Date: Tue, 03 Sep 2019 14:06:18 -0000 From: Alan Somers <asomers@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r345958 - in projects/fuse2: sys/fs/fuse tests/sys/fs/fusefs Message-ID: <201904051721.x35HLNIX020006@repo.freebsd.org>
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Author: asomers Date: Fri Apr 5 17:21:23 2019 New Revision: 345958 URL: https://svnweb.freebsd.org/changeset/base/345958 Log: fusefs: enforce -onoallow_other even beneath the mountpoint When -o allow_other is not in use, fusefs is supposed to prevent access to the filesystem by any user other than the one who owns the daemon. Our fusefs implementation was only enforcing that restriction at the mountpoint itself. That was usually good enough because lookup usually descends from the mountpoint. However, there are cases when it doesn't, such as when using openat relative to a file beneath the mountpoint. PR: 237052 Sponsored by: The FreeBSD Foundation Modified: projects/fuse2/sys/fs/fuse/fuse_internal.c projects/fuse2/tests/sys/fs/fusefs/allow_other.cc Modified: projects/fuse2/sys/fs/fuse/fuse_internal.c ============================================================================== --- projects/fuse2/sys/fs/fuse/fuse_internal.c Fri Apr 5 16:54:20 2019 (r345957) +++ projects/fuse2/sys/fs/fuse/fuse_internal.c Fri Apr 5 17:21:23 2019 (r345958) @@ -140,7 +140,7 @@ fuse_internal_access(struct vnode *vp, return EROFS; } /* Unless explicitly permitted, deny everyone except the fs owner. */ - if (vnode_isvroot(vp) && !(facp->facc_flags & FACCESS_NOCHECKSPY)) { + if (!(facp->facc_flags & FACCESS_NOCHECKSPY)) { if (!(dataflags & FSESS_DAEMON_CAN_SPY)) { int denied = fuse_match_cred(data->daemoncred, cred); @@ -149,6 +149,10 @@ fuse_internal_access(struct vnode *vp, return EPERM; } } + /* + * Set the "skip cred check" flag so future callers that share + * facp can skip fuse_match_cred. + */ facp->facc_flags |= FACCESS_NOCHECKSPY; } if (!(facp->facc_flags & FACCESS_DO_ACCESS)) { Modified: projects/fuse2/tests/sys/fs/fusefs/allow_other.cc ============================================================================== --- projects/fuse2/tests/sys/fs/fusefs/allow_other.cc Fri Apr 5 16:54:20 2019 (r345957) +++ projects/fuse2/tests/sys/fs/fusefs/allow_other.cc Fri Apr 5 17:21:23 2019 (r345958) @@ -179,3 +179,48 @@ TEST_F(NoAllowOther, disallowed) } ); } + +/* + * When -o allow_other is not used, users other than the owner aren't allowed + * to open anything inside of the mount point, not just the mountpoint itself + * This is a regression test for bug 237052 + */ +TEST_F(NoAllowOther, disallowed_beneath_root) +{ + const static char FULLPATH[] = "mountpoint/some_dir"; + const static char RELPATH[] = "some_dir"; + const static char RELPATH2[] = "other_dir"; + const static uint64_t ino = 42; + const static uint64_t ino2 = 43; + int dfd; + + expect_lookup(RELPATH, ino, S_IFDIR | 0755, 0, 1); + EXPECT_LOOKUP(ino, RELPATH2) + .WillRepeatedly(Invoke(ReturnImmediate([=](auto in __unused, auto out) { + SET_OUT_HEADER_LEN(out, entry); + out->body.entry.attr.mode = S_IFREG | 0644; + out->body.entry.nodeid = ino2; + out->body.entry.attr.nlink = 1; + out->body.entry.attr_valid = UINT64_MAX; + }))); + expect_opendir(ino); + dfd = open(FULLPATH, O_DIRECTORY); + ASSERT_LE(0, dfd) << strerror(errno); + + fork(true, [] { + }, [&]() { + int fd; + + fd = openat(dfd, RELPATH2, O_RDONLY); + if (fd >= 0) { + fprintf(stderr, "openat should've failed\n"); + return(1); + } else if (errno != EPERM) { + fprintf(stderr, "Unexpected error: %s\n", + strerror(errno)); + return(1); + } + return 0; + } + ); +}
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