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[71.206.142.238]) by smtp.gmail.com with ESMTPSA id v26-20020a05620a091a00b007887583762csm3803239qkv.94.2024.03.27.04.38.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Mar 2024 04:38:24 -0700 (PDT) From: Joe Simmons-Talbott To: libc-alpha@sourceware.org Cc: Joe Simmons-Talbott , Florian Weimer , Paul Eggert Subject: [PATCH v9] posix: Deprecate group_member for Linux Date: Wed, 27 Mar 2024 07:38:10 -0400 Message-ID: <20240327113822.3095614-1-josimmon@redhat.com> X-Mailer: git-send-email 2.44.0 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP 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: 2.1.30 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libc-alpha-bounces+incoming=patchwork.ozlabs.org@sourceware.org The alloca usage in group_member could lead to stack overflow on Linux. Removing the alloca usage would require group_member to handle the error condition where memory could not be allocated and that cannot be done since group_member returns a boolean value. Thus deprecate group_member. Add an internal only implementation of __group_member2 using a scratch_buffer and return -1 for memory allocation errors. Use __group_member2 for in place of __group_member internally. Add testcases for both group_member and __group_member2. --- Changes to v8: * Remove duplicate calls to __getegid () and __getgid () and convert nested ternary operators into if/else. Changes to v7: * rebased to latest master. Changes to v6: * Use the intial scratch_buffer size as the starting point for determining how much space is needed to store the group list. * Call getgroups() with a zero size and set the scratch_buffer size based on the returned number of groups. Changes to v5: * Add __group_member2 and use it internally in the place of the now deprecated group_member. * Add a testcase for __group_member2. Changes to v4: * Rebase onto latest commit. Changes to v3: * Fix include guards to match file location _BITS_GROUP_MEMBER_H * Fix indentation of preprocessor directives Changes to v2: * Move the linux group_member.h to the bits directory * Include the correct group_member.h in posix/unistd.h Changes to v1: * Add NEWS entry * Move group_member.h to bits/group_member.h * Include bits/group_member.h in installed headers * Add tests to group_member.h files to only be included from unistd.h NEWS | 4 ++ bits/group_member.h | 31 +++++++++++++++ include/unistd.h | 1 + posix/Makefile | 8 ++++ posix/group_member.c | 35 +++++++++++++++++ posix/tst-group_member.c | 41 ++++++++++++++++++++ posix/tst-group_member2.c | 43 +++++++++++++++++++++ posix/unistd.h | 6 +-- sysdeps/posix/euidaccess.c | 9 ++++- sysdeps/unix/sysv/linux/bits/group_member.h | 32 +++++++++++++++ sysdeps/unix/sysv/linux/faccessat.c | 8 +++- 11 files changed, 212 insertions(+), 6 deletions(-) create mode 100644 bits/group_member.h create mode 100644 posix/tst-group_member.c create mode 100644 posix/tst-group_member2.c create mode 100644 sysdeps/unix/sysv/linux/bits/group_member.h diff --git a/NEWS b/NEWS index da4b2223e9..82e1c43306 100644 --- a/NEWS +++ b/NEWS @@ -141,6 +141,10 @@ Deprecated and removed features, and other changes affecting compatibility: * The ia64*-*-linux-gnu configurations are no longer supported. +* Deprecated group_member on Linux as it uses alloca to allocate a large + buffer and has no capability for indicating failure for other memory + allocations. + Changes to build and runtime requirements: * Building on LoongArch requires at a minimum binutils 2.41 for vector diff --git a/bits/group_member.h b/bits/group_member.h