| Message ID | 20241022161009.982584-2-mic@digikod.net (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Paul Moore |
| Headers | show |
| Series | Landlock audit support | expand |
On Tue, Oct 22, 2024 at 12:10 PM Mickaël Salaün <mic@digikod.net> wrote: > > When CONFIG_AUDIT is set, its CONFIG_NET dependency is also set, and the > dev_get_by_index and init_net symbols (used by dump_common_audit_data) > are found by the linker. dump_common_audit_data() should then failed to > build when CONFIG_NET is not set. However, because the compiler is > smart, it knows that audit_log_start() always return NULL when > !CONFIG_AUDIT, and it doesn't build the body of common_lsm_audit(). As > a side effect, dump_common_audit_data() is not built and the linker > doesn't error out because of missing symbols. > > Let's only build lsm_audit.o when CONFIG_AUDIT is set. > > ipv4_skb_to_auditdata() and ipv6_skb_to_auditdata() are only used by > Smack if CONFIG_AUDIT is set, so they don't need fake implementations. > > Because common_lsm_audit() is used in multiple places without > CONFIG_AUDIT checks, add a fake implementation. > > Cc: Casey Schaufler <casey@schaufler-ca.com> > Cc: James Morris <jmorris@namei.org> > Cc: Paul Moore <paul@paul-moore.com> > Cc: Serge E. Hallyn <serge@hallyn.com> > Signed-off-by: Mickaël Salaün <mic@digikod.net> > Link: https://lore.kernel.org/r/20241022161009.982584-2-mic@digikod.net > --- > include/linux/lsm_audit.h | 14 ++++++++++++++ > security/Makefile | 2 +- > 2 files changed, 15 insertions(+), 1 deletion(-) I think this fix is the right thing to do regardless of the rest of the patchset so I've merged it into lsm/dev, if anyone objects please speak up. Thanks!
On Tue, Oct 22, 2024 at 06:09:56PM +0200, Mickaël Salaün wrote: > When CONFIG_AUDIT is set, its CONFIG_NET dependency is also set, and the > dev_get_by_index and init_net symbols (used by dump_common_audit_data) > are found by the linker. dump_common_audit_data() should then failed to > build when CONFIG_NET is not set. However, because the compiler is > smart, it knows that audit_log_start() always return NULL when > !CONFIG_AUDIT, and it doesn't build the body of common_lsm_audit(). As > a side effect, dump_common_audit_data() is not built and the linker > doesn't error out because of missing symbols. > > Let's only build lsm_audit.o when CONFIG_AUDIT is set. > CONFIG_AUDIT and CONFIG_SECURITY are independent of each other. With CONFIG_SECURITY=n and CONFIG_AUDIT=y, we now get: Error log: arm-linux-gnueabi-ld: security/lsm_audit.o: in function `audit_log_lsm_data': security/lsm_audit.c:417:(.text+0x5e4): undefined reference to `lockdown_reasons' arm-linux-gnueabi-ld: security/lsm_audit.c:417:(.text+0x5e8): undefined reference to `lockdown_reasons' make[3]: *** [scripts/Makefile.vmlinux:78: vmlinux] Error 1 make[2]: *** [Makefile:1178: vmlinux] Error 2 make[1]: *** [Makefile:224: __sub-make] Error 2 make: *** [Makefile:224: __sub-make] Error 2 Guenter
On Wed, Oct 23, 2024 at 2:51 PM Guenter Roeck <linux@roeck-us.net> wrote: > > On Tue, Oct 22, 2024 at 06:09:56PM +0200, Mickaël Salaün wrote: > > When CONFIG_AUDIT is set, its CONFIG_NET dependency is also set, and the > > dev_get_by_index and init_net symbols (used by dump_common_audit_data) > > are found by the linker. dump_common_audit_data() should then failed to > > build when CONFIG_NET is not set. However, because the compiler is > > smart, it knows that audit_log_start() always return NULL when > > !CONFIG_AUDIT, and it doesn't build the body of common_lsm_audit(). As > > a side effect, dump_common_audit_data() is not built and the linker > > doesn't error out because of missing symbols. > > > > Let's only build lsm_audit.o when CONFIG_AUDIT is set. > > CONFIG_AUDIT and CONFIG_SECURITY are independent of each other. > With CONFIG_SECURITY=n and CONFIG_AUDIT=y, we now get: Yes, unfortunately the error was seen during linux-next testing too. I'm removing patch 1/14 from lsm/dev now. > Error log: > arm-linux-gnueabi-ld: security/lsm_audit.o: in function `audit_log_lsm_data': > security/lsm_audit.c:417:(.text+0x5e4): undefined reference to `lockdown_reasons' > arm-linux-gnueabi-ld: security/lsm_audit.c:417:(.text+0x5e8): undefined reference to `lockdown_reasons' > make[3]: *** [scripts/Makefile.vmlinux:78: vmlinux] Error 1 > make[2]: *** [Makefile:1178: vmlinux] Error 2 > make[1]: *** [Makefile:224: __sub-make] Error 2 > make: *** [Makefile:224: __sub-make] Error 2
diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h index 97a8b21eb033..c2b01380262c 100644 --- a/include/linux/lsm_audit.h +++ b/include/linux/lsm_audit.h @@ -116,14 +116,28 @@ struct common_audit_data { #define v4info fam.v4 #define v6info fam.v6 +#ifdef CONFIG_AUDIT + int ipv4_skb_to_auditdata(struct sk_buff *skb, struct common_audit_data *ad, u8 *proto); +#if IS_ENABLED(CONFIG_IPV6) int ipv6_skb_to_auditdata(struct sk_buff *skb, struct common_audit_data *ad, u8 *proto); +#endif /* IS_ENABLED(CONFIG_IPV6) */ void common_lsm_audit(struct common_audit_data *a, void (*pre_audit)(struct audit_buffer *, void *), void (*post_audit)(struct audit_buffer *, void *)); +#else /* CONFIG_AUDIT */ + +static inline void common_lsm_audit(struct common_audit_data *a, + void (*pre_audit)(struct audit_buffer *, void *), + void (*post_audit)(struct audit_buffer *, void *)) +{ +} + +#endif /* CONFIG_AUDIT */ + #endif diff --git a/security/Makefile b/security/Makefile index cc0982214b84..e25da79f55d3 100644 --- a/security/Makefile +++ b/security/Makefile @@ -15,7 +15,7 @@ obj-$(CONFIG_SECURITY) += security.o obj-$(CONFIG_SECURITYFS) += inode.o obj-$(CONFIG_SECURITY_SELINUX) += selinux/ obj-$(CONFIG_SECURITY_SMACK) += smack/ -obj-$(CONFIG_SECURITY) += lsm_audit.o +obj-$(CONFIG_AUDIT) += lsm_audit.o obj-$(CONFIG_SECURITY_TOMOYO) += tomoyo/ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/ obj-$(CONFIG_SECURITY_YAMA) += yama/
When CONFIG_AUDIT is set, its CONFIG_NET dependency is also set, and the dev_get_by_index and init_net symbols (used by dump_common_audit_data) are found by the linker. dump_common_audit_data() should then failed to build when CONFIG_NET is not set. However, because the compiler is smart, it knows that audit_log_start() always return NULL when !CONFIG_AUDIT, and it doesn't build the body of common_lsm_audit(). As a side effect, dump_common_audit_data() is not built and the linker doesn't error out because of missing symbols. Let's only build lsm_audit.o when CONFIG_AUDIT is set. ipv4_skb_to_auditdata() and ipv6_skb_to_auditdata() are only used by Smack if CONFIG_AUDIT is set, so they don't need fake implementations. Because common_lsm_audit() is used in multiple places without CONFIG_AUDIT checks, add a fake implementation. Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: James Morris <jmorris@namei.org> Cc: Paul Moore <paul@paul-moore.com> Cc: Serge E. Hallyn <serge@hallyn.com> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20241022161009.982584-2-mic@digikod.net --- include/linux/lsm_audit.h | 14 ++++++++++++++ security/Makefile | 2 +- 2 files changed, 15 insertions(+), 1 deletion(-)