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-rw-r--r--fs/fhandle.c64
-rw-r--r--fs/internal.h1
-rw-r--r--fs/pidfs.c11
-rw-r--r--include/uapi/linux/fcntl.h18
-rw-r--r--include/uapi/linux/pidfd.h15
-rw-r--r--tools/testing/selftests/pidfd/Makefile2
-rw-r--r--tools/testing/selftests/pidfd/pidfd.h6
-rw-r--r--tools/testing/selftests/pidfd/pidfd_file_handle_test.c60
8 files changed, 129 insertions, 48 deletions
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 3e092ae6d142..b1363ead6c5e 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -88,7 +88,7 @@ static long do_sys_name_to_handle(const struct path *path,
if (fh_flags & EXPORT_FH_CONNECTABLE) {
handle->handle_type |= FILEID_IS_CONNECTABLE;
if (d_is_dir(path->dentry))
- fh_flags |= FILEID_IS_DIR;
+ handle->handle_type |= FILEID_IS_DIR;
}
retval = 0;
}
@@ -168,23 +168,32 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
return err;
}
-static int get_path_from_fd(int fd, struct path *root)
+static int get_path_anchor(int fd, struct path *root)
{
+ if (fd >= 0) {
+ CLASS(fd, f)(fd);
+ if (fd_empty(f))
+ return -EBADF;
+ *root = fd_file(f)->f_path;
+ path_get(root);
+ return 0;
+ }
+
if (fd == AT_FDCWD) {
struct fs_struct *fs = current->fs;
spin_lock(&fs->lock);
*root = fs->pwd;
path_get(root);
spin_unlock(&fs->lock);
- } else {
- CLASS(fd, f)(fd);
- if (fd_empty(f))
- return -EBADF;
- *root = fd_file(f)->f_path;
- path_get(root);
+ return 0;
}
- return 0;
+ if (fd == FD_PIDFS_ROOT) {
+ pidfs_get_root(root);
+ return 0;
+ }
+
+ return -EBADF;
}
static int vfs_dentry_acceptable(void *context, struct dentry *dentry)
@@ -323,13 +332,24 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
{
int retval = 0;
struct file_handle f_handle;
- struct file_handle *handle = NULL;
+ struct file_handle *handle __free(kfree) = NULL;
struct handle_to_path_ctx ctx = {};
const struct export_operations *eops;
- retval = get_path_from_fd(mountdirfd, &ctx.root);
+ if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle)))
+ return -EFAULT;
+
+ if ((f_handle.handle_bytes > MAX_HANDLE_SZ) ||
+ (f_handle.handle_bytes == 0))
+ return -EINVAL;
+
+ if (f_handle.handle_type < 0 ||
+ FILEID_USER_FLAGS(f_handle.handle_type) & ~FILEID_VALID_USER_FLAGS)
+ return -EINVAL;
+
+ retval = get_path_anchor(mountdirfd, &ctx.root);
if (retval)
- goto out_err;
+ return retval;
eops = ctx.root.mnt->mnt_sb->s_export_op;
if (eops && eops->permission)
@@ -339,21 +359,6 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
if (retval)
goto out_path;
- if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) {
- retval = -EFAULT;
- goto out_path;
- }
- if ((f_handle.handle_bytes > MAX_HANDLE_SZ) ||
- (f_handle.handle_bytes == 0)) {
- retval = -EINVAL;
- goto out_path;
- }
- if (f_handle.handle_type < 0 ||
- FILEID_USER_FLAGS(f_handle.handle_type) & ~FILEID_VALID_USER_FLAGS) {
- retval = -EINVAL;
- goto out_path;
- }
-
handle = kmalloc(struct_size(handle, f_handle, f_handle.handle_bytes),
GFP_KERNEL);
if (!handle) {
@@ -366,7 +371,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
&ufh->f_handle,
f_handle.handle_bytes)) {
retval = -EFAULT;
- goto out_handle;
+ goto out_path;
}
/*
@@ -384,11 +389,8 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
handle->handle_type &= ~FILEID_USER_FLAGS_MASK;
retval = do_handle_to_path(handle, path, &ctx);
-out_handle:
- kfree(handle);
out_path:
path_put(&ctx.root);
-out_err:
return retval;
}
diff --git a/fs/internal.h b/fs/internal.h
index 22ba066d1dba..ad256bccdc85 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -353,3 +353,4 @@ int anon_inode_getattr(struct mnt_idmap *idmap, const struct path *path,
unsigned int query_flags);
int anon_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
struct iattr *attr);
+void pidfs_get_root(struct path *path);
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 47f5f9e0bdff..4fc7a7f4a3fe 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -31,6 +31,14 @@
static struct kmem_cache *pidfs_attr_cachep __ro_after_init;
static struct kmem_cache *pidfs_xattr_cachep __ro_after_init;
+static struct path pidfs_root_path = {};
+
+void pidfs_get_root(struct path *path)
+{
+ *path = pidfs_root_path;
+ path_get(path);
+}
+
/*
* Stashes information that userspace needs to access even after the
* process has been reaped.
