[PATCH 1/3] Wire up the lsm_manage_policy syscall

[Maxime Bélair]

Add support for the new lsm_manage_policy syscall, providing a unified
API for loading and modifying LSM policies without requiring the LSM’s
pseudo-filesystem.

Benefits:
  - Works even if the LSM pseudo-filesystem isn’t mounted or available
    (e.g. in containers)
  - Offers a logical and unified interface rather than multiple
    heterogeneous pseudo-filesystems.
  - Avoids overhead of other kernel interfaces for better efficiency

Signed-off-by: Maxime Bélair <maxime.belair at canonical.com>
---
 arch/alpha/kernel/syscalls/syscall.tbl            | 1 +
 arch/arm/tools/syscall.tbl                        | 1 +
 arch/x86/entry/syscalls/syscall_32.tbl            | 1 +
 arch/x86/entry/syscalls/syscall_64.tbl            | 1 +
 include/linux/syscalls.h                          | 4 ++++
 include/uapi/asm-generic/unistd.h                 | 4 +++-
 kernel/sys_ni.c                                   | 1 +
 security/lsm_syscalls.c                           | 6 ++++++
 tools/include/uapi/asm-generic/unistd.h           | 4 +++-
 tools/perf/arch/x86/entry/syscalls/syscall_64.tbl | 1 +
 10 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index 2dd6340de6b4..dfe6cd43c584 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -507,3 +507,4 @@
 575	common	listxattrat			sys_listxattrat
 576	common	removexattrat			sys_removexattrat
 577	common	open_tree_attr			sys_open_tree_attr
+578	common	lsm_manage_policy		sys_lsm_manage_policy
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index 27c1d5ebcd91..60abcb3a8a1b 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -482,3 +482,4 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	lsm_manage_policy		sys_lsm_manage_policy
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index ac007ea00979..bb91a929757a 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -473,3 +473,4 @@
 465	i386	listxattrat		sys_listxattrat
 466	i386	removexattrat		sys_removexattrat
 467	i386	open_tree_attr		sys_open_tree_attr
+468	i386	lsm_manage_policy	sys_lsm_manage_policy
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index cfb5ca41e30d..83819d4a5c8a 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -391,6 +391,7 @@
 465	common	listxattrat		sys_listxattrat
 466	common	removexattrat		sys_removexattrat
 467	common	open_tree_attr		sys_open_tree_attr
+468	common	lsm_manage_policy	sys_lsm_manage_policy
 
 #
 # Due to a historical design error, certain syscalls are numbered differently
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index e5603cc91963..f52a0678b1d0 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -989,6 +989,10 @@ asmlinkage long sys_lsm_set_self_attr(unsigned int attr, struct lsm_ctx __user *
 				      u32 size, u32 flags);
 asmlinkage long sys_lsm_list_modules(u64 __user *ids, u32 __user *size, u32 flags);
 
+asmlinkage long sys_lsm_manage_policy(u32 lsm_id, u32 op, void __user *buf,
+		u32 __user *size, u32 flags);
+
+
 /*
  * Architecture-specific system calls
  */
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 2892a45023af..b94369baded8 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -851,9 +851,11 @@ __SYSCALL(__NR_listxattrat, sys_listxattrat)
 __SYSCALL(__NR_removexattrat, sys_removexattrat)
 #define __NR_open_tree_attr 467
 __SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
+#define __NR_lsm_manage_policy 468
+__SYSCALL(__NR_lsm_manage_policy, lsm_manage_policy)
 
 #undef __NR_syscalls
-#define __NR_syscalls 468
+#define __NR_syscalls 469
 
 /*
  * 32 bit systems traditionally used different
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index c00a86931f8c..e556b07d8716 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -172,6 +172,7 @@ COND_SYSCALL_COMPAT(fadvise64_64);
 COND_SYSCALL(lsm_get_self_attr);
 COND_SYSCALL(lsm_set_self_attr);
 COND_SYSCALL(lsm_list_modules);
+COND_SYSCALL(lsm_manage_policy);
 
 /* CONFIG_MMU only */
 COND_SYSCALL(swapon);
diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
index 8440948a690c..dcaad8818679 100644
--- a/security/lsm_syscalls.c
+++ b/security/lsm_syscalls.c
@@ -118,3 +118,9 @@ SYSCALL_DEFINE3(lsm_list_modules, u64 __user *, ids, u32 __user *, size,
 
 	return lsm_active_cnt;
 }
+
+SYSCALL_DEFINE5(lsm_manage_policy, u32, lsm_id, u32, op, void __user *, buf, u32
+		__user *, size, u32, flags)
+{
+	return 0;
+}
diff --git a/tools/include/uapi/asm-generic/unistd.h b/tools/include/uapi/asm-generic/unistd.h
index 2892a45023af..b94369baded8 100644
--- a/tools/include/uapi/asm-generic/unistd.h
+++ b/tools/include/uapi/asm-generic/unistd.h
@@ -851,9 +851,11 @@ __SYSCALL(__NR_listxattrat, sys_listxattrat)
 __SYSCALL(__NR_removexattrat, sys_removexattrat)
 #define __NR_open_tree_attr 467
 __SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
+#define __NR_lsm_manage_policy 468
+__SYSCALL(__NR_lsm_manage_policy, lsm_manage_policy)
 
 #undef __NR_syscalls
-#define __NR_syscalls 468
+#define __NR_syscalls 469
 
 /*
  * 32 bit systems traditionally used different
diff --git a/tools/perf/arch/x86/entry/syscalls/syscall_64.tbl b/tools/perf/arch/x86/entry/syscalls/syscall_64.tbl
index cfb5ca41e30d..83819d4a5c8a 100644
--- a/tools/perf/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/tools/perf/arch/x86/entry/syscalls/syscall_64.tbl
@@ -391,6 +391,7 @@
 465	common	listxattrat		sys_listxattrat
 466	common	removexattrat		sys_removexattrat
 467	common	open_tree_attr		sys_open_tree_attr
+468	common	lsm_manage_policy	sys_lsm_manage_policy
 
 #
 # Due to a historical design error, certain syscalls are numbered differently
-- 
2.48.1