Re: [PATCH v38 39/39] LSM: Create lsm_module_list system call

Create a system call to report the list of Linux Security Modules that are active on the system. The list is provided as an array of LSM ID numbers.

Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; --- arch/x86/entry/syscalls/syscall_64.tbl | 1 + include/linux/syscalls.h | 1 + include/uapi/asm-generic/unistd.h | 5 ++- kernel/sys_ni.c | 1 + security/lsm_syscalls.c | 50 ++++++++++++++++++++++++++ 5 files changed, 57 insertions(+), 1 deletion(-) diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index 56d5c5202fd0..40b35e7069a7 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -373,6 +373,7 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common lsm_self_attr sys_lsm_self_attr +452 common lsm_module_list sys_lsm_module_list

# # Due to a historical design error, certain syscalls are numbered differently diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 7f87ef8be546..e2e2a9e93e8c 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1057,6 +1057,7 @@ asmlinkage long sys_set_mempolicy_home_node(unsigned long start, unsigned long l unsigned long home_node, unsigned long flags); asmlinkage long sys_lsm_self_attr(struct lsm_ctx *ctx, size_t *size, int flags); +asmlinkage long sys_lsm_module_list(unsigned int *ids, size_t *size, int flags); /* * Architecture-specific system calls diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index aa66718e1b48..090617a9a53a 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -889,8 +889,11 @@ __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) #define __NR_lsm_self_attr 451 __SYSCALL(__NR_lsm_self_attr, sys_lsm_self_attr) +#define __NR_lsm_module_list 452 +__SYSCALL(__NR_lsm_module_list, sys_lsm_module_list) + #undef __NR_syscalls -#define __NR_syscalls 452 +#define __NR_syscalls 453

/* * 32 bit systems traditionally used different diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 0fdb0341251d..bde9e74a3473 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -264,6 +264,7 @@ COND_SYSCALL(mremap); /* security/lsm_syscalls.c */ COND_SYSCALL(lsm_self_attr); +COND_SYSCALL(lsm_module_list); /* security/keys/keyctl.c */ COND_SYSCALL(add_key); diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c index da0fab7065e2..41d9ef945ede 100644 --- a/security/lsm_syscalls.c +++ b/security/lsm_syscalls.c @@ -154,3 +154,53 @@ SYSCALL_DEFINE3(lsm_self_attr, kfree(final); return rc; } + +/** + * lsm_module_list - Return a list of the active security modules + * @ids: the LSM module ids + * @size: size of @ids, updated on return + * @flags: reserved for future use, must be zero + * + * Returns a list of the active LSM ids. On success this function + * returns the number of @ids array elements. This value may be zero + * if there are no LSMs active. If @size is insufficient to contain + * the return data -E2BIG is returned and @size is set to the minimum + * required size. In all other cases a negative value indicating the + * error is returned. + */ +SYSCALL_DEFINE3(lsm_module_list, + unsigned int __user *, ids, + size_t __user *, size, + int, flags) +{ + unsigned int *interum; + size_t total_size = lsm_id * sizeof(*interum); + size_t usize; + int rc; + int i; + + if (get_user(usize, size)) + return -EFAULT; + + if (usize < total_size) { + if (put_user(total_size, size) != 0) + return -EFAULT; + return -E2BIG; + } + + interum = kzalloc(total_size, GFP_KERNEL); + if (interum == NULL) + return -ENOMEM; + + for (i = 0; i < lsm_id; i++) + interum[i] = lsm_idlist[i]->id; + + if (copy_to_user(ids, interum, total_size) != 0 || + put_user(total_size, size) != 0) + rc = -EFAULT; + else + rc = lsm_id; + + kfree(interum); + return rc; +}