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| author | Jann Horn <jann@thejh.net> | 2015-09-09 15:38:30 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-10 13:29:01 -0700 |
| commit | 40f705a736eac10e7dca7ab5dd5ed675a6df031d (patch) | |
| tree | 80ad7ecf85ece7a46133fd23b150d05a4074da5a /fs/coredump.c | |
| parent | fbb1816942c04429e85dbf4c1a080accc534299e (diff) | |
| download | lwn-40f705a736eac10e7dca7ab5dd5ed675a6df031d.tar.gz lwn-40f705a736eac10e7dca7ab5dd5ed675a6df031d.zip | |
fs: Don't dump core if the corefile would become world-readable.
On a filesystem like vfat, all files are created with the same owner
and mode independent of who created the file. When a vfat filesystem
is mounted with root as owner of all files and read access for everyone,
root's processes left world-readable coredumps on it (but other
users' processes only left empty corefiles when given write access
because of the uid mismatch).
Given that the old behavior was inconsistent and insecure, I don't see
a problem with changing it. Now, all processes refuse to dump core unless
the resulting corefile will only be readable by their owner.
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/coredump.c')
| -rw-r--r-- | fs/coredump.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/coredump.c b/fs/coredump.c index b696dc2c220d..a8f75640ac86 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -685,11 +685,15 @@ void do_coredump(const siginfo_t *siginfo) if (!S_ISREG(inode->i_mode)) goto close_fail; /* - * Dont allow local users get cute and trick others to coredump - * into their pre-created files. + * Don't dump core if the filesystem changed owner or mode + * of the file during file creation. This is an issue when + * a process dumps core while its cwd is e.g. on a vfat + * filesystem. */ if (!uid_eq(inode->i_uid, current_fsuid())) goto close_fail; + if ((inode->i_mode & 0677) != 0600) + goto close_fail; if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) goto close_fail; if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) |