new file mode 100644 index 0000000000..7c43e7ee06 --- /dev/null +++ b/bits/group_member.h @@ -0,0 +1,31 @@ +/* group_member declaration + Copyright (C) 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 _UNISTD_H +# error "Never use directly; include instead." +#endif + +#ifndef _BITS_GROUP_MEMBER_H +# define _BITS_GROUP_MEMBER_H 1 + +# ifdef __USE_GNU +/* Return nonzero iff the calling process is in group GID. */ +extern int group_member (__gid_t __gid) __THROW; +# endif + +#endif /* _BITS_GROUP_MEMBER_H */ diff --git a/include/unistd.h b/include/unistd.h index e241603b81..39d5bda372 100644 --- a/include/unistd.h +++ b/include/unistd.h @@ -131,6 +131,7 @@ extern __gid_t __getegid (void) attribute_hidden; extern int __getgroups (int __size, __gid_t __list[]) attribute_hidden; libc_hidden_proto (__getpgid) extern int __group_member (__gid_t __gid) attribute_hidden; +extern int __group_member2 (__gid_t __gid) attribute_hidden; extern int __setuid (__uid_t __uid); extern int __setreuid (__uid_t __ruid, __uid_t __euid); extern int __setgid (__gid_t __gid); diff --git a/posix/Makefile b/posix/Makefile index a1e84853a8..b71d6c8750 100644 --- a/posix/Makefile +++ b/posix/Makefile @@ -29,6 +29,7 @@ headers := \ bits/getopt_core.h \ bits/getopt_ext.h \ bits/getopt_posix.h \ + bits/group_member.h \ bits/local_lim.h \ bits/mman_ext.h \ bits/posix1_lim.h \ @@ -291,6 +292,7 @@ tests := \ tst-glob_symlinks \ tst-gnuglob \ tst-gnuglob64 \ + tst-group_member \ tst-mmap \ tst-mmap-offset \ tst-nanosleep \ @@ -479,6 +481,10 @@ tests-special += \ # tests-special endif +# This test calls __group_member2 directly, which is not exported from glibc. +tests-internal += tst-group_member2 +tests-static += tst-group_member2 + include ../Rules ifeq ($(run-built-tests),yes) @@ -606,6 +612,8 @@ bug-glob1-ARGS = "$(objpfx)" tst-execvp3-ARGS = --test-dir=$(objpfx) CFLAGS-tst-spawn3.c += -DOBJPFX=\"$(objpfx)\" +CFLAGS-tst-group_member.c += -Wno-error=deprecated-declarations + # Test voluntarily overflows struct dirent CFLAGS-bug-glob2.c += $(no-fortify-source) diff --git a/posix/group_member.c b/posix/group_member.c index 9d68f57a68..bb92f4d631 100644 --- a/posix/group_member.c +++ b/posix/group_member.c @@ -18,6 +18,7 @@ #include #include +#include #include #include @@ -47,3 +48,37 @@ __group_member (gid_t gid) return 0; } weak_alias (__group_member, group_member) + +int +__group_member2 (gid_t gid) +{ + int n; + gid_t *groups; + struct scratch_buffer sbuf; + scratch_buffer_init (&sbuf); + groups = sbuf.data; + + do + { + n = __getgroups (0, NULL); + if (n > sbuf.length) + { + if (!scratch_buffer_set_array_size (&sbuf, sizeof (*groups), n)) + return -1; + groups = sbuf.data; + } + + n = __getgroups (n, groups); + } + while (n > sbuf.length); + + while (n-- > 0) + if (groups[n] == gid) + { + scratch_buffer_free (&sbuf); + return 1; + } + + scratch_buffer_free (&sbuf); + return 0; +} diff --git a/posix/tst-group_member.c b/posix/tst-group_member.c new file mode 100644 index 0000000000..7f70841832 --- /dev/null +++ b/posix/tst-group_member.c @@ -0,0 +1,41 @@ +/* Basic tests for group_member. + Copyright (C) 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 + . */ + +#include +#include +#include +#include + +#include + +static int do_test (void) +{ + int n; + gid_t *groups; + + n = getgroups (0, NULL); + groups = alloca (n * sizeof (*groups)); + n = getgroups (n, groups); + + while (n-- > 0) + TEST_COMPARE (1, group_member(groups[n])); + + return EXIT_SUCCESS; +} + +#include diff --git a/posix/tst-group_member2.c b/posix/tst-group_member2.c new file mode 100644 