/*
* This does basic POSIX ACL permission checking
*/
-static int acl_permission_check(struct inode *inode, int mask, unsigned int flags,
- int (*check_acl)(struct inode *inode, int mask, unsigned int flags))
+static int acl_permission_check(struct inode *inode, int mask)
{
+ int (*check_acl)(struct inode *inode, int mask);
unsigned int mode = inode->i_mode;
- mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
+ mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
if (current_user_ns() != inode_userns(inode))
goto other_perms;
if (current_fsuid() == inode->i_uid)
mode >>= 6;
else {
+ check_acl = inode->i_op->check_acl;
if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
- int error = check_acl(inode, mask, flags);
+ int error = check_acl(inode, mask);
if (error != -EAGAIN)
return error;
}
/*
* If the DACs are ok we don't need any capability check.
*/
- if ((mask & ~mode) == 0)
+ if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
return 0;
return -EACCES;
}
* 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
* @flags: IPERM_FLAG_ flags.
*
* Used to check for read/write/execute permissions on a file.
* request cannot be satisfied (eg. requires blocking or too much complexity).
* It would then be called again in ref-walk mode.
*/
-int generic_permission(struct inode *inode, int mask, unsigned int flags,
- int (*check_acl)(struct inode *inode, int mask, unsigned int flags))
+int generic_permission(struct inode *inode, int mask)
{
int ret;
/*
* Do the basic POSIX ACL permission checks.
*/
- ret = acl_permission_check(inode, mask, flags, check_acl);
+ ret = acl_permission_check(inode, mask);
if (ret != -EACCES)
return ret;
+ if (S_ISDIR(inode->i_mode)) {
+ /* DACs are overridable for directories */
+ if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
+ return 0;
+ if (!(mask & MAY_WRITE))
+ if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
+ return 0;
+ return -EACCES;
+ }
/*
* Read/write DACs are always overridable.
- * Executable DACs are overridable if at least one exec bit is set.
+ * Executable DACs are overridable when there is
+ * at least one exec bit set.
*/
- if (!(mask & MAY_EXEC) || execute_ok(inode))
+ if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
return 0;
* 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 (mask == MAY_READ)
if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
return 0;
}
if (inode->i_op->permission)
- retval = inode->i_op->permission(inode, mask, 0);
+ retval = inode->i_op->permission(inode, mask);
else
- retval = generic_permission(inode, mask, 0,
- inode->i_op->check_acl);
+ retval = generic_permission(inode, mask);
if (retval)
return retval;
return security_inode_permission(inode, mask);
}
-/**
- * file_permission - check for additional access rights to a given file
- * @file: file to check access rights for
- * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
- *
- * Used to check for read/write/execute permissions on an already opened
- * file.
- *
- * Note:
- * Do not use this function in new code. All access checks should
- * be done using inode_permission().
- */
-int file_permission(struct file *file, int mask)
-{
- return inode_permission(file->f_path.dentry->d_inode, mask);
-}
-
-/*
- * 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_path.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;
-}
-
/**
* path_get - get a reference to a path
* @path: path to get the reference to
goto err_parent;
BUG_ON(nd->inode != parent->d_inode);
} else {
+ if (dentry->d_parent != parent)
+ goto err_parent;
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
if (!__d_rcu_to_refcount(dentry, nd->seq))
goto err_child;
return dentry->d_op->d_revalidate(dentry, nd);
}
-static struct dentry *
-do_revalidate(struct dentry *dentry, struct nameidata *nd)
-{
- int status = d_revalidate(dentry, nd);
- if (unlikely(status <= 0)) {
- /*
- * The dentry failed validation.
- * If d_revalidate returned 0 attempt to invalidate
- * the dentry otherwise d_revalidate is asking us
- * to return a fail status.
- */
- if (status < 0) {
- dput(dentry);
- dentry = ERR_PTR(status);
- } else if (!d_invalidate(dentry)) {
- dput(dentry);
- dentry = NULL;
- }
- }
- return dentry;
-}
-
/**
* complete_walk - successful completion of path walk
* @nd: pointer nameidata
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.
- *
- * 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(struct inode *inode, unsigned int flags)
-{
- int ret;
- struct user_namespace *ns = inode_userns(inode);
-
- if (inode->i_op->permission) {
- ret = inode->i_op->permission(inode, MAY_EXEC, flags);
- } else {
- ret = acl_permission_check(inode, MAY_EXEC, flags,
- inode->i_op->check_acl);
- }
- if (likely(!ret))
- goto ok;
- if (ret == -ECHILD)
- return ret;
-
- if (ns_capable(ns, CAP_DAC_OVERRIDE) ||
- ns_capable(ns, CAP_DAC_READ_SEARCH))
- goto ok;
-
- return ret;
-ok:
- return security_inode_exec_permission(inode, flags);
-}
-
static __always_inline void set_root(struct nameidata *nd)
{
if (!nd->root.mnt)
* Don't forget we might have a non-mountpoint managed dentry
* that wants to block transit.
