From: David Howells <dhowells@redhat.com> To: torvalds@linux-foundation.org Cc: linux-man@vger.kernel.org, linux-api@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org Subject: [PATCH 04/24] Enforce module signatures if the kernel is locked down Date: Wed, 11 Apr 2018 17:25:05 +0100 [thread overview] Message-ID: <152346390539.4030.2913584917609215556.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> If the kernel is locked down, require that all modules have valid signatures that we can verify or that IMA can validate the file. I have adjusted the errors generated: (1) If there's no signature (ENODATA) or we can't check it (ENOPKG, ENOKEY), then: (a) If signatures are enforced then EKEYREJECTED is returned. (b) If IMA will have validated the image, return 0 (okay). (c) If there's no signature or we can't check it, but the kernel is locked down then EPERM is returned (this is then consistent with other lockdown cases). (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we return the error we got. Note that the X.509 code doesn't check for key expiry as the RTC might not be valid or might not have been transferred to the kernel's clock yet. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jiri Bohac <jbohac@suse.cz> cc: "Lee, Chun-Yi" <jlee@suse.com> cc: James Morris <james.l.morris@oracle.com> --- kernel/module.c | 56 ++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 43 insertions(+), 13 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index a6e43a5806a1..9c1709a05037 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -64,6 +64,7 @@ #include <linux/bsearch.h> #include <linux/dynamic_debug.h> #include <linux/audit.h> +#include <linux/ima.h> #include <uapi/linux/module.h> #include "module-internal.h" @@ -2761,10 +2762,12 @@ static inline void kmemleak_load_module(const struct module *mod, #endif #ifdef CONFIG_MODULE_SIG -static int module_sig_check(struct load_info *info, int flags) +static int module_sig_check(struct load_info *info, int flags, + bool can_do_ima_check) { - int err = -ENOKEY; + int err = -ENODATA; const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const char *reason; const void *mod = info->hdr; /* @@ -2779,19 +2782,46 @@ static int module_sig_check(struct load_info *info, int flags) err = mod_verify_sig(mod, &info->len); } - if (!err) { + switch (err) { + case 0: info->sig_ok = true; return 0; - } - /* Not having a signature is only an error if we're strict. */ - if (err == -ENOKEY && !sig_enforce) - err = 0; + /* We don't permit modules to be loaded into trusted kernels + * without a valid signature on them, but if we're not + * enforcing, certain errors are non-fatal. + */ + case -ENODATA: + reason = "Loading of unsigned module"; + goto decide; + case -ENOPKG: + reason = "Loading of module with unsupported crypto"; + goto decide; + case -ENOKEY: + reason = "Loading of module with unavailable key"; + decide: + if (sig_enforce) { + pr_notice("%s is rejected\n", reason); + return -EKEYREJECTED; + } - return err; + if (can_do_ima_check && is_ima_appraise_enabled()) + return 0; + if (kernel_is_locked_down(reason)) + return -EPERM; + return 0; + + /* All other errors are fatal, including nomem, unparseable + * signatures and signature check failures - even if signatures + * aren't required. + */ + default: + return err; + } } #else /* !CONFIG_MODULE_SIG */ -static int module_sig_check(struct load_info *info, int flags) +static int module_sig_check(struct load_info *info, int flags, + bool can_do_ima_check) { return 0; } @@ -3651,13 +3681,13 @@ static int unknown_module_param_cb(char *param, char *val, const char *modname, /* Allocate and load the module: note that size of section 0 is always zero, and we rely on this for optional sections. */ static int load_module(struct load_info *info, const char __user *uargs, - int flags) + int flags, bool can_do_ima_check) { struct module *mod; long err; char *after_dashes; - err = module_sig_check(info, flags); + err = module_sig_check(info, flags, can_do_ima_check); if (err) goto free_copy; @@ -3846,7 +3876,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, if (err) return err; - return load_module(&info, uargs, 0); + return load_module(&info, uargs, 0, false); } SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) @@ -3873,7 +3903,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) info.hdr = hdr; info.len = size; - return load_module(&info, uargs, flags); + return load_module(&info, uargs, flags, true); } static inline int within(unsigned long addr, void *start, unsigned long size)
WARNING: multiple messages have this Message-ID (diff)
