[PATCH v7 7/9] coredump: validate socket name as it is written
From: Christian Brauner <brauner@kernel.org>
Date: 2025-05-14 22:04:34
Also in:
linux-fsdevel, linux-security-module, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
In contrast to other parameters written into /proc/sys/kernel/core_pattern that never fail we can validate enabling the new AF_UNIX support. This is obviously racy as hell but it's always been that way. Signed-off-by: Christian Brauner <brauner@kernel.org> --- fs/coredump.c | 37 ++++++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-)
diff --git a/fs/coredump.c b/fs/coredump.c
index 6ee38e3da108..d4ff08ef03e5 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c@@ -1228,13 +1228,44 @@ void validate_coredump_safety(void) } } +static inline bool check_coredump_socket(void) +{ + if (core_pattern[0] != '@') + return true; + + /* + * Coredump socket must be located in the initial mount + * namespace. Don't give the that impression anything else is + * supported right now. + */ + if (current->nsproxy->mnt_ns != init_task.nsproxy->mnt_ns) + return false; + + /* Must be an absolute path. */ + if (*(core_pattern + 1) != '/') + return false; + + return true; +} + static int proc_dostring_coredump(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { - int error = proc_dostring(table, write, buffer, lenp, ppos); + int error; + ssize_t retval; + char old_core_pattern[CORENAME_MAX_SIZE]; + + retval = strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + + error = proc_dostring(table, write, buffer, lenp, ppos); + if (error) + return error; + if (!check_coredump_socket()) { + strscpy(core_pattern, old_core_pattern, retval + 1); + return -EINVAL; + } - if (!error) - validate_coredump_safety(); + validate_coredump_safety(); return error; }
--
2.47.2