| /* |
| * linux/fs/namei.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| /* |
| * Some corrections by tytso. |
| */ |
| |
| /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname |
| * lookup logic. |
| */ |
| /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. |
| */ |
| |
| #include <linux/init.h> |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/fs.h> |
| #include <linux/namei.h> |
| #include <linux/quotaops.h> |
| #include <linux/pagemap.h> |
| #include <linux/fsnotify.h> |
| #include <linux/smp_lock.h> |
| #include <linux/personality.h> |
| #include <linux/security.h> |
| #include <linux/syscalls.h> |
| #include <linux/mount.h> |
| #include <linux/audit.h> |
| #include <asm/namei.h> |
| #include <asm/uaccess.h> |
| |
| #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) |
| |
| /* [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. |
| */ |
| |
| /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: |
| * inside the path - always follow. |
| * in the last component in creation/removal/renaming - never follow. |
| * if LOOKUP_FOLLOW passed - follow. |
| * if the pathname has trailing slashes - follow. |
| * otherwise - don't follow. |
| * (applied in that order). |
| * |
| * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT |
| * restored for 2.4. This is the last surviving part of old 4.2BSD bug. |
| * During the 2.4 we need to fix the userland stuff depending on it - |
| * hopefully we will be able to get rid of that wart in 2.5. So far only |
| * XEmacs seems to be relying on it... |
| */ |
| /* |
| * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) |
| * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives |
| * any extra contention... |
| */ |
| |
| /* 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). |
| * PATH_MAX includes the nul terminator --RR. |
| */ |
| static inline int do_getname(const char __user *filename, char *page) |
| { |
| int retval; |
| unsigned long len = PATH_MAX; |
| |
| if (!segment_eq(get_fs(), KERNEL_DS)) { |
| if ((unsigned long) filename >= TASK_SIZE) |
| return -EFAULT; |
| if (TASK_SIZE - (unsigned long) filename < PATH_MAX) |
| len = TASK_SIZE - (unsigned long) filename; |
| } |
| |
| retval = strncpy_from_user(page, filename, len); |
| if (retval > 0) { |
| if (retval < len) |
| return 0; |
| return -ENAMETOOLONG; |
| } else if (!retval) |
| retval = -ENOENT; |
| return retval; |
| } |
| |
| char * getname(const char __user * filename) |
| { |
| 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); |
| } |
| } |
| audit_getname(result); |
| return result; |
| } |
| |
| #ifdef CONFIG_AUDITSYSCALL |
| void putname(const char *name) |
| { |
| if (unlikely(current->audit_context)) |
| audit_putname(name); |
| else |
| __putname(name); |
| } |
| EXPORT_SYMBOL(putname); |
| #endif |
| |
| |
| /** |
| * generic_permission - check for access rights on a Posix-like filesystem |
| * @inode: inode to check access rights for |
| * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
| * @check_acl: optional callback to check for Posix ACLs |
| * |
| * 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 generic_permission(struct inode *inode, int mask, |
| int (*check_acl)(struct inode *inode, int mask)) |
| { |
| umode_t mode = inode->i_mode; |
| |
| if (current->fsuid == inode->i_uid) |
| mode >>= 6; |
| else { |
| if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { |
| int error = check_acl(inode, mask); |
| if (error == -EACCES) |
| goto check_capabilities; |
| else if (error != -EAGAIN) |
| return error; |
| } |
| |
| if (in_group_p(inode->i_gid)) |
| mode >>= 3; |
| } |
| |
| /* |
| * If the DACs are ok we don't need any capability check. |
| */ |
| if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)) |
| return 0; |
| |
| check_capabilities: |
| /* |
| * Read/write DACs are always overridable. |
| * Executable DACs are overridable if at least one exec bit is set. |
| */ |
| if (!(mask & MAY_EXEC) || |
| (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) |
| if (capable(CAP_DAC_OVERRIDE)) |
| return 0; |
| |
| /* |
| * Searching includes executable on directories, else just read. |
| */ |
| if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) |
| if (capable(CAP_DAC_READ_SEARCH)) |
| return 0; |
| |
| return -EACCES; |
| } |
| |
| int permission(struct inode *inode, int mask, struct nameidata *nd) |
| { |
| int retval, submask; |
| |
| if (mask & MAY_WRITE) { |
| umode_t mode = inode->i_mode; |
| |
| /* |
| * Nobody gets write access to a read-only fs. |
| */ |
| if (IS_RDONLY(inode) && |
| (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) |
| return -EROFS; |
| |
| /* |
| * Nobody gets write access to an immutable file. |
| */ |
| if (IS_IMMUTABLE(inode)) |
| return -EACCES; |
| } |
| |
| |
| /* Ordinary permission routines do not understand MAY_APPEND. */ |
| submask = mask & ~MAY_APPEND; |
| if (inode->i_op && inode->i_op->permission) |
| retval = inode->i_op->permission(inode, submask, nd); |
| else |
| retval = generic_permission(inode, submask, NULL); |
| if (retval) |
| return retval; |
| |
| return security_inode_permission(inode, mask, nd); |
| } |
| |
| /* |
| * 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. |
| * |
| * Normally we operate on that counter with atomic_{inc,dec} and it's safe |
| * except for the cases where we don't hold i_writecount yet. Then we need to |
| * use {get,deny}_write_access() - these functions check the sign and refuse |
| * to do the change if sign is wrong. Exclusion between them is provided by |
| * the inode->i_lock spinlock. |
| */ |
| |
| int get_write_access(struct inode * inode) |
| { |
| spin_lock(&inode->i_lock); |
| if (atomic_read(&inode->i_writecount) < 0) { |
| spin_unlock(&inode->i_lock); |
| return -ETXTBSY; |
| } |
| atomic_inc(&inode->i_writecount); |
| spin_unlock(&inode->i_lock); |
| |
| return 0; |
| } |
| |
| int deny_write_access(struct file * file) |
| { |
| struct inode *inode = file->f_dentry->d_inode; |
| |
| spin_lock(&inode->i_lock); |
| if (atomic_read(&inode->i_writecount) > 0) { |
| spin_unlock(&inode->i_lock); |
| return -ETXTBSY; |
| } |
| atomic_dec(&inode->i_writecount); |
| spin_unlock(&inode->i_lock); |
| |
| return 0; |
| } |
| |
| void path_release(struct nameidata *nd) |
| { |
| dput(nd->dentry); |
| mntput(nd->mnt); |
| } |
| |
| /* |
| * umount() mustn't call path_release()/mntput() as that would clear |
| * mnt_expiry_mark |
| */ |
| void path_release_on_umount(struct nameidata *nd) |
| { |
| dput(nd->dentry); |
| mntput_no_expire(nd->mnt); |
| } |
| |
| /* |
| * Internal lookup() using the new generic dcache. |
| * SMP-safe |
| */ |
| static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) |
| { |
| struct dentry * dentry = __d_lookup(parent, name); |
| |
| /* lockess __d_lookup may fail due to concurrent d_move() |
| * in some unrelated directory, so try with d_lookup |
| */ |
| if (!dentry) |
| dentry = d_lookup(parent, name); |
| |
| if (dentry && dentry->d_op && dentry->d_op->d_revalidate) { |
| if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) { |
| dput(dentry); |
| dentry = NULL; |
| } |
| } |
| return dentry; |
| } |
| |
| /* |
| * Short-cut version of permission(), for calling by |
| * path_walk(), when dcache lock is held. Combines parts |
