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([2a00:1370:818c:173b:cc34:4e0d:9ea6:c16c]) by smtp.gmail.com with ESMTPSA id j28-20020ac253bc000000b004f76a88dbcbsm1567091lfh.176.2023.06.17.15.22.24 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Jun 2023 15:22:24 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v3 4/5] io: Add FORTIFY_SOURCE check for fcntl arguments Date: Sun, 18 Jun 2023 01:22:17 +0300 Message-ID: <20230617222218.642125-5-bugaevc@gmail.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230617222218.642125-1-bugaevc@gmail.com> References: <20230617222218.642125-1-bugaevc@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-11.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Sergey Bugaev via Libc-alpha From: Sergey Bugaev Reply-To: Sergey Bugaev Errors-To: libc-alpha-bounces+incoming=patchwork.ozlabs.org@sourceware.org Sender: "Libc-alpha" Both open () and fcntl () are "overloaded" to accept either 2 or 3 arguments; whether the last argument is required (and, in case of fcntl, the type of the third argument) depends on the values of the previous arguments. Since C provides no native support for function overloading, this is implemented by making these functions vararg. Unfortunately, this means the compiler is unable to check the number of arguments and their types for correctness at compile time, and will not diagnose any mistakes. To help with this, when FORTIFY_SOURCE is enabled, the special fcntl2.h header replaces open () with a wrapper that checks the passed number of arguments, raising a compile-time or run-time error on mismatch. This commit adds similar handling for fcntl (). Recently, Hector Martin has identified an issue in libwebrtc where fcntl (fd, F_DUPFD_CLOEXEC) was invoked without a third argument [0]. With the patch, the bug would have been detected at compile time, assuming libwebrtc is built with FORTIFY_SOURCE. Hopefully this will help detecting similar bugs in existing software, and prevent more instances of similar bugs from being introduced in the future. [0]: https://social.treehouse.systems/@marcan/110355001391961285 Signed-off-by: Sergey Bugaev --- In manual/maint.texi, how would I properly update the command for generating the list of fortified functions to include fcntl / fcntl64 in absence of __fcntl_2? (The next patch does make it work with __fcntl_2.) debug/tst-fortify.c | 140 ++++++++++++++ include/bits/fcntl3.h | 1 + io/Makefile | 1 + io/bits/fcntl3.h | 420 ++++++++++++++++++++++++++++++++++++++++++ io/fcntl.h | 6 + manual/maint.texi | 9 +- 6 files changed, 575 insertions(+), 2 deletions(-) create mode 100644 include/bits/fcntl3.h create mode 100644 io/bits/fcntl3.h diff --git a/debug/tst-fortify.c b/debug/tst-fortify.c index 3744aada..674ada74 100644 --- a/debug/tst-fortify.c +++ b/debug/tst-fortify.c @@ -36,6 +36,8 @@ #include #include #include +#include +#include #ifndef _GNU_SOURCE # define MEMPCPY memcpy @@ -78,6 +80,15 @@ do_prepare (void) } } +/* Return VALUE, but do it in a way that the compiler cannot + see that it's a compile-time constant. */ +static