From: dhowells@redhat.com (David Howells) To: linux-security-module@vger.kernel.org Subject: [PATCH 04/24] Enforce module signatures if the kernel is locked down Date: Wed, 11 Apr 2018 17:25:05 +0100 [thread overview] Message-ID: <152346390539.4030.2913584917609215556.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> If the kernel is locked down, require that all modules have valid signatures that we can verify or that IMA can validate the file. I have adjusted the errors generated: (1) If there's no signature (ENODATA) or we can't check it (ENOPKG, ENOKEY), then: (a) If signatures are enforced then EKEYREJECTED is returned. (b) If IMA will have validated the image, return 0 (okay). (c) If there's no signature or we can't check it, but the kernel is locked down then EPERM is returned (this is then consistent with other lockdown cases). (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we return the error we got. Note that the X.509 code doesn't check for key expiry as the RTC might not be valid or might not have been transferred to the kernel's clock yet. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jiri Bohac <jbohac@suse.cz> cc: "Lee, Chun-Yi" <jlee@suse.com> cc: James Morris <james.l.morris@oracle.com> --- kernel/module.c | 56 ++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 43 insertions(+), 13 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index a6e43a5806a1..9c1709a05037 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -64,6 +64,7 @@ #include <linux/bsearch.h> #include <linux/dynamic_debug.h> #include <linux/audit.h> +#include <linux/ima.h> #include <uapi/linux/module.h> #include "module-internal.h" @@ -2761,10 +2762,12 @@ static inline void kmemleak_load_module(const struct module *mod, #endif #ifdef CONFIG_MODULE_SIG -static int module_sig_check(struct load_info *info, int flags) +static int module_sig_check(struct load_info *info, int flags, + bool can_do_ima_check) { - int err = -ENOKEY; + int err = -ENODATA; const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const char *reason; const void *mod = info->hdr; /* @@ -2779,19 +2782,46 @@ static int module_sig_check(struct load_info *info, int flags) err = mod_verify_sig(mod, &info->len); } - if (!err) { + switch (err) { + case 0: info->sig_ok = true; return 0; - } - /* Not having a signature is only an error if we're strict. */ - if (err == -ENOKEY && !sig_enforce) - err = 0; + /* We don't permit modules to be loaded into trusted kernels + * without a valid signature on them, but if we're not + * enforcing, certain errors are non-fatal. + */ + case -ENODATA: + reason = "Loading of unsigned module"; + goto decide; + case -ENOPKG: + reason = "Loading of module with unsupported crypto"; + goto decide; + case -ENOKEY: + reason = "Loading of module with unavailable key"; + decide: + if (sig_enforce) { + pr_notice("%s is rejected\n", reason); + return -EKEYREJECTED; + } - return err; + if (can_do_ima_check && is_ima_appraise_enabled()) + return 0; + if (kernel_is_locked_down(reason)) + return -EPERM; + return 0; + + /* All other errors are fatal, including nomem, unparseable + * signatures and signature check failures - even if signatures + * aren't required. + */ + default: + return err; + } } #else /* !CONFIG_MODULE_SIG */ -static int module_sig_check(struct load_info *info, int flags) +static int module_sig_check(struct load_info *info, int flags, + bool can_do_ima_check) { return 0; } @@ -3651,13 +3681,13 @@ static int unknown_module_param_cb(char *param, char *val, const char *modname, /* Allocate and load the module: note that size of section 0 is always zero, and we rely on this for optional sections. */ static int load_module(struct load_info *info, const char __user *uargs, - int flags) + int flags, bool can_do_ima_check) { struct module *mod; long err; char *after_dashes; - err = module_sig_check(info, flags); + err = module_sig_check(info, flags, can_do_ima_check); if (err) goto free_copy; @@ -3846,7 +3876,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, if (err) return err; - return load_module(&info, uargs, 0); + return load_module(&info, uargs, 0, false); } SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) @@ -3873,7 +3903,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) info.hdr = hdr; info.len = size; - return load_module(&info, uargs, flags); + return load_module(&info, uargs, flags, true); } static inline int within(unsigned long addr, void *start, unsigned long size) -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2018-04-11 16:25 UTC|newest] Thread overview: 130+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-11 16:24 [PATCH 00/24] security: Add kernel lockdown David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 16:24 ` [PATCH 01/24] Add the ability to lock down access to the running kernel image David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 16:44 ` Jann Horn 2018-04-11 16:44 ` Jann Horn 2018-04-11 17:37 ` Randy Dunlap 2018-04-11 17:37 ` Randy Dunlap 2018-04-11 18:50 ` Miguel Ojeda 2018-04-11 18:50 ` Miguel Ojeda 2018-04-11 19:56 ` Greg KH 2018-04-11 19:56 ` Greg KH 2018-04-11 17:49 ` David Howells 2018-04-11 17:49 ` David Howells 2018-04-11 18:09 ` Linus Torvalds 2018-04-11 18:09 ` Linus Torvalds 2018-04-11 18:35 ` Justin Forbes 2018-04-11 18:35 ` Justin