Revert "rexec: handle legacy kernels"

src/lxc/file_utils.c

@@ -222,7 +222,7 @@ int lxc_make_tmpfile(char *template, bool rm)
 	mode_t msk;
 
 	msk = umask(0022);
-	fd = mkostemp(template, O_CLOEXEC);
+	fd = mkstemp(template);
 	umask(msk);
 	if (fd < 0)
 		return -1;
@@ -366,33 +366,3 @@ on_error:
 
 	return NULL;
 }
-
-int fd_to_fd(int from, int to)
-{
-	for (;;) {
-		uint8_t buf[PATH_MAX];
-		uint8_t *p = buf;
-		ssize_t bytes_to_write;
-		ssize_t bytes_read;
-
-		bytes_read = lxc_read_nointr(from, buf, sizeof buf);
-		if (bytes_read < 0)
-			return -1;
-		if (bytes_read == 0)
-			break;
-
-		bytes_to_write = (size_t)bytes_read;
-		do {
-			ssize_t bytes_written;
-
-			bytes_written = lxc_write_nointr(to, p, bytes_to_write);
-			if (bytes_written < 0)
-				return -1;
-
-			bytes_to_write -= bytes_written;
-			p += bytes_written;
-		} while (bytes_to_write > 0);
-	}
-
-	return 0;
-}

src/lxc/file_utils.h

@@ -57,6 +57,5 @@ extern FILE *fopen_cloexec(const char *path, const char *mode);
 extern ssize_t lxc_sendfile_nointr(int out_fd, int in_fd, off_t *offset,
 				   size_t count);
 extern char *file_to_buf(char *path, size_t *length);
-extern int fd_to_fd(int from, int to);
 
 #endif /* __LXC_FILE_UTILS_H */

src/lxc/memory_utils.h

@@ -28,8 +28,6 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include "macro.h"
-
 static inline void __auto_free__(void *p)
 {
 	free(*(void **)p);
@@ -47,17 +45,13 @@ static inline void __auto_closedir__(DIR **d)
 		closedir(*d);
 }
 
-#define close_prot_errno_disarm(fd) \
-	if (fd >= 0) {              \
-		int _e_ = errno;    \
-		close(fd);          \
-		errno = _e_;        \
-		fd = -EBADF;        \
-	}
-
 static inline void __auto_close__(int *fd)
 {
-	close_prot_errno_disarm(*fd);
+	if (*fd >= 0) {
+		int e = errno;
+		close(*fd);
+		errno = e;
+	}
 }
 
 #define __do_close_prot_errno __attribute__((__cleanup__(__auto_close__)))

src/lxc/rexec.c

@@ -84,97 +84,42 @@ static int parse_argv(char ***argv)
 static int is_memfd(void)
 {
 	__do_close_prot_errno int fd = -EBADF;
-	int seals;
+	int saved_errno, seals;
 
 	fd = open("/proc/self/exe", O_RDONLY | O_CLOEXEC);
 	if (fd < 0)
 		return -ENOTRECOVERABLE;
 
 	seals = fcntl(fd, F_GET_SEALS);
-	if (seals < 0) {
-		struct stat s = {0};
-
-		if (fstat(fd, &s) == 0) {
-			fprintf(stderr, "AAAAA: %ld\n", (long)s.st_nlink);
-			return (s.st_nlink == 0);
-		}
-
+	if (seals < 0)
 		return -EINVAL;
-	}
 
 	return seals == LXC_MEMFD_REXEC_SEALS;
 }
 
 static void lxc_rexec_as_memfd(char **argv, char **envp, const char *memfd_name)
 {
-	__do_close_prot_errno int fd = -EBADF, memfd = -EBADF, tmpfd = -EBADF;
-	int ret;
+	__do_close_prot_errno int fd = -EBADF, memfd = -EBADF;
+	int saved_errno;
+	ssize_t bytes_sent;
 
 	memfd = memfd_create(memfd_name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
-	if (memfd < 0) {
-		char template[PATH_MAX];
-
-		ret = snprintf(template, sizeof(template),
-			       P_tmpdir "/.%s_XXXXXX", memfd_name);
-		if (ret < 0 || (size_t)ret >= sizeof(template))
-			return;
-
-		tmpfd = lxc_make_tmpfile(template, true);
-		if (tmpfd < 0)
-			return;
-
-		ret = fchmod(tmpfd, 0700);
-		if (ret)
-			return;
-	}
+	if (memfd < 0)
+		return;
 
 	fd = open("/proc/self/exe", O_RDONLY | O_CLOEXEC);
 	if (fd < 0)
 		return;
 
 	/* sendfile() handles up to 2GB. */
-	if (memfd >= 0) {
-		ssize_t bytes_sent = 0;
-		struct stat st = {0};
-
-		ret = fstat(fd, &st);
-		if (ret)
-			return;
-
-		while (bytes_sent < st.st_size) {
-			ssize_t sent;
-			sent = lxc_sendfile_nointr(memfd, fd, NULL,
-						   st.st_size - bytes_sent);
-			if (sent < 0)
-				return;
-			bytes_sent += sent;
-		}
-	} else if (fd_to_fd(fd, tmpfd)) {
+	bytes_sent = lxc_sendfile_nointr(memfd, fd, NULL, LXC_SENDFILE_MAX);
+	if (bytes_sent < 0)
 		return;
-	}
 
-	close_prot_errno_disarm(fd);
-
-	if (memfd >= 0 && fcntl(memfd, F_ADD_SEALS, LXC_MEMFD_REXEC_SEALS))
+	if (fcntl(memfd, F_ADD_SEALS, LXC_MEMFD_REXEC_SEALS))
 		return;
 
-	if (memfd >= 0) {
-		fexecve(memfd, argv, envp);
-	} else {
-		__do_close_prot_errno int execfd = -EBADF;
-		char procfd[LXC_PROC_PID_FD_LEN];
-
-		ret = snprintf(procfd, sizeof(procfd), "/proc/self/fd/%d", tmpfd);
-		if (ret < 0 || (size_t)ret >= sizeof(procfd))
-			return;
-
-		execfd = open(procfd, O_PATH | O_CLOEXEC);
-		close_prot_errno_disarm(tmpfd);
-		if (execfd < 0)
-			return;
-
-		fexecve(execfd, argv, envp);
-	}
+	fexecve(memfd, argv, envp);
 }
 
 /*