From 155ac516c60f20573d15c54bafabfd0e52d21fa6 Mon Sep 17 00:00:00 2001 From: Alan Somers Date: Fri, 15 Apr 2022 13:04:24 -0600 Subject: [PATCH] fusefs: validate servers' error values Formerly fusefs would pass up the stack any error value returned by the fuse server. However, some values aren't valid for userland, but have special meanings within the kernel. One of these, EJUSTRETURN, could cause a kernel page fault if the server returned it in response to FUSE_LOOKUP. Fix by validating all errors returned by the server. Also, fix a data lifetime bug in the FUSE_DESTROY test. PR: 263220 Reported by: Robert Morris MFC after: 3 weeks Sponsored by: Axcient Reviewed by: emaste Differential Revision: https://reviews.freebsd.org/D34931 --- sys/fs/fuse/fuse_device.c | 14 ++++++++++++-- tests/sys/fs/fusefs/lookup.cc | 21 +++++++++++++++++++++ tests/sys/fs/fusefs/mockfs.cc | 9 ++++++++- tests/sys/fs/fusefs/mockfs.hh | 3 +++ tests/sys/fs/fusefs/utils.cc | 2 +- 5 files changed, 45 insertions(+), 4 deletions(-) diff --git a/sys/fs/fuse/fuse_device.c b/sys/fs/fuse/fuse_device.c index 157c3802ec7..7d1afb88edb 100644 --- a/sys/fs/fuse/fuse_device.c +++ b/sys/fs/fuse/fuse_device.c @@ -518,8 +518,18 @@ fuse_device_write(struct cdev *dev, struct uio *uio, int ioflag) "pass ticket to a callback"); /* Sanitize the linuxism of negative errnos */ ohead.error *= -1; - memcpy(&tick->tk_aw_ohead, &ohead, sizeof(ohead)); - err = tick->tk_aw_handler(tick, uio); + if (ohead.error < 0 || ohead.error > ELAST) { + /* Illegal error code */ + ohead.error = EIO; + memcpy(&tick->tk_aw_ohead, &ohead, + sizeof(ohead)); + tick->tk_aw_handler(tick, uio); + err = EINVAL; + } else { + memcpy(&tick->tk_aw_ohead, &ohead, + sizeof(ohead)); + err = tick->tk_aw_handler(tick, uio); + } } else { /* pretender doesn't wanna do anything with answer */ SDT_PROBE2(fusefs, , device, trace, 1, diff --git a/tests/sys/fs/fusefs/lookup.cc b/tests/sys/fs/fusefs/lookup.cc index 32e2a08eb94..0ec02913f66 100644 --- a/tests/sys/fs/fusefs/lookup.cc +++ b/tests/sys/fs/fusefs/lookup.cc @@ -276,6 +276,27 @@ TEST_F(Lookup, dotdot_no_parent_nid) EXPECT_EQ(ESTALE, errno); } +/* + * A daemon that returns an illegal error value should be handled gracefully. + * Regression test for https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=263220 + */ +TEST_F(Lookup, ejustreturn) +{ + const char FULLPATH[] = "mountpoint/does_not_exist"; + const char RELPATH[] = "does_not_exist"; + + EXPECT_LOOKUP(FUSE_ROOT_ID, RELPATH) + .WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto& out) { + out.header.len = sizeof(out.header); + out.header.error = 2; + m_mock->m_expected_write_errno = EINVAL; + }))); + + EXPECT_NE(0, access(FULLPATH, F_OK)); + + EXPECT_EQ(EIO, errno); +} + TEST_F(Lookup, enoent) { const char FULLPATH[] = "mountpoint/does_not_exist"; diff --git a/tests/sys/fs/fusefs/mockfs.cc b/tests/sys/fs/fusefs/mockfs.cc index 231f46b18ab..ddfb5527ef1 100644 --- a/tests/sys/fs/fusefs/mockfs.cc +++ b/tests/sys/fs/fusefs/mockfs.cc @@ -418,6 +418,7 @@ MockFS::MockFS(int max_readahead, bool allow_other, bool default_permissions, const bool trueval = true; m_daemon_id = NULL; + m_expected_write_errno = 0; m_kernel_minor_version = kernel_minor_version; m_maxreadahead = max_readahead; m_maxwrite = MIN(max_write, max_max_write); @@ -779,6 +780,7 @@ void MockFS::loop() { bzero(in.get(), sizeof(*in)); read_request(*in, buflen); + m_expected_write_errno = 0; if (m_quit) break; if (verbosity > 0) @@ -1011,7 +1013,12 @@ void MockFS::write_response(const mockfs_buf_out &out) { FAIL() << "not yet implemented"; } r = write(m_fuse_fd, &out, out.header.len); - ASSERT_TRUE(r > 0 || errno == EAGAIN) << strerror(errno); + if (m_expected_write_errno) { + ASSERT_EQ(-1, r); + ASSERT_EQ(m_expected_write_errno, errno) << strerror(errno); + } else { + ASSERT_TRUE(r > 0 || errno == EAGAIN) << strerror(errno); + } } void* MockFS::service(void *pthr_data) { diff --git a/tests/sys/fs/fusefs/mockfs.hh b/tests/sys/fs/fusefs/mockfs.hh index e35f2efb8da..d471491ea45 100644 --- a/tests/sys/fs/fusefs/mockfs.hh +++ b/tests/sys/fs/fusefs/mockfs.hh @@ -340,6 +340,9 @@ class MockFS { /* pid of child process, for two-process test cases */ pid_t m_child_pid; + /* the expected errno of the next write to /dev/fuse */ + int m_expected_write_errno; + /* Maximum size of a FUSE_WRITE write */ uint32_t m_maxwrite; diff --git a/tests/sys/fs/fusefs/utils.cc b/tests/sys/fs/fusefs/utils.cc index 508c3af2828..65738f4b19a 100644 --- a/tests/sys/fs/fusefs/utils.cc +++ b/tests/sys/fs/fusefs/utils.cc @@ -217,7 +217,7 @@ FuseTest::expect_destroy(int error) return (in.header.opcode == FUSE_DESTROY); }, Eq(true)), _) - ).WillOnce(Invoke( ReturnImmediate([&](auto in, auto& out) { + ).WillOnce(Invoke(ReturnImmediate([=](auto in, auto& out) { m_mock->m_quit = true; out.header.len = sizeof(out.header); out.header.unique = in.header.unique; -- 2.45.0