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| author | Carlos O'Donell <carlos@redhat.com> | 2013-07-19 02:42:03 -0400 |
|---|---|---|
| committer | Carlos O'Donell <carlos@redhat.com> | 2013-07-21 15:39:55 -0400 |
| commit | e4608715e6e1dd2adc91982fd151d5ba4f761d69 (patch) | |
| tree | 04bc13d3736e14045f0f9fc37e0303a067f943cf /sysdeps | |
| parent | da2d62df77de66e5de5755228759f8bc18481871 (diff) | |
| download | glibc-e4608715e6e1dd2adc91982fd151d5ba4f761d69.tar glibc-e4608715e6e1dd2adc91982fd151d5ba4f761d69.tar.gz glibc-e4608715e6e1dd2adc91982fd151d5ba4f761d69.tar.bz2 glibc-e4608715e6e1dd2adc91982fd151d5ba4f761d69.zip | |
CVE-2013-2207, BZ #15755: Disable pt_chown.
The helper binary pt_chown tricked into granting access to another
user's pseudo-terminal.
Pre-conditions for the attack:
* Attacker with local user account
* Kernel with FUSE support
* "user_allow_other" in /etc/fuse.conf
* Victim with allocated slave in /dev/pts
Using the setuid installed pt_chown and a weak check on whether a file
descriptor is a tty, an attacker could fake a pty check using FUSE and
trick pt_chown to grant ownership of a pty descriptor that the current
user does not own. It cannot access /dev/pts/ptmx however.
In most modern distributions pt_chown is not needed because devpts
is enabled by default. The fix for this CVE is to disable building
and using pt_chown by default. We still provide a configure option
to enable hte use of pt_chown but distributions do so at their own
risk.
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/unix/grantpt.c | 8 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/grantpt.c | 5 |
2 files changed, 8 insertions, 5 deletions
diff --git a/sysdeps/unix/grantpt.c b/sysdeps/unix/grantpt.c index d37da13506..431be855a3 100644 --- a/sysdeps/unix/grantpt.c +++ b/sysdeps/unix/grantpt.c @@ -173,9 +173,10 @@ grantpt (int fd) retval = 0; goto cleanup; - /* We have to use the helper program. */ + /* We have to use the helper program if it is available. */ helper:; +#ifdef HAVE_PT_CHOWN pid_t pid = __fork (); if (pid == -1) goto cleanup; @@ -190,9 +191,9 @@ grantpt (int fd) if (__dup2 (fd, PTY_FILENO) < 0) _exit (FAIL_EBADF); -#ifdef CLOSE_ALL_FDS +# ifdef CLOSE_ALL_FDS CLOSE_ALL_FDS (); -#endif +# endif execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL); _exit (FAIL_EXEC); @@ -231,6 +232,7 @@ grantpt (int fd) assert(! "getpt: internal error: invalid exit code from pt_chown"); } } +#endif cleanup: if (buf != _buf) diff --git a/sysdeps/unix/sysv/linux/grantpt.c b/sysdeps/unix/sysv/linux/grantpt.c index 0a3cd472fa..8cebde36ed 100644 --- a/sysdeps/unix/sysv/linux/grantpt.c +++ b/sysdeps/unix/sysv/linux/grantpt.c @@ -11,7 +11,7 @@ #include "pty-private.h" - +#if HAVE_PT_CHOWN /* Close all file descriptors except the one specified. */ static void close_all_fds (void) @@ -38,6 +38,7 @@ close_all_fds (void) __dup2 (STDOUT_FILENO, STDERR_FILENO); } } -#define CLOSE_ALL_FDS() close_all_fds() +# define CLOSE_ALL_FDS() close_all_fds() +#endif #include <sysdeps/unix/grantpt.c> |