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| author | Denys Vlasenko | 2015-10-13 13:49:53 +0200 |
|---|---|---|
| committer | Denys Vlasenko | 2015-10-13 13:49:53 +0200 |
| commit | f7ad927c2059ef9cd1cd6befeb43f26b92f6369f (patch) | |
| tree | 14c58fbd8b7e656dfa644be841ab476c35f72733 | |
| parent | bf74fb44977d9b90c51dba19c1fd7f071147d955 (diff) | |
| download | busybox-f7ad927c2059ef9cd1cd6befeb43f26b92f6369f.zip busybox-f7ad927c2059ef9cd1cd6befeb43f26b92f6369f.tar.gz | |
ftpd: make DIR parameter work for non-root too: chdir to it instead of chroot
Unfortunately, chroot() works only for root user, because of attacks
on setuid binaries (make DIR/lib/ld-linux.so a shell, hardlink to
a setuid binary, chroot to DIR, execute it and get root shell).
function old new delta
ftpd_main 2160 2180 +20
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
| -rw-r--r-- | networking/ftpd.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/networking/ftpd.c b/networking/ftpd.c index 7735b72..8345ae6 100644 --- a/networking/ftpd.c +++ b/networking/ftpd.c @@ -1223,11 +1223,26 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv) #endif argv += optind; if (argv[0]) { + const char *basedir = argv[0]; #if !BB_MMU G.root_fd = xopen("/", O_RDONLY | O_DIRECTORY); close_on_exec_on(G.root_fd); #endif - xchroot(argv[0]); + if (chroot(basedir) == 0) + basedir = "/"; +#if !BB_MMU + else { + close(G.root_fd); + G.root_fd = -1; + } +#endif + /* + * If chroot failed, assume that we aren't root, + * and at least chdir to the specified DIR + * (older versions were dying with error message). + * If chroot worked, move current dir to new "/": + */ + xchdir(basedir); } #if ENABLE_FEATURE_FTP_AUTHENTICATION |