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Diffstat (limited to 'arch/um/os-Linux/skas/process.c')
-rw-r--r--arch/um/os-Linux/skas/process.c126
1 files changed, 91 insertions, 35 deletions
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index e1aaa144e273..e42ffac23e3c 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -16,6 +16,7 @@
#include <sys/mman.h>
#include <sys/wait.h>
#include <sys/stat.h>
+#include <sys/socket.h>
#include <asm/unistd.h>
#include <as-layout.h>
#include <init.h>
@@ -152,7 +153,39 @@ void wait_stub_done_seccomp(struct mm_id *mm_idp, int running, int wait_sigsys)
int ret;
do {
+ const char byte = 0;
+ struct iovec iov = {
+ .iov_base = (void *)&byte,
+ .iov_len = sizeof(byte),
+ };
+ union {
+ char data[CMSG_SPACE(sizeof(mm_idp->syscall_fd_map))];
+ struct cmsghdr align;
+ } ctrl;
+ struct msghdr msgh = {
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ };
+
if (!running) {
+ if (mm_idp->syscall_fd_num) {
+ unsigned int fds_size =
+ sizeof(int) * mm_idp->syscall_fd_num;
+ struct cmsghdr *cmsg;
+
+ msgh.msg_control = ctrl.data;
+ msgh.msg_controllen = CMSG_SPACE(fds_size);
+ cmsg = CMSG_FIRSTHDR(&msgh);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(fds_size);
+ memcpy(CMSG_DATA(cmsg), mm_idp->syscall_fd_map,
+ fds_size);
+
+ CATCH_EINTR(syscall(__NR_sendmsg, mm_idp->sock,
+ &msgh, 0));
+ }
+
data->signal = 0;
data->futex = FUTEX_IN_CHILD;
CATCH_EINTR(syscall(__NR_futex, &data->futex,
@@ -246,14 +279,20 @@ extern char __syscall_stub_start[];
static int stub_exe_fd;
+struct tramp_data {
+ struct stub_data *stub_data;
+ /* 0 is inherited, 1 is the kernel side */
+ int sockpair[2];
+};
+
#ifndef CLOSE_RANGE_CLOEXEC
#define CLOSE_RANGE_CLOEXEC (1U << 2)
#endif
-static int userspace_tramp(void *stack)
+static int userspace_tramp(void *data)
{
+ struct tramp_data *tramp_data = data;
char *const argv[] = { "uml-userspace", NULL };
- int pipe_fds[2];
unsigned long long offset;
struct stub_init_data init_data = {
.seccomp = using_seccomp,
@@ -280,7 +319,8 @@ static int userspace_tramp(void *stack)
&offset);
init_data.stub_code_offset = MMAP_OFFSET(offset);
- init_data.stub_data_fd = phys_mapping(uml_to_phys(stack), &offset);
+ init_data.stub_data_fd = phys_mapping(uml_to_phys(tramp_data->stub_data),
+ &offset);
init_data.stub_data_offset = MMAP_OFFSET(offset);
/*
@@ -291,20 +331,21 @@ static int userspace_tramp(void *stack)
syscall(__NR_close_range, 0, ~0U, CLOSE_RANGE_CLOEXEC);
fcntl(init_data.stub_data_fd, F_SETFD, 0);
- for (iomem = iomem_regions; iomem; iomem = iomem->next)
- fcntl(iomem->fd, F_SETFD, 0);
- /* Create a pipe for init_data (no CLOEXEC) and dup2 to STDIN */
- if (pipe(pipe_fds))
- exit(2);
+ /* In SECCOMP mode, these FDs are passed when needed */
+ if (!using_seccomp) {
+ for (iomem = iomem_regions; iomem; iomem = iomem->next)
+ fcntl(iomem->fd, F_SETFD, 0);
+ }
- if (dup2(pipe_fds[0], 0) < 0)
+ /* dup2 signaling FD/socket to STDIN */
+ if (dup2(tramp_data->sockpair[0], 0) < 0)
exit(3);
- close(pipe_fds[0]);
+ close(tramp_data->sockpair[0]);
/* Write init_data and close write side */
- ret = write(pipe_fds[1], &init_data, sizeof(init_data));
- close(pipe_fds[1]);
+ ret = write(tramp_data->sockpair[1], &init_data, sizeof(init_data));
+ close(tramp_data->sockpair[1]);
if (ret != sizeof(init_data))
exit(4);
@@ -397,7 +438,7 @@ int userspace_pid[NR_CPUS];
/**
* start_userspace() - prepare a new userspace process
- * @stub_stack: pointer to the stub stack.
+ * @mm_id: The corresponding struct mm_id
*
* Setups a new temporary stack page that is used while userspace_tramp() runs
* Clones the kernel process into a new userspace process, with FDs only.