| * of permission() and generic_permission(), and tests ONLY for |
| * MAY_EXEC permission. |
| * |
| * If appropriate, check DAC only. If not appropriate, or |
| * short-cut DAC fails, then call permission() to do more |
| * complete permission check. |
| */ |
| static inline int exec_permission_lite(struct inode *inode, |
| struct nameidata *nd) |
| { |
| umode_t mode = inode->i_mode; |
| |
| if (inode->i_op && inode->i_op->permission) |
| return -EAGAIN; |
| |
| if (current->fsuid == inode->i_uid) |
| mode >>= 6; |
| else if (in_group_p(inode->i_gid)) |
| mode >>= 3; |
| |
| if (mode & MAY_EXEC) |
| goto ok; |
| |
| if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) |
| goto ok; |
| |
| if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) |
| goto ok; |
| |
| if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) |
| goto ok; |
| |
| return -EACCES; |
| ok: |
| return security_inode_permission(inode, MAY_EXEC, nd); |
| } |
| |
| /* |
| * 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.. |
| * SMP-safe |
| */ |
| static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) |
| { |
| 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. |
| * |
| * The "dcache_lock" is purely to protect the RCU list walker |
| * from concurrent renames at this point (we mustn't get false |
| * negatives from the RCU list walk here, unlike the optimistic |
| * fast walk). |
| * |
| * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup |
| */ |
| result = d_lookup(parent, name); |
| if (!result) { |
| struct dentry * dentry = d_alloc(parent, name); |
| result = ERR_PTR(-ENOMEM); |
| if (dentry) { |
| result = dir->i_op->lookup(dir, dentry, nd); |
| if (result) |
| dput(dentry); |
| else |
| result = dentry; |
| } |
| up(&dir->i_sem); |
| return result; |
| } |
| |
| /* |
| * Uhhuh! Nasty case: the cache was re-populated while |
| * we waited on the semaphore. Need to revalidate. |
| */ |
| up(&dir->i_sem); |
| if (result->d_op && result->d_op->d_revalidate) { |
| if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) { |
| dput(result); |
| result = ERR_PTR(-ENOENT); |
| } |
| } |
| return result; |
| } |
| |
| static int __emul_lookup_dentry(const char *, struct nameidata *); |
| |
| /* SMP-safe */ |
| static inline int |
| walk_init_root(const char *name, struct nameidata *nd) |
| { |
| read_lock(¤t->fs->lock); |
| if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { |
| nd->mnt = mntget(current->fs->altrootmnt); |
| nd->dentry = dget(current->fs->altroot); |
| read_unlock(¤t->fs->lock); |
| if (__emul_lookup_dentry(name,nd)) |
| return 0; |
| read_lock(¤t->fs->lock); |
| } |
| nd->mnt = mntget(current->fs->rootmnt); |
| nd->dentry = dget(current->fs->root); |
| read_unlock(¤t->fs->lock); |
| return 1; |
| } |
| |
| static inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
| { |
| int res = 0; |
| char *name; |
| if (IS_ERR(link)) |
| goto fail; |
| |
| if (*link == '/') { |
| path_release(nd); |
| if (!walk_init_root(link, nd)) |
| /* weird __emul_prefix() stuff did it */ |
| goto out; |
| } |
| res = link_path_walk(link, nd); |
| out: |
| if (nd->depth || res || nd->last_type!=LAST_NORM) |
| return res; |
| /* |
| * If it is an iterative symlinks resolution in open_namei() we |
| * have to copy the last component. And all that crap because of |
| * bloody create() on broken symlinks. Furrfu... |
| */ |
| name = __getname(); |
| if (unlikely(!name)) { |
| path_release(nd); |
| return -ENOMEM; |
| } |
| strcpy(name, nd->last.name); |
| nd->last.name = name; |
| return 0; |
| fail: |
| path_release(nd); |
| return PTR_ERR(link); |
| } |
| |
| struct path { |
| struct vfsmount *mnt; |
| struct dentry *dentry; |
| }; |
| |
| static inline int __do_follow_link(struct path *path, struct nameidata *nd) |
| { |
| int error; |
| void *cookie; |
| struct dentry *dentry = path->dentry; |
| |
| touch_atime(path->mnt, dentry); |
| nd_set_link(nd, NULL); |
| |
| if (path->mnt == nd->mnt) |
| mntget(path->mnt); |
| cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
| error = PTR_ERR(cookie); |
| if (!IS_ERR(cookie)) { |
| char *s = nd_get_link(nd); |
| error = 0; |
| if (s) |
| error = __vfs_follow_link(nd, s); |
| if (dentry->d_inode->i_op->put_link) |
| dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
| } |
| dput(dentry); |
| mntput(path->mnt); |
| |
| return error; |
| } |
| |
| static inline void dput_path(struct path *path, struct nameidata *nd) |
| { |
| dput(path->dentry); |
| if (path->mnt != nd->mnt) |
| mntput(path->mnt); |
| } |
| |
| static inline void path_to_nameidata(struct path *path, struct nameidata *nd) |
| { |
| dput(nd->dentry); |
| if (nd->mnt != path->mnt) |
| mntput(nd->mnt); |
| nd->mnt = path->mnt; |
| nd->dentry = path->dentry; |
| } |
| |
| /* |
| * This limits recursive symlink follows to 8, while |
| * limiting consecutive symlinks to 40. |
| * |
| * Without that kind of total limit, nasty chains of consecutive |
| * symlinks can cause almost arbitrarily long lookups. |
| */ |
| static inline int do_follow_link(struct path *path, struct nameidata *nd) |
| { |
| int err = -ELOOP; |
| if (current->link_count >= MAX_NESTED_LINKS) |
| goto loop; |
| if (current->total_link_count >= 40) |
| goto loop; |
| BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
| cond_resched(); |
| err = security_inode_follow_link(path->dentry, nd); |
| if (err) |
| goto loop; |
| current->link_count++; |
| current->total_link_count++; |
| nd->depth++; |
| err = __do_follow_link(path, nd); |
| current->link_count--; |
| nd->depth--; |
| return err; |
| loop: |
| dput_path(path, nd); |
| path_release(nd); |
| return err; |
| } |
| |
| int follow_up(struct vfsmount **mnt, struct dentry **dentry) |
| { |
| struct vfsmount *parent; |
| struct dentry *mountpoint; |
| spin_lock(&vfsmount_lock); |
| parent=(*mnt)->mnt_parent; |
| if (parent == *mnt) { |
| spin_unlock(&vfsmount_lock); |
| return 0; |
| } |
| mntget(parent); |
| mountpoint=dget((*mnt)->mnt_mountpoint); |
| spin_unlock(&vfsmount_lock); |
| dput(*dentry); |
| *dentry = mountpoint; |
| mntput(*mnt); |
| *mnt = parent; |
| return 1; |
| } |
| |
| /* no need for dcache_lock, as serialization is taken care in |
| * namespace.c |
| */ |
| static int __follow_mount(struct path *path) |
| { |
| int res = 0; |
| while (d_mountpoint(path->dentry)) { |
| struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); |
| if (!mounted) |
| break; |
| dput(path->dentry); |
| if (res) |
| mntput(path->mnt); |
| path->mnt = mounted; |
| path->dentry = dget(mounted->mnt_root); |
| res = 1; |
| } |
| return res; |
| } |
| |
| static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) |
| { |
| while (d_mountpoint(*dentry)) { |
| struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); |
| if (!mounted) |
| break; |
| dput(*dentry); |
| mntput(*mnt); |
| *mnt = mounted; |
| *dentry = dget(mounted->mnt_root); |
| } |
| } |
| |
| /* no need for dcache_lock, as serialization is taken care in |
| * namespace.c |
| */ |
| int follow_down(struct vfsmount **mnt, struct dentry **dentry) |
| { |
| struct vfsmount *mounted; |
| |
| mounted = lookup_mnt(*mnt, *dentry); |
| if (mounted) { |
| dput(*dentry); |
| mntput(*mnt); |
| *mnt = mounted; |
| *dentry = dget(mounted->mnt_root); |
