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Fix ldd for PIE binaries after rtld stopped accepting binaries for dlopen.

Browse Source 
ldd proclaims ET_DYN objects as shared libraries and tries to
dlopen(RTLD_TRACE) them to get dependencies. Since PIE binaries are
ET_DYN | DF_1_PIE, refusal to dlopen such binaries breaks ldd.

Fix it by reading and parsing dynamic segment looking for DF_FLAG_1
and taking DF_1_PIE into account when deciding between binary and
library.

Reported by:	Dewayne Geraghty <dewayne@heuristicsystems.com.au>
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D25257
This commit is contained in:
kib 2020-06-13 18:21:31 +00:00
parent c7344298e1
commit dffbc53f60
1 changed files with 69 additions and 10 deletions
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75
usr.bin/ldd/ldd.c
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@ -289,10 +289,18 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
#endif
Elf_Ehdr elf;
} hdr;
int n;
Elf_Phdr phdr, dynphdr;
Elf_Dyn *dynp;
void *dyndata;
#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
Elf32_Phdr phdr32, dynphdr32;
Elf32_Dyn *dynp32;
#endif
int df1pie, dynamic, i, n;
*is_shlib = 0;
*type = TYPE_UNKNOWN;
df1pie = 0;
if ((n = read(fd, &hdr, sizeof(hdr))) == -1) {
warn("%s: can't read program header", fname);
@ -320,8 +328,6 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
if ((size_t)n >= sizeof(hdr.elf32) && IS_ELF(hdr.elf32) &&
hdr.elf32.e_ident[EI_CLASS] == ELFCLASS32) {
/* Handle 32 bit ELF objects */
Elf32_Phdr phdr;
int dynamic, i;
dynamic = 0;
*type = TYPE_ELF32;
@ -331,13 +337,14 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
return (0);
}
for (i = 0; i < hdr.elf32.e_phnum; i++) {
if (read(fd, &phdr, hdr.elf32.e_phentsize) !=
sizeof(phdr)) {
if (read(fd, &phdr32, hdr.elf32.e_phentsize) !=
sizeof(phdr32)) {
warnx("%s: can't read program header", fname);
return (0);
}
if (phdr.p_type == PT_DYNAMIC) {
if (phdr32.p_type == PT_DYNAMIC) {
dynamic = 1;
dynphdr32 = phdr32;
break;
}
}
@ -346,8 +353,35 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
warnx("%s: not a dynamic ELF executable", fname);
return (0);
}
if (hdr.elf32.e_type == ET_DYN) {
if (lseek(fd, dynphdr32.p_offset, SEEK_SET) == -1) {
warnx("%s: dynamic segment out of range",
fname);
return (0);
}
dyndata = malloc(dynphdr32.p_filesz);
if (dyndata == NULL) {
warn("malloc");
return (0);
}
if (read(fd, dyndata, dynphdr32.p_filesz) !=
(ssize_t)dynphdr32.p_filesz) {
free(dyndata);
warnx("%s: can't read dynamic segment", fname);
return (0);
}
for (dynp32 = dyndata; dynp32->d_tag != DT_NULL;
dynp32++) {
if (dynp32->d_tag != DT_FLAGS_1)
continue;
df1pie = (dynp32->d_un.d_val & DF_1_PIE) != 0;
break;
}
free(dyndata);
if (hdr.elf32.e_ident[EI_OSABI] == ELFOSABI_FREEBSD) {
if (!df1pie)
*is_shlib = 1;
return (1);
}
@ -362,8 +396,6 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
if ((size_t)n >= sizeof(hdr.elf) && IS_ELF(hdr.elf) &&
hdr.elf.e_ident[EI_CLASS] == ELF_TARG_CLASS) {
/* Handle default ELF objects on this architecture */
Elf_Phdr phdr;
int dynamic, i;
dynamic = 0;
*type = TYPE_ELF;
@ -380,6 +412,7 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
}
if (phdr.p_type == PT_DYNAMIC) {
dynamic = 1;
dynphdr = phdr;
break;
}
}
@ -388,9 +421,35 @@ is_executable(const char *fname, int fd, int *is_shlib, int *type)
warnx("%s: not a dynamic ELF executable", fname);
return (0);
}
if (hdr.elf.e_type == ET_DYN) {
if (lseek(fd, dynphdr.p_offset, SEEK_SET) == -1) {
warnx("%s: dynamic segment out of range",
fname);
return (0);
}
dyndata = malloc(dynphdr.p_filesz);
if (dyndata == NULL) {
warn("malloc");
return (0);
}
if (read(fd, dyndata, dynphdr.p_filesz) !=
(ssize_t)dynphdr.p_filesz) {
free(dyndata);
warnx("%s: can't read dynamic segment", fname);
return (0);
}
for (dynp = dyndata; dynp->d_tag != DT_NULL; dynp++) {
if (dynp->d_tag != DT_FLAGS_1)
continue;
df1pie = (dynp->d_un.d_val & DF_1_PIE) != 0;
break;
}
free(dyndata);
switch (hdr.elf.e_ident[EI_OSABI]) {
case ELFOSABI_FREEBSD:
if (!df1pie)
*is_shlib = 1;
return (1);
#ifdef __ARM_EABI__