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.
The calling application can use this list determine what LSM
specific actions it might take. That might include chosing an
output format, determining required privilege or bypassing
security module specific behavior.
Signed-off-by: Casey Schaufler <[email protected]>
---
Documentation/userspace-api/lsm.rst | 3 +++
include/linux/syscalls.h | 1 +
kernel/sys_ni.c | 1 +
security/lsm_syscalls.c | 41 +++++++++++++++++++++++++++++
4 files changed, 46 insertions(+)
diff --git a/Documentation/userspace-api/lsm.rst b/Documentation/userspace-api/lsm.rst
index 98a0c191b499..e342d75b99ab 100644
--- a/Documentation/userspace-api/lsm.rst
+++ b/Documentation/userspace-api/lsm.rst
@@ -57,6 +57,9 @@ Get the security attributes of the current process
.. kernel-doc:: security/lsm_syscalls.c
:identifiers: sys_lsm_get_self_attr
+.. kernel-doc:: security/lsm_syscalls.c
+ :identifiers: sys_lsm_module_list
+
Additional documentation
========================
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index a89205c70ffa..9eb4cb6bbeb1 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1061,6 +1061,7 @@ asmlinkage long sys_set_mempolicy_home_node(unsigned long start, unsigned long l
unsigned long flags);
asmlinkage long sys_lsm_get_self_attr(struct lsm_ctx *ctx, size_t *size,
int flags);
+asmlinkage long sys_lsm_module_list(u32 *ids, size_t *size, int flags);
/*
* Architecture-specific system calls
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 7b2513d5605d..af1fd28c0420 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_get_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 55e8bf61ac8a..92af1fcaa654 100644
--- a/security/lsm_syscalls.c
+++ b/security/lsm_syscalls.c
@@ -180,3 +180,44 @@ SYSCALL_DEFINE3(lsm_get_self_attr,
kfree(final);
return rc;
}
+
+/**
+ * sys_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,
+ u32 __user *, ids,
+ size_t __user *, size,
+ u64, flags)
+{
+ size_t total_size = lsm_active_cnt * sizeof(*ids);
+ size_t usize;
+ int i;
+
+ if (flags)
+ return -EINVAL;
+
+ if (get_user(usize, size))
+ return -EFAULT;
+
+ if (put_user(total_size, size) != 0)
+ return -EFAULT;
+
+ if (usize < total_size)
+ return -E2BIG;
+
+ for (i = 0; i < lsm_active_cnt; i++)
+ if (put_user(lsm_idlist[i]->id, ids++))
+ return -EFAULT;
+
+ return lsm_active_cnt;
+}
--
2.39.0
Hi Casey,
I love your patch! Yet something to improve:
[auto build test ERROR on tip/perf/core]
[also build test ERROR on acme/perf/core shuah-kselftest/next shuah-kselftest/fixes linus/master v6.2-rc3 next-20230110]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Casey-Schaufler/LSM-Maintain-a-table-of-LSM-attribute-data/20230110-030739
patch link: https://lore.kernel.org/r/20230109180717.58855-6-casey%40schaufler-ca.com
patch subject: [PATCH v5 5/8] LSM: Create lsm_module_list system call
config: microblaze-randconfig-r011-20230108
compiler: microblaze-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/681c9be927fbd6bf90025a20cbf8e47fc2635063
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Casey-Schaufler/LSM-Maintain-a-table-of-LSM-attribute-data/20230110-030739
git checkout 681c9be927fbd6bf90025a20cbf8e47fc2635063
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=microblaze olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=microblaze SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
In file included from security/lsm_syscalls.c:15:
include/linux/syscalls.h:243:25: error: conflicting types for 'sys_lsm_get_self_attr'; have 'long int(struct lsm_ctx *, size_t *, u32)' {aka 'long int(struct lsm_ctx *, unsigned int *, unsigned int)'}
