Add additional LSM hooks for SafeSetID

SafeSetID is capable of making allow/deny decisions for set*uid calls
 on a system, and we want to add similar functionality for set*gid
 calls. The work to do that is not yet complete, so probably won't make
 it in for v5.8, but we are looking to get this simple patch in for
 v5.8 since we have it ready. We are planning on the rest of the work
 for extending the SafeSetID LSM being merged during the v5.9 merge
 window.
 
 This patch was sent to the security mailing list and there were no objections.
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Merge tag 'LSM-add-setgid-hook-5.8-author-fix' of git://github.com/micah-morton/linux

Pull SafeSetID update from Micah Morton:
 "Add additional LSM hooks for SafeSetID

  SafeSetID is capable of making allow/deny decisions for set*uid calls
  on a system, and we want to add similar functionality for set*gid
  calls.

  The work to do that is not yet complete, so probably won't make it in
  for v5.8, but we are looking to get this simple patch in for v5.8
  since we have it ready.

  We are planning on the rest of the work for extending the SafeSetID
  LSM being merged during the v5.9 merge window"

* tag 'LSM-add-setgid-hook-5.8-author-fix' of git://github.com/micah-morton/linux:
  security: Add LSM hooks to set*gid syscalls
This commit is contained in:
Linus Torvalds 2020-06-14 11:39:31 -07:00
commit 4a87b197c1
5 changed files with 40 additions and 1 deletions

View File

@ -191,6 +191,8 @@ LSM_HOOK(int, 0, kernel_post_read_file, struct file *file, char *buf,
loff_t size, enum kernel_read_file_id id)
LSM_HOOK(int, 0, task_fix_setuid, struct cred *new, const struct cred *old,
int flags)
LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
int flags)
LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
LSM_HOOK(int, 0, task_getsid, struct task_struct *p)

View File

@ -659,6 +659,15 @@
* @old is the set of credentials that are being replaces
* @flags contains one of the LSM_SETID_* values.
* Return 0 on success.
* @task_fix_setgid:
* Update the module's state after setting one or more of the group
* identity attributes of the current process. The @flags parameter
* indicates which of the set*gid system calls invoked this hook.
* @new is the set of credentials that will be installed. Modifications
* should be made to this rather than to @current->cred.
* @old is the set of credentials that are being replaced.
* @flags contains one of the LSM_SETID_* values.
* Return 0 on success.
* @task_setpgid:
* Check permission before setting the process group identifier of the
* process @p to @pgid.

View File

@ -392,6 +392,8 @@ int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
enum kernel_read_file_id id);
int security_task_fix_setuid(struct cred *new, const struct cred *old,
int flags);
int security_task_fix_setgid(struct cred *new, const struct cred *old,
int flags);
int security_task_setpgid(struct task_struct *p, pid_t pgid);
int security_task_getpgid(struct task_struct *p);
int security_task_getsid(struct task_struct *p);
@ -1036,6 +1038,13 @@ static inline int security_task_fix_setuid(struct cred *new,
return cap_task_fix_setuid(new, old, flags);
}
static inline int security_task_fix_setgid(struct cred *new,
const struct cred *old,
int flags)
{
return 0;
}
static inline int security_task_setpgid(struct task_struct *p, pid_t pgid)
{
return 0;

View File

@ -393,6 +393,10 @@ long __sys_setregid(gid_t rgid, gid_t egid)
new->sgid = new->egid;
new->fsgid = new->egid;
retval = security_task_fix_setgid(new, old, LSM_SETID_RE);
if (retval < 0)
goto error;
return commit_creds(new);
error:
@ -435,6 +439,10 @@ long __sys_setgid(gid_t gid)
else
goto error;
retval = security_task_fix_setgid(new, old, LSM_SETID_ID);
if (retval < 0)
goto error;
return commit_creds(new);
error:
@ -756,6 +764,10 @@ long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
new->sgid = ksgid;
new->fsgid = new->egid;
retval = security_task_fix_setgid(new, old, LSM_SETID_RES);
if (retval < 0)
goto error;
return commit_creds(new);
error:
@ -862,7 +874,8 @@ long __sys_setfsgid(gid_t gid)
ns_capable(old->user_ns, CAP_SETGID)) {
if (!gid_eq(kgid, old->fsgid)) {
new->fsgid = kgid;
goto change_okay;
if (security_task_fix_setgid(new,old,LSM_SETID_FS) == 0)
goto change_okay;
}
}

View File

@ -1696,6 +1696,12 @@ int security_task_fix_setuid(struct cred *new, const struct cred *old,
return call_int_hook(task_fix_setuid, 0, new, old, flags);
}
int security_task_fix_setgid(struct cred *new, const struct cred *old,
int flags)
{
return call_int_hook(task_fix_setgid, 0, new, old, flags);
}
int security_task_setpgid(struct task_struct *p, pid_t pgid)
{
return call_int_hook(task_setpgid, 0, p, pgid);