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-rw-r--r--elf/dl-load.c252
1 files changed, 156 insertions, 96 deletions
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 978a81c..6f5f336 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -92,6 +92,24 @@ ELF_PREFERRED_ADDRESS_DATA;
# define ELF_FIXED_ADDRESS(loader, mapstart) ((void) 0)
#endif
+/* Type for the buffer we put the ELF header and hopefully the program
+ header. This buffer does not really have to be too large. In most
+ cases the program header follows the ELF header directly. If this
+ is not the case all bets are off and we can make the header arbitrarily
+ large and still won't get it read. This means the only question is
+ how large are the ELF and program header combined. The ELF header
+ in 64-bit files is 56 bytes long. Each program header entry is again
+ 56 bytes long. I.e., even with a file which has 17 program header
+ entries we only have to read 1kB. And 17 program header entries is
+ plenty, normal files have < 10. If this heuristic should really fail
+ for some file the code in `_dl_map_object_from_fd' knows how to
+ recover. */
+struct filebuf
+{
+ ssize_t len;
+ char buf[1024];
+};
+
size_t _dl_pagesize;
extern const char *_dl_platform;
@@ -724,29 +742,10 @@ lose (int code, int fd, const char *name, char *realname, struct link_map *l,
static
#endif
struct link_map *
-_dl_map_object_from_fd (const char *name, int fd, char *realname,
- struct link_map *loader, int l_type, int mode)
+_dl_map_object_from_fd (const char *name, int fd, struct filebuf *fbp,
+ char *realname, struct link_map *loader, int l_type,
+ int mode)
{
- /* This is the expected ELF header. */
-#define ELF32_CLASS ELFCLASS32
-#define ELF64_CLASS ELFCLASS64
-#ifndef VALID_ELF_HEADER
-# define VALID_ELF_HEADER(hdr,exp,size) (memcmp (hdr, exp, size) == 0)
-# define VALID_ELF_OSABI(osabi) (osabi == ELFOSABI_SYSV)
-# define VALID_ELF_ABIVERSION(ver) (ver == 0)
-#endif
- static const unsigned char expected[EI_PAD] =
- {
- [EI_MAG0] = ELFMAG0,
- [EI_MAG1] = ELFMAG1,
- [EI_MAG2] = ELFMAG2,
- [EI_MAG3] = ELFMAG3,
- [EI_CLASS] = ELFW(CLASS),
- [EI_DATA] = byteorder,
- [EI_VERSION] = EV_CURRENT,
- [EI_OSABI] = ELFOSABI_SYSV,
- [EI_ABIVERSION] = 0
- };
struct link_map *l = NULL;
inline caddr_t map_segment (ElfW(Addr) mapstart, size_t len,
@@ -765,8 +764,6 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname,
const ElfW(Phdr) *ph;
size_t maplength;
int type;
- char *readbuf;
- ssize_t readlength;
struct stat64 st;
/* Get file information. */
@@ -804,64 +801,8 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname,
if (__builtin_expect (_dl_debug_files, 0))
_dl_debug_message (1, "file=", name, "; generating link map\n", NULL);
- /* Read the header directly. */
- readbuf = alloca (_dl_pagesize);
- readlength = __libc_read (fd, readbuf, _dl_pagesize);
- if (readlength < (ssize_t) sizeof (*header))
- LOSE (errno, N_("cannot read file data"));
- header = (void *) readbuf;
-
- /* Check the header for basic validity. */
