_inode)
- return -EEXIST;
- return permission(dir,MAY_WRITE | MAY_EXEC);
- }
- static inline struct dentry *get_parent(struct dentry *dentry)
- {
- return dget(dentry->d_parent);
- }
- static inline void unlock_dir(struct dentry *dir)
- {
- up(&dir->d_inode->i_sem);
- dput(dir);
- }
- /*
- * We need to do a check-parent every time
- * after we have locked the parent - to verify
- * that the parent is still our parent and
- * that we are still hashed onto it..
- *
- * This is requied in case two processes race
- * on removing (or moving) the same entry: the
- * parent lock will serialize them, but the
- * other process will be too late..
- */
- #define check_parent(dir, dentry) \
- ((dir) == (dentry)->d_parent && !list_empty(&dentry->d_hash))
- /*
- * Locking the parent is needed to:
- * - serialize directory operations
- * - make sure the parent doesn't change from
- * under us in the middle of an operation.
- *
- * NOTE! Right now we'd rather use a "struct inode"
- * for this, but as I expect things to move toward
- * using dentries instead for most things it is
- * probably better to start with the conceptually
- * better interface of relying on a path of dentries.
- */
- static inline struct dentry *lock_parent(struct dentry *dentry)
- {
- struct dentry *dir = dget(dentry->d_parent);
- down(&dir->d_inode->i_sem);
- return dir;
- }
- /*
- * Whee.. Deadlock country. Happily there are only two VFS
- * operations that do this..
- */
- static inline void double_lock(struct dentry *d1, struct dentry *d2)
- {
- struct semaphore *s1 = &d1->d_inode->i_sem;
- struct semaphore *s2 = &d2->d_inode->i_sem;
- if (s1 != s2) {
- if ((unsigned long) s1 < (unsigned long) s2) {
- struct semaphore *tmp = s2;
- s2 = s1; s1 = tmp;
- }
- down(s1);
- }
- down(s2);
- }
- static inline void double_unlock(struct dentry *d1, struct dentry *d2)
- {
- struct semaphore *s1 = &d1->d_inode->i_sem;
- struct semaphore *s2 = &d2->d_inode->i_sem;
- up(s1);
- if (s1 != s2)
- up(s2);
- dput(d1);
- dput(d2);
- }
- /*
- * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
- * reasons.
- *
- * O_DIRECTORY translates into forcing a directory lookup.
- */
- static inline int lookup_flags(unsigned int f)
- {
- unsigned long retval = LOOKUP_FOLLOW;
- if (f & O_NOFOLLOW)
- retval &= ~LOOKUP_FOLLOW;
-
- if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
- retval &= ~LOOKUP_FOLLOW;
-
- if (f & O_DIRECTORY)
- retval |= LOOKUP_DIRECTORY;
-
- return retval;
- }
- /*
- * open_namei()
- *
- * namei for open - this is in fact almost the whole open-routine.
- *
- * Note that the low bits of "flag" aren't the same as in the open
- * system call - they are 00 - no permissions needed
- * 01 - read permission needed
- * 10 - write permission needed
- * 11 - read/write permissions needed
- * which is a lot more logical, and also allows the "no perm" needed
- * for symlinks (where the permissions are checked later).
- */
- struct dentry * open_namei(const char * pathname, int flag, int mode)
- {
- int acc_mode, error;
- struct inode *inode;
- struct dentry *dentry;
- mode &= S_IALLUGO & ~current->fs->umask;
- mode |= S_IFREG;
- dentry = lookup_dentry(pathname, NULL, lookup_flags(flag));
- if (IS_ERR(dentry))
- return dentry;
- acc_mode = ACC_MODE(flag);
- if (flag & O_CREAT) {
- struct dentry *dir;
- if (dentry->d_inode) {
- if (!(flag & O_EXCL))
- goto nocreate;
- error = -EEXIST;
- goto exit;
- }
- dir = lock_parent(dentry);
- if (!check_parent(dir, dentry)) {
- /*
- * Really nasty race happened. What's the
- * right error code? We had a dentry, but
- * before we could use it it was removed
- * by somebody else. We could just re-try
- * everything, I guess.
- *
- * ENOENT is definitely wrong.
- */
- error = -ENOENT;
- unlock_dir(dir);
- goto exit;
- }
- /*
- * Somebody might have created the file while we
- * waited for the directory lock.. So we have to
- * re-do the existence test.
