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Commits › aaf7945
libpkg: fall back to Linux for ELF shlib parsing
Isaac Freund committed 1 year ago
commit aaf7945217c16b4cd61b2ee63c9e29f1e4f86479
parent 189bb2a
1 file changed +31 -3
modified libpkg/pkg_elf.c
@@ -151,15 +151,43 @@ analyse_elf(struct pkg *pkg, const char *fpath)
		goto cleanup; /* not a dynamically linked elf: no results */

	}
- 
	/* A shared object for use with dlopen(3) may lack a NOTE section and
- 
           will therefore have unknown elf_abi.os. */

	struct pkg_abi elf_abi;

	elf_parse_abi(e, &elfhdr, &elf_abi);
- 
	if (elf_abi.os == PKG_OS_UNKNOWN || elf_abi.arch == PKG_ARCH_UNKNOWN) {
+ 
	if (elf_abi.arch == PKG_ARCH_UNKNOWN) {

		ret = EPKG_END;

		goto cleanup;

	}
+ 
	if (elf_abi.os == PKG_OS_UNKNOWN) {
+ 
		/* There is no reliable way to identify shared libraries targeting Linux.
+ 
		 * It would be possible to reliably identify Linux executables by checking
+ 
		 * the dynamic linker path in DT_INTERP. Shared libraries however do not
+ 
		 * have DT_INTERP set.
+ 
		 *
+ 
		 * Reading the notes section for NT_GNU_ABI_TAG is not sufficient either
+ 
		 * as this is only required for executables, not shared libraries.
+ 
		 * See https://refspecs.linuxfoundation.org/LSB_1.2.0/gLSB/noteabitag.html
+ 
		 *
+ 
		 * Therefore, if pkg is targeting Linux assume that ELF files with unknown
+ 
		 * target OS are also targeting Linux.
+ 
		 *
+ 
		 * Furthermore, if pkg is targeting FreeBSD also assume that ELF
+ 
		 * files with unknown target OS are targeting Linux. This is consistent
+ 
		 * with the behavior of the FreeBSD kernel, which falls back to Linux by
+ 
		 * default if it is unable to determine the target OS of an ELF file.
+ 
		 * (This behavior can be overridden with a fallback_brand sysctl.)
+ 
		 *
+ 
		 * We could add a pkg option to configure the fallback OS
+ 
		 * in the future if necessary.
+ 
		 */
+ 
		if (ctx.abi.os == PKG_OS_LINUX || ctx.abi.os == PKG_OS_FREEBSD) {
+ 
			elf_abi.os = PKG_OS_LINUX;
+ 
		} else {
+ 
			ret = EPKG_END;
+ 
			goto cleanup;
+ 
		}
+ 
	}
+ 


	enum pkg_shlib_flags flags = pkg_shlib_flags_from_abi(&elf_abi);

	if ((flags & PKG_SHLIB_FLAGS_COMPAT_LINUX) == 0 && elf_abi.os != ctx.abi.os) {

		ret = EPKG_END;