@@ -1068,4 +1076,7 @@ void __init pidfs_init(void)
pidfs_mnt = kern_mount(&pidfs_type);
if (IS_ERR(pidfs_mnt))
panic("Failed to mount pidfs pseudo filesystem");
+
+ pidfs_root_path.mnt = pidfs_mnt;
+ pidfs_root_path.dentry = pidfs_mnt->mnt_root;
}
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index a15ac2fa4b20..f291ab4f94eb 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -90,10 +90,28 @@
#define DN_ATTRIB 0x00000020 /* File changed attibutes */
#define DN_MULTISHOT 0x80000000 /* Don't remove notifier */
+/* Reserved kernel ranges [-100], [-10000, -40000]. */
#define AT_FDCWD -100 /* Special value for dirfd used to
indicate openat should use the
current working directory. */
+/*
+ * The concept of process and threads in userland and the kernel is a confusing
+ * one - within the kernel every thread is a 'task' with its own individual PID,
+ * however from userland's point of view threads are grouped by a single PID,
+ * which is that of the 'thread group leader', typically the first thread
+ * spawned.
+ *
+ * To cut the Gideon knot, for internal kernel usage, we refer to
+ * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel
+ * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread
+ * group leader...
+ */
+#define PIDFD_SELF_THREAD -10000 /* Current thread. */
+#define PIDFD_SELF_THREAD_GROUP -10001 /* Current thread group leader. */
+
+#define FD_PIDFS_ROOT -10002 /* Root of the pidfs filesystem */
+#define FD_INVALID -10009 /* Invalid file descriptor: -10000 - EBADF = -10009 */
/* Generic flags for the *at(2) family of syscalls. */
diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h
index c27a4e238e4b..957db425d459 100644
--- a/include/uapi/linux/pidfd.h
+++ b/include/uapi/linux/pidfd.h
@@ -43,21 +43,6 @@
#define PIDFD_COREDUMP_ROOT (1U << 3) /* coredump was done as root. */
/*
- * The concept of process and threads in userland and the kernel is a confusing
- * one - within the kernel every thread is a 'task' with its own individual PID,
- * however from userland's point of view threads are grouped by a single PID,
- * which is that of the 'thread group leader', typically the first thread
- * spawned.
- *
- * To cut the Gideon knot, for internal kernel usage, we refer to
- * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel
- * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread
- * group leader...
- */
-#define PIDFD_SELF_THREAD -10000 /* Current thread. */
-#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */
-
-/*
* ...and for userland we make life simpler - PIDFD_SELF refers to the current
* thread, PIDFD_SELF_PROCESS refers to the process thread group leader.