| return 1; |
| } |
| return 0; |
| } |
| |
| static inline void follow_dotdot(struct nameidata *nd) |
| { |
| while(1) { |
| struct vfsmount *parent; |
| struct dentry *old = nd->dentry; |
| |
| read_lock(¤t->fs->lock); |
| if (nd->dentry == current->fs->root && |
| nd->mnt == current->fs->rootmnt) { |
| read_unlock(¤t->fs->lock); |
| break; |
| } |
| read_unlock(¤t->fs->lock); |
| spin_lock(&dcache_lock); |
| if (nd->dentry != nd->mnt->mnt_root) { |
| nd->dentry = dget(nd->dentry->d_parent); |
| spin_unlock(&dcache_lock); |
| dput(old); |
| break; |
| } |
| spin_unlock(&dcache_lock); |
| spin_lock(&vfsmount_lock); |
| parent = nd->mnt->mnt_parent; |
| if (parent == nd->mnt) { |
| spin_unlock(&vfsmount_lock); |
| break; |
| } |
| mntget(parent); |
| nd->dentry = dget(nd->mnt->mnt_mountpoint); |
| spin_unlock(&vfsmount_lock); |
| dput(old); |
| mntput(nd->mnt); |
| nd->mnt = parent; |
| } |
| follow_mount(&nd->mnt, &nd->dentry); |
| } |
| |
| /* |
| * It's more convoluted than I'd like it to be, but... it's still fairly |
| * small and for now I'd prefer to have fast path as straight as possible. |
| * It _is_ time-critical. |
| */ |
| static int do_lookup(struct nameidata *nd, struct qstr *name, |
| struct path *path) |
| { |
| struct vfsmount *mnt = nd->mnt; |
| struct dentry *dentry = __d_lookup(nd->dentry, name); |
| |
| if (!dentry) |
| goto need_lookup; |
| if (dentry->d_op && dentry->d_op->d_revalidate) |
| goto need_revalidate; |
| done: |
| path->mnt = mnt; |
| path->dentry = dentry; |
| __follow_mount(path); |
| return 0; |
| |
| need_lookup: |
| dentry = real_lookup(nd->dentry, name, nd); |
| if (IS_ERR(dentry)) |
| goto fail; |
| goto done; |
| |
| need_revalidate: |
| if (dentry->d_op->d_revalidate(dentry, nd)) |
| goto done; |
| if (d_invalidate(dentry)) |
| goto done; |
| dput(dentry); |
| goto need_lookup; |
| |
| fail: |
| return PTR_ERR(dentry); |
| } |
| |
| /* |
| * Name resolution. |
| * This is the basic name resolution function, turning a pathname into |
| * the final dentry. We expect 'base' to be positive and a directory. |
| * |
| * Returns 0 and nd will have valid dentry and mnt on success. |
| * Returns error and drops reference to input namei data on failure. |
| */ |
| static fastcall int __link_path_walk(const char * name, struct nameidata *nd) |
| { |
| struct path next; |
| struct inode *inode; |
| int err; |
| unsigned int lookup_flags = nd->flags; |
| |
| while (*name=='/') |
| name++; |
| if (!*name) |
| goto return_reval; |
| |
| inode = nd->dentry->d_inode; |
| if (nd->depth) |
| lookup_flags = LOOKUP_FOLLOW; |
| |
| /* At this point we know we have a real path component. */ |
| for(;;) { |
| unsigned long hash; |
| struct qstr this; |
| unsigned int c; |
| |
| err = exec_permission_lite(inode, nd); |
| if (err == -EAGAIN) { |
| err = permission(inode, MAY_EXEC, nd); |
| } |
| 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? */ |
| if (!c) |
| goto last_component; |
| while (*++name == '/'); |
| if (!*name) |
| goto last_with_slashes; |
| |
| /* |
| * "." and ".." are special - ".." especially so because it has |
| * to be able to know about the current root directory and |
| * parent relationships. |
| */ |
| if (this.name[0] == '.') switch (this.len) { |
| default: |
| break; |
| case 2: |
| if (this.name[1] != '.') |
| break; |
| follow_dotdot(nd); |
| inode = nd->dentry->d_inode; |
| /* fallthrough */ |
| case 1: |
| continue; |
| } |
| /* |
| * See if the low-level filesystem might want |
| * to use its own hash.. |
| */ |
| if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { |
| err = nd->dentry->d_op->d_hash(nd->dentry, &this); |
| if (err < 0) |
| break; |
| } |
| nd->flags |= LOOKUP_CONTINUE; |
| /* This does the actual lookups.. */ |
| err = do_lookup(nd, &this, &next); |
| if (err) |
| break; |
| |
| err = -ENOENT; |
| inode = next.dentry->d_inode; |
| if (!inode) |
| goto out_dput; |
| err = -ENOTDIR; |
| if (!inode->i_op) |
| goto out_dput; |
| |
| if (inode->i_op->follow_link) { |
| err = do_follow_link(&next, nd); |
| if (err) |
| goto return_err; |
| err = -ENOENT; |
| inode = nd->dentry->d_inode; |
| if (!inode) |
| break; |
| err = -ENOTDIR; |
| if (!inode->i_op) |
| break; |
| } else |
| path_to_nameidata(&next, nd); |
| err = -ENOTDIR; |
| if (!inode->i_op->lookup) |
| break; |
| continue; |
| /* here ends the main loop */ |
| |
| last_with_slashes: |
| lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
| last_component: |
| nd->flags &= ~LOOKUP_CONTINUE; |
| if (lookup_flags & LOOKUP_PARENT) |
| goto lookup_parent; |
| if (this.name[0] == '.') switch (this.len) { |
| default: |
| break; |
| case 2: |
| if (this.name[1] != '.') |
| break; |
| follow_dotdot(nd); |
| inode = nd->dentry->d_inode; |
| /* fallthrough */ |
| case 1: |
| goto return_reval; |
| } |
| if (nd->dentry->d_op && nd->dentry->d_op->d_hash) { |
| err = nd->dentry->d_op->d_hash(nd->dentry, &this); |
| if (err < 0) |
| break; |
| } |
| err = do_lookup(nd, &this, &next); |
| if (err) |
| break; |
| inode = next.dentry->d_inode; |
| if ((lookup_flags & LOOKUP_FOLLOW) |
| && inode && inode->i_op && inode->i_op->follow_link) { |
| err = do_follow_link(&next, nd); |
| if (err) |
| goto return_err; |
| inode = nd->dentry->d_inode; |
| } else |
| path_to_nameidata(&next, nd); |
| err = -ENOENT; |
| if (!inode) |
| break; |
| if (lookup_flags & LOOKUP_DIRECTORY) { |
| err = -ENOTDIR; |
| if (!inode->i_op || !inode->i_op->lookup) |
| break; |
| } |
| goto return_base; |
| lookup_parent: |
| nd->last = this; |
| nd->last_type = LAST_NORM; |
| if (this.name[0] != '.') |
| goto return_base; |
| if (this.len == 1) |
| nd->last_type = LAST_DOT; |
| else if (this.len == 2 && this.name[1] == '.') |
| nd->last_type = LAST_DOTDOT; |
| else |
| goto return_base; |
| return_reval: |
| /* |
| * We bypassed the ordinary revalidation routines. |
| * We may need to check the cached dentry for staleness. |
| */ |
| if (nd->dentry && nd->dentry->d_sb && |
| (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { |
| err = -ESTALE; |
| /* Note: we do not d_invalidate() */ |
| if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd)) |
| break; |
| } |
| return_base: |
| return 0; |
| out_dput: |
| dput_path(&next, nd); |
| break; |
| } |
| path_release(nd); |
| return_err: |
| return err; |
| } |
| |
| /* |
| * Wrapper to retry pathname resolution whenever the underlying |
| * file system returns an ESTALE. |
| * |
| * Retry the whole path once, forcing real lookup requests |
| * instead of relying on the dcache. |
| */ |
| int fastcall link_path_walk(const char *name, struct nameidata *nd) |
| { |
| struct nameidata save = *nd; |
| int result; |
| |
| /* make sure the stuff we saved doesn't go away */ |
| dget(save.dentry); |
| mntget(save.mnt); |
| |
| result = __link_path_walk(name, nd); |
| if (result == -ESTALE) { |
| *nd = save; |
| dget(nd->dentry); |
| mntget(nd->mnt); |
| nd->flags |= LOOKUP_REVAL; |
| result = __link_path_walk(name, nd); |
| } |
| |
| dput(save.dentry); |
| mntput(save.mnt); |
| |
| return result; |
| } |
| |
| int fastcall path_walk(const char * name, struct nameidata *nd) |
| { |
| current->total_link_count = 0; |
| return link_path_walk(name, nd); |
| } |
| |
| /* |
| * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if |
| * everything is done. Returns 0 and drops input nd, if lookup failed; |
| */ |
| static int __emul_lookup_dentry(const char *name, struct nameidata *nd) |
| { |
| if (path_walk(name, nd)) |
| return 0; /* something went wrong... */ |
| |
| if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) { |
| struct dentry *old_dentry = nd->dentry; |
| struct vfsmount *old_mnt = nd->mnt; |
| struct qstr last = nd->last; |
| int last_type = nd->last_type; |
| /* |
| * NAME was not found in alternate root or it's a directory. Try to find |
| * it in the normal root: |
| */ |
| nd->last_type = LAST_ROOT; |
| read_lock(¤t->fs->lock); |
| nd->mnt = mntget(current->fs->rootmnt); |
| nd->dentry = dget(current->fs->root); |
| read_unlock(¤t->fs->lock); |
| if (path_walk(name, nd) == 0) { |
| if (nd->dentry->d_inode) { |
| dput(old_dentry); |
| mntput(old_mnt); |
| return 1; |
| } |
| path_release(nd); |
| } |
| nd->dentry = old_dentry; |
| nd->mnt = old_mnt; |
| nd->last = last; |
| nd->last_type = last_type; |
| } |
| return 1; |
| } |
| |
| void set_fs_altroot(void) |
| { |
| char *emul = __emul_prefix(); |
| struct nameidata nd; |
| struct vfsmount *mnt = NULL, *oldmnt; |
| struct dentry *dentry = NULL, *olddentry; |
| int err; |
| |
| if (!emul) |
| goto set_it; |
| err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd); |
| if (!err) { |
| mnt = nd.mnt; |
| dentry = nd.dentry; |
| } |
| set_it: |
| write_lock(¤t->fs->lock); |
| oldmnt = current->fs->altrootmnt; |
| olddentry = current->fs->altroot; |
| current->fs->altrootmnt = mnt; |
| current->fs->altroot = dentry; |
| write_unlock(¤t->fs->lock); |
| if (olddentry) { |
| dput(olddentry); |
| mntput(oldmnt); |
| } |
| } |
| |
| /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
| int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd) |
| { |
| int retval = 0; |
| |
| nd->last_type = LAST_ROOT; /* if there are only slashes... */ |
| nd->flags = flags; |
| nd->depth = 0; |
| |
| read_lock(¤t->fs->lock); |
| if (*name=='/') { |
| if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) { |
| nd->mnt = mntget(current->fs->altrootmnt); |
| nd->dentry = dget(current->fs->altroot); |
| read_unlock(¤t->fs->lock); |
| if (__emul_lookup_dentry(name,nd)) |
| goto out; /* found in altroot */ |
| read_lock(¤t->fs->lock); |
| } |
| nd->mnt = mntget(current->fs->rootmnt); |
| nd->dentry = dget(current->fs->root); |
| } else { |
| nd->mnt = mntget(current->fs->pwdmnt); |
| nd->dentry = dget(current->fs->pwd); |
| } |
| read_unlock(¤t->fs->lock); |
| current->total_link_count = 0; |
| retval = link_path_walk(name, nd); |
| out: |
| if (unlikely(current->audit_context |
| && nd && nd->dentry && nd->dentry->d_inode)) |
| audit_inode(name, nd->dentry->d_inode); |
| return retval; |
| } |
| |
| /* |
| * Restricted form of lookup. Doesn't follow links, single-component only, |
| * needs parent already locked. Doesn't follow mounts. |
| * SMP-safe. |
| */ |
| static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd) |
| { |
| struct dentry * dentry; |
| struct inode *inode; |
| int err; |
| |
| inode = base->d_inode; |
| err = permission(inode, MAY_EXEC, nd); |
| dentry = ERR_PTR(err); |
| if (err) |
| goto out; |
| |
| /* |
| * See if the low-level filesystem might want |
| * to use its own hash.. |
| */ |
| if (base->d_op && base->d_op->d_hash) { |
| err = base->d_op->d_hash(base, name); |
| dentry = ERR_PTR(err); |
| if (err < 0) |
| goto out; |
| } |
| |
| dentry = cached_lookup(base, name, nd); |
| if (!dentry) { |
| struct dentry *new = d_alloc(base, name); |
| dentry = ERR_PTR(-ENOMEM); |
| if (!new) |
| goto out; |
| dentry = inode->i_op->lookup(inode, new, nd); |
| if (!dentry) |
| dentry = new; |
| else |
| dput(new); |
| } |
| out: |
| return dentry; |
| } |
| |
| struct dentry * lookup_hash(struct qstr *name, struct dentry * base) |
| { |
| return __lookup_hash(name, base, NULL); |
| } |
| |
| /* SMP-safe */ |
| struct dentry * lookup_one_len(const char * name, struct dentry * base, int len) |
| { |
| unsigned long hash; |
| struct qstr this; |
| unsigned int c; |
| |
| this.name = name; |
| this.len = len; |
| if (!len) |
| goto access; |
| |
| hash = init_name_hash(); |
| while (len--) { |
| c = *(const unsigned char *)name++; |
| if (c == '/' || c == '\0') |
| goto access; |
| hash = partial_name_hash(c, hash); |
| } |
| this.hash = end_name_hash(hash); |
| |
| return lookup_hash(&this, base); |
| access: |
| return ERR_PTR(-EACCES); |
| } |
| |
| /* |
| * 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. |
| * SMP-safe |
| */ |
| int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd) |
| { |
| char *tmp = getname(name); |
| int err = PTR_ERR(tmp); |
| |
| if (!IS_ERR(tmp)) { |
| err = path_lookup(tmp, flags, nd); |
| putname(tmp); |
| } |
| return err; |
| } |
| |
| /* |
| * 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. |
| * 10. We don't allow removal of NFS sillyrenamed files; it's handled by |
| * nfs_async_unlink(). |
| */ |
| static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
| { |
| int error; |
| |
| if (!victim->d_inode) |
| return -ENOENT; |
| |
| BUG_ON(victim->d_parent->d_inode != dir); |
| |
| error = permission(dir,MAY_WRITE | MAY_EXEC, NULL); |
| 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; |
| } else if (S_ISDIR(victim->d_inode->i_mode)) |
| return -EISDIR; |
| if (IS_DEADDIR(dir)) |
| return -ENOENT; |
| if (victim->d_flags & DCACHE_NFSFS_RENAMED) |
| return -EBUSY; |
| 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, |
| struct nameidata *nd) |
| { |
| if (child->d_inode) |
| return -EEXIST; |
| if (IS_DEADDIR(dir)) |
| return -ENOENT; |
| return permission(dir,MAY_WRITE | MAY_EXEC, nd); |
| } |
| |
| /* |
| * 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; |
| } |
| |
| /* |
| * p1 and p2 should be directories on the same fs. |
| */ |
| struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) |
| { |
| struct dentry *p; |
| |
| if (p1 == p2) { |
| down(&p1->d_inode->i_sem); |
| return NULL; |
| } |
| |
| down(&p1->d_inode->i_sb->s_vfs_rename_sem); |
| |
| for (p = p1; p->d_parent != p; p = p->d_parent) { |
| if (p->d_parent == p2) { |
| down(&p2->d_inode->i_sem); |
| down(&p1->d_inode->i_sem); |
| return p; |
| } |
| } |
| |
| for (p = p2; p->d_parent != p; p = p->d_parent) { |
| if (p->d_parent == p1) { |
| down(&p1->d_inode->i_sem); |
| down(&p2->d_inode->i_sem); |
| return p; |
| } |
| } |
| |
| down(&p1->d_inode->i_sem); |
| down(&p2->d_inode->i_sem); |
| return NULL; |
| } |
| |
| void unlock_rename(struct dentry *p1, struct dentry *p2) |
| { |
| up(&p1->d_inode->i_sem); |
| if (p1 != p2) { |
| up(&p2->d_inode->i_sem); |
| up(&p1->d_inode->i_sb->s_vfs_rename_sem); |
| } |
| } |
| |
| int vfs_create(struct inode *dir, struct dentry *dentry, int mode, |
| struct nameidata *nd) |
| { |
| int error = may_create(dir, dentry, nd); |
| |
| if (error) |
| return error; |
| |
| if (!dir->i_op || !dir->i_op->create) |
| return -EACCES; /* shouldn't it be ENOSYS? */ |
| mode &= S_IALLUGO; |
| mode |= S_IFREG; |
| error = security_inode_create(dir, dentry, mode); |
| if (error) |
| return error; |
| DQUOT_INIT(dir); |
| error = dir->i_op->create(dir, dentry, mode, nd); |
| if (!error) |