@@ -409,9 +450,12 @@ int userspace_pid[NR_CPUS];
int start_userspace(struct mm_id *mm_id)
{
struct stub_data *proc_data = (void *)mm_id->stack;
+ struct tramp_data tramp_data = {
+ .stub_data = proc_data,
+ };
void *stack;
unsigned long sp;
- int pid, status, n, err;
+ int status, n, err;
/* setup a temporary stack page */
stack = mmap(NULL, UM_KERN_PAGE_SIZE,
@@ -427,25 +471,32 @@ int start_userspace(struct mm_id *mm_id)
/* set stack pointer to the end of the stack page, so it can grow downwards */
sp = (unsigned long)stack + UM_KERN_PAGE_SIZE;
+ /* socket pair for init data and SECCOMP FD passing (no CLOEXEC here) */
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, tramp_data.sockpair)) {
+ err = -errno;
+ printk(UM_KERN_ERR "%s : socketpair failed, errno = %d\n",
+ __func__, errno);
+ return err;
+ }
+
if (using_seccomp)
proc_data->futex = FUTEX_IN_CHILD;
- /* clone into new userspace process */
- pid = clone(userspace_tramp, (void *) sp,
+ mm_id->pid = clone(userspace_tramp, (void *) sp,
CLONE_VFORK | CLONE_VM | SIGCHLD,
- (void *)mm_id->stack);
- if (pid < 0) {
+ (void *)&tramp_data);
+ if (mm_id->pid < 0) {
err = -errno;
printk(UM_KERN_ERR "%s : clone failed, errno = %d\n",
__func__, errno);
- return err;
+ goto out_close;
}
if (using_seccomp) {
wait_stub_done_seccomp(mm_id, 1, 1);
} else {
do {
- CATCH_EINTR(n = waitpid(pid, &status,
+ CATCH_EINTR(n = waitpid(mm_id->pid, &status,
WUNTRACED | __WALL));
if (n < 0) {
err = -errno;
@@ -462,7 +513,7 @@ int start_userspace(struct mm_id *mm_id)
goto out_kill;
}
- if (ptrace(PTRACE_SETOPTIONS, pid, NULL,
+ if (ptrace(PTRACE_SETOPTIONS, mm_id->pid, NULL,
(void *) PTRACE_O_TRACESYSGOOD) < 0) {
err = -errno;
printk(UM_KERN_ERR "%s : PTRACE_SETOPTIONS failed, errno = %d\n",
@@ -478,12 +529,22 @@ int start_userspace(struct mm_id *mm_id)
goto out_kill;
}
- mm_id->pid = pid;
+ close(tramp_data.sockpair[0]);
+ if (using_seccomp)
+ mm_id->sock = tramp_data.sockpair[1];
+ else
+ close(tramp_data.sockpair[1]);
+
+ return 0;
- return pid;
+out_kill:
+ os_kill_ptraced_process(mm_id->pid, 1);
+out_close:
+ close(tramp_data.sockpair[0]);
+ close(tramp_data.sockpair[1]);
+
+ mm_id->pid = -1;
- out_kill:
- os_kill_ptraced_process(pid, 1);
return err;
}
@@ -546,17 +607,8 @@ void userspace(struct uml_pt_regs *regs)
/* Mark pending syscalls for flushing */
proc_data->syscall_data_len = mm_id->syscall_data_len;
- mm_id->syscall_data_len = 0;
- proc_data->signal = 0;
- proc_data->futex = FUTEX_IN_CHILD;
- CATCH_EINTR(syscall(__NR_futex, &proc_data->futex,
- FUTEX_WAKE, 1, NULL, NULL, 0));
- do {
- ret = syscall(__NR_futex, &proc_data->futex,
- FUTEX_WAIT, FUTEX_IN_CHILD, NULL, NULL, 0);
- } while ((ret == -1 && errno == EINTR) ||
- proc_data->futex == FUTEX_IN_CHILD);
+ wait_stub_done_seccomp(mm_id, 0, 0);
sig = proc_data->signal;
@@ -564,9 +616,13 @@ void userspace(struct uml_pt_regs *regs)
printk(UM_KERN_ERR "%s - Error flushing stub syscalls",
__func__);
syscall_stub_dump_error(mm_id);
+ mm_id->syscall_data_len = proc_data->err;
fatal_sigsegv();
}
+ mm_id->syscall_data_len = 0;
+ mm_id->syscall_fd_num = 0;
+
ret = get_stub_state(regs, proc_data, NULL);
if (ret) {
printk(UM_KERN_ERR "%s - failed to get regs: %d",
generated by cgit v1.2.3 (git 2.0.4) at 2025-12-13 22:01:48 +0000