- if (__builtin_expect (!VALID_ELF_HEADER (header->e_ident, expected, EI_PAD),
- 0))
- {
- /* Something is wrong. */
- if (*(Elf32_Word *) &header->e_ident !=
-#if BYTE_ORDER == LITTLE_ENDIAN
- ((ELFMAG0 << (EI_MAG0 * 8)) |
- (ELFMAG1 << (EI_MAG1 * 8)) |
- (ELFMAG2 << (EI_MAG2 * 8)) |
- (ELFMAG3 << (EI_MAG3 * 8)))
-#else
- ((ELFMAG0 << (EI_MAG3 * 8)) |
- (ELFMAG1 << (EI_MAG2 * 8)) |
- (ELFMAG2 << (EI_MAG1 * 8)) |
- (ELFMAG3 << (EI_MAG0 * 8)))
-#endif
- )
- LOSE (0, N_("invalid ELF header"));
- if (header->e_ident[EI_CLASS] != ELFW(CLASS))
- {
- if (__ELF_NATIVE_CLASS == 32)
- LOSE (0, N_("ELF file class not 32-bit"));
- else
- LOSE (0, N_("ELF file class not 64-bit"));
- }
- if (header->e_ident[EI_DATA] != byteorder)
- {
- if (BYTE_ORDER == BIG_ENDIAN)
- LOSE (0, "ELF file data encoding not big-endian");
- else
- LOSE (0, "ELF file data encoding not little-endian");
- }
- if (header->e_ident[EI_VERSION] != EV_CURRENT)
- LOSE (0, N_("ELF file version ident does not match current one"));
- /* XXX We should be able so set system specific versions which are
- allowed here. */
- if (!VALID_ELF_OSABI (header->e_ident[EI_OSABI]))
- LOSE (0, N_("ELF file OS ABI invalid."));
- if (!VALID_ELF_ABIVERSION (header->e_ident[EI_ABIVERSION]))
- LOSE (0, N_("ELF file ABI version invalid."));
- LOSE (0, N_("internal error"));
- }
-
- if (__builtin_expect (header->e_version, EV_CURRENT) != EV_CURRENT)
- LOSE (0, N_("ELF file version does not match current one"));
- if (! __builtin_expect (elf_machine_matches_host (header), 1))
- LOSE (0, N_("ELF file machine architecture does not match"));
- if (__builtin_expect (header->e_phentsize, sizeof (ElfW(Phdr)))
- != sizeof (ElfW(Phdr)))
- LOSE (0, N_("ELF file's phentsize not the expected size"));
+ /* This is the ELF header. We read it in `open_verify'. */
+ header = (void *) fbp->buf;
#ifndef MAP_ANON
# define MAP_ANON 0
@@ -889,8 +830,8 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname,
l->l_phnum = header->e_phnum;
maplength = header->e_phnum * sizeof (ElfW(Phdr));
- if (header->e_phoff + maplength <= readlength)
- phdr = (void *) (readbuf + header->e_phoff);
+ if (header->e_phoff + maplength <= fbp->len)
+ phdr = (void *) (fbp->buf + header->e_phoff);
else
{
phdr = alloca (maplength);
@@ -1254,6 +1195,123 @@ print_search_path (struct r_search_path_elem **list,
_dl_debug_message (0, "\t\t(", what, ")\n", NULL);
}
+/* Open a file and verify it is an ELF file for this architecture. We
+ ignore only ELF files for other architectures. Non-ELF files and
+ ELF files with different header information cause fatal errors since
+ this could mean there is something wrong in the installation and the
+ user might want to know about this. */
+static int
+open_verify (const char *name, struct filebuf *fbp)
+{
+ /* This is the expected ELF header. */
+#define ELF32_CLASS ELFCLASS32
+#define ELF64_CLASS ELFCLASS64
+#ifndef VALID_ELF_HEADER
+# define VALID_ELF_HEADER(hdr,exp,size) (memcmp (hdr, exp, size) == 0)
+# define VALID_ELF_OSABI(osabi) (osabi == ELFOSABI_SYSV)
+# define VALID_ELF_ABIVERSION(ver) (ver == 0)