*
diff --git a/tools/testing/selftests/pidfd/Makefile b/tools/testing/selftests/pidfd/Makefile
index 03a6eede9c9e..764a8f9ecefa 100644
--- a/tools/testing/selftests/pidfd/Makefile
+++ b/tools/testing/selftests/pidfd/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
-CFLAGS += -g $(KHDR_INCLUDES) -pthread -Wall
+CFLAGS += -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) -pthread -Wall
TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test \
pidfd_poll_test pidfd_wait pidfd_getfd_test pidfd_setns_test \
diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h
index efd74063126e..cd244d0860ff 100644
--- a/tools/testing/selftests/pidfd/pidfd.h
+++ b/tools/testing/selftests/pidfd/pidfd.h
@@ -19,6 +19,10 @@
#include "../kselftest.h"
#include "../clone3/clone3_selftests.h"
+#ifndef FD_PIDFS_ROOT
+#define FD_PIDFS_ROOT -10002
+#endif
+
#ifndef P_PIDFD
#define P_PIDFD 3
#endif
@@ -56,7 +60,7 @@
#endif
#ifndef PIDFD_SELF_THREAD_GROUP
-#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */
+#define PIDFD_SELF_THREAD_GROUP -10001 /* Current thread group leader. */
#endif
#ifndef PIDFD_SELF
diff --git a/tools/testing/selftests/pidfd/pidfd_file_handle_test.c b/tools/testing/selftests/pidfd/pidfd_file_handle_test.c
index 439b9c6c0457..6bd2e9c9565b 100644
--- a/tools/testing/selftests/pidfd/pidfd_file_handle_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_file_handle_test.c
@@ -500,4 +500,64 @@ TEST_F(file_handle, valid_name_to_handle_at_flags)
ASSERT_EQ(close(pidfd), 0);
}
+/*
+ * That we decode a file handle without having to pass a pidfd.
+ */
+TEST_F(file_handle, decode_purely_based_on_file_handle)
+{
+ int mnt_id;
+ struct file_handle *fh;
+ int pidfd = -EBADF;
+ struct stat st1, st2;
+
+ fh = malloc(sizeof(struct file_handle) + MAX_HANDLE_SZ);
+ ASSERT_NE(fh, NULL);
+ memset(fh, 0, sizeof(struct file_handle) + MAX_HANDLE_SZ);
+ fh->handle_bytes = MAX_HANDLE_SZ;
+
+ ASSERT_EQ(name_to_handle_at(self->child_pidfd1, "", fh, &mnt_id, AT_EMPTY_PATH), 0);
+
+ ASSERT_EQ(fstat(self->child_pidfd1, &st1), 0);
+
+ pidfd = open_by_handle_at(FD_PIDFS_ROOT, fh, 0);
+ ASSERT_GE(pidfd, 0);
+
+ ASSERT_EQ(fstat(pidfd, &st2), 0);
+ ASSERT_TRUE(st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);
+
+ ASSERT_EQ(close(pidfd), 0);
+
+ pidfd = open_by_handle_at(FD_PIDFS_ROOT, fh, O_CLOEXEC);
+ ASSERT_GE(pidfd, 0);
+
+ ASSERT_EQ(fstat(pidfd, &st2), 0);
+ ASSERT_TRUE(st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);
+
+ ASSERT_EQ(close(pidfd), 0);
+
+ pidfd = open_by_handle_at(FD_PIDFS_ROOT, fh, O_NONBLOCK);
+ ASSERT_GE(pidfd, 0);
+
+ ASSERT_EQ(fstat(pidfd, &st2), 0);
+ ASSERT_TRUE(st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);
+
+ ASSERT_EQ(close(pidfd), 0);
+
+ pidfd = open_by_handle_at(self->pidfd, fh, 0);
+ ASSERT_GE(pidfd, 0);
+
+ ASSERT_EQ(fstat(pidfd, &st2), 0);
+ ASSERT_TRUE(st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);
+
+ ASSERT_EQ(close(pidfd), 0);
+
+ pidfd = open_by_handle_at(-EBADF, fh, 0);
+ ASSERT_LT(pidfd, 0);
+
+ pidfd = open_by_handle_at(AT_FDCWD, fh, 0);
+ ASSERT_LT(pidfd, 0);
+
+ free(fh);
+}
+
TEST_HARNESS_MAIN
generated by cgit v1.2.3 (git 2.39.1) at 2026-01-03 01:41:22 +0000