inline int +hide_constant (int value) +{ + asm ("" : "+rm" (value)); + return value; +} + volatile int chk_fail_ok; volatile int ret; jmp_buf chk_fail_buf; @@ -1811,6 +1822,135 @@ do_test (void) ppoll (fds, l0 + 2, NULL, NULL); CHK_FAIL_END # endif +#endif + + /* Check that we can do basic fcntl operations, both ones that require + the third argument, and ones that do not. */ + res = fcntl (STDIN_FILENO, F_GETFD); + TEST_COMPARE (res, 0); + res = fcntl (STDIN_FILENO, F_SETFD, 0); + TEST_COMPARE (res, 0); + +#ifdef F_OFD_GETLK + /* Check for confusion between 32- and 64-bit versions of the fcntl + interface. */ + int lockfd1 = xopen (temp_filename, O_RDWR, 0); + int lockfd2 = xopen (temp_filename, O_RDWR, 0); + + int ofd_locks_supported = support_fcntl_support_ofd_locks (lockfd1); + + if (ofd_locks_supported) + { + struct flock flock; + + memset (&flock, 0, sizeof (flock)); + flock.l_type = F_WRLCK; + flock.l_whence = SEEK_SET; + flock.l_start = 1234; + flock.l_len = 5678; + flock.l_pid = 0; + + res = fcntl (lockfd1, F_OFD_SETLK, &flock); + TEST_COMPARE (res, 0); + + memset (&flock, 0, sizeof (flock)); + flock.l_type = F_RDLCK; + flock.l_whence = SEEK_SET; + flock.l_start = 3542; + flock.l_len = 411; + flock.l_pid = 0; + + res = fcntl (lockfd2, F_OFD_GETLK, &flock); + TEST_COMPARE (res, 0); + /* Check that we get the expected values. */ + TEST_COMPARE (flock.l_type, F_WRLCK); + TEST_COMPARE (flock.l_whence, SEEK_SET); + TEST_COMPARE (flock.l_start, 1234); + TEST_COMPARE (flock.l_len, 5678); + TEST_COMPARE (flock.l_pid, -1); + } +#endif + + /* Check that we can do fcntl operations with CMD that is not constant + at compile time. */ + res = fcntl (STDIN_FILENO, hide_constant (F_GETFD)); + TEST_COMPARE (res, 0); + res = fcntl (STDIN_FILENO, hide_constant (F_SETFD), 0); + TEST_COMPARE (res, 0); + +#ifdef F_OFD_GETLK + if (ofd_locks_supported) + { + struct flock flock; + + memset (&flock, 0, sizeof (flock)); + flock.l_type = F_RDLCK; + flock.l_whence = SEEK_SET; + flock.l_start = 3542; + flock.l_len = 411; + flock.l_pid = 0; + + res = fcntl (lockfd2, hide_constant (F_OFD_GETLK), &flock); + TEST_COMPARE (res, 0); + /* Check that we get the expected values. */ + TEST_COMPARE (flock.l_type, F_WRLCK); + TEST_COMPARE (flock.l_whence, SEEK_SET); + TEST_COMPARE (flock.l_start, 1234); + TEST_COMPARE (flock.l_len, 5678); + TEST_COMPARE (flock.l_pid, -1); + } +#endif + +#if defined (__USE_LARGEFILE64) || defined (__USE_TIME_BITS64) + /* Also check fcntl64 (). */ + res = fcntl64 (STDIN_FILENO, F_GETFD); + TEST_COMPARE (res, 0); + res = fcntl64 (STDIN_FILENO, F_SETFD, 0); + TEST_COMPARE (res, 0); + res = fcntl64 (STDIN_FILENO, hide_constant (F_GETFD)); + TEST_COMPARE (res, 0); + res = fcntl64 (STDIN_FILENO, hide_constant (F_SETFD), 0); + TEST_COMPARE (res, 0); + +#ifdef F_OFD_GETLK + if (ofd_locks_supported) + { + struct flock64 flock64; + + memset (&flock64, 0, sizeof (flock64)); + flock64.l_type = F_RDLCK; + flock64.l_whence = SEEK_SET; + flock64.l_start = 3542; + flock64.l_len = 411; + flock64.l_pid = 0; + + res = fcntl64 (lockfd2, F_OFD_GETLK, &flock64); + TEST_COMPARE (res, 0); + /* Check that we get the expected values. */ + TEST_COMPARE (flock64.l_type, F_WRLCK); + TEST_COMPARE (flock64.l_whence, SEEK_SET); + TEST_COMPARE (flock64.l_start, 1234); + TEST_COMPARE (flock64.l_len, 5678); + TEST_COMPARE (flock64.l_pid, -1); + + memset (&flock64, 0, sizeof (flock64)); + flock64.l_type = F_RDLCK; + flock64.l_whence = SEEK_SET; + flock64.l_start = 3542; + flock64.l_len = 411; + flock64.l_pid = 0; + + res = fcntl64 (lockfd2, hide_constant (F_OFD_GETLK), &flock64); + TEST_COMPARE (res, 0); + /* Check that we get the expected values. */ + TEST_COMPARE (flock64.l_type, F_WRLCK); + TEST_COMPARE (flock64.l_whence, SEEK_SET); + TEST_COMPARE (flock64.l_start, 1234); + TEST_COMPARE (flock64.l_len, 5678); + TEST_COMPARE (flock64.l_pid, -1); + } +#endif + #endif return ret; diff --git a/include/bits/fcntl3.h b/include/bits/fcntl3.h new file mode 100644 index 00000000..d31154f6 --- /dev/null +++ b/include/bits/fcntl3.h @@ -0,0 +1 @@ +#include "../../io/bits/fcntl3.h" diff --git a/io/Makefile b/io/Makefile index d573064e..21e1914f 100644 --- a/io/Makefile +++ b/io/Makefile @@ -25,6 +25,7 @@ include ../Makeconfig headers := \ bits/fcntl.h \ bits/fcntl2.h \ + bits/fcntl3.h \ bits/poll.h \ bits/poll2.h \ bits/stat.h \ diff --git a/io/bits/fcntl3.h b/io/bits/fcntl3.h new file mode 100644 index 00000000..52a8a0d7 --- /dev/null +++ b/io/bits/fcntl3.h @@ -0,0 +1,420 @@ +/* Checking macros for fcntl functions. + Copyright (C) 2007-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef _FCNTL_H +# error "Never include directly; use instead." +#endif + +#ifndef __USE_TIME_BITS64 + +# ifndef __USE_FILE_OFFSET64 +extern int __REDIRECT (__fcntl_alias, (int __fd, int __cmd, ...), fcntl); +extern int __REDIRECT (__fcntl_warn, (int __fd, int __cmd, ...), fcntl) + __warnattr ("fcntl argument has wrong type for this command"); +# else +extern int __REDIRECT (__fcntl_alias, (int __fd, int __cmd, ...), fcntl64); +extern int __REDIRECT (__fcntl_warn, (int __fd, int __cmd, ...), fcntl64) + __warnattr ("fcntl argument has wrong type for this command"); +# endif /* __USE_FILE_OFFSET64 */ + +# ifdef __USE_LARGEFILE64 +extern int __REDIRECT (__fcntl64_alias, (int __fd, int __cmd, ...), fcntl64); +extern int __REDIRECT (__fcntl64_warn, (int __fd, int __cmd, ...), fcntl64) + __warnattr ("fcntl64 argument has wrong type for this command"); +# endif + +#else /* __USE_TIME_BITS64 */ + +extern int __REDIRECT_NTH (__fcntl_alias, (int __fd, int __cmd, ...), + __fcntl_time64); +extern int __REDIRECT_NTH (__fcntl64_alias, (int __fd, int __cmd, ...), + __fcntl_time64); +extern int __REDIRECT (__fcntl_warn, (int __fd, int __cmd, ...), + __fcntl_time64) + __warnattr ("fcntl argument has wrong type for this command"); +extern int __REDIRECT (__fcntl64_warn, (int __fd, int __cmd, ...), + __fcntl_time64) + __warnattr ("fcntl64 argument has wrong type for this command"); + +#endif /* __USE_TIME_BITS64 */ + + +/* Whether the fcntl CMD is known to require an argument. */ +__extern_always_inline int +__fcntl_requires_arg (int __cmd) +{ + switch (__cmd) + { + case F_DUPFD: + case F_DUPFD_CLOEXEC: + case F_SETFD: + case F_SETFL: +#ifdef F_SETLK + case F_SETLK: + case F_SETLKW: + case F_GETLK: +#endif +#ifdef F_OFD_SETLK + case F_OFD_SETLK: + case F_OFD_SETLKW: + case F_OFD_GETLK: +#endif +#ifdef F_SETOWN + case F_SETOWN: +#endif +#ifdef F_GETOWN_EX + case F_GETOWN_EX: + case F_SETOWN_EX: + case F_SETSIG: +#endif +#ifdef F_SETLEASE + case F_SETLEASE: + case F_NOTIFY: + case F_SETPIPE_SZ: + case F_ADD_SEALS: + case F_GET_RW_HINT: + case F_SET_RW_HINT: + case F_GET_FILE_RW_HINT: + case F_SET_FILE_RW_HINT: +#endif + return 1; + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires an int argument. */ +__extern_always_inline int +__fcntl_is_int (int __cmd) +{ + switch (__cmd) + { + case F_DUPFD: + case F_DUPFD_CLOEXEC: + case F_SETFD: + case F_SETFL: +#ifdef F_SETOWN + case F_SETOWN: +#endif +#ifdef F_SETSIG + case F_SETSIG: +#endif +#ifdef F_SETLEASE + case F_SETLEASE: + case F_NOTIFY: + case F_SETPIPE_SZ: + case F_ADD_SEALS: +#endif + return 1; + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (const uint64_t *) argument. */ +__extern_always_inline int +__fcntl_is_const_uint64_t_ptr (int __cmd) +{ + switch (__cmd) + { +#ifdef F_SET_RW_HINT + case F_SET_RW_HINT: + case F_SET_FILE_RW_HINT: + return 1; +#endif + + default: + return 0; + } +} + + +/* Whether the fcntl CMD requires an (uint64_t *) argument. */ +__extern_always_inline int +__fcntl_is_uint64_t_ptr (int __cmd) +{ + switch (__cmd) + { +#ifdef F_GET_RW_HINT + case F_GET_RW_HINT: + case F_GET_FILE_RW_HINT: + return 1; +#endif + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (const struct f_owner_ex *) argument. */ +__extern_always_inline int +__fcntl_is_const_fowner_ex (int __cmd) +{ + switch (__cmd) + { +#ifdef F_SETOWN_EX + case F_SETOWN_EX: + return 1; +#endif + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (struct f_owner_ex *) argument. */ +__extern_always_inline int +__fcntl_is_fowner_ex (int __cmd) +{ + switch (__cmd) + { +#ifdef F_GETOWN_EX + case F_GETOWN_EX: + return 1; +#endif + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (const struct flock *) argument. */ +__extern_always_inline int +__fcntl_is_const_flock (int __cmd, int __is_fcntl64) +{ + (void) __is_fcntl64; + switch (__cmd) + { +#ifdef F_SETLK + case F_SETLK: + case F_SETLKW: + return 1; +#endif + +#ifdef F_OFD_SETLK + case F_OFD_SETLK: + case F_OFD_SETLKW: + return !__is_fcntl64; +#endif + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (struct flock *) argument. */ +__extern_always_inline int +__fcntl_is_flock (int __cmd, int __is_fcntl64) +{ + (void) __is_fcntl64; + switch (__cmd) + { +#ifdef F_GETLK + case F_GETLK: + return 1; +#endif + +#ifdef F_OFD_GETLK + case F_OFD_GETLK: + return !