*/
- *inode = path->dentry->d_inode;
if (unlikely(managed_dentry_might_block(path->dentry)))
return false;
path->mnt = mounted;
path->dentry = mounted->mnt_root;
nd->seq = read_seqcount_begin(&path->dentry->d_seq);
+ /*
+ * Update the inode too. We don't need to re-check the
+ * dentry sequence number here after this d_inode read,
+ * because a mount-point is always pinned.
+ */
+ *inode = path->dentry->d_inode;
}
return true;
}
* Follow down to the covering mount currently visible to userspace. At each
* point, the filesystem owning that dentry may be queried as to whether the
* caller is permitted to proceed or not.
- *
- * Care must be taken as namespace_sem may be held (indicated by mounting_here
- * being true).
*/
int follow_down(struct path *path)
{
return dentry;
}
+/*
+ * We already have a dentry, but require a lookup to be performed on the parent
+ * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
+ * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
+ * child exists while under i_mutex.
+ */
+static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct inode *inode = parent->d_inode;
+ struct dentry *old;
+
+ /* Don't create child dentry for a dead directory. */
+ if (unlikely(IS_DEADDIR(inode)))
+ return ERR_PTR(-ENOENT);
+
+ old = inode->i_op->lookup(inode, dentry, nd);
+ if (unlikely(old)) {
+ dput(dentry);
+ dentry = old;
+ }
+ return 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.
goto unlazy;
}
}
+ if (unlikely(d_need_lookup(dentry)))
+ goto unlazy;
path->mnt = mnt;
path->dentry = dentry;
if (unlikely(!__follow_mount_rcu(nd, path, inode)))
dentry = __d_lookup(parent, name);
}
+ if (dentry && unlikely(d_need_lookup(dentry))) {
+ dput(dentry);
+ dentry = NULL;
+ }
retry:
if (unlikely(!dentry)) {
struct inode *dir = parent->d_inode;
/* known good */
need_reval = 0;
status = 1;
+ } else if (unlikely(d_need_lookup(dentry))) {
+ dentry = d_inode_lookup(parent, dentry, nd);
+ if (IS_ERR(dentry)) {
+ mutex_unlock(&dir->i_mutex);
+ return PTR_ERR(dentry);
+ }
+ /* known good */
+ need_reval = 0;
+ status = 1;
}
mutex_unlock(&dir->i_mutex);
}
static inline int may_lookup(struct nameidata *nd)
{
if (nd->flags & LOOKUP_RCU) {
- int err = exec_permission(nd->inode, IPERM_FLAG_RCU);
+ int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
if (err != -ECHILD)
return err;
if (unlazy_walk(nd, NULL))
return -ECHILD;
}
- return exec_permission(nd->inode, 0);
+ return inode_permission(nd->inode, MAY_EXEC);
}
static inline int handle_dots(struct nameidata *nd, int type)
if (!S_ISDIR(dentry->d_inode->i_mode))
goto fput_fail;
- retval = file_permission(file, MAY_EXEC);
+ retval = inode_permission(dentry->d_inode, MAY_EXEC);
if (retval)
goto fput_fail;
}
struct dentry *dentry;
int err;
- err = exec_permission(inode, 0);
+ err = inode_permission(inode, MAY_EXEC);
if (err)
return ERR_PTR(err);
*/
dentry = d_lookup(base, name);
- if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE))
- dentry = do_revalidate(dentry, nd);
+ if (dentry && d_need_lookup(dentry)) {
+ /*
+ * __lookup_hash is called with the parent dir's i_mutex already
+ * held, so we are good to go here.
+ */
+ dentry = d_inode_lookup(base, dentry, nd);
+ if (IS_ERR(dentry))
+ return dentry;
+ }
+
+ if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+ int status = d_revalidate(dentry, nd);
+ if (unlikely(status <= 0)) {
+ /*
+ * The dentry failed validation.
+ * If d_revalidate returned 0 attempt to invalidate
+ * the dentry otherwise d_revalidate is asking us
+ * to return a fail status.
+ */
+ if (status < 0) {
+ dput(dentry);
+ return ERR_PTR(status);
+ } else if (!d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ }
+ }
if (!dentry)
dentry = d_alloc_and_lookup(base, name, nd);
EXPORT_SYMBOL(kern_path);
EXPORT_SYMBOL(vfs_path_lookup);
EXPORT_SYMBOL(inode_permission);
-EXPORT_SYMBOL(file_permission);
EXPORT_SYMBOL(unlock_rename);
EXPORT_SYMBOL(vfs_create);
EXPORT_SYMBOL(vfs_follow_link);
git.openpandora.org / pandora-kernel.git / blobdiff