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-rw-r--r--fs/namei.c466
1 files changed, 233 insertions, 233 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 87f97ba90ad1..d2783c8a770b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -35,6 +35,8 @@
#include <linux/fs_struct.h>
#include <asm/uaccess.h>
+#include "internal.h"
+
#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
/* [Feb-1997 T. Schoebel-Theuer]
@@ -108,8 +110,6 @@
* any extra contention...
*/
-static int __link_path_walk(const char *name, struct nameidata *nd);
-
/* 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..
@@ -414,36 +414,55 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
}
/*
- * Internal lookup() using the new generic dcache.
- * SMP-safe
+ * 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 struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
+static int
+force_reval_path(struct path *path, struct nameidata *nd)
{
- struct dentry * dentry = __d_lookup(parent, name);
+ int status;
+ struct dentry *dentry = path->dentry;
- /* lockess __d_lookup may fail due to concurrent d_move()
- * in some unrelated directory, so try with d_lookup
+ /*
+ * 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)
- dentry = d_lookup(parent, name);
+ if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))
+ return 0;
- if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
- dentry = do_revalidate(dentry, nd);
+ status = dentry->d_op->d_revalidate(dentry, nd);
+ if (status > 0)
+ return 0;
- return dentry;
+ if (!status) {
+ d_invalidate(dentry);
+ status = -ESTALE;
+ }
+ return status;
}
/*
- * 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.
+ * 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.
*
* If appropriate, check DAC only. If not appropriate, or
- * short-cut DAC fails, then call permission() to do more
+ * short-cut DAC fails, then call ->permission() to do more
* complete permission check.
*/
-static int exec_permission_lite(struct inode *inode)
+static int exec_permission(struct inode *inode)
{
int ret;
@@ -465,99 +484,6 @@ ok:
return security_inode_permission(inode, MAY_EXEC);
}
-/*
- * 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;
-
- mutex_lock(&dir->i_mutex);
- /*
- * 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;
-
- /* Don't create child dentry for a dead directory. */
- result = ERR_PTR(-ENOENT);
- if (IS_DEADDIR(dir))
- goto out_unlock;
-
- 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;
- }
-out_unlock:
- mutex_unlock(&dir->i_mutex);
- return result;
- }
-
- /*
- * Uhhuh! Nasty case: the cache was re-populated while
- * we waited on the semaphore. Need to revalidate.
- */
- mutex_unlock(&dir->i_mutex);
- if (result->d_op && result->d_op->d_revalidate) {
- result = do_revalidate(result, nd);
- if (!result)
- result = ERR_PTR(-ENOENT);
- }
- return result;
-}
-
-/*
- * 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.
- */
-static __always_inline int link_path_walk(const char *name, struct nameidata *nd)
-{
- struct path save = nd->path;
- int result;
-
- /* make sure the stuff we saved doesn't go away */
- path_get(&save);
-
- result = __link_path_walk(name, nd);
- if (result == -ESTALE) {
- /* nd->path had been dropped */
- nd->path = save;
- path_get(&nd->path);
- nd->flags |= LOOKUP_REVAL;
- result = __link_path_walk(name, nd);
- }
-
- path_put(&save);
-
- return result;
-}
-
static __always_inline void set_root(struct nameidata *nd)
{
if (!nd->root.mnt) {
@@ -569,6 +495,8 @@ static __always_inline void set_root(struct nameidata *nd)
}
}
+static int link_path_walk(const char *, struct nameidata *);
+
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
{
int res = 0;
@@ -641,11 +569,14 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata
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);
}
- path_put(path);
-
return error;
}
@@ -672,6 +603,7 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd)
current->total_link_count++;
nd->depth++;
err = __do_follow_link(path, nd);
+ path_put(path);
current->link_count--;
nd->depth--;
return err;
@@ -797,8 +729,19 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
struct path *path)
{
struct vfsmount *mnt = nd->path.mnt;
- struct dentry *dentry = __d_lookup(nd->path.dentry, name);
+ struct dentry *dentry, *parent;
+ struct inode *dir;
+ /*
+ * See if the low-level filesystem might want
+ * to use its own hash..
