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authorDavid Herrmann <dh.herrmann@gmail.com>2014-08-18 23:54:10 +0200
committerDavid Herrmann <dh.herrmann@gmail.com>2014-08-18 23:56:36 +0200
commit1ac36c67dd4d3fb5b73939293673fcd6debae699 (patch)
treea97ea5e18b5b1e429951939dda7664bfc4bc6cc9
parent9da465df2a7d5d87e4af61364fb1475b1c8cbc6f (diff)
bus: map sealed memfds as MAP_PRIVATE
Mapping files as MAP_SHARED is handled by the kernel as 'writable' mapping. Always! Even with PROT_READ. Reason for that is, mprotect(PROT_WRITE) could change the mapping underneath and currently there is no kernel infrastructure to add protection there. This might change in the future, but until then, map sealed files as MAP_PRIVATE so we don't get EPERM.
-rw-r--r--src/libsystemd/sd-bus/bus-message.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c
index 3e60842172..c058b06f41 100644
--- a/src/libsystemd/sd-bus/bus-message.c
+++ b/src/libsystemd/sd-bus/bus-message.c
@@ -2840,7 +2840,7 @@ int bus_body_part_map(struct bus_body_part *part) {
psz = PAGE_ALIGN(part->size);
if (part->memfd >= 0)
- p = mmap(NULL, psz, PROT_READ, MAP_SHARED, part->memfd, 0);
+ p = mmap(NULL, psz, PROT_READ, MAP_PRIVATE, part->memfd, 0);
else if (part->is_zero)
p = mmap(NULL, psz, PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
else