Re: [PATCH 1/2] security: let security modules use PTRACE_MODE_* with bitmasks

[Casey Schaufler]

On 12/7/2015 1:25 PM, Jann Horn wrote:

It looks like smack and yama weren't aware that the ptrace mode
can have flags ORed into it - PTRACE_MODE_NOAUDIT until now, but
only for /proc/$pid/stat, and with the PTRACE_MODE_*CREDS patch,
all modes have flags ORed into them.

Signed-off-by: Jann Horn <j...@thejh.net>

Acked-by: Casey Schaufler <ca...@schaufler-ca.com>

---
  security/smack/smack_lsm.c | 8 +++-----
  security/yama/yama_lsm.c   | 4 ++--
  2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index ff81026..7c57c7f 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -398,12 +398,10 @@ static int smk_copy_relabel(struct list_head *nhead, 
struct list_head *ohead,
   */
  static inline unsigned int smk_ptrace_mode(unsigned int mode)
  {
-       switch (mode) {
-       case PTRACE_MODE_READ:
-               return MAY_READ;
-       case PTRACE_MODE_ATTACH:
+       if (mode & PTRACE_MODE_ATTACH)
                return MAY_READWRITE;
-       }
+       if (mode & PTRACE_MODE_READ)
+               return MAY_READ;

return 0;

  }
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index d3c19c9..cb6ed10 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -281,7 +281,7 @@ static int yama_ptrace_access_check(struct task_struct 
*child,
        int rc = 0;

/* require ptrace target be a child of ptracer on attach */

-       if (mode == PTRACE_MODE_ATTACH) {
+       if (mode & PTRACE_MODE_ATTACH) {
                switch (ptrace_scope) {
                case YAMA_SCOPE_DISABLED:
                        /* No additional restrictions. */
@@ -307,7 +307,7 @@ static int yama_ptrace_access_check(struct task_struct 
*child,
                }
        }

- if (rc) {

+       if (rc && (mode & PTRACE_MODE_NOAUDIT) == 0) {
                printk_ratelimited(KERN_NOTICE
                        "ptrace of pid %d was attempted by: %s (pid %d)\n",
                        child->pid, current->comm, current->pid);

--
To unsubscribe from this list: send the line "unsubscribe 
linux-security-module" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html