From ffe0896ed01790e62cd617cf01bc6a4076fa4e87 Mon Sep 17 00:00:00 2001
From: Andrei Vagin <avagin@gmail.com>
Date: Sun, 1 Mar 2020 04:26:12 +0300
Subject: [PATCH] fs: use __open_proc instead of open("/proc/...", ... )

Processes can run in a mount namespace without /proc.

Reported-by: Mr Jenkins
Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
 criu/files-reg.c | 4 +---
 criu/memfd.c     | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/criu/files-reg.c b/criu/files-reg.c
index c2a55aeb3..0d0076666 100644
--- a/criu/files-reg.c
+++ b/criu/files-reg.c
@@ -778,14 +778,12 @@ static int dump_ghost_file(int _fd, u32 id, const struct stat *st, dev_t phys_de
 
 	if (S_ISREG(st->st_mode)) {
 		int fd, ret;
-		char lpath[PSFDS];
 
 		/*
 		 * Reopen file locally since it may have no read
 		 * permissions when drained
 		 */
-		sprintf(lpath, "/proc/self/fd/%d", _fd);
-		fd = open(lpath, O_RDONLY);
+		fd = open_proc(PROC_SELF, "fd/%d", _fd);
 		if (fd < 0) {
 			pr_perror("Can't open ghost original file");
 			goto err_out;
diff --git a/criu/memfd.c b/criu/memfd.c
index d17c10fb7..30ccdf22c 100644
--- a/criu/memfd.c
+++ b/criu/memfd.c
@@ -299,7 +299,6 @@ static int memfd_open_inode(struct memfd_inode *inode)
 
 int memfd_open(struct file_desc *d, u32 *fdflags)
 {
-	char lpath[PSFDS];
 	struct memfd_info *mfi;
 	MemfdFileEntry *mfe;
 	int fd, _fd;
@@ -318,14 +317,13 @@ int memfd_open(struct file_desc *d, u32 *fdflags)
 		goto err;
 
 	/* Reopen the fd with original permissions */
-	sprintf(lpath, "/proc/self/fd/%d", fd);
 	flags = fdflags ? *fdflags : mfe->flags;
 	/*
 	 * Ideally we should call compat version open() to not force the
 	 * O_LARGEFILE file flag with regular open(). It doesn't seem that
 	 * important though.
 	 */
-	_fd = open(lpath, flags);
+	_fd = __open_proc(getpid(), 0, flags, "fd/%d", fd);
 	if (_fd < 0) {
 		pr_perror("Can't reopen memfd id=%d", mfe->id);
 		goto err;