[PR PATCH] lxc: fix config parsing with linux5.10

[PR PATCH] lxc: fix config parsing with linux5.10

[ahesford]

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There is a new pull request by ahesford against master on the void-packages repository

https://github.com/ahesford/void-packages lxc
https://github.com/void-linux/void-packages/pull/27352

lxc: fix config parsing with linux5.10
When upgrading to `linux5.10`, I noticed that LXC failed to parse configs, complaining about a failure in `sendfile(2)`. I was unable to start existing containers or create new ones. Upstream commit lxc/lxc@26dffd825842edf019bc17da24a6809ed51c048c already addresses this, dropping use of `sendfile` in the config parser altogether.

@CameronNemo, do you have any objections to including this patch?

A patch file from https://github.com/void-linux/void-packages/pull/27352.patch is attached

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From 7efe838822dbd48429863a625a576960ff85fe6a Mon Sep 17 00:00:00 2001
From: "Andrew J. Hesford" <ajh@sideband.org>
Date: Tue, 22 Dec 2020 09:44:58 -0500
Subject: [PATCH] lxc: fix config parsing with linux5.10

---
 srcpkgs/lxc/patches/fix-config-parsing.patch | 169 +++++++++++++++++++
 srcpkgs/lxc/template                         |   2 +-
 2 files changed, 170 insertions(+), 1 deletion(-)
 create mode 100644 srcpkgs/lxc/patches/fix-config-parsing.patch