- */
- if (dentry->d_inode) {
- error = 0;
- if (flag & O_EXCL)
- error = -EEXIST;
- } else if ((error = may_create(dir->d_inode, dentry)) == 0) {
- if (!dir->d_inode->i_op || !dir->d_inode->i_op->create)
- error = -EACCES;
- else {
- DQUOT_INIT(dir->d_inode);
- error = dir->d_inode->i_op->create(dir->d_inode, dentry, mode);
- /* Don't check for write permission, don't truncate */
- acc_mode = 0;
- flag &= ~O_TRUNC;
- }
- }
- unlock_dir(dir);
- if (error)
- goto exit;
- }
- nocreate:
- error = -ENOENT;
- inode = dentry->d_inode;
- if (!inode)
- goto exit;
- error = -ELOOP;
- if (S_ISLNK(inode->i_mode))
- goto exit;
-
- error = -EISDIR;
- if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
- goto exit;
- error = permission(inode,acc_mode);
- if (error)
- goto exit;
- /*
- * FIFO's, sockets and device files are special: they don't
- * actually live on the filesystem itself, and as such you
- * can write to them even if the filesystem is read-only.
- */
- if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
- flag &= ~O_TRUNC;
- } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
- error = -EACCES;
- if (IS_NODEV(inode))
- goto exit;
- flag &= ~O_TRUNC;
- } else {
- error = -EROFS;
- if (IS_RDONLY(inode) && (flag & 2))
- goto exit;
- }
- /*
- * An append-only file must be opened in append mode for writing.
- */
- error = -EPERM;
- if (IS_APPEND(inode)) {
- if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
- goto exit;
- if (flag & O_TRUNC)
- goto exit;
- }
- if (flag & O_TRUNC) {
- error = get_write_access(inode);
- if (error)
- goto exit;
- /*
- * Refuse to truncate files with mandatory locks held on them.
- */
- error = locks_verify_locked(inode);
- if (!error) {
- DQUOT_INIT(inode);
-
- error = do_truncate(dentry, 0);
- }
- put_write_access(inode);
- if (error)
- goto exit;
- } else
- if (flag & FMODE_WRITE)
- DQUOT_INIT(inode);
- return dentry;
- exit:
- dput(dentry);
- return ERR_PTR(error);
- }
- struct dentry * do_mknod(const char * filename, int mode, dev_t dev)
- {
- int error;
- struct dentry *dir;
- struct dentry *dentry, *retval;
- mode &= ~current->fs->umask;
- dentry = lookup_dentry(filename, NULL, LOOKUP_FOLLOW);
- if (IS_ERR(dentry))
- return dentry;
- dir = lock_parent(dentry);
- error = -ENOENT;
- if (!check_parent(dir, dentry))
- goto exit_lock;
- error = may_create(dir->d_inode, dentry);
- if (error)
- goto exit_lock;
- error = -EPERM;
- if (!dir->d_inode->i_op || !dir->d_inode->i_op->mknod)
- goto exit_lock;
- DQUOT_INIT(dir->d_inode);
- error = dir->d_inode->i_op->mknod(dir->d_inode, dentry, mode, dev);
- exit_lock:
- retval = ERR_PTR(error);
- if (!error)
- retval = dget(dentry);
- unlock_dir(dir);
- dput(dentry);
- return retval;
- }
- asmlinkage int sys_mknod(const char * filename, int mode, dev_t dev)
- {
- int error;
- char * tmp;
- lock_kernel();
- error = -EPERM;
- if (S_ISDIR(mode) || (!S_ISFIFO(mode) && !capable(CAP_SYS_ADMIN)))
- goto out;
- error = -EINVAL;
- switch (mode & S_IFMT) {
- case 0:
- mode |= S_IFREG;
- break;
- case S_IFREG: case S_IFCHR: case S_IFBLK: case S_IFIFO: case S_IFSOCK:
- break;
- default:
- goto out;
- }
- tmp = getname(filename);
- error = PTR_ERR(tmp);
- if (!IS_ERR(tmp)) {
- struct dentry * dentry = do_mknod(tmp,mode,dev);
- putname(tmp);
- error = PTR_ERR(dentry);
- if (!IS_ERR(dentry)) {
- dput(dentry);
- error = 0;
- }
- }
- out:
- unlock_kernel();
- return error;
- }
- /*
- * Look out: this function may change a normal dentry
- * into a directory dentry (different size)..