+ */
+ if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
+ int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name);
+ if (err < 0)
+ return err;
+ }
+ dentry = __d_lookup(nd->path.dentry, name);
if (!dentry)
goto need_lookup;
if (dentry->d_op && dentry->d_op->d_revalidate)
@@ -810,7 +753,59 @@ done:
return 0;
need_lookup:
- dentry = real_lookup(nd->path.dentry, name, nd);
+ parent = nd->path.dentry;
+ dir = parent->d_inode;
+
+ mutex_lock(&dir->i_mutex);
+ /*
+ * 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
+ */
+ dentry = d_lookup(parent, name);
+ if (!dentry) {
+ struct dentry *new;
+
+ /* Don't create child dentry for a dead directory. */
+ dentry = ERR_PTR(-ENOENT);
+ if (IS_DEADDIR(dir))
+ goto out_unlock;
+
+ new = d_alloc(parent, name);
+ dentry = ERR_PTR(-ENOMEM);
+ if (new) {
+ dentry = dir->i_op->lookup(dir, new, nd);
+ if (dentry)
+ dput(new);
+ else
+ dentry = new;
+ }
+out_unlock:
+ mutex_unlock(&dir->i_mutex);
+ if (IS_ERR(dentry))
+ goto fail;
+ goto done;
+ }
+
+ /*
+ * Uhhuh! Nasty case: the cache was re-populated while
+ * we waited on the semaphore. Need to revalidate.
+ */
+ mutex_unlock(&dir->i_mutex);
+ if (dentry->d_op && dentry->d_op->d_revalidate) {
+ dentry = do_revalidate(dentry, nd);
+ if (!dentry)
+ dentry = ERR_PTR(-ENOENT);
+ }
if (IS_ERR(dentry))
goto fail;
goto done;
@@ -835,7 +830,7 @@ fail:
* Returns 0 and nd will have valid dentry and mnt on success.
* Returns error and drops reference to input namei data on failure.
*/
-static int __link_path_walk(const char *name, struct nameidata *nd)
+static int link_path_walk(const char *name, struct nameidata *nd)
{
struct path next;
struct inode *inode;
@@ -858,7 +853,7 @@ static int __link_path_walk(const char *name, struct nameidata *nd)
unsigned int c;
nd->flags |= LOOKUP_CONTINUE;
- err = exec_permission_lite(inode);
+ err = exec_permission(inode);
if (err)
break;
@@ -898,16 +893,6 @@ static int __link_path_walk(const char *name, struct nameidata *nd)
case 1:
continue;
}
- /*
- * See if the low-level filesystem might want
- * to use its own hash..
- */
- if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
- err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
- &this);
- if (err < 0)
- break;
- }
/* This does the actual lookups.. */
err = do_lookup(nd, &this, &next);
if (err)
@@ -953,12 +938,6 @@ last_component:
case 1:
goto return_reval;
}
- if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
- err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
- &this);
- if (err < 0)
- break;
- }
err = do_lookup(nd, &this, &next);
if (err)
break;
@@ -1017,8 +996,27 @@ return_err:
static int path_walk(const char *name, struct nameidata *nd)
{
+ struct path save = nd->path;
+ int result;
+
current->total_link_count = 0;
- return link_path_walk(name, nd);
+
+ /* make sure the stuff we saved doesn't go away */
+ path_get(&save);
+
+ result = link_path_walk(name, nd);
+ if (result == -ESTALE) {
+ /* nd->path had been dropped */
+ current->total_link_count = 0;
+ nd->path = save;
+ path_get(&nd->path);
+ nd->flags |= LOOKUP_REVAL;
+ result = link_path_walk(name, nd);
+ }
+
+ path_put(&save);
+
+ return result;
}
static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
@@ -1141,36 +1139,6 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
return retval;
}
-/**
- * path_lookup_open - lookup a file path with open intent
- * @dfd: the directory to use as base, or AT_FDCWD
- * @name: pointer to file name
- * @lookup_flags: lookup intent flags
- * @nd: pointer to nameidata
- * @open_flags: open intent flags
- */
