#include <linux/fs_struct.h>
#include <asm/uaccess.h>
-#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
+#include "internal.h"
/* [Feb-1997 T. Schoebel-Theuer]
* Fundamental changes in the pathname lookup mechanisms (namei)
/*
* Searching includes executable on directories, else just read.
*/
+ mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
if (capable(CAP_DAC_READ_SEARCH))
return 0;
}
/*
+ * force_reval_path - force revalidation of a dentry
+ *
+ * In some situations the path walking code will trust dentries without
+ * revalidating them. This causes problems for filesystems that depend on
+ * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
+ * (which indicates that it's possible for the dentry to go stale), force
+ * a d_revalidate call before proceeding.
+ *
+ * Returns 0 if the revalidation was successful. If the revalidation fails,
+ * either return the error returned by d_revalidate or -ESTALE if the
+ * revalidation it just returned 0. If d_revalidate returns 0, we attempt to
+ * invalidate the dentry. It's up to the caller to handle putting references
+ * to the path if necessary.
+ */
+static int
+force_reval_path(struct path *path, struct nameidata *nd)
+{
+ int status;
+ struct dentry *dentry = path->dentry;
+
+ /*
+ * only check on filesystems where it's possible for the dentry to
+ * become stale. It's assumed that if this flag is set then the
+ * d_revalidate op will also be defined.
+ */
+ if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))
+ return 0;
+
+ status = dentry->d_op->d_revalidate(dentry, nd);
+ if (status > 0)
+ return 0;
+
+ if (!status) {
+ d_invalidate(dentry);
+ status = -ESTALE;
+ }
+ return status;
+}
+
+/*
* Short-cut version of permission(), for calling on directories
* during pathname resolution. Combines parts of permission()
* and generic_permission(), and tests ONLY for MAY_EXEC permission.
dget(dentry);
}
mntget(path->mnt);
+ nd->last_type = LAST_BIND;
cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(cookie);
if (!IS_ERR(cookie)) {
error = 0;
if (s)
error = __vfs_follow_link(nd, s);
+ else if (nd->last_type == LAST_BIND) {
+ error = force_reval_path(&nd->path, nd);
+ if (error)
+ path_put(&nd->path);
+ }
if (dentry->d_inode->i_op->put_link)
dentry->d_inode->i_op->put_link(dentry, nd, cookie);
}
}
/*
+ * This is a temporary kludge to deal with "automount" symlinks; proper
+ * solution is to trigger them on follow_mount(), so that do_lookup()
+ * would DTRT. To be killed before 2.6.34-final.
+ */
+static inline int follow_on_final(struct inode *inode, unsigned lookup_flags)
+{
+ return inode && unlikely(inode->i_op->follow_link) &&
+ ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode));
+}
+
+/*
* 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.
if (err)
break;
inode = next.dentry->d_inode;
- if ((lookup_flags & LOOKUP_FOLLOW)
- && inode && inode->i_op->follow_link) {
+ if (follow_on_final(inode, lookup_flags)) {
err = do_follow_link(&next, nd);
if (err)
goto return_err;
if (error)
return error;
- error = ima_path_check(path, acc_mode ?
- acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
- ACC_MODE(flag) & (MAY_READ | MAY_WRITE),
- IMA_COUNT_UPDATE);
-
- if (error)
- return error;
/*
* An append-only file must be opened in append mode for writing.
*/
if (IS_APPEND(inode)) {
- error = -EPERM;
if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
- goto err_out;
+ return -EPERM;
if (flag & O_TRUNC)
- goto err_out;
+ return -EPERM;
}
/* O_NOATIME can only be set by the owner or superuser */
- if (flag & O_NOATIME)
- if (!is_owner_or_cap(inode)) {
- error = -EPERM;
- goto err_out;
- }
+ if (flag & O_NOATIME && !is_owner_or_cap(inode))
+ return -EPERM;
/*
* Ensure there are no outstanding leases on the file.
*/
- error = break_lease(inode, flag);
- if (error)
- goto err_out;
-
- if (flag & O_TRUNC) {
- error = get_write_access(inode);
- if (error)
- goto err_out;
-
- /*
- * Refuse to truncate files with mandatory locks held on them.
- */
- error = locks_verify_locked(inode);
- if (!error)
- error = security_path_truncate(path, 0,
- ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
- if (!error) {
- vfs_dq_init(inode);
-
- error = do_truncate(dentry, 0,
- ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
- NULL);
- }
- put_write_access(inode);
- if (error)
- goto err_out;
- } else
- if (flag & FMODE_WRITE)
- vfs_dq_init(inode);
+ return break_lease(inode, flag);
+}
- return 0;
-err_out:
- ima_counts_put(path, acc_mode ?
- acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
- ACC_MODE(flag) & (MAY_READ | MAY_WRITE));
+static int handle_truncate(struct path *path)
+{
+ struct inode *inode = path->dentry->d_inode;
+ int 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)
+ error = security_path_truncate(path, 0,
+ ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
+ if (!error) {
+ error = do_truncate(path->dentry, 0,
+ ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
+ NULL);
+ }
+ put_write_access(inode);
return error;
}
return flag;
}
-static int open_will_write_to_fs(int flag, struct inode *inode)
+static int open_will_truncate(int flag, struct inode *inode)
{
/*
* We'll never write to the fs underlying
struct file *filp;
struct nameidata nd;
int error;
- struct path path, save;
+ struct path path;
struct dentry *dir;
int count = 0;
- int will_write;
+ int will_truncate;
int flag = open_to_namei_flags(open_flag);
+ int force_reval = 0;
/*
* O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
open_flag |= O_DSYNC;
if (!acc_mode)
- acc_mode = MAY_OPEN | ACC_MODE(flag);
+ acc_mode = MAY_OPEN | ACC_MODE(open_flag);
/* O_TRUNC implies we need access checks for write permissions */
if (flag & O_TRUNC)
if (filp == NULL)
return ERR_PTR(-ENFILE);
nd.intent.open.file = filp;
+ filp->f_flags = open_flag;
nd.intent.open.flags = flag;
nd.intent.open.create_mode = 0;
error = do_path_lookup(dfd, pathname,
/*
* Create - we need to know the parent.
*/
+reval:
error = path_init(dfd, pathname, LOOKUP_PARENT, &nd);
if (error)
return ERR_PTR(error);
+ if (force_reval)
+ nd.flags |= LOOKUP_REVAL;
error = path_walk(pathname, &nd);
if (error) {
if (nd.root.mnt)
if (filp == NULL)
goto exit_parent;
nd.intent.open.file = filp;
+ filp->f_flags = open_flag;
nd.intent.open.flags = flag;
nd.intent.open.create_mode = mode;
dir = nd.path.dentry;
mnt_drop_write(nd.path.mnt);
goto exit;
}
- filp = nameidata_to_filp(&nd, open_flag);
- if (IS_ERR(filp))
- ima_counts_put(&nd.path,
- acc_mode & (MAY_READ | MAY_WRITE |
- MAY_EXEC));
+ filp = nameidata_to_filp(&nd);
mnt_drop_write(nd.path.mnt);
if (nd.root.mnt)
path_put(&nd.root);
+ if (!IS_ERR(filp)) {
+ error = ima_file_check(filp, acc_mode);
+ if (error) {
+ fput(filp);
+ filp = ERR_PTR(error);
+ }
+ }
return filp;
}
path_to_nameidata(&path, &nd);
error = -EISDIR;
- if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
+ if (S_ISDIR(path.dentry->d_inode->i_mode))
goto exit;
ok:
/*
* be avoided. Taking this mnt write here
* ensures that (2) can not occur.
*/
- will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode);
- if (will_write) {
+ will_truncate = open_will_truncate(flag, nd.path.dentry->d_inode);
+ if (will_truncate) {
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit;
}
error = may_open(&nd.path, acc_mode, flag);
if (error) {
- if (will_write)
+ if (will_truncate)
mnt_drop_write(nd.path.mnt);
goto exit;
}
- filp = nameidata_to_filp(&nd, open_flag);
- if (IS_ERR(filp))
- ima_counts_put(&nd.path,
- acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC));
+ filp = nameidata_to_filp(&nd);
+ if (!IS_ERR(filp)) {
+ error = ima_file_check(filp, acc_mode);
+ if (error) {
+ fput(filp);
+ filp = ERR_PTR(error);
+ }
+ }
+ if (!IS_ERR(filp)) {
+ if (acc_mode & MAY_WRITE)
+ vfs_dq_init(nd.path.dentry->d_inode);
+
+ if (will_truncate) {
+ error = handle_truncate(&nd.path);
+ if (error) {
+ fput(filp);
+ filp = ERR_PTR(error);
+ }
+ }
+ }
/*
* It is now safe to drop the mnt write
* because the filp has had a write taken
* on its behalf.
*/
- if (will_write)
+ if (will_truncate)
mnt_drop_write(nd.path.mnt);
if (nd.root.mnt)
path_put(&nd.root);
error = security_inode_follow_link(path.dentry, &nd);
if (error)
goto exit_dput;
- save = nd.path;
- path_get(&save);
error = __do_follow_link(&path, &nd);
- if (error == -ESTALE) {
- /* nd.path had been dropped */
- nd.path = save;
- path_get(&nd.path);
- nd.flags |= LOOKUP_REVAL;
- error = __do_follow_link(&path, &nd);
- }
- path_put(&save);
path_put(&path);
if (error) {
/* Does someone understand code flow here? Or it is only
release_open_intent(&nd);
if (nd.root.mnt)
path_put(&nd.root);
+ if (error == -ESTALE && !force_reval) {
+ force_reval = 1;
+ goto reval;
+ }
return ERR_PTR(error);
}
nd.flags &= ~LOOKUP_PARENT;
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff