[PATCH v3 4/5] Smack: Support determination of side-channel
From: Casey Schaufler <hidden>
Date: 2018-08-21 00:05:03
Also in:
lkml, selinux
Subsystem:
security subsystem, smack security module, the rest · Maintainers:
Paul Moore, James Morris, "Serge E. Hallyn", Casey Schaufler, Linus Torvalds
Smack considers its private task data safe if the current task has read access to the passed task. Signed-off-by: Casey Schaufler <redacted> --- security/smack/smack_lsm.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 91750205a5de..85dc053e610c 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c@@ -2299,6 +2299,23 @@ static void smack_task_to_inode(struct task_struct *p, struct inode *inode) isp->smk_inode = skp; } +/** + * smack_task_safe_sidechannel - Are the task and current sidechannel safe? + * @p: task to check on + * + * A crude value for sidechannel safety is that the current task is + * already allowed to read from the other. + * + * Returns 0 if the tasks are sidechannel safe, -EACCES otherwise. + */ +static int smack_task_safe_sidechannel(struct task_struct *p) +{ + struct smack_known *skp = smk_of_task_struct(p); + struct smack_known *ckp = smk_of_task_struct(current); + + return smk_access(ckp, skp, MAY_READ, NULL); +} + /* * Socket hooks. */
@@ -4718,6 +4735,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(task_movememory, smack_task_movememory), LSM_HOOK_INIT(task_kill, smack_task_kill), LSM_HOOK_INIT(task_to_inode, smack_task_to_inode), + LSM_HOOK_INIT(task_safe_sidechannel, smack_task_safe_sidechannel), LSM_HOOK_INIT(ipc_permission, smack_ipc_permission), LSM_HOOK_INIT(ipc_getsecid, smack_ipc_getsecid),
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2.17.1