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-rw-r--r--fs/open.c59
1 files changed, 27 insertions, 32 deletions
diff --git a/fs/open.c b/fs/open.c
index 83cdb9dee0c1..c0a426d5766c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -425,39 +425,33 @@ out:
*/
asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
{
+ const struct cred *old_cred;
+ struct cred *override_cred;
struct path path;
struct inode *inode;
- int old_fsuid, old_fsgid;
- kernel_cap_t uninitialized_var(old_cap); /* !SECURE_NO_SETUID_FIXUP */
int res;
if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
return -EINVAL;
- old_fsuid = current->fsuid;
- old_fsgid = current->fsgid;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ return -ENOMEM;
- current->fsuid = current->uid;
- current->fsgid = current->gid;
+ override_cred->fsuid = override_cred->uid;
+ override_cred->fsgid = override_cred->gid;
if (!issecure(SECURE_NO_SETUID_FIXUP)) {
- /*
- * Clear the capabilities if we switch to a non-root user
- */
-#ifndef CONFIG_SECURITY_FILE_CAPABILITIES
- /*
- * FIXME: There is a race here against sys_capset. The
- * capabilities can change yet we will restore the old
- * value below. We should hold task_capabilities_lock,
- * but we cannot because user_path_at can sleep.
- */
-#endif /* ndef CONFIG_SECURITY_FILE_CAPABILITIES */
- if (current->uid)
- old_cap = cap_set_effective(__cap_empty_set);
+ /* Clear the capabilities if we switch to a non-root user */
+ if (override_cred->uid)
+ cap_clear(override_cred->cap_effective);
else
- old_cap = cap_set_effective(current->cap_permitted);
+ override_cred->cap_effective =
+ override_cred->cap_permitted;
}
+ old_cred = override_creds(override_cred);
+
res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
if (res)
goto out;
@@ -494,12 +488,8 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
out_path_release:
path_put(&path);
out:
- current->fsuid = old_fsuid;
- current->fsgid = old_fsgid;
-
- if (!issecure(SECURE_NO_SETUID_FIXUP))
- cap_set_effective(old_cap);
-
+ revert_creds(old_cred);
+ put_cred(override_cred);
return res;
}
@@ -792,7 +782,8 @@ static inline int __get_file_write_access(struct inode *inode,
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
int flags, struct file *f,
- int (*open)(struct inode *, struct file *))
+ int (*open)(struct inode *, struct file *),
+ const struct cred *cred)
{
struct inode *inode;
int error;
@@ -816,7 +807,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_op = fops_get(inode->i_fop);
file_move(f, &inode->i_sb->s_files);
- error = security_dentry_open(f);
+ error = security_dentry_open(f, cred);
if (error)
goto cleanup_all;
@@ -891,6 +882,8 @@ cleanup_file:
struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
int (*open)(struct inode *, struct file *))
{
+ const struct cred *cred = current_cred();
+
if (IS_ERR(nd->intent.open.file))
goto out;
if (IS_ERR(dentry))
@@ -898,7 +891,7 @@ struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry
nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
nd->intent.open.flags - 1,
nd->intent.open.file,
- open);
+ open, cred);
out:
return nd->intent.open.file;
out_err:
@@ -917,6 +910,7 @@ EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
*/
struct file *nameidata_to_filp(struct nameidata *nd, int flags)
{
+ const struct cred *cred = current_cred();
struct file *filp;
/* Pick up the filp from the open intent */
@@ -924,7 +918,7 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
/* Has the filesystem initialised the file for us? */
if (filp->f_path.dentry == NULL)
filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
- NULL);
+ NULL, cred);
else
path_put(&nd->path);
return filp;
@@ -934,7 +928,8 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
* dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
* error.
*/
-struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
+struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
+ const struct cred *cred)
{
int error;
struct file *f;
@@ -959,7 +954,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
return ERR_PTR(error);
}
- return __dentry_open(dentry, mnt, flags, f, NULL);
+ return __dentry_open(dentry, mnt, flags, f, NULL, cred);
}
EXPORT_SYMBOL(dentry_open);