index 0000000000..ee448c578a --- /dev/null +++ b/posix/tst-group_member2.c @@ -0,0 +1,43 @@ +/* Basic tests for group_member. + Copyright (C) 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 + . */ + +#include +#include +#include +#include + +#include + +extern int __group_member2 (__gid_t __gid); + +static int do_test (void) +{ + int n; + gid_t *groups; + + n = getgroups (0, NULL); + groups = alloca (n * sizeof (*groups)); + n = getgroups (n, groups); + + while (n-- > 0) + TEST_COMPARE (1, __group_member2(groups[n])); + + return EXIT_SUCCESS; +} + +#include diff --git a/posix/unistd.h b/posix/unistd.h index 54d7d7527e..411de1d6d4 100644 --- a/posix/unistd.h +++ b/posix/unistd.h @@ -710,10 +710,10 @@ extern __gid_t getegid (void) __THROW; of its supplementary groups in LIST and return the number written. */ extern int getgroups (int __size, __gid_t __list[]) __THROW __wur __fortified_attr_access (__write_only__, 2, 1); + #ifdef __USE_GNU -/* Return nonzero iff the calling process is in group GID. */ -extern int group_member (__gid_t __gid) __THROW; -#endif +# include +#endif /* Set the user ID of the calling process to UID. If the calling process is the super-user, set the real diff --git a/sysdeps/posix/euidaccess.c b/sysdeps/posix/euidaccess.c index 4c5c2220bd..0c19021a30 100644 --- a/sysdeps/posix/euidaccess.c +++ b/sysdeps/posix/euidaccess.c @@ -81,7 +81,7 @@ extern int errno; #ifdef _LIBC -# define group_member __group_member +# define group_member __group_member2 # define euidaccess __euidaccess #else @@ -167,9 +167,14 @@ euidaccess (const char *path, int mode) || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)))) return 0; + int gm = group_member (stats.st_gid); + if (euid != stats.st_uid && egid != stats.st_gid) + if (gm == -1) + return -1; + if (euid == stats.st_uid) granted = (unsigned int) (stats.st_mode & (mode << 6)) >> 6; - else if (egid == stats.st_gid || group_member (stats.st_gid)) + else if (egid == stats.st_gid || gm) granted = (unsigned int) (stats.st_mode & (mode << 3)) >> 3; else granted = (stats.st_mode & mode); diff --git a/sysdeps/unix/sysv/linux/bits/group_member.h b/sysdeps/unix/sysv/linux/bits/group_member.h new file mode 100644 index 0000000000..0dd9505c76 --- /dev/null +++ b/sysdeps/unix/sysv/linux/bits/group_member.h @@ -0,0 +1,32 @@ +/* group_member declaration + Copyright (C) 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 _UNISTD_H +# error "Never use directly; include instead." +#endif + +#ifndef _BITS_GROUP_MEMBER_H +# define _BITS_GROUP_MEMBER_H 1 + +# ifdef __USE_GNU +/* Return nonzero iff the calling process is in group GID. Deprecated */ +extern int group_member (__gid_t __gid) __THROW + __attribute_deprecated_msg__ ("may overflow the stack"); +# endif + +#endif /* _BITS_GROUP_MEMBER_H */ diff --git a/sysdeps/unix/sysv/linux/faccessat.c b/sysdeps/unix/sysv/linux/faccessat.c index 2fa57fd63d..c6fb73aa84 100644 --- a/sysdeps/unix/sysv/linux/faccessat.c +++ b/sysdeps/unix/sysv/linux/faccessat.c @@ -59,11 +59,17 @@ __faccessat (int fd, const char *file, int mode, int flag) || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)))) return 0; + int gm = __group_member2 (stats.st_gid); + if (uid != stats.st_uid && + (stats.st_gid != ((flag & AT_EACCESS) ? __getegid () : __getgid ()))) + if (gm == -1) + return -1; + int granted = (uid == stats.st_uid ? (unsigned int) (stats.st_mode & (mode << 6)) >> 6 : (stats.st_gid == ((flag & AT_EACCESS) ? __getegid () : __getgid ()) - || __group_member (stats.st_gid)) + || gm) ? (unsigned int) (stats.st_mode & (mode << 3)) >> 3 : (stats.st_mode & mode));