From 498052bba55ecaff58db6a1436b0e25bfd75a7ff Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 30 Mar 2009 07:20:30 -0400 Subject: New locking/refcounting for fs_struct * all changes of current->fs are done under task_lock and write_lock of old fs->lock * refcount is not atomic anymore (same protection) * its decrements are done when removing reference from current; at the same time we decide whether to free it. * put_fs_struct() is gone * new field - ->in_exec. Set by check_unsafe_exec() if we are trying to do execve() and only subthreads share fs_struct. Cleared when finishing exec (success and failure alike). Makes CLONE_FS fail with -EAGAIN if set. * check_unsafe_exec() may fail with -EAGAIN if another execve() from subthread is in progress. Signed-off-by: Al Viro --- fs/compat.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'fs/compat.c') diff --git a/fs/compat.c b/fs/compat.c index 55efdfebdf5a..baabf203b847 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -51,6 +51,7 @@ #include #include #include +#include #include #include @@ -1441,12 +1442,15 @@ int compat_do_execve(char * filename, bprm->cred = prepare_exec_creds(); if (!bprm->cred) goto out_unlock; - check_unsafe_exec(bprm); + + retval = check_unsafe_exec(bprm); + if (retval) + goto out_unlock; file = open_exec(filename); retval = PTR_ERR(file); if (IS_ERR(file)) - goto out_unlock; + goto out_unmark; sched_exec(); @@ -1488,6 +1492,9 @@ int compat_do_execve(char * filename, goto out; /* execve succeeded */ + write_lock(¤t->fs->lock); + current->fs->in_exec = 0; + write_unlock(¤t->fs->lock); current->in_execve = 0; mutex_unlock(¤t->cred_exec_mutex); acct_update_integrals(current); @@ -1506,6 +1513,11 @@ out_file: fput(bprm->file); } +out_unmark: + write_lock(¤t->fs->lock); + current->fs->in_exec = 0; + write_unlock(¤t->fs->lock); + out_unlock: current->in_execve = 0; mutex_unlock(¤t->cred_exec_mutex); -- cgit v1.2.3