diff options
| author | Fan Wu <wufan@linux.microsoft.com> | 2024-08-03 09:08:19 +0300 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2024-08-20 21:01:41 +0300 |
| commit | 2fea0c26b82f304f43b3905e56d954cf98a6d0e9 (patch) | |
| tree | 75d2e25539d522736a0fa0d878ee67cae2f7cb8e | |
| parent | 52443cb60c356707df494910fa134bbb0a8b1a66 (diff) | |
| download | linux-2fea0c26b82f304f43b3905e56d954cf98a6d0e9.tar.xz | |
initramfs,lsm: add a security hook to do_populate_rootfs()
This patch introduces a new hook to notify security system that the
content of initramfs has been unpacked into the rootfs.
Upon receiving this notification, the security system can activate
a policy to allow only files that originated from the initramfs to
execute or load into kernel during the early stages of booting.
This approach is crucial for minimizing the attack surface by
ensuring that only trusted files from the initramfs are operational
in the critical boot phase.
Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
| -rw-r--r-- | include/linux/lsm_hook_defs.h | 2 | ||||
| -rw-r--r-- | include/linux/security.h | 8 | ||||
| -rw-r--r-- | init/initramfs.c | 3 | ||||
| -rw-r--r-- | security/security.c | 10 |
4 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 520730fe2d94..22a14fc794fe 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -449,3 +449,5 @@ LSM_HOOK(int, 0, uring_override_creds, const struct cred *new) LSM_HOOK(int, 0, uring_sqpoll, void) LSM_HOOK(int, 0, uring_cmd, struct io_uring_cmd *ioucmd) #endif /* CONFIG_IO_URING */ + +LSM_HOOK(void, LSM_RET_VOID, initramfs_populated, void) diff --git a/include/linux/security.h b/include/linux/security.h index 62233fec8ead..3298855abdbc 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2256,4 +2256,12 @@ static inline int security_uring_cmd(struct io_uring_cmd *ioucmd) #endif /* CONFIG_SECURITY */ #endif /* CONFIG_IO_URING */ +#ifdef CONFIG_SECURITY +extern void security_initramfs_populated(void); +#else +static inline void security_initramfs_populated(void) +{ +} +#endif /* CONFIG_SECURITY */ + #endif /* ! __LINUX_SECURITY_H */ diff --git a/init/initramfs.c b/init/initramfs.c index 814241b64827..bc911e466d5b 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -17,6 +17,7 @@ #include <linux/namei.h> #include <linux/init_syscalls.h> #include <linux/umh.h> +#include <linux/security.h> #include "do_mounts.h" @@ -712,6 +713,8 @@ static void __init do_populate_rootfs(void *unused, async_cookie_t cookie) } done: + security_initramfs_populated(); + /* * If the initrd region is overlapped with crashkernel reserved region, * free only memory that is not part of crashkernel region. diff --git a/security/security.c b/security/security.c index 645a660320cb..fafd2d43cba0 100644 --- a/security/security.c +++ b/security/security.c @@ -5778,3 +5778,13 @@ int security_uring_cmd(struct io_uring_cmd *ioucmd) return call_int_hook(uring_cmd, ioucmd); } #endif /* CONFIG_IO_URING */ + +/** + * security_initramfs_populated() - Notify LSMs that initramfs has been loaded + * + * Tells the LSMs the initramfs has been unpacked into the rootfs. + */ +void security_initramfs_populated(void) +{ + call_void_hook(initramfs_populated); +} |