user/sven/linux.git/kernel/module.c, branch v5.11.20

module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols

2021-03-04T11:15:35Z

commit ebfac7b778fac8b0e8e92ec91d0b055f046b4604 upstream. clang-12 -fno-pic (since https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` on x86. The two forms should have identical behaviors on x86-64 but the former causes GNU as<2.37 to produce an unreferenced undefined symbol _GLOBAL_OFFSET_TABLE_. (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the linker behavior is identical as far as Linux kernel is concerned.) Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for external function calls on x86. Note: ld -z defs and dynamic loaders do not error for unreferenced undefined symbols so the module loader is reading too much. If we ever need to ignore more symbols, the code should be refactored to ignore unreferenced symbols. Cc: Link: https://github.com/ClangBuiltLinux/linux/issues/1250 Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27178 Reported-by: Marco Elver Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Tested-by: Marco Elver Signed-off-by: Fangrui Song Signed-off-by: Jessica Yu Signed-off-by: Greg Kroah-Hartman

module: harden ELF info handling

2021-03-04T11:14:40Z

[ Upstream commit ec2a29593c83ed71a7f16e3243941ebfcf75fdf6 ] 5fdc7db644 ("module: setup load info before module_sig_check()") moved the ELF setup, so that it was done before the signature check. This made the module name available to signature error messages. However, the checks for ELF correctness in setup_load_info are not sufficient to prevent bad memory references due to corrupted offset fields, indices, etc. So, there's a regression in behavior here: a corrupt and unsigned (or badly signed) module, which might previously have been rejected immediately, can now cause an oops/crash. Harden ELF handling for module loading by doing the following: - Move the signature check back up so that it comes before ELF initialization. It's best to do the signature check to see if we can trust the module, before using the ELF structures inside it. This also makes checks against info->len more accurate again, as this field will be reduced by the length of the signature in mod_check_sig(). The module name is now once again not available for error messages during the signature check, but that seems like a fair tradeoff. - Check if sections have offset / size fields that at least don't exceed the length of the module. - Check if sections have section name offsets that don't fall outside the section name table. - Add a few other sanity checks against invalid section indices, etc. This is not an exhaustive consistency check, but the idea is to at least get through the signature and blacklist checks without crashing because of corrupted ELF info, and to error out gracefully for most issues that would have caused problems later on. Fixes: 5fdc7db6448a ("module: setup load info before module_sig_check()") Signed-off-by: Frank van der Linden Signed-off-by: Jessica Yu Signed-off-by: Sasha Levin

Merge tag 'modules-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

2020-12-17T21:01:31Z

Pull modules updates from Jessica Yu: "Summary of modules changes for the 5.11 merge window: - Fix a race condition between systemd/udev and the module loader. The module loader was sending a uevent before the module was fully initialized (i.e., before its init function has been called). This means udev can start processing the module uevent before the module has finished initializing, and some udev rules expect that the module has initialized already upon receiving the uevent. This resulted in some systemd mount units failing if udev processes the event faster than the module can finish init. This is fixed by delaying the uevent until after the module has called its init routine. - Make the linker array sections for kernel params and module version attributes more robust by switching to use the alignment of the type in question. Namely, linker section arrays will be constructed using the alignment required by the struct (using __alignof__()) as opposed to a specific value such as sizeof(void *) or sizeof(long). This is less likely to cause breakages should the size of the type ever change (Johan Hovold) - Fix module state inconsistency by setting it back to GOING when a module fails to load and is on its way out (Miroslav Benes) - Some comment and code cleanups (Sergey Shtylyov)" * tag 'modules-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux: module: delay kobject uevent until after module init call module: drop semicolon from version macro init: use type alignment for kernel parameters params: clean up module-param macros params: use type alignment for kernel parameters params: drop redundant "unused" attributes module: simplify version-attribute handling module: drop version-attribute alignment module: fix comment style module: add more 'kernel-doc' comments module: fix up 'kernel-doc' comments module: only handle errors with the *switch* statement in module_sig_check() module: avoid *goto*s in module_sig_check() module: merge repetitive strings in module_sig_check() module: set MODULE_STATE_GOING state when a module fails to load

