path: root/security/commoncap.c
diff options
authorSerge E. Hallyn <serue@us.ibm.com>2007-11-28 16:21:47 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-29 09:24:53 -0800
commit8ec2328f1138a58eaea55ec6150985a1623b01c5 (patch)
treeebaecf41dd8c8789f0c49ee9c0f30c0ce40e3e39 /security/commoncap.c
parentd0eec99ce50baa5cc2ac02363cdb2a771ed4e1e2 (diff)
file capabilities: don't prevent signaling setuid root programs
An unprivileged process must be able to kill a setuid root program started by the same user. This is legacy behavior needed for instance for xinit to kill X when the window manager exits. When an unprivileged user runs a setuid root program in !SECURE_NOROOT mode, fP, fI, and fE are set full on, so pP' and pE' are full on. Then cap_task_kill() prevents the user from signaling the setuid root task. This is a change in behavior compared to when !CONFIG_SECURITY_FILE_CAPABILITIES. This patch introduces a special check into cap_task_kill() just to check whether a non-root user is signaling a setuid root program started by the same user. If so, then signal is allowed. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Andrew Morgan <morgan@kernel.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Cc: Chris Wright <chrisw@sous-sol.org> Cc: James Morris <jmorris@namei.org> Cc: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/commoncap.c')
1 files changed, 9 insertions, 0 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index 302e8d0839a..5bc1895f3f9 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -526,6 +526,15 @@ int cap_task_kill(struct task_struct *p, struct siginfo *info,
if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
return 0;
+ /*
+ * Running a setuid root program raises your capabilities.
+ * Killing your own setuid root processes was previously
+ * allowed.
+ * We must preserve legacy signal behavior in this case.
+ */
+ if (p->euid == 0 && p->uid == current->uid)
+ return 0;
/* sigcont is permitted within same session */
if (sig == SIGCONT && (task_session_nr(current) == task_session_nr(p)))
return 0;