-static int path_lookup_open(int dfd, const char *name,
- unsigned int lookup_flags, struct nameidata *nd, int open_flags)
-{
- struct file *filp = get_empty_filp();
- int err;
-
- if (filp == NULL)
- return -ENFILE;
- nd->intent.open.file = filp;
- nd->intent.open.flags = open_flags;
- nd->intent.open.create_mode = 0;
- err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
- if (IS_ERR(nd->intent.open.file)) {
- if (err == 0) {
- err = PTR_ERR(nd->intent.open.file);
- path_put(&nd->path);
- }
- } else if (err != 0)
- release_open_intent(nd);
- return err;
-}
-
static struct dentry *__lookup_hash(struct qstr *name,
struct dentry *base, struct nameidata *nd)
{
@@ -1191,7 +1159,17 @@ static struct dentry *__lookup_hash(struct qstr *name,
goto out;
}
- dentry = cached_lookup(base, name, nd);
+ dentry = __d_lookup(base, 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(base, name);
+
+ if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
+ dentry = do_revalidate(dentry, nd);
+
if (!dentry) {
struct dentry *new;
@@ -1223,7 +1201,7 @@ static struct dentry *lookup_hash(struct nameidata *nd)
{
int err;
- err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC);
+ err = exec_permission(nd->path.dentry->d_inode);
if (err)
return ERR_PTR(err);
return __lookup_hash(&nd->last, nd->path.dentry, nd);
@@ -1273,7 +1251,7 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
if (err)
return ERR_PTR(err);
- err = inode_permission(base->d_inode, MAY_EXEC);
+ err = exec_permission(base->d_inode);
if (err)
return ERR_PTR(err);
return __lookup_hash(&this, base, NULL);
@@ -1511,69 +1489,45 @@ int may_open(struct path *path, int acc_mode, int flag)
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;
}
@@ -1628,7 +1582,7 @@ static inline int open_to_namei_flags(int flag)
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
@@ -1650,10 +1604,10 @@ struct file *do_filp_open(int dfd, const char *pathname,
struct file *filp;
struct nameidata nd;
int error;
- struct path path;
+ struct path path, save;
struct dentry *dir;
int count = 0;
- int will_write;
+ int will_truncate;
int flag = open_to_namei_flags(open_flag);
/*
@@ -1681,8 +1635,22 @@ struct file *do_filp_open(int dfd, const char *pathname,
* The simplest case - just a plain lookup.
*/
if (!(flag & O_CREAT)) {
- error = path_lookup_open(dfd, pathname, lookup_flags(flag),
- &nd, flag);
+ filp = get_empty_filp();
+
+ if (filp == NULL)
+ return ERR_PTR(-ENFILE);
+ nd.intent.open.file = filp;
+ nd.intent.open.flags = flag;
+ nd.intent.open.create_mode = 0;
+ error = do_path_lookup(dfd, pathname,
+ lookup_flags(flag)|LOOKUP_OPEN, &nd);
+ if (IS_ERR(nd.intent.open.file)) {
+ if (error == 0) {
+ error = PTR_ERR(nd.intent.open.file);
+ path_put(&nd.path);
+ }
+ } else if (error)
+ release_open_intent(&nd);
if (error)
return ERR_PTR(error);
goto ok;
@@ -1758,13 +1726,17 @@ do_last:
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));
mnt_drop_write(nd.path.mnt);
if (nd.root.mnt)
path_put(&nd.root);
+ if (!IS_ERR(filp)) {
+ error = ima_path_check(&filp->f_path, filp->f_mode &
+ (MAY_READ | MAY_WRITE | MAY_EXEC));
+ if (error) {
+ fput(filp);
+ filp = ERR_PTR(error);
+ }
+ }
return filp;
}
@@ -1805,28 +1777,45 @@ 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));
+ if (!IS_ERR(filp)) {
+ error = ima_path_check(&filp->f_path, filp->f_mode &
+ (MAY_READ | MAY_WRITE | MAY_EXEC));
+ 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);
@@ -1863,7 +1852,18 @@ do_link:
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
* me so stupid? Anathema to whoever designed this non-sense