+#endif
+ static const unsigned char expected[EI_PAD] =
+ {
+ [EI_MAG0] = ELFMAG0,
+ [EI_MAG1] = ELFMAG1,
+ [EI_MAG2] = ELFMAG2,
+ [EI_MAG3] = ELFMAG3,
+ [EI_CLASS] = ELFW(CLASS),
+ [EI_DATA] = byteorder,
+ [EI_VERSION] = EV_CURRENT,
+ [EI_OSABI] = ELFOSABI_SYSV,
+ [EI_ABIVERSION] = 0
+ };
+ int fd;
+
+ /* Open the file. We always open files read-only. */
+ fd = __open (name, O_RDONLY);
+ if (fd != -1)
+ {
+ ElfW(Ehdr) *ehdr;
+
+ /* We successfully openened the file. Now verify it is a file
+ we can use. */
+ __set_errno (0);
+ fbp->len = __libc_read (fd, fbp->buf, sizeof (fbp->buf));
+
+ /* This is where the ELF header is loaded. */
+ assert (sizeof (fbp->buf) > sizeof (ElfW(Ehdr)));
+ ehdr = (ElfW(Ehdr) *) fbp->buf;
+
+ /* Now run the tests. */
+ if (__builtin_expect (fbp->len < (ssize_t) sizeof (ElfW(Ehdr)), 0))
+ lose (errno, fd, name, NULL, NULL,
+ errno == 0 ? N_("file too short") : N_("cannot read file data"));
+
+ /* See whether the ELF header is what we expect. */
+ if (__builtin_expect (! VALID_ELF_HEADER (ehdr->e_ident, expected,
+ EI_PAD), 0))
+ {
+ /* Something is wrong. */
+ if (*(Elf32_Word *) &ehdr->e_ident !=
+#if BYTE_ORDER == LITTLE_ENDIAN
+ ((ELFMAG0 << (EI_MAG0 * 8)) |
+ (ELFMAG1 << (EI_MAG1 * 8)) |
+ (ELFMAG2 << (EI_MAG2 * 8)) |
+ (ELFMAG3 << (EI_MAG3 * 8)))
+#else
+ ((ELFMAG0 << (EI_MAG3 * 8)) |
+ (ELFMAG1 << (EI_MAG2 * 8)) |
+ (ELFMAG2 << (EI_MAG1 * 8)) |
+ (ELFMAG3 << (EI_MAG0 * 8)))
+#endif
+ )
+ lose (0, fd, name, NULL, NULL, N_("invalid ELF header"));
+
+ if (ehdr->e_ident[EI_CLASS] != ELFW(CLASS))
+ /* This is not a fatal error. On architectures where
+ 32-bit and 64-bit binaries can be run this might
+ happen. */
+ goto close_and_out;
+
+ if (ehdr->e_ident[EI_DATA] != byteorder)
+ {
+ if (BYTE_ORDER == BIG_ENDIAN)
+ lose (0, fd, name, NULL, NULL,
+ "ELF file data encoding not big-endian");
+ else
+ lose (0, fd, name, NULL, NULL,
+ "ELF file data encoding not little-endian");
+ }
+ if (ehdr->e_ident[EI_VERSION] != EV_CURRENT)
+ lose (0, fd, name, NULL, NULL,
+ N_("ELF file version ident does not match current one"));
+ /* XXX We should be able so set system specific versions which are
+ allowed here. */
+ if (!VALID_ELF_OSABI (ehdr->e_ident[EI_OSABI]))
+ lose (0, fd, name, NULL, NULL, N_("ELF file OS ABI invalid."));
+ if (!VALID_ELF_ABIVERSION (ehdr->e_ident[EI_ABIVERSION]))
+ lose (0, fd, name, NULL, NULL,
+ N_("ELF file ABI version invalid."));
+ lose (0, fd, name, NULL, NULL, N_("internal error"));
+ }
+
+ if (__builtin_expect (ehdr->e_version, EV_CURRENT) != EV_CURRENT)
+ lose (0, fd, name, NULL, NULL,
+ N_("ELF file version does not match current one"));
+ if (! __builtin_expect (elf_machine_matches_host (ehdr), 1))
+ {
+ close_and_out:
+ __close (fd);
+ __set_errno (ENOENT);
+ fd = -1;
+ }
+ else if (__builtin_expect (ehdr->e_phentsize, sizeof (ElfW(Phdr)))
+ != sizeof (ElfW(Phdr)))
+ lose (0, fd, name, NULL, NULL,
+ N_("ELF file's phentsize not the expected size"));
+ }
+
+ return fd;
+}
+
/* Try to open NAME in one of the directories in *DIRSP.
