diff mbox series

[V4] security/selinux: Always allow FIOCLEX and FIONCLEX

Message ID 20220225175438.302365-1-richard_c_haines@btinternet.com (mailing list archive)
State Accepted
Delegated to: Paul Moore
Headers show
Series [V4] security/selinux: Always allow FIOCLEX and FIONCLEX | expand

Commit Message

Richard Haines Feb. 25, 2022, 5:54 p.m. UTC
These ioctls are equivalent to fcntl(fd, F_SETFD, flags), which SELinux
always allows too.  Furthermore, a failed FIOCLEX could result in a file
descriptor being leaked to a process that should not have access to it.

As this patch removes access controls, a policy capability needs to be
enabled in policy to always allow these ioctls.

Based-on-patch-by: Demi Marie Obenour <demiobenour@gmail.com>
Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
---
V2 Change: Control via a policy capability.
V3 Change: Update switch check.
V4 Change: Use POLICYDB_CAPABILITY_IOCTL_SKIP_CLOEXEC

 security/selinux/hooks.c                   | 6 ++++++
 security/selinux/include/policycap.h       | 1 +
 security/selinux/include/policycap_names.h | 3 ++-
 security/selinux/include/security.h        | 7 +++++++
 4 files changed, 16 insertions(+), 1 deletion(-)

Comments

Paul Moore Feb. 25, 2022, 8:46 p.m. UTC | #1
On Fri, Feb 25, 2022 at 12:54 PM Richard Haines
<richard_c_haines@btinternet.com> wrote:
>
> These ioctls are equivalent to fcntl(fd, F_SETFD, flags), which SELinux
> always allows too.  Furthermore, a failed FIOCLEX could result in a file
> descriptor being leaked to a process that should not have access to it.
>
> As this patch removes access controls, a policy capability needs to be
> enabled in policy to always allow these ioctls.
>
> Based-on-patch-by: Demi Marie Obenour <demiobenour@gmail.com>
> Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
> ---
> V2 Change: Control via a policy capability.
> V3 Change: Update switch check.
> V4 Change: Use POLICYDB_CAPABILITY_IOCTL_SKIP_CLOEXEC
>
>  security/selinux/hooks.c                   | 6 ++++++
>  security/selinux/include/policycap.h       | 1 +
>  security/selinux/include/policycap_names.h | 3 ++-
>  security/selinux/include/security.h        | 7 +++++++
>  4 files changed, 16 insertions(+), 1 deletion(-)

Merged into selinux/next, thanks everyone!
diff mbox series

Patch

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 5b6895e4f..d369c2d82 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3745,6 +3745,12 @@  static int selinux_file_ioctl(struct file *file, unsigned int cmd,
 					    CAP_OPT_NONE, true);
 		break;
 
+	case FIOCLEX:
+	case FIONCLEX:
+		if (!selinux_policycap_ioctl_skip_cloexec())
+			error = ioctl_has_perm(cred, file, FILE__IOCTL, (u16) cmd);
+		break;
+
 	/* default case assumes that the command will go
 	 * to the file's ioctl() function.
 	 */
diff --git a/security/selinux/include/policycap.h b/security/selinux/include/policycap.h
index 2ec038efb..a9e572ca4 100644
--- a/security/selinux/include/policycap.h
+++ b/security/selinux/include/policycap.h
@@ -11,6 +11,7 @@  enum {
 	POLICYDB_CAPABILITY_CGROUPSECLABEL,
 	POLICYDB_CAPABILITY_NNP_NOSUID_TRANSITION,
 	POLICYDB_CAPABILITY_GENFS_SECLABEL_SYMLINKS,
+	POLICYDB_CAPABILITY_IOCTL_SKIP_CLOEXEC,
 	__POLICYDB_CAPABILITY_MAX
 };
 #define POLICYDB_CAPABILITY_MAX (__POLICYDB_CAPABILITY_MAX - 1)
diff --git a/security/selinux/include/policycap_names.h b/security/selinux/include/policycap_names.h
index b89289f09..ebd64afe1 100644
--- a/security/selinux/include/policycap_names.h
+++ b/security/selinux/include/policycap_names.h
@@ -12,7 +12,8 @@  const char *selinux_policycap_names[__POLICYDB_CAPABILITY_MAX] = {
 	"always_check_network",
 	"cgroup_seclabel",
 	"nnp_nosuid_transition",
-	"genfs_seclabel_symlinks"
+	"genfs_seclabel_symlinks",
+	"ioctl_skip_cloexec"
 };
 
 #endif /* _SELINUX_POLICYCAP_NAMES_H_ */
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index ac0ece013..c0d966020 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -219,6 +219,13 @@  static inline bool selinux_policycap_genfs_seclabel_symlinks(void)
 	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_GENFS_SECLABEL_SYMLINKS]);
 }
 
+static inline bool selinux_policycap_ioctl_skip_cloexec(void)
+{
+	struct selinux_state *state = &selinux_state;
+
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_IOCTL_SKIP_CLOEXEC]);
+}
+
 struct selinux_policy_convert_data;
 
 struct selinux_load_state {