243 | asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
| ^~~
include/linux/syscalls.h:229:9: note: in expansion of macro '__SYSCALL_DEFINEx'
229 | __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
| ^~~~~~~~~~~~~~~~~
include/linux/syscalls.h:220:36: note: in expansion of macro 'SYSCALL_DEFINEx'
220 | #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
| ^~~~~~~~~~~~~~~
security/lsm_syscalls.c:61:1: note: in expansion of macro 'SYSCALL_DEFINE3'
61 | SYSCALL_DEFINE3(lsm_get_self_attr,
| ^~~~~~~~~~~~~~~
include/linux/syscalls.h:1062:17: note: previous declaration of 'sys_lsm_get_self_attr' with type 'long int(struct lsm_ctx *, size_t *, int)' {aka 'long int(struct lsm_ctx *, unsigned int *, int)'}
1062 | asmlinkage long sys_lsm_get_self_attr(struct lsm_ctx *ctx, size_t *size,
| ^~~~~~~~~~~~~~~~~~~~~
>> include/linux/syscalls.h:243:25: error: conflicting types for 'sys_lsm_module_list'; have 'long int(u32 *, size_t *, u64)' {aka 'long int(unsigned int *, unsigned int *, long long unsigned int)'}
243 | asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
| ^~~
include/linux/syscalls.h:229:9: note: in expansion of macro '__SYSCALL_DEFINEx'
229 | __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
| ^~~~~~~~~~~~~~~~~
include/linux/syscalls.h:220:36: note: in expansion of macro 'SYSCALL_DEFINEx'
220 | #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
| ^~~~~~~~~~~~~~~
security/lsm_syscalls.c:197:1: note: in expansion of macro 'SYSCALL_DEFINE3'
197 | SYSCALL_DEFINE3(lsm_module_list,
| ^~~~~~~~~~~~~~~
include/linux/syscalls.h:1064:17: note: previous declaration of 'sys_lsm_module_list' with type 'long int(u32 *, size_t *, int)' {aka 'long int(unsigned int *, unsigned int *, int)'}
1064 | asmlinkage long sys_lsm_module_list(u32 *ids, size_t *size, int flags);
| ^~~~~~~~~~~~~~~~~~~
vim +243 include/linux/syscalls.h
bed1ffca022cc8 Frederic Weisbecker 2009-03-13 217
6c5979631b4b03 Heiko Carstens 2009-02-11 218 #define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
6c5979631b4b03 Heiko Carstens 2009-02-11 219 #define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
6c5979631b4b03 Heiko Carstens 2009-02-11 @220 #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
6c5979631b4b03 Heiko Carstens 2009-02-11 221 #define SYSCALL_DEFINE4(name, ...) SYSCALL_DEFINEx(4, _##name, __VA_ARGS__)
6c5979631b4b03 Heiko Carstens 2009-02-11 222 #define SYSCALL_DEFINE5(name, ...) SYSCALL_DEFINEx(5, _##name, __VA_ARGS__)
6c5979631b4b03 Heiko Carstens 2009-02-11 223 #define SYSCALL_DEFINE6(name, ...) SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)
1a94bc34768e46 Heiko Carstens 2009-01-14 224
609320c8a22715 Yonghong Song 2017-09-07 225 #define SYSCALL_DEFINE_MAXARGS 6
609320c8a22715 Yonghong Song 2017-09-07 226
bed1ffca022cc8 Frederic Weisbecker 2009-03-13 227 #define SYSCALL_DEFINEx(x, sname, ...) \
99e621f796d7f0 Al Viro 2013-03-05 228 SYSCALL_METADATA(sname, x, __VA_ARGS__) \
bed1ffca022cc8 Frederic Weisbecker 2009-03-13 229 __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
bed1ffca022cc8 Frederic Weisbecker 2009-03-13 230
2cf0966683430b Al Viro 2013-01-21 231 #define __PROTECT(...) asmlinkage_protect(__VA_ARGS__)
1bd21c6c21e848 Dominik Brodowski 2018-04-05 232
e145242ea0df6b Dominik Brodowski 2018-04-09 233 /*
e145242ea0df6b Dominik Brodowski 2018-04-09 234 * The asmlinkage stub is aliased to a function named __se_sys_*() which
e145242ea0df6b Dominik Brodowski 2018-04-09 235 * sign-extends 32-bit ints to longs whenever needed. The actual work is
e145242ea0df6b Dominik Brodowski 2018-04-09 236 * done within __do_sys_*().