Return the fd, or -1. If successful, fill in *REALNAME
with the malloc'd full directory name. If it turns out
@@ -1263,7 +1321,8 @@ print_search_path (struct r_search_path_elem **list,
static int
open_path (const char *name, size_t namelen, int preloaded,
- struct r_search_path_struct *sps, char **realname)
+ struct r_search_path_struct *sps, char **realname,
+ struct filebuf *fbp)
{
struct r_search_path_elem **dirs = sps->dirs;
char *buf;
@@ -1305,7 +1364,7 @@ open_path (const char *name, size_t namelen, int preloaded,
if (__builtin_expect (_dl_debug_libs, 0))
_dl_debug_message (1, " trying file=", buf, "\n", NULL);
- fd = __open (buf, O_RDONLY);
+ fd = open_verify (buf, fbp);
if (this_dir->status[cnt] == unknown)
{
if (fd != -1)
@@ -1398,6 +1457,7 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
char *realname;
char *name_copy;
struct link_map *l;
+ struct filebuf fb;
/* Look for this name among those already loaded. */
for (l = _dl_loaded; l; l = l->l_next)
@@ -1475,12 +1535,12 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
if (l->l_rpath_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded,
- &l->l_rpath_dirs, &realname);
+ &l->l_rpath_dirs, &realname, &fb);
}
}
else if (l->l_rpath_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded, &l->l_rpath_dirs,
- &realname);
+ &realname, &fb);
}
/* If dynamically linked, try the DT_RPATH of the executable
@@ -1489,13 +1549,13 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
if (fd == -1 && l && l->l_type != lt_loaded && l != loader
&& l->l_rpath_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded, &l->l_rpath_dirs,
- &realname);
+ &realname, &fb);
}
/* Try the LD_LIBRARY_PATH environment variable. */
if (fd == -1 && env_path_list.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded, &env_path_list,
- &realname);
+ &realname, &fb);
/* Look at the RUNPATH informaiton for this binary. */
if (loader != NULL && loader->l_runpath_dirs.dirs != (void *) -1)
@@ -1515,12 +1575,12 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
if (loader->l_runpath_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded,
- &loader->l_runpath_dirs, &realname);
+ &loader->l_runpath_dirs, &realname, &fb);
}
}
else if (loader->l_runpath_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded,
- &loader->l_runpath_dirs, &realname);
+ &loader->l_runpath_dirs, &realname, &fb);
}
if (fd == -1)
@@ -1562,7 +1622,7 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
if (cached)
{
- fd = __open (cached, O_RDONLY);
+ fd = open_verify (cached, &fb);
if (fd != -1)
{
realname = local_strdup (cached);
@@ -1582,7 +1642,7 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
__builtin_expect (!(l->l_flags_1 & DF_1_NODEFLIB), 1))
&& rtld_search_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, preloaded, &rtld_search_dirs,
- &realname);
+ &realname, &fb);
/* Add another newline when we a tracing the library loading. */
if (__builtin_expect (_dl_debug_libs, 0))
@@ -1598,7 +1658,7 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
fd = -1;
else
{
- fd = __open (realname, O_RDONLY);
+ fd = open_verify (realname, &fb);
if (fd == -1)
free (realname);
}
@@ -1634,5 +1694,5 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
_dl_signal_error (errno, name, N_("cannot open shared object file"));
}
- return _dl_map_object_from_fd (name, fd, realname, loader, type, mode);
+ return _dl_map_object_from_fd (name, fd, &fb, realname, loader, type, mode);
}
generated by cgit v1.1 at 2024-11-17 12:28:16 +0000