diff options
| author | Samanta Navarro <ferivoz@riseup.net> | 2023-05-23 11:53:53 +0000 |
|---|---|---|
| committer | Serge Hallyn <serge@hallyn.com> | 2023-05-25 08:25:42 -0500 |
| commit | 4ad359ccc69ebfac5e6447562fca5a1741111324 (patch) | |
| tree | 91ba30c534682e8f846fdbc7baac61685175712e | |
| parent | 419cf1f1c4721829c4d68c9e5fee112a5da5890f (diff) | |
subsystem: Prevent endless loop
If a user has home directory "/" and login shell "*" then login and su
enter an endless loop by constantly switching to the next subsystem.
This could also be achieved with a layered approach so just checking
for "/" as home directory is not enough to protect against such a
misconfiguration.
Just break the loop if it progressed too far. I doubt that this has
negative impact on any real setup.
Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
| -rw-r--r-- | libmisc/sub.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/libmisc/sub.c b/libmisc/sub.c index d30c4c76..821596d1 100644 --- a/libmisc/sub.c +++ b/libmisc/sub.c @@ -15,8 +15,10 @@ #include <sys/types.h> #include "prototypes.h" #include "defines.h" +#define MAX_SUBROOT2 "maximum subsystem depth reached\n" #define BAD_SUBROOT2 "invalid root `%s' for user `%s'\n" #define NO_SUBROOT2 "no subsystem root `%s' for user `%s'\n" +#define MAX_DEPTH 1024 /* * subsystem - change to subsystem root * @@ -27,6 +29,18 @@ */ void subsystem (const struct passwd *pw) { + static int depth = 0; + + /* + * Prevent endless loop on misconfigured systems. + */ + if (++depth > MAX_DEPTH) { + printf (_("Maximum subsystem depth reached\n")); + SYSLOG ((LOG_WARN, MAX_SUBROOT2)); + closelog (); + exit (EXIT_FAILURE); + } + /* * The new root directory must begin with a "/" character. */ |