__is_fcntl64; +#endif + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (const struct flock64 *) argument. */ +__extern_always_inline int +__fcntl_is_const_flock64 (int __cmd, int __is_fcntl64) +{ + (void) __is_fcntl64; + switch (__cmd) + { +#ifdef F_SETLK64 + case F_SETLK64: + case F_SETLKW64: + return 1; +#endif + +#ifdef F_OFD_SETLK + case F_OFD_SETLK: + case F_OFD_SETLKW: + return __is_fcntl64; +#endif + + default: + return 0; + } +} + +/* Whether the fcntl CMD requires a (struct flock64 *) argument. */ +__extern_always_inline int +__fcntl_is_flock64 (int __cmd, int __is_fcntl64) +{ + (void) __is_fcntl64; + switch (__cmd) + { +#ifdef F_GETLK64 + case F_GETLK64: + return 1; +#endif + +#ifdef F_OFD_GETLK + case F_OFD_GETLK: + return __is_fcntl64; +#endif + + default: + return 0; + } +} + +#ifndef __cplusplus + +# define __fcntl_types_compatible(arg, type) \ + __builtin_types_compatible_p (__typeof (arg), type) + +#else + +extern "C++" { + +template +struct __fcntl_types_compatible_helper +{ + __always_inline static int + __compatible () + { + return 0; + } +}; + +template +struct __fcntl_types_compatible_helper<__T, __T> +{ + __always_inline static int + __compatible () + { + return 1; + } +}; + +# define __fcntl_types_compatible(arg, type) \ + __fcntl_types_compatible_helper<__typeof (arg), type>::__compatible () + +} /* extern C++ */ + +#endif /* __cplusplus */ + +#define __fcntl_type_check_int(arg) __fcntl_types_compatible (arg, int) + +#define __fcntl_type_check_const_uint64_t_ptr(arg) \ + (__fcntl_types_compatible (arg, const __uint64_t *) \ + || __fcntl_types_compatible (arg, __uint64_t *)) + +#define __fcntl_type_check_uint64_t_ptr(arg) \ + __fcntl_types_compatible (arg, __uint64_t *) + +#define __fcntl_type_check_const_fowner_ex(arg) \ + (__fcntl_types_compatible (arg, const struct f_owner_ex *) \ + || __fcntl_types_compatible (arg, struct f_owner_ex *)) + +#define __fcntl_type_check_fowner_ex(arg) \ + __fcntl_types_compatible (arg, struct f_owner_ex *) + +#define __fcntl_type_check_const_flock(arg) \ + (__fcntl_types_compatible (arg, const struct flock *) \ + || __fcntl_types_compatible (arg, struct flock *)) + +#define __fcntl_type_check_flock(arg) \ + __fcntl_types_compatible (arg, struct flock *) + +#ifdef __USE_LARGEFILE64 + +# define __fcntl_type_check_const_flock64(arg) \ + (__fcntl_types_compatible (arg, const struct flock64 *) \ + || __fcntl_types_compatible (arg, struct flock64 *)) + +# define __fcntl_type_check_flock64(arg) \ + __fcntl_types_compatible (arg, struct flock64 *) + +#else + +# define __fcntl_type_check_const_flock64(arg) 0 +# define __fcntl_type_check_flock64(arg) 0 + +#endif /* __USE_LARGEFILE64 */ + +#define __fcntl_type_check(cmd, arg, is_fcntl64) \ + (__fcntl_is_int (cmd) ? __fcntl_type_check_int (arg) : \ + __fcntl_is_const_uint64_t_ptr (cmd) \ + ? __fcntl_type_check_const_uint64_t_ptr (arg) : \ + __fcntl_is_uint64_t_ptr (cmd) ? __fcntl_type_check_uint64_t_ptr (arg) : \ + __fcntl_is_const_fowner_ex (cmd) \ + ? __fcntl_type_check_const_fowner_ex (arg) : \ + __fcntl_is_fowner_ex (cmd) ? __fcntl_type_check_fowner_ex (arg) : \ + __fcntl_is_const_flock (cmd, is_fcntl64) \ + ? __fcntl_type_check_const_flock (arg) : \ + __fcntl_is_flock (cmd, is_fcntl64) ? __fcntl_type_check_flock (arg) : \ + __fcntl_is_const_flock64 (cmd, is_fcntl64) \ + ? __fcntl_type_check_const_flock64 (arg) : \ + __fcntl_is_flock64 (cmd, is_fcntl64) ? __fcntl_type_check_flock64 (arg) : \ + 1) + + +__errordecl (__fcntl_missing_arg, + "fcntl with with this command needs 3 arguments"); + +__fortify_function int +__fcntl_2_inline (int __fd, int __cmd) +{ + if (!