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Code Issues Releases Activity

proc: Fix /proc/cpuinfo not respecting personality

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It was found that the personality within the container was not being
properly respected, which for large numbers of CPUs would break
reporting of /proc/cpuinfo in arm32 containers running on an arm64 host.

Signed-off-by: Mathias Gibbens <gibmat@debian.org>
This commit is contained in:
Mathias Gibbens
2023-09-04 00:13:57 +00:00
parent 587c661b7a
commit fc8f593bda
1 changed files with 47 additions and 2 deletions
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49
src/proc_fuse.c
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@@ -82,6 +82,45 @@ static off_t get_procfile_size(const char *path)
return answer;
}
static off_t get_procfile_size_with_personality(const char *path)
{
struct fuse_context *fc = fuse_get_context();
__u32 host_personality = liblxcfs_personality(), caller_personality;
bool change_personality;
int ret;
off_t procfile_size_ret;
if (get_task_personality(fc->pid, &caller_personality) < 0)
return log_error(0, "Failed to get caller process (pid: %d) personality", fc->pid);
/* do we need to change thread personality? */
change_personality = host_personality != caller_personality;
if (change_personality) {
ret = personality(caller_personality);
if (ret == -1)
return log_error(0, "Call to personality(%d) failed: %s\n",
caller_personality, strerror(errno));
lxcfs_debug("task (tid: %d) personality was changed %d -> %d\n",
(int)syscall(SYS_gettid), ret, caller_personality);
}
procfile_size_ret = get_procfile_size(path);
if (change_personality) {
ret = personality(host_personality);
if (ret == -1)
return log_error(0, "Call to personality(%d) failed: %s\n",
host_personality, strerror(errno));
lxcfs_debug("task (tid: %d) personality was restored %d -> %d\n",
(int)syscall(SYS_gettid), ret, host_personality);
}
return procfile_size_ret;
}
__lxcfs_fuse_ops int proc_getattr(const char *path, struct stat *sb)
{
struct timespec now;
@@ -106,7 +145,10 @@ __lxcfs_fuse_ops int proc_getattr(const char *path, struct stat *sb)
strcmp(path, "/proc/swaps") == 0 ||
strcmp(path, "/proc/loadavg") == 0 ||
strcmp(path, "/proc/slabinfo") == 0) {
sb->st_size = get_procfile_size(path);
if (liblxcfs_functional())
sb->st_size = get_procfile_size_with_personality(path);
else
sb->st_size = get_procfile_size(path);
sb->st_mode = S_IFREG | 00444;
sb->st_nlink = 1;
return 0;
@@ -164,7 +206,10 @@ __lxcfs_fuse_ops int proc_open(const char *path, struct fuse_file_info *fi)
info->type = type;
info->buflen = get_procfile_size(path) + BUF_RESERVE_SIZE;
if (liblxcfs_functional())
info->buflen = get_procfile_size_with_personality(path) + BUF_RESERVE_SIZE;
else
info->buflen = get_procfile_size(path) + BUF_RESERVE_SIZE;
info->buf = zalloc(info->buflen);
if (!info->buf)