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fix(driver): fix potential deadlock #1629

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merged 2 commits into from
Jan 24, 2024
Merged

fix(driver): fix potential deadlock #1629

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0e26451
fix(driver): fix potential deadlock
therealbobo Jan 18, 2024
7b2459a
fix(driver): fix another potential deadlock
therealbobo Jan 19, 2024
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32 changes: 24 additions & 8 deletions driver/ppm_fillers.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1391,15 +1391,23 @@ int f_proc_startupdate(struct event_filler_arguments *args)
{
/* Support exe_writable */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 3, 0)
exe_writable |= (file_permission(exe_file, MAY_WRITE) == 0);
exe_writable |= (file_permission(exe_file, MAY_WRITE | MAY_NOT_BLOCK) == 0);
exe_writable |= inode_owner_or_capable(file_mnt_idmap(exe_file), file_inode(exe_file));
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 12, 0)
exe_writable |= (inode_permission(current_user_ns(), file_inode(exe_file), MAY_WRITE) == 0);
exe_writable |= (inode_permission(current_user_ns(), file_inode(exe_file), MAY_WRITE | MAY_NOT_BLOCK) == 0);
exe_writable |= inode_owner_or_capable(current_user_ns(), file_inode(exe_file));
#else
exe_writable |= (inode_permission(file_inode(exe_file), MAY_WRITE) == 0);
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(3, 1, 0)
exe_writable |= (inode_permission(file_inode(exe_file), MAY_WRITE | MAY_NOT_BLOCK) == 0);
exe_writable |= inode_owner_or_capable(file_inode(exe_file));
#endif
/*
* Kernels < 3.1.0 doesn't support the exe_writable flags due to the MAY_NOT_BLOCK not being
* available. This limitation is related to the fact that this function (f_sched_prog_exec)
* is in a RCU critical section: this means that this function (and its callee) MUST NOT
* call functions that can yield the processor (e.g. inode_permission that deep down in its
* call stack calls a down_read()). This is addressed after the Kernel 3.1.0 where the
* MAY_OT_BLOCK flag is introduced and avoids the processor to being yield.
*/

/* Support exe_upper_layer */
exe_upper_layer = ppm_is_upper_layer(exe_file);
Expand Down Expand Up @@ -7416,15 +7424,23 @@ int f_sched_prog_exec(struct event_filler_arguments *args)
{
/* Support exe_writable */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 3, 0)
exe_writable |= (file_permission(exe_file, MAY_WRITE) == 0);
exe_writable |= (file_permission(exe_file, MAY_WRITE | MAY_NOT_BLOCK) == 0);
exe_writable |= inode_owner_or_capable(file_mnt_idmap(exe_file), file_inode(exe_file));
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 12, 0)
exe_writable |= (inode_permission(current_user_ns(), file_inode(exe_file), MAY_WRITE) == 0);
exe_writable |= (inode_permission(current_user_ns(), file_inode(exe_file), MAY_WRITE | MAY_NOT_BLOCK) == 0);
exe_writable |= inode_owner_or_capable(current_user_ns(), file_inode(exe_file));
#else
exe_writable |= (inode_permission(file_inode(exe_file), MAY_WRITE) == 0);
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(3, 1, 0)
exe_writable |= (inode_permission(file_inode(exe_file), MAY_WRITE | MAY_NOT_BLOCK) == 0);
exe_writable |= inode_owner_or_capable(file_inode(exe_file));
#endif
/*
* Kernels < 3.1.0 doesn't support the exe_writable flags due to the MAY_NOT_BLOCK not being
* available. This limitation is related to the fact that this function (f_sched_prog_exec)
* is in a RCU critical section: this means that this function (and its callee) MUST NOT
* call functions that can yield the processor (e.g. inode_permission that deep down in its
* call stack calls a down_read()). This is addressed after the Kernel 3.1.0 where the
* MAY_OT_BLOCK flag is introduced and avoids the processor to being yield.
*/

/* Support exe_upper_layer */
exe_upper_layer = ppm_is_upper_layer(exe_file);
Expand Down