e145242ea0df6b Dominik Brodowski 2018-04-09 237 */
1bd21c6c21e848 Dominik Brodowski 2018-04-05 238 #ifndef __SYSCALL_DEFINEx
bed1ffca022cc8 Frederic Weisbecker 2009-03-13 239 #define __SYSCALL_DEFINEx(x, name, ...) \
bee20031772af3 Arnd Bergmann 2018-06-19 240 __diag_push(); \
bee20031772af3 Arnd Bergmann 2018-06-19 241 __diag_ignore(GCC, 8, "-Wattribute-alias", \
bee20031772af3 Arnd Bergmann 2018-06-19 242 "Type aliasing is used to sanitize syscall arguments");\
83460ec8dcac14 Andi Kleen 2013-11-12 @243 asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
e145242ea0df6b Dominik Brodowski 2018-04-09 244 __attribute__((alias(__stringify(__se_sys##name)))); \
c9a211951c7c79 Howard McLauchlan 2018-03-21 245 ALLOW_ERROR_INJECTION(sys##name, ERRNO); \
e145242ea0df6b Dominik Brodowski 2018-04-09 246 static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
e145242ea0df6b Dominik Brodowski 2018-04-09 247 asmlinkage long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
e145242ea0df6b Dominik Brodowski 2018-04-09 248 asmlinkage long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
1a94bc34768e46 Heiko Carstens 2009-01-14 249 { \
e145242ea0df6b Dominik Brodowski 2018-04-09 250 long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
07fe6e00f6cca6 Al Viro 2013-01-21 251 __MAP(x,__SC_TEST,__VA_ARGS__); \
2cf0966683430b Al Viro 2013-01-21 252 __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
2cf0966683430b Al Viro 2013-01-21 253 return ret; \
1a94bc34768e46 Heiko Carstens 2009-01-14 254 } \
bee20031772af3 Arnd Bergmann 2018-06-19 255 __diag_pop(); \
e145242ea0df6b Dominik Brodowski 2018-04-09 256 static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
1bd21c6c21e848 Dominik Brodowski 2018-04-05 257 #endif /* __SYSCALL_DEFINEx */
1a94bc34768e46 Heiko Carstens 2009-01-14 258
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
On Mon, Jan 9, 2023 at 1:09 PM Casey Schaufler <[email protected]> wrote:
>
> 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.
>
> The calling application can use this list determine what LSM
> specific actions it might take. That might include chosing an
> output format, determining required privilege or bypassing
> security module specific behavior.
>
> Signed-off-by: Casey Schaufler <[email protected]>
> ---
> Documentation/userspace-api/lsm.rst | 3 +++
> include/linux/syscalls.h | 1 +
> kernel/sys_ni.c | 1 +
> security/lsm_syscalls.c | 41 +++++++++++++++++++++++++++++
> 4 files changed, 46 insertions(+)
...
> diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
> index 55e8bf61ac8a..92af1fcaa654 100644
> --- a/security/lsm_syscalls.c
> +++ b/security/lsm_syscalls.c
> @@ -180,3 +180,44 @@ SYSCALL_DEFINE3(lsm_get_self_attr,
> kfree(final);
> return rc;
> }
> +
> +/**
> + * sys_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,
> + u32 __user *, ids,
> + size_t __user *, size,
> + u64, flags)
> +{
> + size_t total_size = lsm_active_cnt * sizeof(*ids);
> + size_t usize;
> + int i;
> +
> + if (flags)
> + return -EINVAL;
> +
> + if (get_user(usize, size))
> + return -EFAULT;
> +
> + if (put_user(total_size, size) != 0)
> + return -EFAULT;
> +
> + if (usize < total_size)
> + return -E2BIG;
> +
> + for (i = 0; i < lsm_active_cnt; i++)
> + if (put_user(lsm_idlist[i]->id, ids++))
> + return -EFAULT;
> +
> + return lsm_active_cnt;
> +}
Similar to my comments in 4/8, I would probably create a new LSM hook
for this syscall so that the lsm_ctx is passed through the LSM layer
directly to the target LSM:
int security_sys_setselfattr(u64 attr, struct lsm_ctx __user *ctx,
size_t len);
--
paul-moore.com
On 1/11/2023 1:07 PM, Paul Moore wrote:
> On Mon, Jan 9, 2023 at 1:09 PM Casey Schaufler <[email protected]> wrote:
>> 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.
>>
>> The calling application can use this list determine what LSM
>> specific actions it might take. That might include chosing an
>> output format, determining required privilege or bypassing
>> security module specific behavior.
>>
>> Signed-off-by: Casey Schaufler <[email protected]>
>> ---
>> Documentation/userspace-api/lsm.rst | 3 +++
>> include/linux/syscalls.h | 1 +
>> kernel/sys_ni.c | 1 +
>> security/lsm_syscalls.c | 41 +++++++++++++++++++++++++++++
>> 4 files changed, 46 insertions(+)
> ..