- */
- #ifdef OSKIT
- int do_mkdir(const char * pathname, int mode)
- #else
- static inline int do_mkdir(const char * pathname, int mode)
- #endif
- {
- int error;
- struct dentry *dir;
- struct dentry *dentry;
- dentry = lookup_dentry(pathname, NULL, LOOKUP_SLASHOK);
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry))
- goto exit;
- /*
- * EEXIST is kind of a strange error code to
- * return, but basically if the dentry was moved
- * or unlinked while we locked the parent, we
- * do know that it _did_ exist before, and as
- * such it makes perfect sense.. In contrast,
- * ENOENT doesn't make sense for mkdir.
- */
- dir = lock_parent(dentry);
- error = -EEXIST;
- if (!check_parent(dir, dentry))
- goto exit_lock;
- error = may_create(dir->d_inode, dentry);
- if (error)
- goto exit_lock;
- error = -EPERM;
- if (!dir->d_inode->i_op || !dir->d_inode->i_op->mkdir)
- goto exit_lock;
- DQUOT_INIT(dir->d_inode);
- mode &= 0777 & ~current->fs->umask;
- error = dir->d_inode->i_op->mkdir(dir->d_inode, dentry, mode);
- exit_lock:
- unlock_dir(dir);
- dput(dentry);
- exit:
- return error;
- }
- asmlinkage int sys_mkdir(const char * pathname, int mode)
- {
- int error;
- char * tmp;
- lock_kernel();
- tmp = getname(pathname);
- error = PTR_ERR(tmp);
- if (!IS_ERR(tmp)) {
- error = do_mkdir(tmp,mode);
- putname(tmp);
- }
- unlock_kernel();
- return error;
- }
- int vfs_rmdir(struct inode *dir, struct dentry *dentry)
- {
- int error;
- error = may_delete(dir, dentry, 1);
- if (error)
- return error;
- if (!dir->i_op || !dir->i_op->rmdir)
- return -EPERM;
- DQUOT_INIT(dir);
- /*
- * We try to drop the dentry early: we should have
- * a usage count of 2 if we're the only user of this
- * dentry, and if that is true (possibly after pruning
- * the dcache), then we drop the dentry now.
- *
- * A low-level filesystem can, if it choses, legally
- * do a
- *
- * if (!list_empty(&dentry->d_hash))
- * return -EBUSY;
- *
- * if it cannot handle the case of removing a directory
- * that is still in use by something else..
- */
- switch (dentry->d_count) {
- default:
- shrink_dcache_parent(dentry);
- if (dentry->d_count != 2)
- break;
- case 2:
- d_drop(dentry);
- }
- error = dir->i_op->rmdir(dir, dentry);
- return error;
- }
- #ifdef OSKIT
- int do_rmdir(const char * name)
- #else
- static inline int do_rmdir(const char * name)
- #endif
- {
- int error;
- struct dentry *dir;
- struct dentry *dentry;
- dentry = lookup_dentry(name, NULL, 0);
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry))
- goto exit;
- error = -ENOENT;
- if (!dentry->d_inode)
- goto exit_dput;
- dir = dget(dentry->d_parent);
- /*
- * The dentry->d_count stuff confuses d_delete() enough to
- * not kill the inode from under us while it is locked. This
- * wouldn't be needed, except the dentry semaphore is really
- * in the inode, not in the dentry..
