【发布时间】：2021-12-29 23:21:46
【问题描述】：
我正在尝试使用来自libcrypto.so.3 的函数EVP_PKEY_new_raw_private_key。
当我与-l:libcrypot.so.3 链接时，它可以工作。
当我尝试使用dlmopen+dlsym 打开同一个文件时，调用该函数时是SEGV。
MWE 是 here:
main.c
#define _GNU_SOURCE
#include <assert.h>
#include <dlfcn.h>
#include <openssl/evp.h>
// c.f. objects/objects.pl
#define NID_X25519 1034
// some data to call new with
unsigned const char scalar[] = {
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x10, 0x11,
0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x20, 0x21, 0x22,
0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x30, 0x31, 0x32,
};
int main(int argc, char **argv) {
int keylen = 32;
assert(keylen == sizeof(scalar));
// open the library
void *libhandle = dlmopen(LM_ID_NEWLM, "/usr/local/lib64/libcrypto.so.3",
RTLD_LAZY | RTLD_DEEPBIND | RTLD_LOCAL);
assert(libhandle != NULL);
// declare the pointer to the function
EVP_PKEY *(*dl_EVP_PKEY_new_raw_private_key)(
int type, ENGINE *e, const unsigned char *key, size_t keylen);
// load from libhandle
if ((dl_EVP_PKEY_new_raw_private_key =
dlsym(libhandle, "EVP_PKEY_new_raw_private_key")) == NULL) {
fprintf(stderr, "dlsym EVP_PKEY_new_raw_private_key: %s\n", dlerror());
}
// create a private key form it.
EVP_PKEY *skey = NULL;
printf("about to create the skey\n");
if (argc > 1) {
// this segfaults somewhere in the library
skey = dl_EVP_PKEY_new_raw_private_key(NID_X25519, NULL, scalar, keylen);
} else {
// this does not
skey = EVP_PKEY_new_raw_private_key(NID_X25519, NULL, scalar, keylen);
}
printf("created the skey\n");
assert(skey != NULL);
dlclose(libhandle);
return 0;
}
生成文件
LIBRARY_PATH=/usr/local/lib64
LIBRARY_NAME=libcrypto.so.3
all: ok fail
a.out: main.c $(LD_LIBRARY_PATH)/$(LIBRARY_NAME)
gcc main.c -ldl -L $(LD_LIBRARY_PATH) -l:$(LIBRARY_NAME)
ok: a.out
@echo sould be ok
LD_LIBRARY_PATH=$(LIBRARY_PATH) ldd ./${^}
LD_LIBRARY_PATH=$(LIBRARY_PATH) ./${^}
@echo ok
@echo
fail: a.out
@echo should segfault
LD_LIBRARY_PATH=$(LIBRARY_PATH) ldd ./${^}
LD_LIBRARY_PATH=$(LIBRARY_PATH) ./${^} dl
@echo wont be able to read this
echo
执行make 时，您可以看到第二个调用，我们调用dlsymd 函数，SIGSEGVs。我们还看到，使用了相同的libcrypto.so.3。
$ make
sould be ok
LD_LIBRARY_PATH=/usr/local/lib64 ldd ./a.out
linux-vdso.so.1 (0x00007ffc0b7b9000)
libdl.so.2 => /usr/lib/libdl.so.2 (0x00007fd36def3000)
libcrypto.so.3 => /usr/local/lib64/libcrypto.so.3 (0x00007fd36dad5000)
libc.so.6 => /usr/lib/libc.so.6 (0x00007fd36d909000)
/lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007fd36df21000)
libpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007fd36d8e8000)
LD_LIBRARY_PATH=/usr/local/lib64 ./a.out
about to create the skey
created the skey
ok
should segfault
LD_LIBRARY_PATH=/usr/local/lib64 ldd ./a.out
linux-vdso.so.1 (0x00007ffc7bbac000)
libdl.so.2 => /usr/lib/libdl.so.2 (0x00007f9d68d2d000)
libcrypto.so.3 => /usr/local/lib64/libcrypto.so.3 (0x00007f9d6890f000)
libc.so.6 => /usr/lib/libc.so.6 (0x00007f9d68743000)
/lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007f9d68d5b000)
libpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007f9d68722000)
LD_LIBRARY_PATH=/usr/local/lib64 ./a.out dl
about to create the skey
make: *** [Makefile:18: fail] Segmentation fault (core dumped)
注意事项：
- 在使用 libcrypto.so.1.1 文件时确实有效
- 我用
./Configure --api=3.0.0 no-deprecated && make -j从here（提交f87b4c4ea67393c9269663ed40a7ea3463cc59d3）编译OpenSSL，并将生成的libcrypto.so.3复制到/usr/local/lib64/ - 当使用
./Configure --api=3.0.0 no-deprecated no-threads时，一切都完美无缺，这让我觉得libpthread+dlsym有问题... - 该线程的堆栈跟踪似乎是（来自
coredumpctl debug）
Stack trace of thread 1903409:
#0 0x00007fb6d8f8f8ec __pthread_rwlock_rdlock (/usr/lib/libpthread-2.33.so + 0xd8ec)
#1 0x00007fb6d91ba539 CRYPTO_THREAD_read_lock (/usr/local/lib64/libcrypto.so.3 + 0x210539)
#2 0x00007fb6d91a8627 ossl_lib_ctx_get_data (/usr/local/lib64/libcrypto.so.3 + 0x1fe627)
#3 0x00007fb6d91813f4 evp_generic_fetch (/usr/local/lib64/libcrypto.so.3 + 0x1d73f4)
#4 0x00007fb6d918b1c8 EVP_KEYMGMT_fetch (/usr/local/lib64/libcrypto.so.3 + 0x1e11c8)
#5 0x00007fb6d91976f9 EVP_PKEY_CTX_new_from_name (/usr/local/lib64/libcrypto.so.3 + 0x1ed6f9)
#6 0x00007fb6d9192be1 EVP_PKEY_new_raw_private_key (/usr/local/lib64/libcrypto.so.3 + 0x1e8be1)
#7 0x00005575befac2c2 n/a (/home/joel/mwe-dl-libcrypto3/a.out + 0x12c2)
#8 0x00007fb6d9447b25 __libc_start_main (libc.so.6 + 0x27b25)
#9 0x00005575befac0de n/a (/home/joel/mwe-dl-libcrypto3/a.out + 0x10de)
我做错了什么？这是dlmopen 问题还是openssl 问题？ （在我看来两者都不太可能）
【问题讨论】：
标签： openssl pthreads shared-libraries dlopen libcrypto