diff --git a/srcpkgs/lxc/patches/fix-config-parsing.patch b/srcpkgs/lxc/patches/fix-config-parsing.patch
new file mode 100644
index 00000000000..cbb435c3e4a
--- /dev/null
+++ b/srcpkgs/lxc/patches/fix-config-parsing.patch
@@ -0,0 +1,169 @@
+From 26dffd825842edf019bc17da24a6809ed51c048c Mon Sep 17 00:00:00 2001
+From: Christian Brauner <christian.brauner@ubuntu.com>
+Date: Mon, 16 Nov 2020 12:18:14 +0100
+Subject: [PATCH] parse: rework config parsing routine
+
+Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
+---
+ src/lxc/file_utils.c |  7 +++++--
+ src/lxc/file_utils.h |  6 +++++-
+ src/lxc/parse.c      | 49 ++++++++++++++++++++++++--------------------
+ 3 files changed, 37 insertions(+), 25 deletions(-)
+
+diff --git src/lxc/file_utils.c src/lxc/file_utils.c
+index fafaba354c..3b4bffb399 100644
+--- src/lxc/file_utils.c
++++ src/lxc/file_utils.c
+@@ -382,8 +382,10 @@ ssize_t lxc_sendfile_nointr(int out_fd, int in_fd, off_t *offset, size_t count)
+ 	return ret;
+ }
+ 
+-int fd_to_fd(int from, int to)
++ssize_t __fd_to_fd(int from, int to)
+ {
++	ssize_t total_bytes = 0;
++
+ 	for (;;) {
+ 		uint8_t buf[PATH_MAX];
+ 		uint8_t *p = buf;
+@@ -407,9 +409,10 @@ int fd_to_fd(int from, int to)
+ 			bytes_to_write -= bytes_written;
+ 			p += bytes_written;
+ 		} while (bytes_to_write > 0);
++		total_bytes += bytes_to_write;
+ 	}
+ 
+-	return 0;
++	return total_bytes;
+ }
+ 
+ int fd_to_buf(int fd, char **buf, size_t *length)
+diff --git src/lxc/file_utils.h src/lxc/file_utils.h
+index ea9570dd18..11acdb3a7b 100644
+--- src/lxc/file_utils.h
++++ src/lxc/file_utils.h
+@@ -68,7 +68,11 @@ __hidden extern FILE *fopen_cloexec(const char *path, const char *mode);
+ __hidden extern ssize_t lxc_sendfile_nointr(int out_fd, int in_fd, off_t *offset, size_t count);
+ __hidden extern char *file_to_buf(const char *path, size_t *length);
+ __hidden extern int fd_to_buf(int fd, char **buf, size_t *length);
+-__hidden extern int fd_to_fd(int from, int to);
++__hidden extern ssize_t __fd_to_fd(int from, int to);
++static inline int fd_to_fd(int from, int to)
++{
++	return __fd_to_fd(from, to) >= 0;
++}
+ __hidden extern int lxc_open_dirfd(const char *dir);
+ __hidden extern FILE *fdopen_cached(int fd, const char *mode, void **caller_freed_buffer);
+ __hidden extern FILE *fopen_cached(const char *path, const char *mode, void **caller_freed_buffer);
+diff --git src/lxc/parse.c src/lxc/parse.c
+index 291bf3efc1..5a5b853458 100644
+--- src/lxc/parse.c
++++ src/lxc/parse.c
+@@ -5,6 +5,7 @@
+ #endif
+ #include <dirent.h>
+ #include <errno.h>
++#include <limits.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <string.h>
+@@ -50,11 +51,12 @@ int lxc_strmunmap(void *addr, size_t length)
+ 
+ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *data)
+ {
+-	int saved_errno;
+-	ssize_t ret = -1, bytes_sent;
+-	char *line;
+-	int fd = -1, memfd = -1;
++	__do_close int fd = -EBADF, memfd = -EBADF;
++	ssize_t ret = -1;
+ 	char *buf = NULL;
++	struct stat st = {};
++	ssize_t bytes;
++	char *line;
+ 
+ 	memfd = memfd_create(".lxc_config_file", MFD_CLOEXEC);
+ 	if (memfd < 0) {
+@@ -65,8 +67,7 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da
+ 			goto on_error;
+ 		}
+ 
+-		TRACE("Failed to create in-memory file. Falling back to "
+-		      "temporary file");
++		TRACE("Failed to create in-memory file. Falling back to temporary file");
+ 		memfd = lxc_make_tmpfile(template, true);
+ 		if (memfd < 0) {
+ 			SYSERROR("Failed to create temporary file \"%s\"", template);
+@@ -80,10 +81,21 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da
+ 		goto on_error;
+ 	}
+ 
+-	/* sendfile() handles up to 2GB. No config file should be that big. */
+-	bytes_sent = lxc_sendfile_nointr(memfd, fd, NULL, LXC_SENDFILE_MAX);
+-	if (bytes_sent < 0) {
+-		SYSERROR("Failed to sendfile \"%s\"", file);
++	ret = fstat(fd, &st);
++	if (ret) {
++		SYSERROR("Failed to stat file \"%s\"", file);
++		goto on_error;
++	}
++
++	if (st.st_size > INT_MAX) {
++		SYSERROR("Excessively large config file \"%s\"", file);
++		goto on_error;
++	}
++
++
++	bytes = __fd_to_fd(fd, memfd);
++	if (bytes < 0) {
++		SYSERROR("Failed to copy config file \"%s\"", file);
+ 		goto on_error;
+ 	}
+ 
+@@ -92,7 +104,7 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da
+ 		SYSERROR("Failed to append zero byte");
+ 		goto on_error;
+ 	}
+-	bytes_sent++;
++	bytes++;
+ 
+ 	ret = lseek(memfd, 0, SEEK_SET);
+ 	if (ret < 0) {
+@@ -101,8 +113,7 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da
+ 	}
+ 
+ 	ret = -1;
+-	buf = mmap(NULL, bytes_sent, PROT_READ | PROT_WRITE,
+-		   MAP_SHARED | MAP_POPULATE, memfd, 0);
++	buf = mmap(NULL, bytes, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_POPULATE, memfd, 0);
+ 	if (buf == MAP_FAILED) {
+ 		buf = NULL;
+ 		SYSERROR("Failed to mmap");
+@@ -117,24 +128,18 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da
+ 			 * error.
+ 			 */
+ 			if (ret < 0)
+-				ERROR("Failed to parse config file \"%s\" at "
+-				      "line \"%s\"", file, line);
++				ERROR("Failed to parse config file \"%s\" at line \"%s\"",
++				      file, line);
+ 			break;
+ 		}
+ 	}
+ 
+ on_error:
+-	saved_errno = errno;
+-	if (fd >= 0)
+-		close(fd);
+-	if (memfd >= 0)
+-		close(memfd);
+-	if (buf && munmap(buf, bytes_sent)) {
++	if (buf && munmap(buf, bytes)) {
+ 		SYSERROR("Failed to unmap");
+ 		if (ret == 0)
+ 			ret = -1;
+ 	}
+-	errno = saved_errno;
+ 
+ 	return ret;
+ }
diff --git a/srcpkgs/lxc/template b/srcpkgs/lxc/template
index 128024dc038..03fbeb400f5 100644
--- a/srcpkgs/lxc/template
+++ b/srcpkgs/lxc/template
@@ -3,7 +3,7 @@ _desc="Linux Containers"
 
 pkgname=lxc
 version=4.0.5
-revision=2
+revision=3
 build_style=gnu-configure
 configure_args="--enable-doc --enable-seccomp
  --enable-capabilities --enable-apparmor --with-distro=none

Re: lxc: fix config parsing with linux5.10

[CameronNemo]

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New comment by CameronNemo on void-packages repository

https://github.com/void-linux/void-packages/pull/27352#issuecomment-749632428

Comment:
I do not see why I would. LGTM.

Re: [PR PATCH] [Merged]: lxc: fix config parsing with linux5.10

[ahesford]

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There's a merged pull request on the void-packages repository

lxc: fix config parsing with linux5.10
https://github.com/void-linux/void-packages/pull/27352

Description:
When upgrading to `linux5.10`, I noticed that LXC failed to parse configs, complaining about a failure in `sendfile(2)`. I was unable to start existing containers or create new ones. Upstream commit lxc/lxc@26dffd825842edf019bc17da24a6809ed51c048c already addresses this, dropping use of `sendfile` in the config parser altogether.

@CameronNemo, do you have any objections to including this patch?