diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 2454 |
1 files changed, 2454 insertions, 0 deletions
diff --git a/fs/namei.c b/fs/namei.c new file mode 100644 index 000000000000..9e4aef2a1a21 --- /dev/null +++ b/fs/namei.c @@ -0,0 +1,2454 @@ +/* + * 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/dnotify.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(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); +} + +static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd) +{ + int error; + + touch_atime(nd->mnt, dentry); + nd_set_link(nd, NULL); + error = dentry->d_inode->i_op->follow_link(dentry, nd); + if (!error) { + char *s = nd_get_link(nd); + 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); + } + + return error; +} + +/* + * 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 dentry *dentry, 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(dentry, nd); + if (err) + goto loop; + current->link_count++; + current->total_link_count++; + nd->depth++; + err = __do_follow_link(dentry, nd); + current->link_count--; + nd->depth--; + return err; +loop: + 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 vfsmount **mnt, struct dentry **dentry) +{ + int res = 0; + while (d_mountpoint(*dentry)) { + struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); + if (!mounted) + break; + mntput(*mnt); + *mnt = mounted; + dput(*dentry); + *dentry = dget(mounted->mnt_root); + res = 1; + } + return res; +} + +/* no need for dcache_lock, as serialization is taken care in + * namespace.c + */ +static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry) +{ + struct vfsmount *mounted; + + mounted = lookup_mnt(*mnt, *dentry); + if (mounted) { + mntput(*mnt); + *mnt = mounted; + dput(*dentry); + *dentry = dget(mounted->mnt_root); + return 1; + } + return 0; +} + +int follow_down(struct vfsmount **mnt, struct dentry **dentry) +{ + return __follow_down(mnt,dentry); +} + +static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry) +{ + while(1) { + struct vfsmount *parent; + struct dentry *old = *dentry; + + read_lock(¤t->fs->lock); + if (*dentry == current->fs->root && + *mnt == current->fs->rootmnt) { + read_unlock(¤t->fs->lock); + break; + } + read_unlock(¤t->fs->lock); + spin_lock(&dcache_lock); + if (*dentry != (*mnt)->mnt_root) { + *dentry = dget((*dentry)->d_parent); + spin_unlock(&dcache_lock); + dput(old); + break; + } + spin_unlock(&dcache_lock); + spin_lock(&vfsmount_lock); + parent = (*mnt)->mnt_parent; + if (parent == *mnt) { + spin_unlock(&vfsmount_lock); + break; + } + mntget(parent); + *dentry = dget((*mnt)->mnt_mountpoint); + spin_unlock(&vfsmount_lock); + dput(old); + mntput(*mnt); + *mnt = parent; + } + follow_mount(mnt, dentry); +} + +struct path { + struct vfsmount *mnt; + struct dentry *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; + 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. + */ +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->mnt, &nd->dentry); + 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; + /* Check mountpoints.. */ + follow_mount(&next.mnt, &next.dentry); + + 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) { + mntget(next.mnt); + err = do_follow_link(next.dentry, nd); + dput(next.dentry); + mntput(next.mnt); + if (err) + goto return_err; + err = -ENOENT; + inode = nd->dentry->d_inode; + if (!inode) + break; + err = -ENOTDIR; + if (!inode->i_op) + break; + } else { + dput(nd->dentry); + nd->mnt = next.mnt; + nd->dentry = next.dentry; + } + 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->mnt, &nd->dentry); + 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; + follow_mount(&next.mnt, &next.dentry); + inode = next.dentry->d_inode; + if ((lookup_flags & LOOKUP_FOLLOW) + && inode && inode->i_op && inode->i_op->follow_link) { + mntget(next.mnt); + err = do_follow_link(next.dentry, nd); + dput(next.dentry); + mntput(next.mnt); + if (err) + goto return_err; + inode = nd->dentry->d_inode; + } else { + dput(nd->dentry); + nd->mnt = next.mnt; + nd->dentry = next.dentry; + } + 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(next.dentry); + 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 if everything is done */ +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); + } +} + +int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd) +{ + int retval; + + 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)) + return 0; + 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); + 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) { + inode_dir_notify(dir, DN_CREATE); + security_inode_post_create(dir, dentry, mode); + } + 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 dentry *dentry; + 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); + dentry = __lookup_hash(&nd->last, nd->dentry, nd); + +do_last: + error = PTR_ERR(dentry); + if (IS_ERR(dentry)) { + up(&dir->d_inode->i_sem); + goto exit; + } + + /* Negative dentry, just create the file */ + if (!dentry->d_inode) { + if (!IS_POSIXACL(dir->d_inode)) + mode &= ~current->fs->umask; + error = vfs_create(dir->d_inode, dentry, mode, nd); + up(&dir->d_inode->i_sem); + dput(nd->dentry); + nd->dentry = 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 (d_mountpoint(dentry)) { + error = -ELOOP; + if (flag & O_NOFOLLOW) + goto exit_dput; + while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry)); + } + error = -ENOENT; + if (!dentry->d_inode) + goto exit_dput; + if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link) + goto do_link; + + dput(nd->dentry); + nd->dentry = dentry; + error = -EISDIR; + if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) + goto exit; +ok: + error = may_open(nd, acc_mode, flag); + if (error) + goto exit; + return 0; + +exit_dput: + dput(dentry); +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(dentry, nd); + if (error) + goto exit_dput; + error = __do_follow_link(dentry, nd); + dput(dentry); + if (error) + return error; + nd->flags &= ~LOOKUP_PARENT; + if (nd->last_type == LAST_BIND) { + dentry = nd->dentry; + 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); + dentry = __lookup_hash(&nd->last, nd->dentry, nd); + 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. + */ +struct dentry *lookup_create(struct nameidata *nd, int is_dir) +{ + struct dentry *dentry; + + down(&nd->dentry->d_inode->i_sem); + dentry = ERR_PTR(-EEXIST); + if (nd->last_type != LAST_NORM) + goto fail; + nd->flags &= ~LOOKUP_PARENT; + dentry = lookup_hash(&nd->last, nd->dentry); + if (IS_ERR(dentry)) + goto fail; + 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; +} + +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) { + inode_dir_notify(dir, DN_CREATE); + security_inode_post_mknod(dir, dentry, mode, dev); + } + 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) { + inode_dir_notify(dir, DN_CREATE); + security_inode_post_mkdir(dir,dentry, mode); + } + 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) { + inode_dir_notify(dir, DN_DELETE); + 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); + inode_dir_notify(dir, DN_DELETE); + } + 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) { + inode_dir_notify(dir, DN_CREATE); + security_inode_post_symlink(dir, dentry, oldname); + } + 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) { + inode_dir_notify(dir, DN_CREATE); + 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]. + */ +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; +} + +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); + + 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); + + 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) { + if (old_dir == new_dir) + inode_dir_notify(old_dir, DN_RENAME); + else { + inode_dir_notify(old_dir, DN_DELETE); + inode_dir_notify(new_dir, DN_CREATE); + } + } + 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; + int res; + nd.depth = 0; + res = dentry->d_inode->i_op->follow_link(dentry, &nd); + if (!res) { + 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); + } + return res; +} + +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; +} + +int page_follow_link_light(struct dentry *dentry, struct nameidata *nd) +{ + struct page *page; + nd_set_link(nd, page_getlink(dentry, &page)); + return 0; +} + +void page_put_link(struct dentry *dentry, struct nameidata *nd) +{ + if (!IS_ERR(nd_get_link(nd))) { + struct page *page; + page = find_get_page(dentry->d_inode->i_mapping, 0); + if (!page) + BUG(); + kunmap(page); + page_cache_release(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); |