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It can be accessed and reviewed at: https://github.com/lxc/lxc/pull/3348
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=== Description (from pull-request) ===
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
From c353b0b9508988d4aeb44fa3d0403d801a63f2a8 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Thu, 2 Apr 2020 11:50:27 +0200
Subject: [PATCH 1/2] utils: rework fix_stdio_permissions()
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
src/lxc/attach.c | 6 ++++--
src/lxc/start.c | 6 ++++--
src/lxc/utils.c | 49 ++++++++++++++++++++++++------------------------
src/lxc/utils.h | 3 +--
4 files changed, 33 insertions(+), 31 deletions(-)
diff --git a/src/lxc/attach.c b/src/lxc/attach.c
index 07eb814c9a..406b8ec740 100644
--- a/src/lxc/attach.c
+++ b/src/lxc/attach.c
@@ -875,9 +875,11 @@ static int attach_child_main(struct attach_clone_payload
*payload)
if (new_gid == ns_root_gid)
new_gid = LXC_INVALID_GID;
-
+
/* Make sure that the processes STDIO is correctly owned by the user
that we are switching to */
- fix_stdio_permissions(new_uid);
+ ret = fix_stdio_permissions(new_uid);
+ if (ret)
+ WARN("Failed to ajust stdio permissions");
if (!lxc_switch_uid_gid(new_uid, new_gid))
goto on_error;
diff --git a/src/lxc/start.c b/src/lxc/start.c
index e4c8712e13..9d800e30bb 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -1363,9 +1363,11 @@ static int do_start(void *data)
if (new_gid == nsgid)
new_gid = LXC_INVALID_GID;
-
+
/* Make sure that the processes STDIO is correctly owned by the user
that we are switching to */
- fix_stdio_permissions(new_uid);
+ ret = fix_stdio_permissions(new_uid);
+ if (ret)
+ WARN("Failed to ajust stdio permissions");
/* If we are in a new user namespace we already dropped all groups when
* we switched to root in the new user namespace further above. Only
diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index 96c35e8084..70414f8123 100644
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -1861,47 +1861,46 @@ bool lxc_can_use_pidfd(int pidfd)
return log_trace(true, "Kernel supports pidfds");
}
-void fix_stdio_permissions(uid_t uid)
+int fix_stdio_permissions(uid_t uid)
{
- int std_fds[3] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO};
- int devnull_fd = -1;
+ __do_close int devnull_fd = -EBADF;
+ int fret = 0;
+ int std_fds[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO};
int ret;
- int i = 0;
- struct stat st;
- struct stat null_st;
+ struct stat st, st_null;
devnull_fd = open_devnull();
- if (devnull_fd < 0) {
- ERROR("Open /dev/null failed");
- goto out;
- }
-
- ret = fstat(devnull_fd, &null_st);
+ if (devnull_fd < 0)
+ return log_warn_errno(-1, errno, "Failed to open
\"/dev/null\"");
+
+ ret = fstat(devnull_fd, &st_null);
+ if (ret)
+ return log_warn_errno(-errno, errno, "Failed to stat
\"/dev/null\"");
- for (; i < 3; i++) {
+ for (int i = 0; i < ARRAY_SIZE(std_fds); i++) {
ret = fstat(std_fds[i], &st);
- if (ret != 0) {
- ERROR("Failed to get fd %d stat", std_fds[i]);
+ if (ret) {
+ SYSWARN("Failed to stat standard I/O file descriptor
%d", std_fds[i]);
+ fret = -1;
continue;
}
- if (st.st_rdev == null_st.st_rdev) {
+ if (st.st_rdev == st_null.st_rdev)
continue;
- }
ret = fchown(std_fds[i], uid, st.st_gid);
- if (ret != 0) {
- ERROR("Failed to change fd %d owner", std_fds[i]);
+ if (ret) {
+ SYSWARN("Failed to chown standard I/O file descriptor
%d to uid %d and gid %d",
+ std_fds[i], uid, st.st_gid);
+ fret = -1;
}
ret = fchmod(std_fds[i], 0700);
- if (ret != 0) {
- ERROR("Failed to change fd %d mode", std_fds[i]);
+ if (ret) {
+ SYSWARN("Failed to chmod standard I/O file descriptor
%d", std_fds[i]);
+ fret = -1;
}
}
-out:
- if (devnull_fd >= 0) {
- close(devnull_fd);
- }
+ return fret;
}
diff --git a/src/lxc/utils.h b/src/lxc/utils.h
index bd7a86136b..339217c506 100644
--- a/src/lxc/utils.h
+++ b/src/lxc/utils.h
@@ -239,7 +239,6 @@ extern int lxc_rm_rf(const char *dirname);
extern int lxc_setup_keyring(char *keyring_label);
extern bool lxc_can_use_pidfd(int pidfd);
-/* Fix the permissions of init PID's STDIO within the container to the
specified user */
-extern void fix_stdio_permissions(uid_t uid);
+extern int fix_stdio_permissions(uid_t uid);
#endif /* __LXC_UTILS_H */
From 2ed0ea489a503945e9d0c983c842dadabb4ecf55 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Thu, 2 Apr 2020 11:51:13 +0200
Subject: [PATCH 2/2] utils: use setres{u,g}id() in lxc_switch_uid_gid()
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
src/lxc/utils.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index 70414f8123..2cf99945fb 100644
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -1336,7 +1336,7 @@ bool lxc_switch_uid_gid(uid_t uid, gid_t gid)
int ret = 0;
if (gid != LXC_INVALID_GID) {
- ret = setgid(gid);
+ ret = setresgid(gid, gid, gid);
if (ret < 0) {
SYSERROR("Failed to switch to gid %d", gid);
return false;
@@ -1345,7 +1345,7 @@ bool lxc_switch_uid_gid(uid_t uid, gid_t gid)
}
if (uid != LXC_INVALID_UID) {
- ret = setuid(uid);
+ ret = setresuid(uid, uid, uid);
if (ret < 0) {
SYSERROR("Failed to switch to uid %d", uid);
return false;
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