diff options
Diffstat (limited to 'pkg/rootless/rootless_linux.c')
| -rw-r--r-- | pkg/rootless/rootless_linux.c | 35 |
1 files changed, 23 insertions, 12 deletions
diff --git a/pkg/rootless/rootless_linux.c b/pkg/rootless/rootless_linux.c index 94933ddd0..193c788c0 100644 --- a/pkg/rootless/rootless_linux.c +++ b/pkg/rootless/rootless_linux.c @@ -19,20 +19,31 @@ #include <sys/select.h> #include <stdio.h> -#ifndef RENAME_NOREPLACE -# define RENAME_NOREPLACE (1 << 0) - -int renameat2 (int olddirfd, const char *oldpath, int newdirfd, const char *newpath, unsigned int flags) +int rename_noreplace (int olddirfd, const char *oldpath, int newdirfd, const char *newpath) { -# ifdef __NR_renameat2 - return (int) syscall (__NR_renameat2, olddirfd, oldpath, newdirfd, newpath, flags); -# else - /* no way to implement it atomically. */ - errno = ENOSYS; - return -1; + int ret; + +# ifdef SYS_renameat2 +# ifndef RENAME_NOREPLACE +# define RENAME_NOREPLACE (1 << 0) +# endif + + ret = (int) syscall (SYS_renameat2, olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE); + if (ret == 0 || errno != EINVAL) + return ret; + + /* Fallback in case of errno==EINVAL. */ # endif + + /* This might be an issue if another process is trying to read the file while it is empty. */ + ret = open (newpath, O_EXCL|O_CREAT, 0700); + if (ret < 0) + return ret; + close (ret); + + /* We are sure we created the file, let's overwrite it. */ + return rename (oldpath, newpath); } -#endif #ifndef TEMP_FAILURE_RETRY #define TEMP_FAILURE_RETRY(expression) \ @@ -449,7 +460,7 @@ create_pause_process (const char *pause_pid_file_path, char **argv) /* There can be another process at this point trying to configure the user namespace and the pause process, do not override the pid file if it already exists. */ - if (renameat2 (AT_FDCWD, tmp_file_path, AT_FDCWD, pause_pid_file_path, RENAME_NOREPLACE) < 0) + if (rename_noreplace (AT_FDCWD, tmp_file_path, AT_FDCWD, pause_pid_file_path) < 0) { unlink (tmp_file_path); kill (pid, SIGKILL); |