- */
- dentry->d_count++;
- double_lock(dir, dentry);
- error = -ENOENT;
- if (check_parent(dir, dentry))
- error = vfs_rmdir(dir->d_inode, dentry);
- double_unlock(dentry, dir);
- exit_dput:
- dput(dentry);
- exit:
- return error;
- }
- asmlinkage int sys_rmdir(const char * pathname)
- {
- int error;
- char * tmp;
- lock_kernel();
- tmp = getname(pathname);
- error = PTR_ERR(tmp);
- if (!IS_ERR(tmp)) {
- error = do_rmdir(tmp);
- putname(tmp);
- }
- unlock_kernel();
- return error;
- }
- int vfs_unlink(struct inode *dir, struct dentry *dentry)
- {
- int error;
- error = may_delete(dir, dentry, 0);
- if (!error) {
- error = -EPERM;
- if (dir->i_op && dir->i_op->unlink) {
- DQUOT_INIT(dir);
- error = dir->i_op->unlink(dir, dentry);
- }
- }
- return error;
- }
- #ifdef OSKIT
- int do_unlink(const char * name)
- #else
- static inline int do_unlink(const char * name)
- #endif
- {
- int error;
- struct dentry *dir;
- struct dentry *dentry;
- dentry = lookup_dentry(name, NULL, 0);
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry))
- goto exit;
- dir = lock_parent(dentry);
- error = -ENOENT;
- if (check_parent(dir, dentry))
- error = vfs_unlink(dir->d_inode, dentry);
- unlock_dir(dir);
- dput(dentry);
- exit:
- return error;
- }
- asmlinkage int sys_unlink(const char * pathname)
- {
- int error;
- char * tmp;
- lock_kernel();
- tmp = getname(pathname);
- error = PTR_ERR(tmp);
- if (!IS_ERR(tmp)) {
- error = do_unlink(tmp);
- putname(tmp);
- }
- unlock_kernel();
- return error;
- }
- #ifdef OSKIT
- int do_symlink(const char * oldname, const char * newname)
- #else
- static inline int do_symlink(const char * oldname, const char * newname)
- #endif
- {
- int error;
- struct dentry *dir;
- struct dentry *dentry;
- dentry = lookup_dentry(newname, NULL, 0);
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry))
- goto exit;
- dir = lock_parent(dentry);
- error = -ENOENT;
- if (!check_parent(dir, dentry))
- goto exit_lock;
- error = may_create(dir->d_inode, dentry);
- if (error)
- goto exit_lock;
- error = -EPERM;
- if (!dir->d_inode->i_op || !dir->d_inode->i_op->symlink)
- goto exit_lock;
- DQUOT_INIT(dir->d_inode);
- error = dir->d_inode->i_op->symlink(dir->d_inode, dentry, oldname);
- exit_lock:
- unlock_dir(dir);
- dput(dentry);
- exit:
- return error;
- }
- asmlinkage int sys_symlink(const char * oldname, const char * newname)
- {
- int error;
- char * from;
- lock_kernel();
- from = getname(oldname);
- error = PTR_ERR(from);
- if (!IS_ERR(from)) {
- char * to;
- to = getname(newname);
- error = PTR_ERR(to);
- if (!IS_ERR(to)) {
- error = do_symlink(from,to);
- putname(to);
- }
- putname(from);
- }
- unlock_kernel();
- return error;
- }
- #ifdef OSKIT
- int do_link(struct dentry *dentry, const char * newname)
- #else
- static inline int do_link(const char * oldname, const char * newname)
- #endif
- {
- struct dentry *old_dentry, *new_dentry, *dir;
- struct inode *inode;
- int error;
- /*
- * Hardlinks are often used in delicate situations. We avoid
- * security-related surprises by not following symlinks on the
- * newname. --KAB
- *
- * We don't follow them on the oldname either to be compatible
- * with linux 2.0, and to avoid hard-linking to directories
- * and other special files. --ADM
- */
- #ifdef OSKIT
- dget(dentry);
- old_dentry = dentry;
- #else
- old_dentry = lookup_dentry(oldname, NULL, 0);
- #endif
- error = PTR_ERR(old_dentry);
- if (IS_ERR(old_dentry))
- goto exit;
- new_dentry = lookup_dentry(newname, NULL, 0);
- error = PTR_ERR(new_dentry);
- if (IS_ERR(new_dentry))
- goto exit_old;
- dir = lock_parent(new_dentry);
- error = -ENOENT;
- if (!check_parent(dir, new_dentry))
- goto exit_lock;
- error = -ENOENT;
- inode = old_dentry->d_inode;
- if (!inode)
- goto exit_lock;
- error = may_create(dir->d_inode, new_dentry);
- if (error)
- goto exit_lock;
- error = -EXDEV;
- if (dir->d_inode->i_dev != inode->i_dev)
- goto exit_lock;
- /*
- * A link to an append-only or immutable file cannot be created.
- */
- error = -EPERM;
- if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
- goto exit_lock;
- error = -EPERM;
- if (!dir->d_inode->i_op || !dir->d_inode->i_op->link)
- goto exit_lock;
- DQUOT_INIT(dir->d_inode);
- error = dir->d_inode->i_op->link(old_dentry, dir->d_inode, new_dentry);
- exit_lock:
- unlock_dir(dir);
- dput(new_dentry);
- exit_old:
- dput(old_dentry);
- exit:
- return error;
- }
- #ifndef OSKIT
- asmlinkage int sys_link(const char * oldname, const char * newname)
- {
- int error;
- char * from;
- lock_kernel();
- from = getname(oldname);
- error = PTR_ERR(from);
- if (!IS_ERR(from)) {
- char * to;
- to = getname(newname);
- error = PTR_ERR(to);
- if (!IS_ERR(to)) {
- error = do_link(from,to);
- putname(to);
- }
- putname(from);
- }
- unlock_kernel();
- return error;
- }
- #endif
- int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
- {
- int error;
- int need_rehash = 0;
- if (old_dentry->d_inode == new_dentry->d_inode)
- return 0;
- error = may_delete(old_dir, old_dentry, 1);
- if (error)
- return error;
- if (new_dir->i_dev != old_dir->i_dev)
- return -EXDEV;
- if (!new_dentry->d_inode)
- error = may_create(new_dir, new_dentry);
- else
- error = may_delete(new_dir, new_dentry, 1);
- if (error)
- return error;
- if (!old_dir->i_op || !old_dir->i_op->rename)
- return -EPERM;
- /*
- * If we are going to change the parent - check write permissions,
- * we'll need to flip '..'.
