From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- include/net/scm.h | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 include/net/scm.h (limited to 'include/net/scm.h') diff --git a/include/net/scm.h b/include/net/scm.h new file mode 100644 index 000000000..c52519669 --- /dev/null +++ b/include/net/scm.h @@ -0,0 +1,119 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_NET_SCM_H +#define __LINUX_NET_SCM_H + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* Well, we should have at least one descriptor open + * to accept passed FDs 8) + */ +#define SCM_MAX_FD 253 + +struct scm_creds { + u32 pid; + kuid_t uid; + kgid_t gid; +}; + +#ifdef CONFIG_UNIX +struct unix_edge; +#endif + +struct scm_fp_list { + short count; + short count_unix; + short max; +#ifdef CONFIG_UNIX + bool inflight; + bool dead; + struct list_head vertices; + struct unix_edge *edges; +#endif + struct user_struct *user; + struct file *fp[SCM_MAX_FD]; +}; + +struct scm_cookie { + struct pid *pid; /* Skb credentials */ + struct scm_fp_list *fp; /* Passed files */ + struct scm_creds creds; /* Skb credentials */ +#ifdef CONFIG_SECURITY_NETWORK + u32 secid; /* Passed security ID */ +#endif +}; + +void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); +void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); +int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); +void __scm_destroy(struct scm_cookie *scm); +struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl); + +#ifdef CONFIG_SECURITY_NETWORK +static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) +{ + security_socket_getpeersec_dgram(sock, NULL, &scm->secid); +} +#else +static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm) +{ } +#endif /* CONFIG_SECURITY_NETWORK */ + +static __inline__ void scm_set_cred(struct scm_cookie *scm, + struct pid *pid, kuid_t uid, kgid_t gid) +{ + scm->pid = get_pid(pid); + scm->creds.pid = pid_vnr(pid); + scm->creds.uid = uid; + scm->creds.gid = gid; +} + +static __inline__ void scm_destroy_cred(struct scm_cookie *scm) +{ + put_pid(scm->pid); + scm->pid = NULL; +} + +static __inline__ void scm_destroy(struct scm_cookie *scm) +{ + scm_destroy_cred(scm); + if (scm->fp) + __scm_destroy(scm); +} + +static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, bool forcecreds) +{ + memset(scm, 0, sizeof(*scm)); + scm->creds.uid = INVALID_UID; + scm->creds.gid = INVALID_GID; + if (forcecreds) + scm_set_cred(scm, task_tgid(current), current_uid(), current_gid()); + unix_get_peersec_dgram(sock, scm); + if (msg->msg_controllen <= 0) + return 0; + return __scm_send(sock, msg, scm); +} + +void scm_recv(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, int flags); +void scm_recv_unix(struct socket *sock, struct msghdr *msg, + struct scm_cookie *scm, int flags); + +static inline int scm_recv_one_fd(struct file *f, int __user *ufd, + unsigned int flags) +{ + if (!ufd) + return -EFAULT; + return receive_fd(f, ufd, flags); +} + +#endif /* __LINUX_NET_SCM_H */ + -- cgit v1.3.1