__builtin_constant_p (__cmd)) + return __fcntl_alias (__fd, __cmd); + + if (__fcntl_requires_arg (__cmd)) + __fcntl_missing_arg (); + + return __fcntl_alias (__fd, __cmd); +} + +__glibc_warn_system_headers_begin + +#define fcntl(fd, cmd, ...) \ + (__VA_OPT__ (0 ?) __fcntl_2_inline (fd, cmd) \ + __VA_OPT__ (: \ + !__builtin_constant_p (cmd) ? __fcntl_alias (fd, cmd, __VA_ARGS__) \ + : __fcntl_type_check (cmd, __VA_ARGS__, 0) \ + ? __fcntl_alias (fd, cmd, __VA_ARGS__) \ + : __fcntl_warn (fd, cmd, __VA_ARGS__))) + +#ifdef __USE_LARGEFILE64 + +#define fcntl64(fd, cmd, ...) \ + (__VA_OPT__ (0 ?) __fcntl_2_inline (fd, cmd) \ + __VA_OPT__ (: \ + !__builtin_constant_p (cmd) ? __fcntl64_alias (fd, cmd, __VA_ARGS__) \ + : __fcntl_type_check (cmd, __VA_ARGS__, 1) \ + ? __fcntl64_alias (fd, cmd, __VA_ARGS__) \ + : __fcntl64_warn (fd, cmd, __VA_ARGS__))) + + +#endif + +__glibc_warn_system_headers_end diff --git a/io/fcntl.h b/io/fcntl.h index dd620c08..61738f42 100644 --- a/io/fcntl.h +++ b/io/fcntl.h @@ -337,11 +337,17 @@ extern int posix_fallocate64 (int __fd, off64_t __offset, off64_t __len); /* Define some inlines helping to catch common problems. */ + #if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function \ && defined __va_arg_pack_len # include #endif +#if __USE_FORTIFY_LEVEL > 0 && defined (__fortify_function) \ + && (__GNUC_PREREQ (8, 1) || __glibc_clang_prereq (12, 0)) +# include +#endif + __END_DECLS #endif /* fcntl.h */ diff --git a/manual/maint.texi b/manual/maint.texi index 89da704f..11509def 100644 --- a/manual/maint.texi +++ b/manual/maint.texi @@ -200,7 +200,7 @@ functions but may also include checks for validity of other inputs to the functions. When the @code{_FORTIFY_SOURCE} macro is defined, it enables code that -validates inputs passed to some functions in @theglibc to determine if +validates inputs passed to some functions in @theglibc{} to determine if they are safe. If the compiler is unable to determine that the inputs to the function call are safe, the call may be replaced by a call to its hardened variant that does additional safety checks at runtime. Some @@ -221,7 +221,8 @@ returned by the @code{__builtin_object_size} compiler builtin function. If the function returns @code{(size_t) -1}, the function call is left untouched. Additionally, this level also enables validation of flags to the @code{open}, @code{open64}, @code{openat} and @code{openat64} -functions. +functions, as well as validation of the presence and the type of the +third argument to the @code{fcntl} and @code{fcntl64} functions. @item @math{2}: This behaves like @math{1}, with the addition of some checks that may trap code that is conforming but unsafe, e.g. accepting @@ -267,6 +268,10 @@ The following functions and macros are fortified in @theglibc{}: @item @code{explicit_bzero} +@item @code{fcntl} + +@item @code{fcntl64} + @item @code{FD_SET} @item @code{FD_CLR}