>
>> diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
>> index 55e8bf61ac8a..92af1fcaa654 100644
>> --- a/security/lsm_syscalls.c
>> +++ b/security/lsm_syscalls.c
>> @@ -180,3 +180,44 @@ SYSCALL_DEFINE3(lsm_get_self_attr,
>> kfree(final);
>> return rc;
>> }
>> +
>> +/**
>> + * sys_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,
>> + u32 __user *, ids,
>> + size_t __user *, size,
>> + u64, flags)
>> +{
>> + size_t total_size = lsm_active_cnt * sizeof(*ids);
>> + size_t usize;
>> + int i;
>> +
>> + if (flags)
>> + return -EINVAL;
>> +
>> + if (get_user(usize, size))
>> + return -EFAULT;
>> +
>> + if (put_user(total_size, size) != 0)
>> + return -EFAULT;
>> +
>> + if (usize < total_size)
>> + return -E2BIG;
>> +
>> + for (i = 0; i < lsm_active_cnt; i++)
>> + if (put_user(lsm_idlist[i]->id, ids++))
>> + return -EFAULT;
>> +
>> + return lsm_active_cnt;
>> +}
> Similar to my comments in 4/8, I would probably create a new LSM hook
> for this syscall so that the lsm_ctx is passed through the LSM layer
> directly to the target LSM:
>
> int security_sys_setselfattr(u64 attr, struct lsm_ctx __user *ctx,
> size_t len);
That seems like a whole lot of work when you can just look it up
in an existing table.
> --
> paul-moore.com
On Wed, Jan 11, 2023 at 8:39 PM Casey Schaufler <[email protected]> wrote:
> On 1/11/2023 1:07 PM, Paul Moore wrote:
> > On Mon, Jan 9, 2023 at 1:09 PM Casey Schaufler <[email protected]> wrote:
> >> 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.
> >>
> >> The calling application can use this list determine what LSM
> >> specific actions it might take. That might include chosing an
> >> output format, determining required privilege or bypassing
> >> security module specific behavior.
> >>
> >> Signed-off-by: Casey Schaufler <[email protected]>
> >> ---
> >> Documentation/userspace-api/lsm.rst | 3 +++
> >> include/linux/syscalls.h | 1 +
> >> kernel/sys_ni.c | 1 +
> >> security/lsm_syscalls.c | 41 +++++++++++++++++++++++++++++
> >> 4 files changed, 46 insertions(+)
> > ..
> >
> >> diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
> >> index 55e8bf61ac8a..92af1fcaa654 100644
> >> --- a/security/lsm_syscalls.c
> >> +++ b/security/lsm_syscalls.c
> >> @@ -180,3 +180,44 @@ SYSCALL_DEFINE3(lsm_get_self_attr,
> >> kfree(final);
> >> return rc;
> >> }
> >> +
> >> +/**
> >> + * sys_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,
> >> + u32 __user *, ids,
> >> + size_t __user *, size,
> >> + u64, flags)
> >> +{
> >> + size_t total_size = lsm_active_cnt * sizeof(*ids);
> >> + size_t usize;
> >> + int i;
> >> +
> >> + if (flags)
> >> + return -EINVAL;
> >> +
> >> + if (get_user(usize, size))
> >> + return -EFAULT;
> >> +
> >> + if (put_user(total_size, size) != 0)
> >> + return -EFAULT;
> >> +
> >> + if (usize < total_size)
> >> + return -E2BIG;
> >> +
> >> + for (i = 0; i < lsm_active_cnt; i++)
> >> + if (put_user(lsm_idlist[i]->id, ids++))
> >> + return -EFAULT;
> >> +
> >> + return lsm_active_cnt;
> >> +}
> > Similar to my comments in 4/8, I would probably create a new LSM hook
> > for this syscall so that the lsm_ctx is passed through the LSM layer
> > directly to the target LSM:
> >
> > int security_sys_setselfattr(u64 attr, struct lsm_ctx __user *ctx,
> > size_t len);
>
> That seems like a whole lot of work when you can just look it up
> in an existing table.
D'oh! Sorry, this comment was intended for patch 6/8, the
lsm_set_self_attr() syscall patch. I agree, it would be very silly to
have a dedicated hook for lsm_module_list() :)
--
paul-moore.com