diff options
| -rw-r--r-- | ChangeLog | 11 | ||||
| -rw-r--r-- | elf/dl-load.c | 18 | ||||
| -rw-r--r-- | include/link.h | 4 | ||||
| -rw-r--r-- | sysdeps/generic/dl-fileid.h | 46 | ||||
| -rw-r--r-- | sysdeps/nacl/dl-fileid.h | 8 | ||||
| -rw-r--r-- | sysdeps/posix/dl-fileid.h | 50 |
6 files changed, 125 insertions, 12 deletions
@@ -1,3 +1,14 @@ +2015-07-14 Roland McGrath <roland@hack.frob.com> + + * sysdeps/generic/dl-fileid.h: New file. + * sysdeps/posix/dl-fileid.h: New file. + * sysdeps/nacl/dl-fileid.h: New file. + * include/link.h: Include <dl-fileid.h>. + (struct link_map): Replace l_dev and l_ino with l_file_id. + * elf/dl-load.c (_dl_map_object_from_fd): Use _dl_get_file_id rather + than __fxstat64. Use _dl_file_id_match_p rather than comparing l_dev + and l_ino directly. Initialize l_file_id rather than l_dev and l_ino. + 2015-07-14 Siddhesh Poyarekar <siddhesh@redhat.com> * stdlib/tst-tls-atexit.c (do_test): Fix typo. diff --git a/elf/dl-load.c b/elf/dl-load.c index 41b91fc..0c052e4 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -872,7 +872,6 @@ _dl_map_object_from_fd (const char *name, int fd, struct filebuf *fbp, const ElfW(Phdr) *ph; size_t maplength; int type; - struct stat64 st; /* Initialize to keep the compiler happy. */ const char *errstring = NULL; int errval = 0; @@ -880,7 +879,8 @@ _dl_map_object_from_fd (const char *name, int fd, struct filebuf *fbp, bool make_consistent = false; /* Get file information. */ - if (__glibc_unlikely (__fxstat64 (_STAT_VER, fd, &st) < 0)) + struct r_file_id id; + if (__glibc_unlikely (!_dl_get_file_id (fd, &id))) { errstring = N_("cannot stat shared object"); call_lose_errno: @@ -891,8 +891,8 @@ _dl_map_object_from_fd (const char *name, int fd, struct filebuf *fbp, } /* Look again to see if the real name matched another already loaded. */ - for (l = GL(dl_ns)[nsid]._ns_loaded; l; l = l->l_next) - if (l->l_removed == 0 && l->l_ino == st.st_ino && l->l_dev == st.st_dev) + for (l = GL(dl_ns)[nsid]._ns_loaded; l != NULL; l = l->l_next) + if (!l->l_removed && _dl_file_id_match_p (&l->l_file_id, &id)) { /* The object is already loaded. Just bump its reference count and return it. */ @@ -910,8 +910,7 @@ _dl_map_object_from_fd (const char *name, int fd, struct filebuf *fbp, /* When loading into a namespace other than the base one we must avoid loading ld.so since there can only be one copy. Ever. */ if (__glibc_unlikely (nsid != LM_ID_BASE) - && ((st.st_ino == GL(dl_rtld_map).l_ino - && st.st_dev == GL(dl_rtld_map).l_dev) + && (_dl_file_id_match_p (&id, &GL(dl_rtld_map).l_file_id) || _dl_name_match_p (name, &GL(dl_rtld_map)))) { /* This is indeed ld.so. Create a new link_map which refers to @@ -1220,7 +1219,7 @@ cannot allocate TLS data structures for initial thread"); l_map_start, l_map_end, l_addr, l_contiguous, l_text_end, l_phdr */ errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds, - maplength, has_holes, loader); + maplength, has_holes, loader); if (__glibc_unlikely (errstring != NULL)) goto call_lose; } @@ -1390,8 +1389,7 @@ cannot enable executable stack as shared object requires"); GL(dl_initfirst) = l; /* Finally the file information. */ - l->l_dev = st.st_dev; - l->l_ino = st.st_ino; + l->l_file_id = id; /* When we profile the SONAME might be needed for something else but loading. Add it right away. */ @@ -1890,7 +1888,7 @@ open_path (const char *name, size_t namelen, int mode, free (sps->dirs); /* rtld_search_dirs and env_path_list are attribute_relro, therefore - avoid writing into it. */ + avoid writing into it. */ if (sps != &rtld_search_dirs && sps != &env_path_list) sps->dirs = (void *) -1; } diff --git a/include/link.h b/include/link.h index 7ccd9c3..423a695 100644 --- a/include/link.h +++ b/include/link.h @@ -40,6 +40,7 @@ extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid, #include <stdint.h> #include <stddef.h> #include <bits/linkmap.h> +#include <dl-fileid.h> #include <dl-lookupcfg.h> #include <tls.h> #include <bits/libc-lock.h> @@ -235,8 +236,7 @@ struct link_map /* This information is kept to check for sure whether a shared object is the same as one already loaded. */ - dev_t l_dev; - ino64_t l_ino; + struct r_file_id l_file_id; /* Collected information about own RUNPATH directories. */ struct r_search_path_struct l_runpath_dirs; diff --git a/sysdeps/generic/dl-fileid.h b/sysdeps/generic/dl-fileid.h new file mode 100644 index 0000000..2cbd21d --- /dev/null +++ b/sysdeps/generic/dl-fileid.h @@ -0,0 +1,46 @@ +/* File identity for the dynamic linker. Stub version. + Copyright (C) 2015 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 + <http://www.gnu.org/licenses/>. */ + +#include <stdbool.h> + +/* This type stores whatever information is fetched by _dl_get_file_id + and compared by _dl_file_id_match_p. */ +struct r_file_id + { + /* In the stub version, we don't record anything at all. */ + }; + +/* Sample FD to fill in *ID. Returns true on success. + On error, returns false, with errno set. */ +static inline bool +_dl_get_file_id (int fd __attribute__ ((unused)), + struct r_file_id *id __attribute__ ((unused))) +{ + return true; +} + +/* Compare two results from _dl_get_file_id for equality. + It's crucial that this never return false-positive matches. + It's ideal that it never return false-negative mismatches either, + but lack of matches is survivable. */ +static inline bool +_dl_file_id_match_p (const struct r_file_id *a __attribute__ ((unused)), + const struct r_file_id *b __attribute__ ((unused))) +{ + return false; +} diff --git a/sysdeps/nacl/dl-fileid.h b/sysdeps/nacl/dl-fileid.h new file mode 100644 index 0000000..4c34581 --- /dev/null +++ b/sysdeps/nacl/dl-fileid.h @@ -0,0 +1,8 @@ +/* Bypass sysdeps/posix/dl-fileid.h, which relies on st_dev/st_ino being + reliable. Under NaCl, we cannot always expect them to be useful. + Fortunately, in the ways NaCl is used it's far less likely that two + different names for the same file would be used in dlopen or the like, + so failing to notice re-opening the same file is not so likely to be a + problem in practice. */ + +#include <sysdeps/generic/dl-fileid.h> diff --git a/sysdeps/posix/dl-fileid.h b/sysdeps/posix/dl-fileid.h new file mode 100644 index 0000000..d0d5436 --- /dev/null +++ b/sysdeps/posix/dl-fileid.h @@ -0,0 +1,50 @@ +/* File identity for the dynamic linker. Generic POSIX.1 version. + Copyright (C) 2015 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 + <http://www.gnu.org/licenses/>. */ + +#include <stdbool.h> +#include <sys/stat.h> + +/* For POSIX.1 systems, the pair of st_dev and st_ino constitute + a unique identifier for a file. */ +struct r_file_id + { + dev_t dev; + ino64_t ino; + }; + +/* Sample FD to fill in *ID. Returns true on success. + On error, returns false, with errno set. */ +static inline bool +_dl_get_file_id (int fd, struct r_file_id *id) +{ + struct stat64 st; + + if (__glibc_unlikely (__fxstat64 (_STAT_VER, fd, &st) < 0)) + return false; + + id->dev = st.st_dev; + id->ino = st.st_ino; + return true; +} + +/* Compare two results from _dl_get_file_id for equality. */ +static inline bool +_dl_file_id_match_p (const struct r_file_id *a, const struct r_file_id *b) +{ + return a->dev == b->dev && a->ino == b->ino; +} |