| fsnotify_create(dir, dentry->d_name.name); |
| return error; |
| } |
| |
| int may_open(struct nameidata *nd, int acc_mode, int flag) |
| { |
| struct dentry *dentry = nd->dentry; |
| struct inode *inode = dentry->d_inode; |
| int error; |
| |
| if (!inode) |
| return -ENOENT; |
| |
| if (S_ISLNK(inode->i_mode)) |
| return -ELOOP; |
| |
| if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) |
| return -EISDIR; |
| |
| error = permission(inode, acc_mode, nd); |
| if (error) |
| return error; |
| |
| /* |
| * 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)) { |
| if (nd->mnt->mnt_flags & MNT_NODEV) |
| return -EACCES; |
| |
| flag &= ~O_TRUNC; |
| } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) |
| return -EROFS; |
| /* |
| * An append-only file must be opened in append mode for writing. |
| */ |
| if (IS_APPEND(inode)) { |
| if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) |
| return -EPERM; |
| if (flag & O_TRUNC) |
| return -EPERM; |
| } |
| |
| /* O_NOATIME can only be set by the owner or superuser */ |
| if (flag & O_NOATIME) |
| if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) |
| return -EPERM; |
| |
| /* |
| * Ensure there are no outstanding leases on the file. |
| */ |
| error = break_lease(inode, flag); |
| if (error) |
| return error; |
| |
| if (flag & O_TRUNC) { |
| error = get_write_access(inode); |
| if (error) |
| return error; |
| |
| /* |
| * 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) |
| return error; |
| } else |
| if (flag & FMODE_WRITE) |
| DQUOT_INIT(inode); |
| |
| return 0; |
| } |
| |
| /* |
| * 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). |
| * SMP-safe |
| */ |
| int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) |
| { |
| int acc_mode, error = 0; |
| struct path path; |
| struct dentry *dir; |
| int count = 0; |
| |
| acc_mode = ACC_MODE(flag); |
| |
| /* Allow the LSM permission hook to distinguish append |
| access from general write access. */ |
| if (flag & O_APPEND) |
| acc_mode |= MAY_APPEND; |
| |
| /* Fill in the open() intent data */ |
| nd->intent.open.flags = flag; |
| nd->intent.open.create_mode = mode; |
| |
| /* |
| * The simplest case - just a plain lookup. |
| */ |
| if (!(flag & O_CREAT)) { |
| error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd); |
| if (error) |
| return error; |
| goto ok; |
| } |
| |
| /* |
| * Create - we need to know the parent. |
| */ |
| error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd); |
| if (error) |
| return error; |
| |
| /* |
| * We have the parent and last component. First of all, check |
| * that we are not asked to creat(2) an obvious directory - that |
| * will not do. |
| */ |
| error = -EISDIR; |
| if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len]) |
| goto exit; |
| |
| dir = nd->dentry; |
| nd->flags &= ~LOOKUP_PARENT; |
| down(&dir->d_inode->i_sem); |
| path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); |
| path.mnt = nd->mnt; |
| |
| do_last: |
| error = PTR_ERR(path.dentry); |
| if (IS_ERR(path.dentry)) { |
| up(&dir->d_inode->i_sem); |
| goto exit; |
| } |
| |
| /* Negative dentry, just create the file */ |
| if (!path.dentry->d_inode) { |
| if (!IS_POSIXACL(dir->d_inode)) |
| mode &= ~current->fs->umask; |
| error = vfs_create(dir->d_inode, path.dentry, mode, nd); |
| up(&dir->d_inode->i_sem); |
| dput(nd->dentry); |
| nd->dentry = path.dentry; |
| if (error) |
| goto exit; |
| /* Don't check for write permission, don't truncate */ |
| acc_mode = 0; |
| flag &= ~O_TRUNC; |
| goto ok; |
| } |
| |
| /* |
| * It already exists. |
| */ |
| up(&dir->d_inode->i_sem); |
| |
| error = -EEXIST; |
| if (flag & O_EXCL) |
| goto exit_dput; |
| |
| if (__follow_mount(&path)) { |
| error = -ELOOP; |
| if (flag & O_NOFOLLOW) |
| goto exit_dput; |
| } |
| error = -ENOENT; |
| if (!path.dentry->d_inode) |
| goto exit_dput; |
| if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) |
| goto do_link; |
| |
| path_to_nameidata(&path, nd); |
| error = -EISDIR; |
| if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) |
| goto exit; |
| ok: |
| error = may_open(nd, acc_mode, flag); |
| if (error) |
| goto exit; |
| return 0; |
| |
| exit_dput: |
| dput_path(&path, nd); |
| exit: |
| path_release(nd); |
| return error; |
| |
| do_link: |
| error = -ELOOP; |
| if (flag & O_NOFOLLOW) |
| goto exit_dput; |
| /* |
| * This is subtle. Instead of calling do_follow_link() we do the |
| * thing by hands. The reason is that this way we have zero link_count |
| * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. |
| * After that we have the parent and last component, i.e. |
| * we are in the same situation as after the first path_walk(). |
| * Well, almost - if the last component is normal we get its copy |
| * stored in nd->last.name and we will have to putname() it when we |
| * are done. Procfs-like symlinks just set LAST_BIND. |
| */ |
| nd->flags |= LOOKUP_PARENT; |
| error = security_inode_follow_link(path.dentry, nd); |
| if (error) |
| goto exit_dput; |
| error = __do_follow_link(&path, nd); |
| if (error) |
| return error; |
| nd->flags &= ~LOOKUP_PARENT; |
| if (nd->last_type == LAST_BIND) |
| goto ok; |
| error = -EISDIR; |
| if (nd->last_type != LAST_NORM) |
| goto exit; |
| if (nd->last.name[nd->last.len]) { |
| putname(nd->last.name); |
| goto exit; |
| } |
| error = -ELOOP; |
| if (count++==32) { |
| putname(nd->last.name); |
| goto exit; |
| } |
| dir = nd->dentry; |
| down(&dir->d_inode->i_sem); |
| path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); |
| path.mnt = nd->mnt; |
| putname(nd->last.name); |
| goto do_last; |
| } |
| |
| /** |
| * lookup_create - lookup a dentry, creating it if it doesn't exist |
| * @nd: nameidata info |
| * @is_dir: directory flag |
| * |
| * Simple function to lookup and return a dentry and create it |
| * if it doesn't exist. Is SMP-safe. |
| * |
| * Returns with nd->dentry->d_inode->i_sem locked. |
| */ |
| struct dentry *lookup_create(struct nameidata *nd, int is_dir) |
| { |
| struct dentry *dentry = ERR_PTR(-EEXIST); |
| |
| down(&nd->dentry->d_inode->i_sem); |
| /* |
| * Yucky last component or no last component at all? |
| * (foo/., foo/.., /////) |
| */ |
| if (nd->last_type != LAST_NORM) |
| goto fail; |
| nd->flags &= ~LOOKUP_PARENT; |
| |
| /* |
| * Do the final lookup. |
| */ |
| dentry = lookup_hash(&nd->last, nd->dentry); |
| if (IS_ERR(dentry)) |
| goto fail; |
| |
| /* |
| * Special case - lookup gave negative, but... we had foo/bar/ |
| * From the vfs_mknod() POV we just have a negative dentry - |
| * all is fine. Let's be bastards - you had / on the end, you've |
| * been asking for (non-existent) directory. -ENOENT for you. |
| */ |
| if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) |
| goto enoent; |
| return dentry; |
| enoent: |
| dput(dentry); |
| dentry = ERR_PTR(-ENOENT); |
| fail: |
| return dentry; |
| } |
| EXPORT_SYMBOL_GPL(lookup_create); |
| |
| int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
| { |
| int error = may_create(dir, dentry, NULL); |
| |
| if (error) |
| return error; |
| |
| if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
| return -EPERM; |
| |
| if (!dir->i_op || !dir->i_op->mknod) |
| return -EPERM; |
| |
| error = security_inode_mknod(dir, dentry, mode, dev); |