module: delay kobject uevent until after module init call

2020-12-09T08:42:47Z

Apparently there has been a longstanding race between udev/systemd and the module loader. Currently, the module loader sends a uevent right after sysfs initialization, but before the module calls its init function. However, some udev rules expect that the module has initialized already upon receiving the uevent. This race has been triggered recently (see link in references) in some systemd mount unit files. For instance, the configfs module creates the /sys/kernel/config mount point in its init function, however the module loader issues the uevent before this happens. sys-kernel-config.mount expects to be able to mount /sys/kernel/config upon receipt of the module loading uevent, but if the configfs module has not called its init function yet, then this directory will not exist and the mount unit fails. A similar situation exists for sys-fs-fuse-connections.mount, as the fuse sysfs mount point is created during the fuse module's init function. If udev is faster than module initialization then the mount unit would fail in a similar fashion. To fix this race, delay the module KOBJ_ADD uevent until after the module has finished calling its init routine. References: https://github.com/systemd/systemd/issues/17586 Reviewed-by: Greg Kroah-Hartman Tested-By: Nicolas Morey-Chaisemartin Signed-off-by: Jessica Yu

bpf: Keep module's btf_data_size intact after load

2020-12-04T01:38:20Z

Having real btf_data_size stored in struct module is benefitial to quickly determine which kernel modules have associated BTF object and which don't. There is no harm in keeping this info, as opposed to keeping invalid pointer. Fixes: 607c543f939d ("bpf: Sanitize BTF data pointer after module is loaded") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201203204634.1325171-3-andrii@kernel.org

bpf: Sanitize BTF data pointer after module is loaded

2020-11-24T23:05:21Z

Given .BTF section is not allocatable, it will get trimmed after module is loaded. BPF system handles that properly by creating an independent copy of data. But prevent any accidental misused by resetting the pointer to BTF data. Fixes: 36e68442d1af ("bpf: Load and verify kernel module BTFs") Suggested-by: Jessica Yu Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Jessica Yu Cc: Greg Kroah-Hartman Link: https://lore.kernel.org/bpf/20201121070829.2612884-2-andrii@kernel.org

bpf: Load and verify kernel module BTFs

2020-11-10T23:25:53Z

Add kernel module listener that will load/validate and unload module BTF. Module BTFs gets ID generated for them, which makes it possible to iterate them with existing BTF iteration API. They are given their respective module's names, which will get reported through GET_OBJ_INFO API. They are also marked as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. Also, similarly to vmlinux BTF, kernel module BTFs are exposed through sysfs as /sys/kernel/btf/. This is convenient for user-space tools to inspect module BTF contents and dump their types with existing tools: [vmuser@archvm bpf]$ ls -la /sys/kernel/btf total 0 drwxr-xr-x 2 root root 0 Nov 4 19:46 . drwxr-xr-x 13 root root 0 Nov 4 19:46 .. ... -r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass -r--r--r-- 1 root root 100225 Nov 4 19:46 kvm -r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel -r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr -r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw -r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Reviewed-by: Greg Kroah-Hartman Link: https://lore.kernel.org/bpf/20201110011932.3201430-5-andrii@kernel.org

module: fix comment style

2020-11-09T13:28:12Z

Many comments in this module do not comply with the preferred multi-line comment style as reported by 'scripts/checkpatch.pl': WARNING: Block comments use * on subsequent lines WARNING: Block comments use a trailing */ on a separate line Fix those comments, along with (unreported for some reason?) the starts of the multi-line comments not being /* on their own line... Signed-off-by: Sergey Shtylyov Signed-off-by: Jessica Yu

module: add more 'kernel-doc' comments

2020-11-09T12:47:42Z

Some functions have the proper 'kernel-doc' comments but these don't start with proper /** -- fix that, along with adding () to the function name on the following lines to fully comply with the 'kernel-doc' format. Signed-off-by: Sergey Shtylyov Signed-off-by: Jessica Yu

module: fix up 'kernel-doc' comments

2020-11-09T12:46:58Z

Some 'kernel-doc' function comments do not fully comply with the specified format due to: - missing () after the function name; - "RETURNS:"/"Returns:" instead of "Return:" when documenting the function's result. - empty line before describing the function's arguments. Signed-off-by: Sergey Shtylyov Signed-off-by: Jessica Yu