Date: Tue, 7 May 2019 22:38:14 +0000 (UTC) From: Alan Somers <asomers@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r347236 - in projects/fuse2: sys/fs/fuse tests/sys/fs/fusefs Message-ID: <201905072238.x47McEtS064722@repo.freebsd.org>
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Author: asomers Date: Tue May 7 22:38:13 2019 New Revision: 347236 URL: https://svnweb.freebsd.org/changeset/base/347236 Log: fusefs: drop suid after a successful chown by a non-root user Drop sgid too. Also, drop them after a successful chgrp. Reported by: pjdfstest Sponsored by: The FreeBSD Foundation Modified: projects/fuse2/sys/fs/fuse/fuse_vnops.c projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc Modified: projects/fuse2/sys/fs/fuse/fuse_vnops.c ============================================================================== --- projects/fuse2/sys/fs/fuse/fuse_vnops.c Tue May 7 21:15:11 2019 (r347235) +++ projects/fuse2/sys/fs/fuse/fuse_vnops.c Tue May 7 22:38:13 2019 (r347236) @@ -1524,6 +1524,7 @@ fuse_vnop_setattr(struct vop_setattr_args *ap) int err = 0, err2; accmode_t accmode = 0; bool checkperm; + bool drop_suid = false; gid_t cr_gid; mp = vnode_mount(vp); @@ -1553,12 +1554,15 @@ fuse_vnop_setattr(struct vop_setattr_args *ap) return err; else accmode |= VADMIN; + drop_suid = true; } else accmode |= VADMIN; } else accmode |= VADMIN; } if (vap->va_gid != (gid_t)VNOVAL) { + if (checkperm && priv_check_cred(cred, PRIV_VFS_CHOWN)) + drop_suid = true; if (checkperm && !groupmember(vap->va_gid, cred)) { /* @@ -1574,8 +1578,7 @@ fuse_vnop_setattr(struct vop_setattr_args *ap) return (err2); if (vap->va_gid != old_va.va_gid) return err; - else - accmode |= VADMIN; + accmode |= VADMIN; } else accmode |= VADMIN; } else @@ -1611,6 +1614,16 @@ fuse_vnop_setattr(struct vop_setattr_args *ap) accmode |= VADMIN; if (vap->va_mtime.tv_sec != VNOVAL) accmode |= VADMIN; + if (drop_suid) { + if (vap->va_mode != (mode_t)VNOVAL) + vap->va_mode &= ~(S_ISUID | S_ISGID); + else { + err = fuse_internal_getattr(vp, &old_va, cred, td); + if (err) + return (err); + vap->va_mode = old_va.va_mode & ~(S_ISUID | S_ISGID); + } + } if (vap->va_mode != (mode_t)VNOVAL) { /* Only root may set the sticky bit on non-directories */ if (checkperm && vp->v_type != VDIR && (vap->va_mode & S_ISTXT) Modified: projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc ============================================================================== --- projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc Tue May 7 21:15:11 2019 (r347235) +++ projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc Tue May 7 22:38:13 2019 (r347236) @@ -322,6 +322,41 @@ TEST_F(Chown, chown_to_self) EXPECT_EQ(0, chown(FULLPATH, uid, -1)) << strerror(errno); } +/* + * A successful chown by a non-privileged non-owner should clear a file's SUID + * bit + */ +TEST_F(Chown, clear_suid) +{ + const char FULLPATH[] = "mountpoint/some_file.txt"; + const char RELPATH[] = "some_file.txt"; + uint64_t ino = 42; + const mode_t oldmode = 06755; + const mode_t newmode = 0755; + uid_t uid = geteuid(); + uint32_t valid = FATTR_UID | FATTR_MODE; + + expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, uid); + expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX, uid); + EXPECT_CALL(*m_mock, process( + ResultOf([=](auto in) { + return (in->header.opcode == FUSE_SETATTR && + in->header.nodeid == ino && + in->body.setattr.valid == valid && + in->body.setattr.mode == newmode); + }, Eq(true)), + _) + ).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) { + SET_OUT_HEADER_LEN(out, attr); + out->body.attr.attr.ino = ino; // Must match nodeid + out->body.attr.attr.mode = S_IFREG | newmode; + out->body.attr.attr_valid = UINT64_MAX; + }))); + + EXPECT_EQ(0, chown(FULLPATH, uid, -1)) << strerror(errno); +} + + /* Only root may change a file's owner */ TEST_F(Chown, eperm) { @@ -341,6 +376,41 @@ TEST_F(Chown, eperm) EXPECT_NE(0, chown(FULLPATH, 0, -1)); EXPECT_EQ(EPERM, errno); +} + +/* + * A successful chgrp by a non-privileged non-owner should clear a file's SUID + * bit + */ +TEST_F(Chgrp, clear_suid) +{ + const char FULLPATH[] = "mountpoint/some_file.txt"; + const char RELPATH[] = "some_file.txt"; + uint64_t ino = 42; + const mode_t oldmode = 06755; + const mode_t newmode = 0755; + uid_t uid = geteuid(); + gid_t gid = getegid(); + uint32_t valid = FATTR_GID | FATTR_MODE; + + expect_getattr(1, S_IFDIR | 0755, UINT64_MAX, 1, uid); + expect_lookup(RELPATH, ino, S_IFREG | oldmode, UINT64_MAX, uid, gid); + EXPECT_CALL(*m_mock, process( + ResultOf([=](auto in) { + return (in->header.opcode == FUSE_SETATTR && + in->header.nodeid == ino && + in->body.setattr.valid == valid && + in->body.setattr.mode == newmode); + }, Eq(true)), + _) + ).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) { + SET_OUT_HEADER_LEN(out, attr); + out->body.attr.attr.ino = ino; // Must match nodeid + out->body.attr.attr.mode = S_IFREG | newmode; + out->body.attr.attr_valid = UINT64_MAX; + }))); + + EXPECT_EQ(0, chown(FULLPATH, -1, gid)) << strerror(errno); } /* non-root users may only chgrp a file to a group they belong to */
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