| if (error) |
| return error; |
| |
| DQUOT_INIT(dir); |
| error = dir->i_op->mknod(dir, dentry, mode, dev); |
| if (!error) |
| fsnotify_create(dir, dentry->d_name.name); |
| return error; |
| } |
| |
| asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev) |
| { |
| int error = 0; |
| char * tmp; |
| struct dentry * dentry; |
| struct nameidata nd; |
| |
| if (S_ISDIR(mode)) |
| return -EPERM; |
| tmp = getname(filename); |
| if (IS_ERR(tmp)) |
| return PTR_ERR(tmp); |
| |
| error = path_lookup(tmp, LOOKUP_PARENT, &nd); |
| if (error) |
| goto out; |
| dentry = lookup_create(&nd, 0); |
| error = PTR_ERR(dentry); |
| |
| if (!IS_POSIXACL(nd.dentry->d_inode)) |
| mode &= ~current->fs->umask; |
| if (!IS_ERR(dentry)) { |
| switch (mode & S_IFMT) { |
| case 0: case S_IFREG: |
| error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd); |
| break; |
| case S_IFCHR: case S_IFBLK: |
| error = vfs_mknod(nd.dentry->d_inode,dentry,mode, |
| new_decode_dev(dev)); |
| break; |
| case S_IFIFO: case S_IFSOCK: |
| error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0); |
| break; |
| case S_IFDIR: |
| error = -EPERM; |
| break; |
| default: |
| error = -EINVAL; |
| } |
| dput(dentry); |
| } |
| up(&nd.dentry->d_inode->i_sem); |
| path_release(&nd); |
| out: |
| putname(tmp); |
| |
| return error; |
| } |
| |
| int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
| { |
| int error = may_create(dir, dentry, NULL); |
| |
| if (error) |
| return error; |
| |
| if (!dir->i_op || !dir->i_op->mkdir) |
| return -EPERM; |
| |
| mode &= (S_IRWXUGO|S_ISVTX); |
| error = security_inode_mkdir(dir, dentry, mode); |
| if (error) |
| return error; |
| |
| DQUOT_INIT(dir); |
| error = dir->i_op->mkdir(dir, dentry, mode); |
| if (!error) |
| fsnotify_mkdir(dir, dentry->d_name.name); |
| return error; |
| } |
| |
| asmlinkage long sys_mkdir(const char __user * pathname, int mode) |
| { |
| int error = 0; |
| char * tmp; |
| |
| tmp = getname(pathname); |
| error = PTR_ERR(tmp); |
| if (!IS_ERR(tmp)) { |
| struct dentry *dentry; |
| struct nameidata nd; |
| |
| error = path_lookup(tmp, LOOKUP_PARENT, &nd); |
| if (error) |
| goto out; |
| dentry = lookup_create(&nd, 1); |
| error = PTR_ERR(dentry); |
| if (!IS_ERR(dentry)) { |
| if (!IS_POSIXACL(nd.dentry->d_inode)) |
| mode &= ~current->fs->umask; |
| error = vfs_mkdir(nd.dentry->d_inode, dentry, mode); |
| dput(dentry); |
| } |
| up(&nd.dentry->d_inode->i_sem); |
| path_release(&nd); |
| out: |
| putname(tmp); |
| } |
| |
| return error; |
| } |
| |
| /* |
| * 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 (!d_unhashed(dentry)) |
| * return -EBUSY; |
| * |
| * if it cannot handle the case of removing a directory |
| * that is still in use by something else.. |
| */ |
| void dentry_unhash(struct dentry *dentry) |
| { |
| dget(dentry); |
| if (atomic_read(&dentry->d_count)) |
| shrink_dcache_parent(dentry); |
| spin_lock(&dcache_lock); |
| spin_lock(&dentry->d_lock); |
| if (atomic_read(&dentry->d_count) == 2) |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&dcache_lock); |
| } |
| |
| int vfs_rmdir(struct inode *dir, struct dentry *dentry) |
| { |
| int error = may_delete(dir, dentry, 1); |
| |
| if (error) |
| return error; |
| |
| if (!dir->i_op || !dir->i_op->rmdir) |
| return -EPERM; |
| |
| DQUOT_INIT(dir); |
| |
| down(&dentry->d_inode->i_sem); |
| dentry_unhash(dentry); |
| if (d_mountpoint(dentry)) |
| error = -EBUSY; |
| else { |
| error = security_inode_rmdir(dir, dentry); |
| if (!error) { |
| error = dir->i_op->rmdir(dir, dentry); |
| if (!error) |
| dentry->d_inode->i_flags |= S_DEAD; |
| } |
| } |
| up(&dentry->d_inode->i_sem); |
| if (!error) { |
| d_delete(dentry); |
| } |
| dput(dentry); |
| |
| return error; |
| } |
| |
| asmlinkage long sys_rmdir(const char __user * pathname) |
| { |
| int error = 0; |
| char * name; |
| struct dentry *dentry; |
| struct nameidata nd; |
| |
| name = getname(pathname); |
| if(IS_ERR(name)) |
| return PTR_ERR(name); |
| |
| error = path_lookup(name, LOOKUP_PARENT, &nd); |
| if (error) |
| goto exit; |
| |
| switch(nd.last_type) { |
| case LAST_DOTDOT: |
| error = -ENOTEMPTY; |
| goto exit1; |
| case LAST_DOT: |
| error = -EINVAL; |
| goto exit1; |
| case LAST_ROOT: |
| error = -EBUSY; |
| goto exit1; |
| } |
| down(&nd.dentry->d_inode->i_sem); |
| dentry = lookup_hash(&nd.last, nd.dentry); |
| error = PTR_ERR(dentry); |
| if (!IS_ERR(dentry)) { |
| error = vfs_rmdir(nd.dentry->d_inode, dentry); |
| dput(dentry); |
| } |
| up(&nd.dentry->d_inode->i_sem); |
| exit1: |
| path_release(&nd); |
| exit: |
| putname(name); |
| return error; |
| } |
| |
| int vfs_unlink(struct inode *dir, struct dentry *dentry) |
| { |
| int error = may_delete(dir, dentry, 0); |
| |
| if (error) |
| return error; |
| |
| if (!dir->i_op || !dir->i_op->unlink) |
| return -EPERM; |
| |
| DQUOT_INIT(dir); |
| |
| down(&dentry->d_inode->i_sem); |
| if (d_mountpoint(dentry)) |
| error = -EBUSY; |
| else { |
| error = security_inode_unlink(dir, dentry); |
| if (!error) |
| error = dir->i_op->unlink(dir, dentry); |
| } |
| up(&dentry->d_inode->i_sem); |
| |
| /* We don't d_delete() NFS sillyrenamed files--they still exist. */ |
| if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { |
| d_delete(dentry); |
| } |
| |
| return error; |
| } |
| |
| /* |
| * Make sure that the actual truncation of the file will occur outside its |
| * directory's i_sem. Truncate can take a long time if there is a lot of |
| * writeout happening, and we don't want to prevent access to the directory |
| * while waiting on the I/O. |
| */ |
| asmlinkage long sys_unlink(const char __user * pathname) |
| { |
| int error = 0; |
| char * name; |
| struct dentry *dentry; |
| struct nameidata nd; |
| struct inode *inode = NULL; |
| |
| name = getname(pathname); |
| if(IS_ERR(name)) |
| return PTR_ERR(name); |
| |
| error = path_lookup(name, LOOKUP_PARENT, &nd); |
| if (error) |
| goto exit; |
| error = -EISDIR; |
| if (nd.last_type != LAST_NORM) |
| goto exit1; |
| down(&nd.dentry->d_inode->i_sem); |
| dentry = lookup_hash(&nd.last, nd.dentry); |
| error = PTR_ERR(dentry); |
| if (!IS_ERR(dentry)) { |
| /* Why not before? Because we want correct error value */ |
| if (nd.last.name[nd.last.len]) |
| goto slashes; |
| inode = dentry->d_inode; |
| if (inode) |
| atomic_inc(&inode->i_count); |
| error = vfs_unlink(nd.dentry->d_inode, dentry); |
| exit2: |
| dput(dentry); |
| } |
| up(&nd.dentry->d_inode->i_sem); |
| if (inode) |
| iput(inode); /* truncate the inode here */ |
| exit1: |
| path_release(&nd); |
| exit: |
| putname(name); |
| return error; |
| |
| slashes: |
| error = !dentry->d_inode ? -ENOENT : |
| S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; |
| goto exit2; |
| } |
| |
| int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode) |
| { |
| int error = may_create(dir, dentry, NULL); |
| |
| if (error) |
| return error; |
| |
| if (!dir->i_op || !dir->i_op->symlink) |
| return -EPERM; |
| |
| error = security_inode_symlink(dir, dentry, oldname); |
| if (error) |
| return error; |
| |
| DQUOT_INIT(dir); |
| error = dir->i_op->symlink(dir, dentry, oldname); |
| if (!error) |
| fsnotify_create(dir, dentry->d_name.name); |
| return error; |
| } |
| |
| asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname) |
| { |
| int error = 0; |
| char * from; |
| char * to; |
| |
| from = getname(oldname); |
| if(IS_ERR(from)) |
| return PTR_ERR(from); |
| to = getname(newname); |
| error = PTR_ERR(to); |
| if (!IS_ERR(to)) { |
| struct dentry *dentry; |
| struct nameidata nd; |
| |
| error = path_lookup(to, LOOKUP_PARENT, &nd); |
| if (error) |
| goto out; |
| dentry = lookup_create(&nd, 0); |
| error = PTR_ERR(dentry); |
| if (!IS_ERR(dentry)) { |
| error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO); |
| dput(dentry); |
| } |
| up(&nd.dentry->d_inode->i_sem); |
| path_release(&nd); |
| out: |
| putname(to); |
| } |
| putname(from); |
| return error; |
| } |
| |
| int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
| { |
| struct inode *inode = old_dentry->d_inode; |
| int error; |
| |
| if (!inode) |
| return -ENOENT; |
| |
| error = may_create(dir, new_dentry, NULL); |
| if (error) |
| return error; |
| |
| if (dir->i_sb != inode->i_sb) |
| return -EXDEV; |
| |
| /* |
| * A link to an append-only or immutable file cannot be created. |
| */ |
| if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) |
| return -EPERM; |
| if (!dir->i_op || !dir->i_op->link) |
| return -EPERM; |
| if (S_ISDIR(old_dentry->d_inode->i_mode)) |
| return -EPERM; |
| |
| error = security_inode_link(old_dentry, dir, new_dentry); |
| if (error) |
| return error; |
| |
| down(&old_dentry->d_inode->i_sem); |
| DQUOT_INIT(dir); |
| error = dir->i_op->link(old_dentry, dir, new_dentry); |
| up(&old_dentry->d_inode->i_sem); |
| if (!error) { |
| fsnotify_create(dir, new_dentry->d_name.name); |
| security_inode_post_link(old_dentry, dir, new_dentry); |
| } |
| return 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 |
| */ |
| asmlinkage long sys_link(const char __user * oldname, const char __user * newname) |
| { |
| struct dentry *new_dentry; |
| struct nameidata nd, old_nd; |
| int error; |
| char * to; |
| |
| to = getname(newname); |
| if (IS_ERR(to)) |
| return PTR_ERR(to); |
| |
| error = __user_walk(oldname, 0, &old_nd); |
| if (error) |
| goto exit; |
| error = path_lookup(to, LOOKUP_PARENT, &nd); |
| if (error) |
| goto out; |
| error = -EXDEV; |
| if (old_nd.mnt != nd.mnt) |
| goto out_release; |
| new_dentry = lookup_create(&nd, 0); |
| error = PTR_ERR(new_dentry); |
| if (!IS_ERR(new_dentry)) { |
| error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry); |
| dput(new_dentry); |
| } |
| up(&nd.dentry->d_inode->i_sem); |
| out_release: |
| path_release(&nd); |
| out: |
| path_release(&old_nd); |
| exit: |
| putname(to); |
| |
| return error; |
| } |
| |
| /* |
| * The worst of all namespace operations - renaming directory. "Perverted" |
| * doesn't even start to describe it. Somebody in UCB had a heck of a trip... |
| * Problems: |
| * a) we can get into loop creation. Check is done in is_subdir(). |
| * b) race potential - two innocent renames can create a loop together. |
| * That's where 4.4 screws up. Current fix: serialization on |
| * sb->s_vfs_rename_sem. We might be more accurate, but that's another |
| * story. |
| * c) we have to lock _three_ objects - parents and victim (if it exists). |
| * And that - after we got ->i_sem on parents (until then we don't know |
| * whether the target exists). Solution: try to be smart with locking |
| * order for inodes. We rely on the fact that tree topology may change |
| * only under ->s_vfs_rename_sem _and_ that parent of the object we |
| * move will be locked. Thus we can rank directories by the tree |
| * (ancestors first) and rank all non-directories after them. |
| * That works since everybody except rename does "lock parent, lookup, |
| * lock child" and rename is under ->s_vfs_rename_sem. |
| * HOWEVER, it relies on the assumption that any object with ->lookup() |
| * has no more than 1 dentry. If "hybrid" objects will ever appear, |
| * we'd better make sure that there's no link(2) for them. |
| * d) some filesystems don't support opened-but-unlinked directories, |
| * either because of layout or because they are not ready to deal with |
| * all cases correctly. The latter will be fixed (taking this sort of |
| * stuff into VFS), but the former is not going away. Solution: the same |
| * trick as in rmdir(). |
| * e) conversion from fhandle to dentry may come in the wrong moment - when |
| * we are removing the target. Solution: we will have to grab ->i_sem |
| * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
| * ->i_sem on parents, which works but leads to some truely excessive |
| * locking]. |
| */ |
| static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry) |
| { |
| int error = 0; |
| struct inode *target; |
| |
| /* |
| * 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, NULL); |
| if (error) |
| return error; |
| } |
| |
| error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
| if (error) |
| return error; |
| |
| target = new_dentry->d_inode; |
| if (target) { |
| down(&target->i_sem); |
| dentry_unhash(new_dentry); |
| } |
| if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
| error = -EBUSY; |
| else |
| error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
| if (target) { |
| if (!error) |
| target->i_flags |= S_DEAD; |
| up(&target->i_sem); |
| if (d_unhashed(new_dentry)) |
| d_rehash(new_dentry); |
| dput(new_dentry); |
| } |
| if (!error) { |
| d_move(old_dentry,new_dentry); |
| security_inode_post_rename(old_dir, old_dentry, |
| new_dir, new_dentry); |
| } |
| return error; |
| } |
| |
| static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry) |
| { |
| struct inode *target; |
| int error; |
| |
| error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
| if (error) |
| return error; |
| |
| dget(new_dentry); |
| target = new_dentry->d_inode; |
| if (target) |
| down(&target->i_sem); |
| if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
| error = -EBUSY; |
| else |
| error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
| if (!error) { |
| /* The following d_move() should become unconditional */ |
| if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME)) |
| d_move(old_dentry, new_dentry); |
| security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry); |
| } |
| if (target) |
| up(&target->i_sem); |
| dput(new_dentry); |
| return error; |
| } |
| |
| int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry) |
| { |
| int error; |
| int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); |
| const char *old_name; |
| |
| if (old_dentry->d_inode == new_dentry->d_inode) |
| return 0; |
| |
| error = may_delete(old_dir, old_dentry, is_dir); |
| if (error) |
| return error; |
| |
| if (!new_dentry->d_inode) |
| error = may_create(new_dir, new_dentry, NULL); |
| else |
| error = may_delete(new_dir, new_dentry, is_dir); |
| if (error) |
| return error; |
| |
| if (!old_dir->i_op || !old_dir->i_op->rename) |
| return -EPERM; |
| |
| DQUOT_INIT(old_dir); |
| DQUOT_INIT(new_dir); |
| |
| old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
| |
| if (is_dir) |
| error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); |
| else |
| error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); |
| if (!error) { |
| const char *new_name = old_dentry->d_name.name; |
| fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, |
| new_dentry->d_inode, old_dentry->d_inode); |
| } |
| fsnotify_oldname_free(old_name); |
| |
| return error; |
| } |
| |
| static inline int do_rename(const char * oldname, const char * newname) |
| { |
| int error = 0; |
| struct dentry * old_dir, * new_dir; |
| struct dentry * old_dentry, *new_dentry; |
| struct dentry * trap; |
| struct nameidata oldnd, newnd; |
| |
| error = path_lookup(oldname, LOOKUP_PARENT, &oldnd); |
| if (error) |
| goto exit; |
| |
| error = path_lookup(newname, LOOKUP_PARENT, &newnd); |
| if (error) |
| goto exit1; |
| |
| error = -EXDEV; |
| if (oldnd.mnt != newnd.mnt) |
| goto exit2; |
| |
| old_dir = oldnd.dentry; |
| error = -EBUSY; |
| if (oldnd.last_type != LAST_NORM) |
| goto exit2; |
| |
| new_dir = newnd.dentry; |
| if (newnd.last_type != LAST_NORM) |
| goto exit2; |
| |
| trap = lock_rename(new_dir, old_dir); |
| |
| old_dentry = lookup_hash(&oldnd.last, old_dir); |
| error = PTR_ERR(old_dentry); |
| if (IS_ERR(old_dentry)) |
| goto exit3; |
| /* source must exist */ |
| error = -ENOENT; |
| if (!old_dentry->d_inode) |
| goto exit4; |
| /* unless the source is a directory trailing slashes give -ENOTDIR */ |
| if (!S_ISDIR(old_dentry->d_inode->i_mode)) { |
| error = -ENOTDIR; |
| if (oldnd.last.name[oldnd.last.len]) |
| goto exit4; |
| if (newnd.last.name[newnd.last.len]) |
| goto exit4; |
| } |
| /* source should not be ancestor of target */ |
| error = -EINVAL; |
| if (old_dentry == trap) |
| goto exit4; |
| new_dentry = lookup_hash(&newnd.last, new_dir); |
| error = PTR_ERR(new_dentry); |
| if (IS_ERR(new_dentry)) |
| goto exit4; |
| /* target should not be an ancestor of source */ |
| error = -ENOTEMPTY; |
| if (new_dentry == trap) |
| goto exit5; |
| |
| error = vfs_rename(old_dir->d_inode, old_dentry, |
| new_dir->d_inode, new_dentry); |
| exit5: |
| dput(new_dentry); |
| exit4: |
| dput(old_dentry); |
| exit3: |
| unlock_rename(new_dir, old_dir); |
| exit2: |
| path_release(&newnd); |
| exit1: |
| path_release(&oldnd); |
| exit: |
| return error; |
| } |
| |
| asmlinkage long sys_rename(const char __user * oldname, const char __user * newname) |
| { |
| int error; |
| char * from; |
| char * to; |
| |
| from = getname(oldname); |
| if(IS_ERR(from)) |
| return PTR_ERR(from); |
| to = getname(newname); |
| error = PTR_ERR(to); |
| if (!IS_ERR(to)) { |
| error = do_rename(from,to); |
| putname(to); |
| } |
| putname(from); |
| return error; |
| } |
| |
| int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
| { |
| int len; |
| |
| len = PTR_ERR(link); |
| if (IS_ERR(link)) |
| goto out; |
| |
| len = strlen(link); |
| if (len > (unsigned) buflen) |
| len = buflen; |
| if (copy_to_user(buffer, link, len)) |
| len = -EFAULT; |
| out: |
| return len; |
| } |
| |
| /* |
| * A helper for ->readlink(). This should be used *ONLY* for symlinks that |
| * have ->follow_link() touching nd only in nd_set_link(). Using (or not |
| * using) it for any given inode is up to filesystem. |
| */ |
| int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
| { |
| struct nameidata nd; |
| void *cookie; |
| |
| nd.depth = 0; |
| cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
| if (!IS_ERR(cookie)) { |
| int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); |
| if (dentry->d_inode->i_op->put_link) |
| dentry->d_inode->i_op->put_link(dentry, &nd, cookie); |
| cookie = ERR_PTR(res); |
| } |
| return PTR_ERR(cookie); |
| } |
| |
| int vfs_follow_link(struct nameidata *nd, const char *link) |
| { |
| return __vfs_follow_link(nd, link); |
| } |
| |
| /* get the link contents into pagecache */ |
| static char *page_getlink(struct dentry * dentry, struct page **ppage) |
| { |
| struct page * page; |
| struct address_space *mapping = dentry->d_inode->i_mapping; |
| page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage, |
| NULL); |
| if (IS_ERR(page)) |
| goto sync_fail; |
| wait_on_page_locked(page); |
| if (!PageUptodate(page)) |
| goto async_fail; |
| *ppage = page; |
| return kmap(page); |
| |
| async_fail: |
| page_cache_release(page); |
| return ERR_PTR(-EIO); |
| |
| sync_fail: |
| return (char*)page; |
| } |
| |
| int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
| { |
| struct page *page = NULL; |
| char *s = page_getlink(dentry, &page); |
| int res = vfs_readlink(dentry,buffer,buflen,s); |
| if (page) { |
| kunmap(page); |
| page_cache_release(page); |
| } |
| return res; |
| } |
| |
| void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
| { |
| struct page *page = NULL; |
| nd_set_link(nd, page_getlink(dentry, &page)); |
| return page; |
| } |
| |
| void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
| { |
| struct page *page = cookie; |
| |
| if (page) { |
| kunmap(page); |
| page_cache_release(page); |
| } |
| } |
| |
| int page_symlink(struct inode *inode, const char *symname, int len) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct page *page = grab_cache_page(mapping, 0); |
| int err = -ENOMEM; |
| char *kaddr; |
| |
| if (!page) |
| goto fail; |
| err = mapping->a_ops->prepare_write(NULL, page, 0, len-1); |
| if (err) |
| goto fail_map; |
| kaddr = kmap_atomic(page, KM_USER0); |
| memcpy(kaddr, symname, len-1); |
| kunmap_atomic(kaddr, KM_USER0); |
| mapping->a_ops->commit_write(NULL, page, 0, len-1); |
| /* |
| * Notice that we are _not_ going to block here - end of page is |
| * unmapped, so this will only try to map the rest of page, see |
| * that it is unmapped (typically even will not look into inode - |
| * ->i_size will be enough for everything) and zero it out. |
| * OTOH it's obviously correct and should make the page up-to-date. |
| */ |
| if (!PageUptodate(page)) { |
| err = mapping->a_ops->readpage(NULL, page); |
| wait_on_page_locked(page); |
| } else { |
| unlock_page(page); |
| } |
| page_cache_release(page); |
| if (err < 0) |
| goto fail; |
| mark_inode_dirty(inode); |
| return 0; |
| fail_map: |
| unlock_page(page); |
| page_cache_release(page); |
| fail: |
| return err; |
| } |
| |
| struct inode_operations page_symlink_inode_operations = { |
| .readlink = generic_readlink, |
| .follow_link = page_follow_link_light, |
| .put_link = page_put_link, |
| }; |
| |
| EXPORT_SYMBOL(__user_walk); |
| EXPORT_SYMBOL(follow_down); |
| EXPORT_SYMBOL(follow_up); |
| EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ |
| EXPORT_SYMBOL(getname); |
| EXPORT_SYMBOL(lock_rename); |
| EXPORT_SYMBOL(lookup_hash); |
| EXPORT_SYMBOL(lookup_one_len); |
| EXPORT_SYMBOL(page_follow_link_light); |
| EXPORT_SYMBOL(page_put_link); |
| EXPORT_SYMBOL(page_readlink); |
| EXPORT_SYMBOL(page_symlink); |
| EXPORT_SYMBOL(page_symlink_inode_operations); |
| EXPORT_SYMBOL(path_lookup); |
| EXPORT_SYMBOL(path_release); |
| EXPORT_SYMBOL(path_walk); |
| EXPORT_SYMBOL(permission); |
| EXPORT_SYMBOL(unlock_rename); |
| EXPORT_SYMBOL(vfs_create); |
| EXPORT_SYMBOL(vfs_follow_link); |
| EXPORT_SYMBOL(vfs_link); |
| EXPORT_SYMBOL(vfs_mkdir); |
| EXPORT_SYMBOL(vfs_mknod); |
| EXPORT_SYMBOL(generic_permission); |
| EXPORT_SYMBOL(vfs_readlink); |
| EXPORT_SYMBOL(vfs_rename); |
| EXPORT_SYMBOL(vfs_rmdir); |
| EXPORT_SYMBOL(vfs_symlink); |
| EXPORT_SYMBOL(vfs_unlink); |
| EXPORT_SYMBOL(dentry_unhash); |
| EXPORT_SYMBOL(generic_readlink); |