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authorDavid S. Miller <davem@davemloft.net>2020-06-17 13:26:55 -0700
committerDavid S. Miller <davem@davemloft.net>2020-06-17 13:26:55 -0700
commitb9d37bbb55b8993d296a86fa21f98fa550b61967 (patch)
tree73a93a246e9261c7738595af15e6f5a0cf44115a /Documentation
parent69119673bd50b176ded34032fadd41530fb5af21 (diff)
parent8030e250d882db174cbcd88273570ffb36a13080 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Alexei Starovoitov says: ==================== pull-request: bpf 2020-06-17 The following pull-request contains BPF updates for your *net* tree. We've added 10 non-merge commits during the last 2 day(s) which contain a total of 14 files changed, 158 insertions(+), 59 deletions(-). The main changes are: 1) Important fix for bpf_probe_read_kernel_str() return value, from Andrii. 2) [gs]etsockopt fix for large optlen, from Stanislav. 3) devmap allocation fix, from Toke. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/bpf/prog_cgroup_sockopt.rst14
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/bpf/prog_cgroup_sockopt.rst b/Documentation/bpf/prog_cgroup_sockopt.rst
index c47d974629ae..172f957204bf 100644
--- a/Documentation/bpf/prog_cgroup_sockopt.rst
+++ b/Documentation/bpf/prog_cgroup_sockopt.rst
@@ -86,6 +86,20 @@ then the next program in the chain (A) will see those changes,
*not* the original input ``setsockopt`` arguments. The potentially
modified values will be then passed down to the kernel.
+Large optval
+============
+When the ``optval`` is greater than the ``PAGE_SIZE``, the BPF program
+can access only the first ``PAGE_SIZE`` of that data. So it has to options:
+
+* Set ``optlen`` to zero, which indicates that the kernel should
+ use the original buffer from the userspace. Any modifications
+ done by the BPF program to the ``optval`` are ignored.
+* Set ``optlen`` to the value less than ``PAGE_SIZE``, which
+ indicates that the kernel should use BPF's trimmed ``optval``.
+
+When the BPF program returns with the ``optlen`` greater than
+``PAGE_SIZE``, the userspace will receive ``EFAULT`` errno.
+
Example
=======