| Message ID | 20240403021808.309900-3-vinicius.gomes@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | overlayfs: Optimize override/revert creds | expand |
Hi Vinicius, kernel test robot noticed the following build warnings: [auto build test WARNING on brauner-vfs/vfs.all] [also build test WARNING on linus/master v6.9-rc2 next-20240403] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Vinicius-Costa-Gomes/cred-Add-a-light-version-of-override-revert_creds/20240403-101954 base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all patch link: https://lore.kernel.org/r/20240403021808.309900-3-vinicius.gomes%40intel.com patch subject: [PATCH v1 2/3] fs: Optimize credentials reference count for backing file ops config: i386-randconfig-061-20240403 (https://download.01.org/0day-ci/archive/20240403/202404032344.SKdrnkhI-lkp@intel.com/config) compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240403/202404032344.SKdrnkhI-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202404032344.SKdrnkhI-lkp@intel.com/ sparse warnings: (new ones prefixed by >>) fs/backing-file.c: note: in included file (through include/linux/sched/signal.h, include/linux/rcuwait.h, include/linux/percpu-rwsem.h, ...): >> include/linux/cred.h:182:41: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct cred const *old @@ got struct cred const [noderef] __rcu *cred @@ include/linux/cred.h:182:41: sparse: expected struct cred const *old include/linux/cred.h:182:41: sparse: got struct cred const [noderef] __rcu *cred >> include/linux/cred.h:182:41: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct cred const *old @@ got struct cred const [noderef] __rcu *cred @@ include/linux/cred.h:182:41: sparse: expected struct cred const *old include/linux/cred.h:182:41: sparse: got struct cred const [noderef] __rcu *cred >> include/linux/cred.h:182:41: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct cred const *old @@ got struct cred const [noderef] __rcu *cred @@ include/linux/cred.h:182:41: sparse: expected struct cred const *old include/linux/cred.h:182:41: sparse: got struct cred const [noderef] __rcu *cred >> include/linux/cred.h:182:41: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct cred const *old @@ got struct cred const [noderef] __rcu *cred @@ include/linux/cred.h:182:41: sparse: expected struct cred const *old include/linux/cred.h:182:41: sparse: got struct cred const [noderef] __rcu *cred >> include/linux/cred.h:182:41: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct cred const *old @@ got struct cred const [noderef] __rcu *cred @@ include/linux/cred.h:182:41: sparse: expected struct cred const *old include/linux/cred.h:182:41: sparse: got struct cred const [noderef] __rcu *cred vim +182 include/linux/cred.h 58319057b78476 Andy Lutomirski 2015-09-04 174 dd60a254548056 Vinicius Costa Gomes 2024-04-02 175 /* dd60a254548056 Vinicius Costa Gomes 2024-04-02 176 * Override creds without bumping reference count. Caller must ensure dd60a254548056 Vinicius Costa Gomes 2024-04-02 177 * reference remains valid or has taken reference. Almost always not the dd60a254548056 Vinicius Costa Gomes 2024-04-02 178 * interface you want. Use override_creds()/revert_creds() instead. dd60a254548056 Vinicius Costa Gomes 2024-04-02 179 */ dd60a254548056 Vinicius Costa Gomes 2024-04-02 180 static inline const struct cred *override_creds_light(const struct cred *override_cred) dd60a254548056 Vinicius Costa Gomes 2024-04-02 181 { dd60a254548056 Vinicius Costa Gomes 2024-04-02 @182 const struct cred *old = current->cred; dd60a254548056 Vinicius Costa Gomes 2024-04-02 183 dd60a254548056 Vinicius Costa Gomes 2024-04-02 184 rcu_assign_pointer(current->cred, override_cred); dd60a254548056 Vinicius Costa Gomes 2024-04-02 185 return old; dd60a254548056 Vinicius Costa Gomes 2024-04-02 186 } dd60a254548056 Vinicius Costa Gomes 2024-04-02 187
diff --git a/fs/backing-file.c b/fs/backing-file.c index 740185198db3..9610d5166736 100644 --- a/fs/backing-file.c +++ b/fs/backing-file.c @@ -140,7 +140,6 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter, struct backing_file_ctx *ctx) { struct backing_aio *aio = NULL; - const struct cred *old_cred; ssize_t ret; if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING))) @@ -153,7 +152,7 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter, !(file->f_mode & FMODE_CAN_ODIRECT)) return -EINVAL; - old_cred = override_creds(ctx->cred); + cred_guard(ctx->cred); if (is_sync_kiocb(iocb)) { rwf_t rwf = iocb_to_rw_flags(flags); @@ -174,8 +173,6 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter, backing_aio_cleanup(aio, ret); } out: - revert_creds(old_cred); - if (ctx->accessed) ctx->accessed(ctx->user_file); @@ -187,7 +184,6 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, struct kiocb *iocb, int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; ssize_t ret; if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING))) @@ -210,7 +206,7 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, */ flags &= ~IOCB_DIO_CALLER_COMP; - old_cred = override_creds(ctx->cred); + cred_guard(ctx->cred); if (is_sync_kiocb(iocb)) { rwf_t rwf = iocb_to_rw_flags(flags); @@ -222,12 +218,12 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, ret = backing_aio_init_wq(iocb); if (ret) - goto out; + return ret; ret = -ENOMEM; aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); if (!aio) - goto out; + return ret; aio->orig_iocb = iocb; aio->end_write = ctx->end_write; @@ -240,9 +236,6 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, if (ret != -EIOCBQUEUED) backing_aio_cleanup(aio, ret); } -out: - revert_creds(old_cred); - return ret; } EXPORT_SYMBOL_GPL(backing_file_write_iter); @@ -252,15 +245,13 @@ ssize_t backing_file_splice_read(struct file *in, loff_t *ppos, unsigned int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; ssize_t ret; if (WARN_ON_ONCE(!(in->f_mode & FMODE_BACKING))) return -EIO; - old_cred = override_creds(ctx->cred); + cred_guard(ctx->cred); ret = vfs_splice_read(in, ppos, pipe, len, flags); - revert_creds(old_cred); if (ctx->accessed) ctx->accessed(ctx->user_file); @@ -274,7 +265,6 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe, unsigned int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; ssize_t ret; if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING))) @@ -284,11 +274,10 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe, if (ret) return ret; - old_cred = override_creds(ctx->cred); + cred_guard(ctx->cred); file_start_write(out); ret = iter_file_splice_write(pipe, out, ppos, len, flags); file_end_write(out); - revert_creds(old_cred); if (ctx->end_write) ctx->end_write(ctx->user_file); @@ -300,7 +289,6 @@ EXPORT_SYMBOL_GPL(backing_file_splice_write); int backing_file_mmap(struct file *file, struct vm_area_struct *vma, struct backing_file_ctx *ctx) { - const struct cred *old_cred; int ret; if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) || @@ -312,9 +300,8 @@ int backing_file_mmap(struct file *file, struct vm_area_struct *vma, vma_set_file(vma, file); - old_cred = override_creds(ctx->cred); + cred_guard(ctx->cred); ret = call_mmap(vma->vm_file, vma); - revert_creds(old_cred); if (ctx->accessed) ctx->accessed(ctx->user_file);
For backing file operations, users are expected to pass credentials that will outlive the backing file common operations. Use the specialized guard statements to override/revert the credentials. Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> --- fs/backing-file.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-)