From 5a73e0ca54c77e067c3b12ea6f35e3e8681e8cf8 Mon Sep 17 00:00:00 2001 From: Bram Moolenaar Date: Sat, 4 Nov 2017 21:35:01 +0100 Subject: [PATCH] patch 8.0.1263: others can read the swap file if a user is careless Problem: Others can read the swap file if a user is careless with his primary group. Solution: If the group permission allows for reading but the world permissions doesn't, make sure the group is right. --- src/Makefile | 1 + src/fileio.c | 24 +++++++++- src/testdir/test_swap.vim | 112 ++++++++++++++++++++++++++++++---------------- src/version.c | 2 + 4 files changed, 99 insertions(+), 40 deletions(-) diff --git a/src/fileio.c b/src/fileio.c index 87b85cf..34dcdb6 100644 --- a/src/fileio.c +++ b/src/fileio.c @@ -716,7 +716,29 @@ readfile( /* Set swap file protection bits after creating it. */ if (swap_mode > 0 && curbuf->b_ml.ml_mfp != NULL && curbuf->b_ml.ml_mfp->mf_fname != NULL) - (void)mch_setperm(curbuf->b_ml.ml_mfp->mf_fname, (long)swap_mode); + { + char_u *swap_fname = curbuf->b_ml.ml_mfp->mf_fname; + + /* + * If the group-read bit is set but not the world-read bit, then + * the group must be equal to the group of the original file. If + * we can't make that happen then reset the group-read bit. This + * avoids making the swap file readable to more users when the + * primary group of the user is too permissive. + */ + if ((swap_mode & 044) == 040) + { + stat_T swap_st; + + if (mch_stat((char *)swap_fname, &swap_st) >= 0 + && st.st_gid != swap_st.st_gid + && fchown(curbuf->b_ml.ml_mfp->mf_fd, -1, st.st_gid) + == -1) + swap_mode &= 0600; + } + + (void)mch_setperm(swap_fname, (long)swap_mode); + } #endif }