- */
- if (new_dir != old_dir) {
- error = permission(old_dentry->d_inode, MAY_WRITE);
- }
- if (error)
- return error;
- DQUOT_INIT(old_dir);
- DQUOT_INIT(new_dir);
- down(&old_dir->i_sb->s_vfs_rename_sem);
- error = -EINVAL;
- if (is_subdir(new_dentry, old_dentry))
- goto out_unlock;
- if (new_dentry->d_inode) {
- error = -EBUSY;
- if (d_invalidate(new_dentry)<0)
- goto out_unlock;
- need_rehash = 1;
- }
- error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
- if (need_rehash)
- d_rehash(new_dentry);
- if (!error)
- d_move(old_dentry,new_dentry);
- out_unlock:
- up(&old_dir->i_sb->s_vfs_rename_sem);
- return error;
- }
- int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
- {
- int error;
- if (old_dentry->d_inode == new_dentry->d_inode)
- return 0;
- error = may_delete(old_dir, old_dentry, 0);
- if (error)
- return error;
- if (new_dir->i_dev != old_dir->i_dev)
- return -EXDEV;
- if (!new_dentry->d_inode)
- error = may_create(new_dir, new_dentry);
- else
- error = may_delete(new_dir, new_dentry, 0);
- if (error)
- return error;
- if (!old_dir->i_op || !old_dir->i_op->rename)
- return -EPERM;
- DQUOT_INIT(old_dir);
- DQUOT_INIT(new_dir);
- error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
- if (error)
- return error;
- /* The following d_move() should become unconditional */
- if (!(old_dir->i_sb->s_flags & MS_ODD_RENAME)) {
- d_move(old_dentry, new_dentry);
- }
- return 0;
- }
- int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
- {
- if (S_ISDIR(old_dentry->d_inode->i_mode))
- return vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
- else
- return vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
- }
- #ifdef OSKIT
- int do_rename(const char * oldname, const char * newname)
- #else
- static inline int do_rename(const char * oldname, const char * newname)
- #endif
- {
- int error;
- struct dentry * old_dir, * new_dir;
- struct dentry * old_dentry, *new_dentry;
- old_dentry = lookup_dentry(oldname, NULL, 0);
- error = PTR_ERR(old_dentry);
- if (IS_ERR(old_dentry))
- goto exit;
- error = -ENOENT;
- if (!old_dentry->d_inode)
- goto exit_old;
- {
- unsigned int flags = 0;
- if (S_ISDIR(old_dentry->d_inode->i_mode))
- flags = LOOKUP_SLASHOK;
- new_dentry = lookup_dentry(newname, NULL, flags);
- }
- error = PTR_ERR(new_dentry);
- if (IS_ERR(new_dentry))
- goto exit_old;
- new_dir = get_parent(new_dentry);
- old_dir = get_parent(old_dentry);
- double_lock(new_dir, old_dir);
- error = -ENOENT;
- if (check_parent(old_dir, old_dentry) && check_parent(new_dir, new_dentry))
- error = vfs_rename(old_dir->d_inode, old_dentry,
- new_dir->d_inode, new_dentry);
- double_unlock(new_dir, old_dir);
- dput(new_dentry);
- exit_old:
- dput(old_dentry);
- exit:
- return error;
- }
- asmlinkage int sys_rename(const char * oldname, const char * newname)
- {
- int error;
- char * from;
- lock_kernel();
- from = getname(oldname);
- error = PTR_ERR(from);
- if (!IS_ERR(from)) {
- char * to;
- to = getname(newname);
- error = PTR_ERR(to);
- if (!IS_ERR(to)) {
- error = do_rename(from,to);
- putname(to);
- }
- putname(from);
- }
- unlock_kernel();
- return error;
- }