Forbes 2018-04-11 21:05 ` Jordan Glover 2018-04-11 21:05 ` Jordan Glover 2018-04-11 22:38 ` Linus Torvalds 2018-04-11 22:38 ` Linus Torvalds 2018-04-12 13:09 ` Justin Forbes 2018-04-12 13:09 ` Justin Forbes 2018-04-12 16:52 ` Linus Torvalds 2018-04-12 16:52 ` Linus Torvalds 2018-04-12 2:57 ` Andy Lutomirski 2018-04-12 2:57 ` Andy Lutomirski 2018-04-11 16:24 ` [PATCH 02/24] Add a SysRq option to lift kernel lockdown David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 17:05 ` Jann Horn 2018-04-11 17:05 ` Jann Horn 2018-04-13 20:22 ` Pavel Machek 2018-04-11 16:24 ` [PATCH 03/24] ima: require secure_boot rules in lockdown mode David Howells 2018-04-11 16:24 ` David Howells 2018-04-11 16:25 ` David Howells [this message] 2018-04-11 16:25 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells 2018-04-11 16:25 ` [PATCH 05/24] Restrict /dev/{mem, kmem, port} when " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 06/24] kexec_load: Disable at runtime if " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 19:00 ` Eric W. Biederman 2018-04-11 19:00 ` Eric W. Biederman 2018-04-11 20:09 ` Mimi Zohar 2018-04-11 20:09 ` Mimi Zohar 2018-04-12 11:38 ` Mimi Zohar 2018-04-12 11:38 ` Mimi Zohar 2018-04-11 20:05 ` David Howells 2018-04-11 20:05 ` David Howells 2018-04-11 20:05 ` David Howells 2018-04-11 16:25 ` [PATCH 07/24] hibernate: Disable when " David Howells 2018-04-11 16:25 ` David Howells 2018-04-13 20:22 ` Pavel Machek 2018-04-19 14:38 ` David Howells 2018-04-19 14:38 ` David Howells 2018-04-22 14:34 ` Andy Lutomirski 2018-04-22 14:34 ` Andy Lutomirski 2018-04-26 7:26 ` Pavel Machek 2018-04-26 7:34 ` Rafael J. Wysocki 2018-04-26 7:34 ` Rafael J. Wysocki 2018-04-26 8:20 ` Jiri Kosina 2018-04-26 8:20 ` Jiri Kosina 2018-05-23 8:46 ` joeyli 2018-05-23 8:46 ` joeyli 2018-04-11 16:25 ` [PATCH 08/24] uswsusp: " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 09/24] PCI: Lock down BAR access " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 10/24] x86: Lock down IO port " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 11/24] x86/msr: Restrict MSR " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:25 ` [PATCH 12/24] ACPI: Limit access to custom_method " David Howells 2018-04-11 16:25 ` David Howells 2018-04-11 16:26 ` [PATCH 13/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 14/24] acpi: Disable ACPI table override if the kernel is " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 15/24] acpi: Disable APEI error injection " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 16/24] Prohibit PCMCIA CIS storage when " David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 17/24] Lock down TIOCSSERIAL David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 18/24] Lock down module params that specify hardware parameters (eg. ioport) David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 17:22 ` Randy Dunlap 2018-04-11 17:22 ` Randy Dunlap 2018-04-11 16:26 ` [PATCH 19/24] x86/mmiotrace: Lock down the testmmiotrace module David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 20/24] Lock down /proc/kcore David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:26 ` [PATCH 21/24] Lock down kprobes David Howells 2018-04-11 16:26 ` David Howells 2018-04-11 16:27 ` [PATCH 22/24] bpf: Restrict kernel image access functions when the kernel is locked down David Howells 2018-04-11 16:27 ` David Howells 2018-04-11 16:27 ` [PATCH 23/24] Lock down perf David Howells 2018-04-11 16:27 ` David Howells 2018-04-11 16:27 ` [PATCH 24/24] debugfs: Restrict debugfs when the kernel is locked down David Howells 2018-04-11 16:27 ` David Howells 2018-04-11 17:26 ` Randy Dunlap 2018-04-11 17:26 ` Randy Dunlap 2018-04-11 18:50 ` Eric W. Biederman 2018-04-11 18:50 ` Eric W. Biederman 2018-04-11 19:54 ` Greg KH 2018-04-11 19:54 ` Greg KH 2018-04-11 20:08 ` David Howells 2018-04-11 20:08 ` David Howells 2018-04-11 20:08 ` David Howells 2018-04-11 20:09 ` David Howells 2018-04-11 20:09 ` David Howells 2018-04-11 20:33 ` Greg KH 2018-04-11 20:33 ` Greg KH 2018-04-12 2:54 ` Andy Lutomirski 2018-04-12 2:54 ` Andy Lutomirski 2018-04-12 8:23 ` Greg KH 2018-04-12 8:23 ` Greg KH 2018-04-12 14:19 ` Andy Lutomirski 2018-04-12 14:19 ` Andy Lutomirski 2018-04-13 20:22 ` Pavel Machek 2018-04-19 14:35 ` David Howells 2018-04-19 14:35 ` David Howells 2018-05-10 11:01 ` Pavel Machek -- strict thread matches above, loose matches on Subject: below -- 2017-04-05 20:14 [PATCH 00/24] Kernel lockdown David Howells 2017-04-05 20:15 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells 2017-04-05 20:15 ` David Howells 2017-04-05 17:09 [PATCH 00/24] Kernel lockdown David Howells 2017-04-05 17:10 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:10 ` David Howells 2017-04-05 17:07 [PATCH 00/24] Kernel lockdown David Howells 2017-04-05 17:07 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells 2017-04-05 17:07 ` David Howells
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