Messages in this thread Patch in this message | | | Date | Fri, 2 Feb 2007 14:20:37 +0300 | From | Alexey Dobriyan <> | Subject | [PATCH v2] Allow access to /proc/$PID/fd after setuid() |
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crap, Pavel reminded that get_proc_task() can return NULL. ------------------------------------------------------------------------ /proc/$PID/fd has r-x------ permissions, so if process does setuid(), it will not be able to access /proc/*/fd/. This breaks fstatat() emulation in glibc.
open("foo", O_RDONLY|O_DIRECTORY) = 4 setuid32(65534) = 0 stat64("/proc/self/fd/4/bar", 0xbfafb298) = -1 EACCES (Permission denied)
Comment from Andrew Morton.
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org> ---
fs/proc/base.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)
--- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1414,10 +1414,33 @@ static struct file_operations proc_fd_op }; /* + * /proc/pid/fd needs a special permission handler so that a process can still + * access /proc/self/fd after it has executed a setuid(). + */ +static int proc_fd_permission(struct inode *inode, int mask, + struct nameidata *nd) +{ + struct task_struct *tsk; + int rv; + + rv = generic_permission(inode, mask, NULL); + if (rv == 0) + return 0; + tsk = get_proc_task(inode); + if (tsk) { + if (tsk == current) + rv = 0; + put_task_struct(tsk); + } + return rv; +} + +/* * proc directories can do almost nothing.. */ static struct inode_operations proc_fd_inode_operations = { .lookup = proc_lookupfd, + .permission = proc_fd_permission, .setattr = proc_setattr, }; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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